Knut Reidar Wangen

• Terzic, Dajana & Wangen, Knut Reidar (2025). Spatial analysis of colorectal cancer outcomes: investigating the impact of place-specific factors using causal inference methods for spatial data. Journal of Public Health. ISSN 1741-3842. 47(3), s. 446–453. doi: 10.1093/pubmed/fdaf044. Fulltekst i vitenarkiv Vis sammendrag

  Background Disparities in health outcomes across regions may arise from place-specific factors, encompassing both contextual elements such as healthcare accessibility and compositional factors tied to the unique population characteristics. This study seeks to investigate the impact of various place-specific factors on late-stage incidence and mortality rates within Norwegian municipalities. Method Municipality-level data on colorectal cancer (CRC) late-stage diagnosis and mortality rates were acquired from the Cancer Registry of Norway and the Norwegian Cause of Death Registry. Screening utilization rates were obtained from the Norwegian Patient Registry. To explore the region-level effects of place-specific factors on CRC outcomes, a causal inference method for spatial data—neighborhood adjustment method via spatial smoothing (NA approach)—was employed. Results The findings indicate that a one-unit increase in screening rates (or a 1% rise in screening uptake) corresponds to a 2.9% decrease in late-stage incidence, with a 95% credible interval ranging from −0.055 to −0.003. However, no significant relationship between screening rates and mortality rates was observed. Conclusion This study underscores the importance of maximizing the utilization of screening services to prevent advance-stage diagnosis. Moreover, the research underscores the significance of improving access to screening services, particularly in rural and medically underserved areas.

• Abrahamsen, Cathrine; Wangen, Knut Reidar; Lindbæk, Morten & Werner, Erik Lønnmark (2024). Predictors of treatment outcomes for patients with persistent physical symptoms in primary care: findings from a cluster randomised controlled trial. British Journal of General Practice Open. 8(4), s. 1–8. doi: 10.3399/BJGPO.2024.0004. Fulltekst i vitenarkiv Vis sammendrag

  Background Persistent physical symptoms (PPS) are consistently prevalent among primary care patients. PPS can negatively affect quality of life, healthcare costs, and work participation. In a previous study, we found substantially improved outcomes and reduced sick leave for patients treated by a work-focused communication tool, known as the Individual Challenge Inventory Tool (ICIT), compared with a control group. Aim To examine predictors of treatment outcome in patients who received treatment by ICIT, delivered by the patient’s GP. Design & setting This study is based on the findings of our previous cluster randomised controlled trial undertaken in Norway. Method Regression analyses of the intervention group were used to identify predictors (all measured at baseline) of improvements in Patient Global Impression of Change (PGIC) and sick leave after 11 weeks follow-up. Results Living alone predicted improvement in the adjusted model (odds ratio [OR] 4.03, 95% confidence interval [CI] = 1.33 to 12.25, P = 0.014). Receiving long-term benefits predicted improved PGIC in both the unadjusted (OR 2.30, 95% CI = 1.21 to 4.39, P = 0.011) and adjusted models (OR 2.46, 95% CI = 1.04 to 5.83, P = 0.040). In addition, living alone predicted reduced sick leave in the adjusted model (OR 3.23, 95%CI = 1.11 to 9.42, P = 0.032). Conclusion In general, there were few factors to predict the outcome of the work-focused communication tool. We therefore suggest that this work-focused communication tool is applicable to most patients with PPS. GPs may consider using the ICIT for all primary care patients who exhibit ineffective coping strategies in their daily lives and work, especially those who live alone.

• Hansen, Johan Andre Liseth & Wangen, Knut Reidar (2024). Trajectories of opioid use among patients with low back pain: Association to work absence. European Journal of Pain. ISSN 1090-3801. doi: 10.1002/ejp.4706. Fulltekst i vitenarkiv Vis sammendrag

  Background Low back pain (LBP) is a leading reason for opioid use and a closer examination of opioid use and productivity losses among these patients is needed. We identify opioid use trajectories using a group-based trajectory model (GBTM) and estimate productivity losses across the trajectories. Methods Patients diagnosed with LBP in Swedish specialty care between 2011 and 2015, between the ages of 20 and 60, were included. Two GBTMs were estimated on monthly opioid use (converted to oral morphine equivalents) during the two 12-month periods preceding and following diagnosis. Productivity losses were estimated using the human-capital approach. Results In total, 147,035 patients were included. The mean age at diagnosis was 43 years of age and 49% of the patients were male. A qualitative assessment of the identified groups in the GBTM models was made based on the patterns of opioid use. We chose three pre-diagnosis groups characterized as ‘Pre-low’ (N = 109,492), ‘Pre-increase’ (N = 27,336) and ‘Pre-high’ (N = 10,207). Similarly, four post-diagnosis groups were chosen and characterized as ‘Post-low’ (N = 73,287), ‘Post-decrease’ (N = 39,446), ‘Post-moderate’ (N = 20,001) and ‘Post-high’ (N = 13,595). Only 50% of the patients in the ‘Pre-high’ group were in the ‘Post-high’ group. The total productivity losses by the pre-diagnosis groups were more than 2.7 billion Euros over the total 6-year study period. Conclusion This study highlights how patients with LBP and high use of opioids are highly correlated before and after diagnosis. Patients with high use of opioids also exhibit high work absence and productivity losses. Significance Statement This was the first study to estimate trajectories of opioids in the two time periods before and after a diagnosis of low back pain. For the first time, productivity losses were also estimated across the identified opioid use trajectories.

• Trent, Pernille Kristina Bjerre; Eriksson, Ane Gerda Zahl; Staff, Anne Cathrine; Juul-Hansen, Knut Erling; Burger, Emily Annika & Wangen, Knut Reidar (2024). A cost-effectiveness analysis of sentinel lymph node biopsy compared with lymphadenectomy in intermediate- and high-risk endometrial carcinoma. International Journal of Gynecological Cancer. ISSN 1048-891X. 35(1). doi: 10.1136/ijgc-2024-005906. Fulltekst i vitenarkiv Vis sammendrag

  Background Sentinel lymph node biopsy (SLN) is increasingly used for surgical staging of endometrial carcinoma. Objective To estimate the effect and cost-effectiveness of the implementation of an SLN algorithm for surgical staging in patients with intermediate- and high-risk endometrial carcinoma compared with lymphadenectomy. Methods We performed a model-based, cost-effectiveness analysis using primary data from a tertiary referral hospital that included 829 patients with endometrial carcinoma undergoing surgical staging. We quantified the health and economic outcomes from two time periods, before and after implementation of the SLN algorithm by robotic surgery. Costs were measured directly from the hospital’s financial department, while long-term health outcomes were estimated using self-reported lymphedema and health-related quality-of-life among survivors. Sensitivity analyses were conducted to evaluate uncertainty. Results We projected that the SLN implementation period, predominately reflecting use of robotic SLN, simultaneously improved health outcomes (0.08 incremental quality-adjusted life-years) and lowered costs (US$1051) compared with the prior period involving robotic or open lymphadenectomy. SLN remained more beneficial and less costly across key sensitivity analyses—namely, varying the cost of the robotic platform, surgical equipment, number of yearly robotic procedures, percentage of robotic procedures versus percentage of laparotomies, length of stay, and lymphedema development. After 1000 simulations of the model, SLN implementation provided greater health benefits for lower costs (ie, cost saving) in 89% of simulations. Conclusion Implementation of an SLN algorithm in the staging of intermediate- and high-risk endometrial carcinoma improved health outcomes for lower costs compared with lymphadenectomy. Cost-effectiveness could further improve by continuing to increase the proportion of robotic procedures.

• Trent, Pernille Kristina Bjerre; Nordskar, Nina Jebens; Wangen, Knut Reidar; Engeskaug, Ida; Opheim, Linn Øvstebø & Aune, Guro [Vis alle 10 forfattere av denne artikkelen] (2023). Self-reported lower extremity lymphedema and quality of life after surgical staging of endometrial carcinoma: A population based cross-sectional study. Gynecologic Oncology. ISSN 0090-8258. 175, s. 72–80. doi: 10.1016/j.ygyno.2023.05.070. Fulltekst i vitenarkiv Vis sammendrag

  Objectives Sentinel lymph node biopsy (SLN) has replaced lymphadenectomy in staging of endometrial carcinoma. The aims of the study were to explore the prevalence of self-reported lymphedema (LEL), identify factors associated with LEL, compare quality of life (QoL) scores using thresholds of clinical importance, and assess correlation between different questionnaires. Methods Women who underwent staging for endometrial carcinoma from 2006 to 2021 were invited to complete the Lower Extremity Lymphedema Screening Questionnaire (LELSQ), EORTC QLQ-C30, QLQ-EN24 and EQ-5D-5L. Results Of 2156 invited survivors, 61% participated in the study, whereof 1127 were evaluable by LELSQ. The LEL prevalence was 51%, 36% and 40% after lymphadenectomy, SLN and hysterectomy, respectively (p < 0.001). Higher BMI, undergoing lymphadenectomy and receiving adjuvant chemotherapy were associated with LEL; odds ratios 1.07 (95% CI 1.05–1.09), 1.42 (95% CI 1.03–1.97) and 1.43 (95% CI 1.08–1.89) respectively. QoL was lower for women with LEL compared to those without. In women with musculoskeletal complaints the prevalence of LEL was 59%, 50% and 53% after lymphadenectomy, SLN and hysterectomy (p = 0.115), respectively, compared to 39%, 17% and 18% (p < 0.001) in women without musculoskeletal complaints. Spearman's correlation was moderate to strong between the questionnaires. Conclusion SLN implementation is not associated with increased LEL prevalence compared to hysterectomy alone, but is associated with a significantly lower prevalence compared to lymphadenectomy. LEL is associated with lower QoL. Our study demonstrates moderate to strong correlation between self-reported LEL and QoL scores. Available questionnaires may not distinguish between symptoms caused by LEL and musculoskeletal disease.

• Hansen, Johan Andre Liseth; Fast, Thomas & Wangen, Knut Reidar (2023). Productivity Loss Across Socioeconomic Groups Among Patients With Low Back Pain or Osteoarthritis: Estimates Using the Friction-Cost Approach in Norway. PharmacoEconomics (Auckland). ISSN 1170-7690. doi: 10.1007/s40273-023-01269-4. Fulltekst i vitenarkiv
• Abrahamsen, Cathrine; Reme, Silje Endresen; Wangen, Knut Reidar; Lindbæk, Morten & Werner, Erik Lønnmark (2023). The effects of a structured communication tool in patients with medically unexplained physical symptoms: a cluster randomized trial. EClinicalMedicine. doi: 10.1016/j.eclinm.2023.102262. Fulltekst i vitenarkiv Vis sammendrag

  Background Medically Unexplained Physical Symptoms (MUPS) are prevalent among primary care patients and frequently lead to diminished quality of life, increased healthcare costs, and decreased work participation. We aimed to examine the effects of a work-focused structured communication tool based on cognitive-behavioral therapy in patients with MUPS. Methods In a Norwegian two-arm cluster randomized trial, the effectiveness of the structured communication tool Individual Challenge Inventory Tool (ICIT) was compared to usual care for patients with MUPS using a two-arm cluster randomized design. Enrollment period was between March 7 and April 1, 2022. Ten groups (clusters) of 103 General Practitioners (GPs) were randomized to provide the ICIT or usual care for 11 weeks. Patients received two or more sessions with their GP, and outcomes were assessed individually. Primary outcome was patient-reported change in function, symptoms, and quality of life measured by the Patient Global Impression of Change (PGIC). Secondary outcomes included sick leave, work-related self-efficacy (RTW-SE), health-related quality of life (RAND-36), and patient experiences with consultants (PEQ). The trial was registered on ClinicalTrials.gov (NCT05128019). Findings A total of 541 patients with MUPS were enrolled in the study. In the intervention group 76% (n = 223) showed a significant overall improvement in function, symptoms, and quality of life as measured by the PGIC, compared to 38% (n = 236) in the usual care group (mean difference −0.8 ([95% CI −1.0 to −0.6]; p < 0.0001). At 11 weeks, the intervention group had a 27-percentage point decrease in sick leave (from 52.0 to 25.2), compared to 4-percentage point decrease (from 49.7 to 45.7) in the usual care group. Furthermore, compared to usual care, the intervention group reported significant improvements in work-related self-efficacy, health-related quality of life, and greater satisfaction with the communication during the consultations. No adverse events were reported. Interpretation The implementation of the structured communication tool ICIT in primary care significantly improved patient outcomes and reduced sick leave among patients with MUPS.

• Draganic, Dajana & Wangen, Knut Reidar (2023). The effect of physician density on colorectal cancer stage at diagnosis: causal inference methods for spatial data applied on regional-level data. International Journal of Health Geographics. 22(1). doi: 10.1186/s12942-023-00323-w. Fulltekst i vitenarkiv Vis sammendrag

  Background The early detection of colorectal cancer (CRC) through regular screening decreases its incidence and mortality rates and improves survival rates. Norway has an extremely high percentage of CRC cases diagnosed at late stages, with large variations across municipalities and hospital catchment areas. This study examined whether the availability of physicians related to CRC primary diagnosis and preoperative investigations, or physician density, contributes to the observed geographical differences in late-stage incidence rates. Method Municipality-level data on CRC stage at diagnosis were obtained from the Cancer Registry of Norway for the period 2012–2020. Physician density was calculated as the number of physicians related to CRC investigations, general practitioners (GPs) and specialists per 10,000 people, using physician counts per municipality and hospital areas from Statistics Norway. The relationship was examined using a novel causal inference method for spatial data—neighbourhood adjustment method via spatial smoothing (NA approach)—which allowed for studying the region-level effect of physician supply on CRC outcome by using spatially referenced data and still providing causal relationships. Results According to the NA approach, an increase in one general practitioner per 10,000 people will result in a 3.6% (CI −0.064 to −0.008) decrease in late-stage CRC rates. For specialists, there was no evidence of a significant correlation with late-stage CRC distribution, while for both groups, GPs and specialists combined, an increase of 1 physician per 10,000 people would be equal to an average decrease in late-stage incidence rates by 2.79% (CI −0.055 to −0.001). Conclusion The study confirmed previous findings that an increase in GP supply will significantly improve CRC outcomes. In contrast to previous research, this study identified the importance of accessibility to both groups of physicians—GPs and specialists. If GPs encounter insufficient workforces in hospitals and long delays in colonoscopy scheduling, they will less often recommend colonoscopy examinations to patients. This study also highlighted the efficiency of the novel methodology for spatially referenced data, which allowed us to study the effect of physician density on cancer outcomes within a causal inference framework.

• Ahmed, Md Montasir; Muhoozi, Grace Kyamazima Mehangye; Atukunda, Prudence; Westerberg, Ane Cecilie; Iversen, Per Ole & Wangen, Knut Reidar (2023). Cognitive development among children in a low-income setting: Cost-effectiveness analysis of a maternal nutrition education intervention in rural Uganda. PLOS ONE. 18(8). doi: 10.1371/journal.pone.0290379. Fulltekst i vitenarkiv Vis sammendrag

  Inadequate nutrition and insufficient stimulation in early childhood can lead to long-term deficits in cognitive and social development. Evidence for policy and decision-making regarding the cost of delivering nutrition education is lacking in low and middle-income countries (LMIC). In rural Uganda, we conducted a cluster-randomized controlled trial (RCT) examining the effect of a maternal nutrition education intervention on developmental outcomes among children aged 6–8 months. This intervention led to significantly improved cognitive scores when the children reached the age of 20–24 months. When considering the potential for this intervention’s future implementation, the desired effects should be weighed against the increased costs. This study therefore aimed to assess the cost-effectiveness of this education intervention compared with current practice. Health outcome data were based on the RCT. Cost data were initially identified by reviewing publications from the RCT, while more detailed information was obtained by interviewing researchers involved in processing the intervention. This study considered a healthcare provider perspective for an 18-months’ time horizon. The control group was considered as the current practice for the future large-scale implementation of this intervention. A cost-effectiveness analysis was performed, including calculations of incremental cost-effectiveness ratios (ICERs). In addition, uncertainty in the results was characterized using one-way and probabilistic sensitivity analyses. The ICER for the education intervention compared with current practice was USD 16.50 per cognitive composite score gained, with an incremental cost of USD 265.79 and an incremental cognitive composite score of 16.11. The sensitivity analyses indicated the robustness of these results. The ICER was sensitive to changes in cognitive composite score and the cost of personnel. The education intervention can be considered cost-effective compared with the current practice. The outcome of this study, including the cost analysis, health outcome, cost-effectiveness, and sensitivity analysis, can be useful to inform policymakers and stakeholders about effective resource allocation processes in Uganda and possibly other LMIC.

• Njie, Hassan; Ilboudo, Patrick Christian Gueswende; Gopinathan, Unni; Chola, Lumbwe & Wangen, Knut Reidar (2023). Preferences of healthcare workers for provider payment systems in The Gambia’s National Health Insurance Scheme. BMC Health Services Research. 23(853). doi: 10.1186/s12913-023-09885-8. Fulltekst i vitenarkiv Vis sammendrag

  Background The Government of The Gambia introduced a national health insurance scheme (NHIS) in 2021 to promote universal health coverage (UHC). Provider payment systems (PPS) are strategic purchasing arrangements that can enhance provider performance, accountability, and efficiency in the NHIS. This study assessed healthcare workers’ (HCWs’) preferences for PPS across major service areas in the NHIS. Methods A facility-based cross-sectional study was conducted using a probability proportionate to size sampling technique to select an appropriate sample size. Health care workers were presented with options for PPS to choose from across major service areas. Descriptive statistics explored HCW socio-demographic and health service characteristics. Multinomial logistic regressions were used to assess the association between these characteristics and choices of PPS. Results The majority of HCW did not have insurance coverage, but more than 60% of them were willing to join and pay for the NHIS. Gender, professional cadre, facility level, and region influenced HCW’s preference for PPS across the major service areas. The preferred PPS varied among HCW depending on the service area, with capitation being the least preferred PPS across all service areas. Conclusion The National Health Insurance Authority (NHIA) needs to consider HCW’s preference for PPS and factors that influence their preferences when choosing various payment systems. Strategic purchasing decisions should consider the incentives these payment systems may create to align incentives to guide provider behaviour towards UHC. The findings of this study can inform policy and decision-makers on the right mix of PPS to spur provider performance and value for money in The Gambia’s NHIS.

• Njie, Hassan; Wangen, Knut Reidar; Chola, Lumbwe; Gopinathan, Unni; Mdala, Ibrahimu & Sundby, Johanne Sommerschild [Vis alle 7 forfattere av denne artikkelen] (2022). Willingness to pay for a national health insurance scheme in The Gambia: A contingent valuation study. Health Policy and Planning. ISSN 0268-1080. 38(1), s. 61–73. doi: 10.1093/heapol/czac089. Fulltekst i vitenarkiv Vis sammendrag

  In pursuit of universal health coverage, many low- and middle-income countries are reforming their health financing systems and introducing health insurance schemes. As part of these reforms, lawmakers in The Gambia enacted ‘The National Health Insurance Bill, 2021’. The Act will establish a National Health Insurance Scheme (NHIS) that pays for the cost of healthcare services for its members. This study assessed Gambians’ willingness to pay (WTP) for a NHIS. Using multistage sampling design with no replacement, head/co-head of households were presented with a hypothetical health insurance scheme from July to August 2020. Their WTP and factors influencing WTP were elicited using a contingent valuation method. Descriptive statistics were used to describe sample characteristics. Lopez-Feldman’s modified ordered probit model and linear regression were applied to estimate respondents’ WTP as well as identify factors that influence their WTP. More than 90% of the respondents—677 (94.4%) were willing to join and pay for the scheme. Half of these respondents—398 (58.8%) agreed to pay the first bid of US dollars (US$) 20.78 or Gambian dalasi (GMD) 1000. The average WTP was estimated at US$23.27 (GMD1119.82), whereas average maximum amount to pay was US$26.01 (GMD1251.16). Results of the two models together showed that gender, level of education and household income were statistically significant, with the latter showing negative influence on WTP. The study found that Gambians were largely receptive to the scheme and have stated their willingness to contribute. Our findings can inform policymakers in The Gambia and other sub-Saharan countries when establishing contribution rates and exemption criteria during social health insurance scheme implementation.

• Yang, Fan; Wangen, Knut Reidar; Victor, Mattias Erik; Solbakken, Ole Andre & Holman, Per Arne (2022). Referral assessment and patient waiting time decisions in specialized mental healthcare: an exploratory study of early routine collection of PROM (LOVePROM). BMC Health Services Research. 22(1). doi: 10.1186/s12913-022-08877-4. Fulltekst i vitenarkiv Vis sammendrag

  Background Norway has prioritized health services according to the principle of “severity of conditions”, where waiting time reflects patients’ medical urgency. We aim to investigate if the “severity-of-condition” principle performs well in the priority setting of waiting time, between and within groups of patients using community mental health services. We also aim to investigate the association between patients’ diagnoses and symptom severity at the start of treatment and the corresponding waiting time. Methods The study analyzed routine data from Lovisenberg electronic Patient-Reported Outcome Measurement (LOVePROM) at Lovisenberg Diaconal Hospital in Norway. We estimated patient-reported severity by using Clinical Outcomes in Routine Evaluation – Outcome Measure (CORE-OM), together with patients’ diagnoses to identify patients’ needs in general. To assess the performance of current prioritization, we compared waiting times for patients with major depressive disorder and their maximum recommended waiting time. Multivariate regression models were used to assess the association between patient-reported severity, their diagnosis, and waiting times. Results Of the 6108 mental health disorder patients, patients with moderate to severe conditions waited seven weeks, while patients with mild conditions or below clinical cutoff waited 8 weeks. Included in the sample, 1583 were diagnosed with depression. Results indicated that patients with moderate and severe depression had a slightly shorter wait-time than patients with mild depression. However, 32.4% patients with moderate depression and 83.3% patients with severe depression, waited longer than their maximum recommended waiting time. CORE-OM identified depressive patients with risk-to-self harm, who had a 0.84 weeks shorter wait-time. These results were also applied to patients with other common mental health disorders. Conclusion Overall, patients waited in accordance with the “severity of condition” principle, but the trend was not strong. Therefore, we advocate that there is substantial room for quality improvements in priority setting on waiting time. We suggest further research should investigate if routine collection of PROM and assessment of referral letters, can better inform specialists when deciding on waiting time.

• Vibeto, Jon Hjellum; Vallersnes, Odd Martin; Dobloug, Andrea; Brekke, Mette; Jacobsen, Dag & Ekeberg, Øivind [Vis alle 7 forfattere av denne artikkelen] (2021). Treating patients with opioid overdose at a primary care emergency outpatient clinic: a cost-minimization analysis. Cost Effectiveness and Resource Allocation. 19(1), s. 1–12. doi: 10.1186/s12962-021-00303-6. Fulltekst i vitenarkiv Vis sammendrag

  Background Treating patients with acute poisoning by substances of abuse in a primary care emergency clinic has previously been shown to be a safe strategy. We conducted an economic evaluation of this strategy compared to hospital treatment, which is the usual strategy. Methods Assuming equal health outcomes, we conducted a cost-minimization analysis. We constructed a representative opioid overdose patient based on a cohort of 359 patients treated for opioid overdose at the Oslo Accident and Emergency Outpatient Clinic (OAEOC) from 1.10.2011 to 30.9.2012. Using a health care system perspective, we estimated the expected resources used on the representative patient in primary care based on data from the observed OAEOC cohort and on information from key informants at the OAEOC. A likely course of treatment of the same patient in a hospital setting was established from information from key informants on provider procedures at Drammen Hospital, as were estimates of hospital use of resources. We calculated expected costs for both settings. Given that the treatments usually last for less than one day, we used undiscounted cost values. Results The estimated per patient cost in primary care was 121 EUR (2018 EUR 1.00 = NOK 9.5962), comprising 97 EUR on personnel costs and 24 EUR on treatment costs. In the hospital setting, the corresponding cost was 612 EUR, comprising 186 EUR on personnel costs, 183 EUR on treatment costs, and 243 EUR associated with intensive care unit admission. The point estimate of the cost difference per patient was 491 EUR, with a low-difference scenario estimated at 264 EUR and a high-difference scenario at 771 EUR. Conclusions Compared to hospital treatment, treating patients with opioid overdose in a primary care setting costs substantially less. Our findings are probably generalizable to poisoning with other substances of abuse. Implementing elements of the OAEOC procedure in primary care emergency clinics and in hospital emergency departments could improve the use of health care resources.

• Sjølie, Hanne Kathrine; Wangen, Knut Reidar; Lindstad, Berit Hauger & Solberg, Birger (2019). The importance of timber prices and other factors for harvest increase among nonindustrial private forest owners. Canadian Journal of Forest Research. ISSN 0045-5067. 49(5), s. 543–552. doi: 10.1139/cjfr-2018-0292. Fulltekst i vitenarkiv Vis sammendrag

  Increased harvest is high on the forestry and climate policy agenda in several countries. We explored to what extent private non-industrial forest owners in Norway are willing to increase harvest due to elevated hypothetical prices by carrying out a national-wide survey of forest owners. The results indicate that owners who have not harvested timber for sale the last fifteen years do not respond to large price shifts. Instead, ownership objectives and knowledge of a key policy instrument predict willingness to enter the timber market among these owners. The willingness among owners who have sold timber the last fifteen years depends on these factors, in addition to price, forest area, income and gender. Female owners were significantly less willing than male owners to increase harvest. Once the decision to harvest was taken, the stated timber supply volume per area unit decreases with productive forest area both among active and inactive owners. With regard to sources of information, owners who have not harvested timber the last fifteen years use to less extent the information sources other owners do. Forest policies and extension services should acknowledge that for stimulating forest owners outside the timber market to supply wood,other factors than price are important, and that alternative information pathways should be explored for reaching these owners.

• Wangen, Knut Reidar & Grepperud, Sverre (2018). Supply factors as determinants of treatment costs: clinicians’ assessments of a given set of referrals to community mental health centers in Norway. BMC Health Services Research. 18(60). doi: 10.1186/s12913-018-2884-5. Fulltekst i vitenarkiv Vis sammendrag

  Background Previous works that uses patterns of prior spending to predict future mental health care expenses (utilization models) are mainly concerned with demand (need) variables. In this paper, we introduce supply variables, both individual rater variables and center variables. The aim is to assess these variables’ explanatory power, and to investigate whether not accounting for such variables could create biased estimates for the effects of need variables. Methods We employed an observational study design where the same set of referrals was assessed by a sample of clinicians, thus creating data with a panel structure being particularly relevant for analyzing supply factors. The referrals were obtained from Norwegian Community Mental Health Centers (outpatient services), and the clinicians assessed the referrals with respect to recommended treatment costs and health status. Results Supply variables accounted for more than 10% of the total variation and about one third of the explained variation. Two groups of supply variables, individual rater variables and center variables (institutions) were equally important. Conclusions Our results confirm that supply factors are important but ignoring such variables, when analyzing demand variables, do not generally seem to produce biased (confounded) coefficients.

• Wangen, Knut Reidar; Zhu, Dawei & Wang, Jian (2018). Hepatitis B vaccination among 1997-2011 birth cohorts in rural China: the potential for further catch-up vaccination and factors associated with infant coverage rates. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. doi: 10.1080/21645515.2018.1520582. Fulltekst i vitenarkiv Vis sammendrag

  Hepatitis B vaccination rates in China have recently increased. This study aimed to investigate infant vaccination coverage for birth cohorts from 1997 to 2011 in rural regions and to assess catch-up vaccination potential. We used questionnaire-based interviews from a cross-section of 6,529 individuals from seven provinces. Logistic regression analyses were used to model two measures of infant vaccination status, namely, birth dose within 24 hours and three doses within the first year of life. During interviews, individuals’ vaccination status and vaccination plan were recorded. Unvaccinated individuals without plans for future vaccination were presented with a hypothetical offer of free vaccination and indirect cost compensation. Institutional birth rates were higher than vaccination rates, but both increased over time. Vaccination coverage rates were not significantly associated with sex. Infant vaccination coverage was positively associated with a mother’s educational level, household income level, knowledge of transmission routes, and perceived duration of protection obtained through vaccination. Vaccination status at the time of the survey showed the occurrence of catch-up vaccinations, but a notable percentage of individuals remained unvaccinated and had no plans for future vaccination. Of these individuals, approximately 50% were prepared to accept vaccination if offered free of charge.

• Zhu, Dawei; Guo, Na; Wang, Jian; Nicholas, Stephen; Wang, Zhen & Zhang, Guojie [Vis alle 8 forfattere av denne artikkelen] (2017). Socioeconomic inequality in Hepatitis B vaccination of rural adults in China. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 14(2), s. 464–470. doi: 10.1080/21645515.2017.1396401. Fulltekst i vitenarkiv Vis sammendrag

  Hepatitis B (HB) vaccination is the most effective way to prevent HB virus infection. While measures taken to control the prevalence of HB have achieved significant results, HB prevalence in rural China among adults remains problematic. This study sheds new light on the determinants of HB vaccine uptake and its inequality according to socioeconomic status in rural areas of China. We interviewed 22,283 adults, aged 18–59 years, from 8444 households, in 48 villages from 8 provinces. Vaccination status was modeled by using two logistic models: whether take at least one HB vaccine and whether to complete the entire vaccination regime. The Erreygers’ concentration index (ECI ) was used to quantify the degree of inequality and the decomposition approach was used to uncover the determinants of inequality in vaccine uptake. We found that the coverage rate of HB vaccination is 20.2%, and the completion rate is 16.0%. The ECI of at least one dose (0.081) and three doses (0.076) revealed a substantial pro-rich inequality. Income contributed the largest percentage to HB vaccination inequalities (52.17% for at least one dose and 52.03% for complete vaccinations). HB awareness was another important cause of inequality in HB vaccination (around 30%). These results imply that rich had a greater tendency to vaccinate and inequality favouring the rich was almost equal for the complete three doses. While the factors associated with HB vaccination uptake and inequalities were multifaceted, income status and HB awareness were the main barriers for the poor to take HB vaccine by adults in rural China. This is an Accepted Manuscript of an article published by Taylor & Francis, available online: http://www.tandfonline.com.

• Klitkou, Søren Toksvig & Wangen, Knut Reidar (2017). Educational attainment and differences in relative survival after acute myocardial infarction in Norway: a registry-based population study. BMJ Open. doi: 10.1136/bmjopen-2016-014787. Fulltekst i vitenarkiv Vis sammendrag

  Background Although there is a broad societal interest in socioeconomic differences in survival after an acute myocardial infarction, only a few studies have investigated how such differences relate to the survival in general population groups. We aimed to investigate education-specific survival after acute myocardial infarction and to compare this with the survival of corresponding groups in the general population. Methods Our study included the entire population of Norwegian patients admitted to hospitals for acute myocardial infarction during 2008–2010, with a 6- year follow-up period. Patient survival was measured relative to the expected survival in the general population for three educational groups: primary, secondary and tertiary. Education, sex, age and calendar year-specific expected survival were obtained from population life tables and adjusted for the presence of infarction-related mortality. Results Six-year patient survivals were 56.3% (55.3–57.2) and 65.5% (65.6–69.3) for the primary and tertiary educational groups (95% CIs), respectively. Also 6-year relative survival was markedly lower for the primary educational group: 70.2% (68.6–71.8) versus 81.2% (77.4–84.4). Throughout the follow-up period, patient survival tended to remain lower than the survival in the general population with the same educational background. Conclusion Both patient survival and relative survival after acute myocardial infarction are positively associated with educational level. Our findings may suggest that secondary prevention has been more effective for the highly educated.

• Zheng, Juan; Li, Quan; Wang, Jian; Zhang, Guojie & Wangen, Knut Reidar (2017). Inequality in the hepatitis B awareness level in rural residents from 7 provinces in China. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 13(5), s. 1005–1013. doi: 10.1080/21645515.2016.1265714. Fulltekst i vitenarkiv Vis sammendrag

  The hepatitis B (HB) awareness level is an important factor affecting the rates of HB virus vaccination. To better understand income-related inequalities in the HB awareness level, it is imperative to identify the sources of inequalities and assess the contribution rates of these influential factors. This study analyzed the unequal distribution of the HB awareness level and the contributions of various influential factors. We performed a cross-sectional household survey with questionnaire-based, face-to-face interviews in 7 Chinese provinces. Responses from 7271 respondents were used in this analysis. Multinomial logistic regression was used for the analysis of contributing factors, and the concentration index was used as a measure of HB awareness inequalities. The HB awareness level varied across participants with different characteristics. Multinomial logistic regression of the explanatory factors of the HB awareness level showed that several estimated coefficients and relative risk ratios were statistically significant for middle- and high-level awareness, except for sex, occupation, and household income. The concentration index of the HB knowledge score was 0.140, indicating inequality gradients disadvantageous to the poor. The contribution rate of socioeconomic factors was the largest (60.8%), followed by demographic characteristics (29.0%) and geographic factors (4.3%). Demographic, socioeconomic, and geographic factors are associated with the HB awareness inequality. Therefore, to reduce inequality, HB-related health education targeting individuals with low socioeconomic status should be performed. Less-developed provinces, especially with high proportions of poor residents, warrant particular attention. Our findings may be beneficial to improve the HB virus vaccination rate for individuals with low socioeconomic status. This is an Accepted Manuscript of an article published by Taylor & Francis, available online: http://www.tandfonline.com.

• Leng, Anli; Li, Youwei; Wangen, Knut Reidar; Nicholas, Stephen; Maitland, Elizabeth & Wang, Jian (2016). Hepatitis B discrimination in everyday life by rural migrant workers in Beijing. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 12(5), s. 1164–1171. doi: 10.1080/21645515.2015.1131883. Fulltekst i vitenarkiv
• Yu, Lijie; Wang, Jian; Wangen, Knut Reidar; Chen, Ruohan; Maitland, Elizabeth & Nicholas, Stephen (2016). Factors associated with adults' perceived need to vaccinate against hepatitis B in rural China. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 12(5), s. 1149–1154. doi: 10.1080/21645515.2015.1132964. Fulltekst i vitenarkiv
• Liu, Rugang; Li, Youwei; Wangen, Knut Reidar; Maitland, Elizabeth; Nicholas, Stephen & Wang, Jian (2016). Analysis of hepatitis B vaccination behavior and vaccination willingness among migrant workers from rural China based on protection motivation theory. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 12(5), s. 1155–1163. doi: 10.1080/21645515.2015.1123358. Fulltekst i vitenarkiv
• Chen, Rouhan; Li, Youwei; Wangen, Knut Reidar; Nicholas, Stephen; Maitland, Elizabeth & Wang, Jian (2016). Hepatitis B birth dose vaccination rates among children in Beijing: A comparison of local residents and first and second generation migrants. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. 12(5), s. 1141–1148. doi: 10.1080/21645515.2015.1131370. Fulltekst i vitenarkiv
• Mokienko, Anastasia & Wangen, Knut Reidar (2016). Disenrollment from general practitioners among chronic patients: a register-based longitudinal study of Norwegian claims data. BMC Family Practice. 17(1), s. 1–10. doi: 10.1186/s12875-016-0571-3. Fulltekst i vitenarkiv Vis sammendrag

  Background Norwegian general practitioners (GPs) consult on a variety of conditions with a mix of patient types. Patients with chronic diseases benefit from appropriate continuity of care and generally visit their GPs more often than the average patient. Our aim was to study disenrollment patterns among patients with chronic diseases in Norway, because such patterns could indicate otherwise unobserved GP quality. For instance, higher quality GPs could have both a greater share of patients with chronic diseases and lower disenrollment rates. Methods Data on 384,947 chronic patients and 3,974 GPs for the years 2009–2011 were obtained from national registers, including patient and GP characteristics, disenrollment data, and patient list composition. The birth cohorts from 1940 and 1970 (146,906 patients) were included for comparison. Patient and GP characteristics, comorbidity, and patient list composition were analyzed using descriptive statistics. Patients’ voluntary disenrollment was analyzed using logistic regression models. Results The GPs’ proportion of patients with a given chronic disease varied more than expected when the allocation was purely random. The proportions of patients with different chronic diseases were positively correlated, partly due to comorbidity. Patients tended to have lower disenrollment rates from GPs who had higher shares of patients with the same chronic disease. Disenrollment rates were generally lower from GPs with higher shares of patients with arthritis or depression, and higher from GPs who had higher shares of patients with diabetes type 1 and schizophrenia. This was the same in the comparison group. Conclusion Patients with a chronic disease appeared to prefer GPs who have higher shares of patients with the same disease. High shares of patients with some diseases were also negatively associated with disenrollment for all patient groups, while other diseases were positively associated. These findings may reflect the GPs’ general quality, but could alternatively result from the GPs’ specialization in particular diseases. The supportive findings for the comparison group make it more plausible that high shares of chronic patients could indicate GP quality. Keywords Chronic patients – Switching – Primary health care – Schizophrenia – Epilepsy – Diabetes type 1 – Diabetes type 2 – Asthma – Arthritis – Depression

• Yu, Lijie; Wang, Jian; Zhu, Dawei; Leng, Anli & Wangen, Knut Reidar (2015). Hepatitis B-related knowledge and vaccination in association with discrimination against Hepatitis B in rural China. Human Vaccines & Immunotherapeutics. ISSN 2164-5515. doi: 10.1080/21645515.2015.1069932. Fulltekst i vitenarkiv
• Grepperud, Sverre; Holman, Per Arne & Wangen, Knut Reidar (2014). Factors explaining priority setting at community mental health centres: a quantitative analysis of referral assessments. BMC Health Services Research. 14, s. 620–623. doi: 10.1186/s12913-014-0620-3. Fulltekst i vitenarkiv Vis sammendrag

  Background Clinicians at Norwegian community mental health centres assess referrals from general practitioners and classify them into three priority groups (high priority, low priority, and refusal) according to need where need is defined by three prioritization criteria (severity, effect, and cost-effectiveness). In this study, we seek to operationalize the three criteria and analyze to what extent they have an effect on clinical-level priority setting after controlling for clinician characteristics and organisational factors. Methods Twenty anonymous referrals were rated by 42 admission team members employed at 14 community mental health centres in the South-East Health Region of Norway. Intra-class correlation coefficients were calculated and logistic regressions were performed. Results Variation in clinicians’ assessments of the three criteria was highest for effect and cost-effectiveness. An ordered logistic regression model showed that all three criteria for prioritization, three clinician characteristics (education, being a manager or not, and “guideline awareness”), and the centres themselves (fixed effects), explained priority decisions. The relative importance of the explanatory factors, however, depended on the priority decision studied. For the classification of all admitted patients into high- and low-priority groups, all clinician characteristics became insignificant. For the classification of patients, into those admitted and non-admitted, one criterion (effect) and “being a manager or not” became insignificant, while profession (“being a psychiatrist”) became significant. Conclusions Our findings suggest that variation in priority decisions can be reduced by: (i) reducing the disagreement in clinicians’ assessments of cost-effectiveness and effect, and (ii) restricting priority decisions to clinicians with a similar background (education, being a manager or not, and “guideline awareness”).

• Zhu, Dawei; Jian, Wang & Wangen, Knut Reidar (2014). Hepatitis B vaccination coverage rates among adults in rural China: Are economic barriers relevant? Vaccine. ISSN 0264-410X. 32(49), s. 6705–6710. doi: 10.1016/j.vaccine.2013.06.095. Fulltekst i vitenarkiv
• Alstadsæter, Annette & Wangen, Knut Reidar (2010). Small corporations' income shifting through choice of ownership structure - A Norwegian case. Finnish economic papers. ISSN 0784-5197. 23(2), s. 73–87. Fulltekst i vitenarkiv
• Bolkesjø, Torjus Folsland; Solberg, Birger & Wangen, Knut Reidar (2007). Heterogeneity in nonindustrial private roundwood supply: Lessons from a large panel of forest owners. Journal of Forest Economics. ISSN 1104-6899. 13(1), s. 7–28. doi: 10.1016/j.jfe.2006.08.003. Fulltekst i vitenarkiv
• Biørn, Erik; Skjerpen, Terje & Wangen, Knut Reidar (2006). Can Random Coefficient Cobb-Douglas Production Functions be Aggregated to Similar Macro Functions? I Baltagi, Badi (Red.), Panel Data Econometrics: Theoretical Contributions and Empirical Applications. Elsevier. ISSN 9780444521729. s. 229–258. doi: 10.1016/S0573-8555(06)74009-3. Fulltekst i vitenarkiv
• Wangen, Knut Reidar & Biørn, Erik (2006). How Do Consumers Switch Between Close Substitutes when Price Variation is Small? The Case of Cigarette Types. Spanish Economic Review. ISSN 1435-5469. 8(4), s. 239–253. Fulltekst i vitenarkiv Vis sammendrag

  Past empirical studies report ambiguous results regarding the magnitude and significance of substitution between different types of smoking tobacco. Since all types of tobacco contain nicotine this is quite surprising. Using a twenty-year rotating panel data set of Norwegian households and a multinomial logit model, we find evidence that consumers switch between tobacco types: first, estimated price effects on choice probabilities have mostly expected signs, albeit their statistical significance vary across different metrics, second, household characteristics affect tobacco composition significantly. These findings suggest that consumers' choices are `locked' when the relative price variation is small, as has been the case in most of the data period, but that larger changes could induce large-scale switching between tobacco types. Our conjecture is that there is a latent potential for switching, which will become manifest if prices change sufficiently. Similar considerations are likely to have relevance for other close substitutes.

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• Aas, Eline; Kinge, Jonas Minet; Burger, Emily Annika; Pedersen, Kine; Iversen, Tor & Godager, Geir [Vis alle 14 forfattere av denne artikkelen] (2025). Feil tallgrunnlag kan koste liv i helsetjenesten. Fulltekst i vitenarkiv
• Trent, Pernille Kristina Bjerre; Nordskar, Nina Jebens; Wangen, Knut Reidar; Engeskaug, Ida; Opheim, Linn Øvstebø & Aune, Guro [Vis alle 10 forfattere av denne artikkelen] (2024). Corrigendum to “Self-reported lower extremity lymphedema and quality of life after surgical staging of endometrial carcinoma: A population based cross-sectional study” [Gynecologic Oncology 175 (2023) 72–80, (S0090825823003232), (10.1016/j.ygyno.2023.05.070)]. Gynecologic Oncology. ISSN 0090-8258. 183, s. 7–8. doi: 10.1016/j.ygyno.2024.02.026. Fulltekst i vitenarkiv
• Kardel, Kristin Reimers; Iversen, Per Ole; Kaaya, Archileo Natigo; Muhoozi, Grace Kyamazima Mehangye; Veierød, Marit Bragelien & Wangen, Knut Reidar [Vis alle 8 forfattere av denne artikkelen] (2024). A pragmatic randomized trial to examine the effect of combining healthy diet with mindfulness cognitive therapy to reduce depressive symptoms among university students in a low-resource setting: protocol for the NutriMind Project. BMC Psychiatry. 24, s. 1–8. doi: 10.1186/s12888-024-06056-9. Fulltekst i vitenarkiv Vis sammendrag

  Background Mental health disorders still rank as leading causes of morbidity worldwide despite increasing awareness and improvements in treatment. Notably, low- and middle-income countries like Uganda, are disproportionately affected by such disorders. The burden of depressive symptoms in these countries is particularly high among students, aggravated by poverty, malnutrition, and inadequate public health governance, yet it is clearly under-researched, making it hard to achieve several of UN Sustainability Development Goals. Current treatment options are insufficient to tackle the increased burden of depressive disease. This is more challenging for low-resource regions especially in Sub-Saharan Africa, suggesting the need for alternative treatments that can swiftly be applied if proven effective. The main aim of this randomized controlled trial (RCT) is therefore to examine if a low-cost healthy diet (based on local Ugandan foods) combined with easy-to access mindfulness cognitive therapy can reduce depressive symptoms among university students in Uganda. Methods We will recruit female and male students at Makerere University, the largest public university in Uganda, to an open, intention-to-treat, two-armed RCT. Those who score above a predefined threshold on a self-reported assessment of depressive symptoms, measured by the Center for Epidemiological Studies – Depression score (CES-D), are eligible for study inclusion and will be randomized to either an intervention (n = 125) or a control (n = 125) group. The intervention group will receive educational group-based sessions on how to prepare a Mediterranean-type of healthy diet and how to adhere to the principles of mindfulness-based cognitive therapy. Outcome measures include self-reported depression symptoms, quality of life, and dietary intakes. In addition we will perform a cost-effectiveness analysis. The RCT intervention will last 9 months, followed by additional 15 months with regular data collections. Discussion We here describe a novel approach to treat depressive symptoms among university students living in resource constraint settings, by combining a healthy diet with low threshold psychotherapy. If this intervention succeeds, our project can be viewed as a step towards evidence-based behavior practices for young adults with a common mental disorder (depression) that are beneficial to public mental health initiatives and management. Trial registration The RCT is registered in ClinicalTrials.gov (ID: NCT05848973). The date of registration was August 14, 2023.

• Vibeto, Jon Hjellum; Vallersnes, Odd Martin; Dobloug, Andrea; Brekke, Mette; Jacobsen, Dag & Ekeberg, Øivind [Vis alle 7 forfattere av denne artikkelen] (2020). Treating patients with opioid overdose at a primary care emergency outpatient clinic: a cost-minimization analysis. Fulltekst i vitenarkiv
• Sjølie, Hanne Kathrine; Wangen, Knut Reidar; Lindstad, Berit Hauger & Solberg, Birger (2016). The importance of timber prices for harvest increase among active and inactive nonindustrial private forest owners in Norway. Scandinavian Forest Economics. ISSN 0355-032X. 46, s. 105–105. Fulltekst i vitenarkiv
• Mokienko, Anastasia & Wangen, Knut Reidar (2015). GP switching and composition of the lists. Fulltekst i vitenarkiv
• Mokienko, Anastasia & Wangen, Knut Reidar (2015). Chronic patients and choice of GP. Fulltekst i vitenarkiv
• Wangen, Knut Reidar (2011). To what extent do user fees affect Hepatitis B vaccine coverage rates in China? Fulltekst i vitenarkiv
• Biørn, Erik & Wangen, Knut Reidar (2009). Limited Dependent Variables Models: Reconsidering the Typology and a Suggested Synthesis. Fulltekst i vitenarkiv
• Alstadsæter, Annette & Wangen, Knut Reidar (2008). Selskapers skattetilpasning ved hjelp av eierstruktur. Fulltekst i vitenarkiv
• Alstadsæter, Annette & Wangen, Knut Reidar (2008). Corporations' choice of tax regime when transition costs are small and income shifting potential is large. Fulltekst i vitenarkiv
• Alstadsæter, Annette & Wangen, Knut Reidar (2007). Evidence on Corporations' Choice of Tax Regime when Transition Costs are Small. Fulltekst i vitenarkiv
• Terzic, Dajana & Wangen, Knut Reidar (2026). Exploring the impact of healthcare access and centralization on colorectal cancer outcomes: spatial analyses across Norwegian regions. University of Oslo (UiO). ISSN 9788234807565. Fulltekst i vitenarkiv Vis sammendrag

  This thesis investigates place-based drivers and policies contributing to geographical differences in colorectal cancer (CRC) outcomes at the municipality and hospital levels in Norway, where substantial regional variation exists. It also examines spatial health economic factors that predict spatial dependence and interactions among networked entities (e.g., GPs, hospitals, municipalities, counties), as well as geographic clustering of unobserved place-based characteristics, using spatial methods. It lies at the intersection of health economics and epidemiology/public health. Using nationwide registry data at the municipality and hospital levels, the thesis applies advanced spatial causal models to account for spatial dependence and spatial confounding. The methods include comparisons between traditional spatial regression models and novel causal spatial approaches designed to address unmeasured spatial confounding, as well as comparisons of traditional and spatial difference-in-differences approaches. Papers 1 and 2 examine place-specific drivers, such as physician density and screening uptake, and their effects on CRC outcome. The results show that increased access to general practitioners and higher screening rates significantly reduce late-stage CRC incidence. These findings highlight the importance of improving access to physicians and screening services in underserved and rural areas. Paper 3 evaluates the hospital centralization reform—specifically, the closure of surgical treatment services in one hospital—and its impact on the quality and efficiency of nearby hospitals facing increased workloads. The findings show that neighboring hospitals improved efficiency without compromising quality. Overall, the findings emphasize the importance of accounting for spatial dimensions when analyzing regional CRC outcomes to avoid biased results and misinformed policy decisions. Tailored, place-based policies are essential to reduce disparities and improve patient outcomes.

• Biørn, Erik & Wangen, Knut Reidar (2012). New Taxonomies for Limited Dependent Variables Models. Munich Personal RePEc Archive. Fulltekst i vitenarkiv Vis sammendrag

  We establish a `map' for describing a wide class of Limited Dependent Variables models much used in the econometric literature. The classification system, or language, is an extension of Amemiya's typology for tobit models and is intended to facilitate communication among researchers. The class is defined in relation to distributions of latent variables of an arbitrarily high dimension; the region of support can be divided into an arbitrary number of subsets, and the observation rules in each subset can be any combination of the observed, censored, and missing status. Consistent labeling is suggested at different levels of detail.

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