Odd Olai Aalen

• Maltzahn, Niklas; Hoff, Rune; Aalen, Odd O.; Mehlum, Ingrid S.; Putter, Hein & Gran, Jon Michael (2021). A hybrid landmark Aalen-Johansen estimator for transition probabilities in partially non-Markov multi-state models. Lifetime Data Analysis. ISSN 1380-7870. 27, s. 737–760. doi: 10.1007/s10985-021-09534-4. Fulltekst i vitenarkiv Vis sammendrag

  Multi-state models are increasingly being used to model complex epidemiological and clinical outcomes over time. It is common to assume that the models are Markov, but the assumption can often be unrealistic. The Markov assumption is seldomly checked and violations can lead to biased estimation of many parameters of interest. This is a well known problem for the standard Aalen-Johansen estimator of transition probabilities and several alternative estimators, not relying on the Markov assumption, have been suggested. A particularly simple approach known as landmarking have resulted in the Landmark-Aalen-Johansen estimator. Since landmarking is a stratification method a disadvantage of landmarking is data reduction, leading to a loss of power. This is problematic for “less traveled” transitions, and undesirable when such transitions indeed exhibit Markov behaviour. Introducing the concept of partially non-Markov multi-state models, we suggest a hybrid landmark Aalen-Johansen estimator for transition probabilities. We also show how non-Markov transitions can be identified using a testing procedure. The proposed estimator is a compromise between regular Aalen-Johansen and landmark estimation, using transition specific landmarking, and can drastically improve statistical power. We show that the proposed estimator is consistent, but that the traditional variance estimator can underestimate the variance of both the hybrid and landmark estimator. Bootstrapping is therefore recommended. The methods are compared in a simulation study and in a real data application using registry data to model individual transitions for a birth cohort of 184 951 Norwegian men between states of sick leave, disability, education, work and unemployment.

• Aalen, John; Donal, Erwan; Larsen, Camilla Kjellstad; Duchenne, Jürgen; Lederlin, Mathieu & Cvijic, Marta [Vis alle 19 forfattere av denne artikkelen] (2020). Imaging predictors of response to cardiac resynchronization therapy: left ventricular work asymmetry by echocardiography and septal viability by cardiac magnetic resonance. European Heart Journal. ISSN 0195-668X. 41(39), s. 3813–3823. doi: 10.1093/eurheartj/ehaa603. Fulltekst i vitenarkiv
• Stensrud, Mats Julius & Aalen, Odd O. (2019). Skal vi skrinlegge begrepet statistisk signifikans? Tidsskrift for Den norske legeforening. ISSN 0029-2001. 139(11). doi: 10.4045/tidsskr.19.0311.
• Aalen, Odd O.; Stensrud, Mats Julius; Didelez, Vanessa; Daniel, Rhian; Røysland, Kjetil & Strohmaier, Susanne (2019). Time-dependent mediators in survival analysis: Modeling direct and indirect effects with the additive hazards model. Biometrical Journal. ISSN 0323-3847. s. 1–18. doi: 10.1002/bimj.201800263.
• Stensrud, Mats Julius; Aalen, John; Aalen, Odd O. & Valberg, Morten (2019). Limitations of hazard ratios in clinical trials. European Heart Journal. ISSN 0195-668X. 40(17), s. 1378–1383. doi: 10.1093/eurheartj/ehy770.
• Valberg, Morten; Stensrud, Mats Julius & Aalen, Odd O. (2018). The surprising implications of familial association in disease risk. BMC Public Health. ISSN 1471-2458. 18. doi: 10.1186/s12889-018-5033-5.
• Aalen, Odd O.; Gran, Jon Michael; Røysland, Kjetil; Stensrud, Mats Julius & Strohmaier, Susanne (2018). Feedback and Mediation in Causal Inference Illustrated by Stochastic Process Models. Scandinavian Journal of Statistics. ISSN 0303-6898. 45(1), s. 62–86. doi: 10.1111/sjos.12286.
• Gran, Jon Michael; Hoff, Rune; Røysland, Kjetil; Ledergerber, Bruno; Young, James & Aalen, Odd O. (2017). Estimating the treatment effect on the treated under time-dependent confounding in an application to the Swiss HIV Cohort Study. The Journal of the Royal Statistical Society, Series C (Applied Statistics). ISSN 0035-9254. 67(1), s. 103–125. doi: 10.1111/rssc.12221. Fulltekst i vitenarkiv
• Stensrud, Mats Julius; Aalen, Odd O.; Valberg, Morten & Røysland, Kjetil (2017). Exploring selection bias by causal frailty models: The magnitude matters. Epidemiology. ISSN 1044-3983. 28(3), s. 379–386. doi: 10.1097/EDE.0000000000000621.
• Stensrud, Mats Julius; Strohmaier, Susanne; Valberg, Morten & Aalen, Odd O. (2017). Can chance cause cancer? A causal consideration. European Journal of Cancer. ISSN 0959-8049. 75, s. 83–85. doi: 10.1016/j.ejca.2016.12.022.
• Valberg, Morten; Grotmol, Tom; Tretli, Steinar; Veierød, Marit Bragelien; Moger, Tron Anders & Devesa, Susan S. [Vis alle 7 forfattere av denne artikkelen] (2016). Prostate-specific antigen testing for prostate cancer: Depleting a limited pool of susceptible individuals? European Journal of Epidemiology (EJE). ISSN 0393-2990. 20(6), s. 511–520. doi: 10.1007/s10654-016-0185-z.
• Aalen, Odd O.; Røysland, Kjetil; Gran, Jon Michael; Kouyos, Roger & Lange, Theis (2016). Can we believe the DAGs? A comment on the relationship between causal DAGs and mechanisms. Statistical Methods in Medical Research. ISSN 0962-2802. 25(5), s. 2294–2314. doi: 10.1177/0962280213520436.
• Strohmaier, Susanne; Røysland, Kjetil; Hoff, Rune; Borgan, Ørnulf; Pedersen, Terje Rolf & Aalen, Odd O. (2015). Dynamic path analysis - a useful tool to investigate mediation processes in clinical survival trials. Statistics in Medicine. ISSN 0277-6715. 34(29), s. 3866–3887. doi: 10.1002/sim.6598.
• Gran, Jon Michael; Lie, Stein Atle; Øyeflaten, Irene Larsen; Borgan, Ørnulf & Aalen, Odd O. (2015). Causal inference in multi-state models-sickness absence and work for 1145 participants after work rehabilitation. BMC Public Health. ISSN 1471-2458. 15:1082. doi: 10.1186/s12889-015-2408-8. Fulltekst i vitenarkiv
• Aalen, Odd O.; Cook, Richard J. & Røysland, Kjetil (2015). Does Cox analysis of a randomized survival study yield a causal treatment effect? Lifetime Data Analysis. ISSN 1380-7870. 21(4), s. 579–593. doi: 10.1007/s10985-015-9335-y.
• Fairbairn, Catharine E.; Sayette, Michael; Aalen, Odd O. & Frigessi, Arnoldo (2015). Alcohol and Emotional Contagion An Examination of the Spreading of Smiles in Male and Female Drinking Groups. Clinical Psychological Science. ISSN 2167-7026. 3(5), s. 686–701. doi: 10.1177/2167702614548892.
• Aalen, Odd O.; Valberg, Morten; Grotmol, Tom & Tretli, Steinar (2015). Understanding variation in disease risk: the elusive concept of frailty. International Journal of Epidemiology. ISSN 0300-5771. 44(4), s. 1408–1421. doi: 10.1093/ije/dyu192.
• Valberg, Morten; Grotmol, Tom; Tretli, Steinar; Veierød, Marit Bragelien; Moger, Tron Anders & Aalen, Odd O. (2014). A hierarchical frailty model for familial testicular germ-cell tumors. American Journal of Epidemiology. ISSN 0002-9262. 179(4), s. 499–506. doi: 10.1093/aje/kwt267.
• Alvik, Astrid; Aalen, Odd O. & Lindemann, Rolf (2013). Early Fetal Binge Alcohol Exposure Predicts High Behavioral Symptom Scores in 5.5-Year-Old Children. Alcoholism: Clinical and Experimental Research. ISSN 0145-6008. 37(11), s. 1954–1962. doi: 10.1111/acer.12182.
• Sanchez-Niubo, Albert; Aalen, Odd O.; Domingo-Salvany, Antonia; Amundsen, Ellen Johanna; Fortiana, Josep & Røysland, Kjetil (2013). A multi-state model to estimate incidence of heroin use. BMC Medical Research Methodology. ISSN 1471-2288. 13. doi: 10.1186/1471-2288-13-4. Vis sammendrag

  Overgang fra injisering til sniffing/røyking av heroin Røyking og sniffing av heroin er en mye mindre skadelig inntaksmåte enn injisering. Norge ligger dessverre på toppen i Europa i antall narkotikadødsfall per innbygger. Dette er knyttet til stort omfang av heroinbruk blant brukere av tunge illegale narkotiske stoffer og at heroinet inntas med sprøyte. For å redusere narkotikadødsfall og overdoser må det arbeides for at injisering av heroinbruk reduseres, både ved å redusere rekruttering til heroinbruk, hjelpe eksisterende brukere til å slutte helt eller gå over til substitusjonsbehandling og å arbeide for at røyking og sniffing blir mer populært i brukergruppa. I Spania, nærmere bestemt i Madrid og Barcelona, har en forskergruppe beregnet at rekrutteringen til heroinbruk steg jevnt fra 1970 til ca. 1990, for deretter å falle drastisk fram mot 2006. Et annet funn var at blant de som ble rekruttert til heroinbruk var det fra midten av 80-tallet mer vanlig å røyke stoffet (chase the dragon) enn å injisere det (Sânchez-Niubò et al 2013). Annen litteratur om bruk av heroin i Spania påpeker at det ikke har vært tiltak fra myndighetenes side som har bidratt til redusert rekruttering til heroinbruk og røyking av det istedenfor injisering. Hovedforklaringene knyttes til ulike subkulturer og heroinmarkeder i spanske regioner. I regioner hvor det hvite heroinet dominerte, ble stoffet injisert, mens i regioner hvor det brune heroinet dominerte ble det røykt i mye større grad. Når det hvite heroinet forsvant fra markedet, økte omfanget av røyking. Spania har hatt en stor HIV epidemi blant sprøytebrukere, men risikoen for å bli HIV smittet ser ikke ut til å ha påvirket overgangen til sniffing (de la Fuente et al. 1996, 1997a og 1997b). Det er altså ikke så mye lærdom om virksomme tiltak å hente fra Spania til Norge. Men er det mulig å påvirke markedet og injeksjonskulturen ved å se til teori og empiri om endring av risikoatferd??

• Aalen, Odd O.; Røysland, Kjetil; Gran, Jon Michael & Ledergerber, Bruno (2012). Causality, mediation and time: a dynamic viewpoint. Journal of the Royal Statistical Society: Series A (Statistics in Society). ISSN 0964-1998. 175(4), s. 831–861. doi: 10.1111/j.1467-985X.2011.01030.x.
• Valberg, Morten; Grotmol, Tom; Tretli, Steinar; Veierød, Marit Bragelien; Devesa, Susan & Aalen, Odd O. (2012). Frailty modeling of age-incidence curves of osteosarcoma and Ewing sarcoma among individuals younger than 40 years. Statistics in Medicine. ISSN 0277-6715. 31(28), s. 3731–3747. doi: 10.1002/sim.5441.
• Misiri, Humphrey; Edriss, Abdi; Aalen, Odd O. & Dahl, Fredrik Andreas (2012). Estimation of HIV incidence in Malawi from cross-sectional population-based sero-prevalence data. Journal of the International AIDS Society. ISSN 1758-2652. 15. doi: 10.1186/1758-2652-15-14.
• Aalen, Odd O. (2012). Discussion of 'The Current Duration Approach to Estimating Time to Pregnancy'. Scandinavian Journal of Statistics. ISSN 0303-6898. 39(2), s. 205–206. doi: 10.1111/j.1467-9469.2012.00793.x.
• Aalen, Odd O. (2012). Armitage lecture 2010: Understanding treatment effects: the value of integrating longitudinal data and survival analysis. Statistics in Medicine. ISSN 0277-6715. 31(18), s. 1903–1917. doi: 10.1002/sim.5324.
• Røysland, Kjetil; Gran, Jon Michael; Ledergerber, Bruno; von Wyl, Viktor; Young, James A. & Aalen, Odd O. (2011). Analyzing direct and indirect effects of treatment using dynamic path analysis applied to data from the Swiss HIV Cohort Study. Statistics in Medicine. ISSN 0277-6715. 30(24), s. 2947–2958. doi: 10.1002/sim.4324.
• Alvik, Astrid; Torgersen, Anne Mari; Aalen, Odd O. & Lindemann, Rolf (2011). Binge alchohol exposure once a week in early pregnancy predicts temperament and sleeping problems in infants. Early Human Development. ISSN 0378-3782. 87, s. 827–833. doi: 10.1016/j.earlhumdev.2011.06.009.
• Grotmol, Tom; Bray, Freddie Ian; Holte, Harald; Haugen, Marion; Kunz, Lauren & Tretli, Steinar [Vis alle 8 forfattere av denne artikkelen] (2011). Frailty Modeling of the Bimodal Age-Incidence of Hodgkin Lymphoma in the Nordic Countries. Cancer Epidemiology, Biomarkers and Prevention. ISSN 1055-9965. 20(7), s. 1350–1357. doi: 10.1158/1055-9965.EPI-10-1014.
• De Blasio, Birgitte Freiesleben; Seierstad, Taral Guldahl & Aalen, Odd O. (2011). Frailty effects in networks: comparison and identification of individual heterogeneity versus preferential attachment in evolving networks. The Journal of the Royal Statistical Society, Series C (Applied Statistics). ISSN 0035-9254. 60, s. 239–259. doi: 10.1111/j.1467-9876.2010.00746.x.
• Wisløff, Torbjørn; Aalen, Odd O. & Kristiansen, Ivar Sønbø (2011). Considerable variation in NNT - A study based on Monte Carlo simulations. Journal of Clinical Epidemiology. ISSN 0895-4356. 64(4), s. 444–450. doi: 10.1016/j.jclinepi.2010.04.025.
• Gran, Jon Michael; Iversen, Bjørn Gunnar; Hungnes, Olav & Aalen, Odd O. (2010). Estimating influenza-related excess mortality and reproduction numbers for seasonal influenza in Norway, 1975-2004. Epidemiology and Infection. ISSN 0950-2688. 138(11), s. 1559–1568. doi: 10.1017/S0950268810000671.
• Gran, Jon Michael; Røysland, Kjetil; Wolbers, Marcel; Didelez, Vanessa; Sterne, Jonathan AC & Ledergerber, Bruno [Vis alle 9 forfattere av denne artikkelen] (2010). A sequential Cox approach for estimating the causal effect of treatment in the presence of time-dependent confounding applied to data from the Swiss HIV Cohort Study. Statistics in Medicine. ISSN 0277-6715. 29(26), s. 2757–2768. doi: 10.1002/sim.4048.
• Weedon-Fekjaer, H; Tretli, Steinar & Aalen, Odd O. (2010). Estimating screening test sensitivity and tumour progression using tumour size and time since previous screening. Statistical Methods in Medical Research. ISSN 0962-2802. 19(5), s. 507–527. doi: 10.1177/0962280209359860.
• Aalen, Odd O. & Gunnes, Nina (2010). A dynamic approach for reconstructing missing longitudinal data using the linear increments model. Biostatistics. ISSN 1465-4644. 11(3), s. 453–472. doi: 10.1093/biostatistics/kxq014.
• Gjessing, Håkon K.; Røysland, Kjetil; Aalen, Odd O. & Pena, Edsel A (2010). Recurrent events and the exploding Cox model. Lifetime Data Analysis. ISSN 1380-7870. 16(4), s. 525–546. doi: 10.1007/s10985-010-9180-y.
• Wisløff, Torbjørn; Aalen, Odd O. & Kristiansen, Ivar Sønbø (2010). Considerable variation in NNT - A study based on Monte Carlo simulations. Journal of Clinical Epidemiology. ISSN 0895-4356. doi: 10.1016/j.jclinepi.2010.04.025.
• Gunnes, Nina; Farewell, DM; Seierstad, Taral Guldahl & Aalen, Odd O. (2009). Analysis of censored discrete longitudinal data: Estimation of mean response. Statistics in Medicine. ISSN 0277-6715. 28(4), s. 605–624. doi: 10.1002/sim.3492.
• Haugen, Marion; Bray, Freddie Ian; Grotmol, Tom; Tretli, Steinar; Aalen, Odd O. & Moger, Tron Anders (2009). Frailty modeling of bimodal age-incidence curves of nasopharyngeal carcinoma in low-risk populations. Biostatistics. ISSN 1465-4644. 10(3), s. 501–514. doi: 10.1093/biostatistics/kxp007.
• Aalen, Odd O.; Andersen, Per Kragh; Borgan, Ørnulf; Gill, Richard D. & Keiding, Niels (2009). History of applications of martingales in survival analysis. Journal Électronique d'Histoire des Probabililtés et de la Statistique. ISSN 1773-0074. 5(1), s. 1–28.
• Gunnes, Nina; Seierstad, Taral Guldahl; Aamdal, Steinar; Brunsvig, Paal Fr.; Jacobsen, Anne-Birgitte & Sundstrøm, Stein [Vis alle 7 forfattere av denne artikkelen] (2009). Assessing quality of life in a randomized clinical trial: Correcting for missing data. BMC Medical Research Methodology. ISSN 1471-2288. 9(28). doi: 10.1186/1471-2288-9-28.
• Moger, Tron Anders & Aalen, Odd O. (2008). Regression models for infant mortality data in Norwegian siblings, using a compound Poisson frailty distribution with random scale. Biostatistics. ISSN 1465-4644. 9, s. 577–591. doi: 10.1093/biostatistics/kxn003.
• Weedon-Fekjær, Harald; Weedon-Fekjaer, H; Lindqvist, Bo Henry; Vatten, Lars Johan; Aalen, O & Tretli, Steinar (2008). Estimating mean sojourn time and screening sensitivity using questionnaire data on time since previous screening. Journal of Medical Screening. ISSN 0969-1413. 15, s. 83–90. doi: 10.1258/jms.2008.007071.
• Weedon-Fekjaer, H; Weedon-Fekjær, Harald; Lindqvist, Bo Henry; Vatten, Lars Johan; Aalen, OO & Tretli, Steinar (2008). Breast cancer tumor growth estimated through mammography screening data. Breast Cancer Research. ISSN 1465-5411. 10(3). doi: 10.1186/bcr2092.
• Gran, JM; Wasmuth, L; Amundsen, EJ; Lindqvist, Bo Henry & Aalen, OO (2008). Growth rates in epidemic models: Application to a model for HIV/AIDS progression. Statistics in Medicine. ISSN 0277-6715. 27, s. 4819–4836. doi: 10.1002/sim.3219. Vis sammendrag

  The most common quantity used to describe the growth of an epidemic when modelling infectious diseases is the basic reproduction number R0. While R0 is most appropriate for epidemics with short-lasting infections, long-lasting infections such as HIV/AIDS may call for the use of growth rates with other properties. For a group of multi-state compartment models we define both R0, the actual reproduction number Ra(t), and the intrinsic growth rate r .We study the relationship between these different reproduction numbers and growth rates and take a brief look at how they could be estimated from actual observed data. The work is illustrated by a model for HIV/AIDS progression among homosexual men in England and Wales. We conclude that other measures of growth, in addition to R0, give important supplementary information.

• Bray, Freddie Ian; Haugen, Marion; Moger, Tron Anders; Tretli, Steinar; Aalen, Odd O. & Grotmol, T (2008). Age-incidence curves of nasopharyngeal carcinoma worldwide: Bimodality in low-risk populations and aetiologic implications. Cancer Epidemiology, Biomarkers and Prevention. ISSN 1055-9965. 17, s. 2356–2365. doi: 10.1158/1055-9965.EPI-08-0461.
• Gravseth, Hans Magne; Bjerkedal, Tor; Irgens, Lorentz M; Aalen, Odd O; Selmer, Randi Marie & Kristensen, Petter (2008). Influence of physical, mental and intellectual development on disability in young Norwegian men. European Journal of Public Health. ISSN 1101-1262. 18(6), s. 650–655. doi: 10.1093/eurpub/ckn055.
• Gandy, A; Therneau, TM & Aalen, Odd O. (2008). Global tests in the additive hazards regression model. Statistics in Medicine. ISSN 0277-6715. 27. doi: 10.1002/sim.2972.
• Martinussen, T; Aalen, Odd O. & Scheike, TH (2008). The Mizon-Richard encompassing test for the Cox and Aalen additive hazards models. Biometrics. ISSN 0006-341X. 64. doi: 10.1111/j.1541-0420.2007.00840.x.
• Gravseth, Hans Magne Ulrik; Bjerkedal, Tor; Irgens, Lorentz M; Aalen, Odd O.; Selmer, Randi Marie & Kristensen, Petter (2007). Life course determinants for early disability pension: a follow-up of Norwegian men and women born 1967-1976. European Journal of Epidemiology (EJE). ISSN 0393-2990. 22(8), s. 533–543. doi: 10.1007/s10654-007-9139-9.
• Gunnes, Nina; Borgan, Ørnulf & Aalen, Odd O. (2007). Estimating stage occupation probabilities in non-Markov models. Lifetime Data Analysis. ISSN 1380-7870. 13, s. 211–240. doi: 10.1007/s10985-007-9034-4.
• Aalen, Odd O. & Frigessi, Arnoldo (2007). What can statistics contribute to a causal understanding? Scandinavian Journal of Statistics. ISSN 0303-6898. 34(1), s. 155–168. doi: 10.1111/j.1467-9469.2006.00549.x.
• Hanssen-Bauer, K; Gowers, S; Aalen, Odd O.; Bilenber, N; Brann, P & Garralda, E [Vis alle 8 forfattere av denne artikkelen] (2007). Cross-national reliability of clinician-rated outcome measures in child and adolescent mental health services. Administration and Policy in Mental Health and Mental Health Services Research. ISSN 0894-587X. 34, s. 513–518. doi: 10.1007/s10488-007-0135-x. Vis sammendrag

  Clinician-rated measures are in extensive use as routine outcome measures in child and adolescent mental health services. We investigated cross-national differences and inter-rater reliability of the Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA), the Children’s Global Assessment Scale (CGAS) and the Global Assessment of Psychosocial Disability (GAPD). Thirty clinicians from 5 nations independently rated 20 written vignettes. The national groups afterwards established national consensus ratings. There were no cross-national differences in independent scores, but there were differences in national consensus scores, which were also more severe than independent scores. The ICC for the HoNOSCA total score was 0.84, for the CGAS 0.61 and for the GAPD 0.54. These measures may usefully contribute to cross-national comparison studies.

• Hanssen-Bauer, Ketil; Aalen, Odd O.; Ruud, Torleif & Heyerdahl, Sonja (2007). Inter-rater reliability of clinician-rated outcome measures in child and adolescent mental health services. Administration and Policy in Mental Health and Mental Health Services Research. ISSN 0894-587X. 34(6), s. 504–512. doi: 10.1007/s10488-007-0134-y. Vis sammendrag

  This study investigated the inter-rater reliability when 169 out of 171 clinicians working in 10 Norwegian child and adolescent mental health services rated 20 written vignettes using the following outcome measures: Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA), Children’s Global Assessment Scale (CGAS) and Global Assessment of Psychosocial Disability (GAPD). Three clinicians rated both patients and vignettes. On vignettes the intraclass correlation coefficient (ICC) for the HoNOSCA total score was 0.81 (single scales 0.47–0.96), for the CGAS 0.61 and for the GAPD 0.60. The reliability was not lower on patients. The rater’s profession, experience or clinic did not have effect on the scores

• Sponheim, Eili; Myhre, Anne Margrethe; Reichelt, Karl Ludvig & Aalen, Odd Olai (2006). Peptidmønstre i urin hos barn med mildere former for autisme. Tidsskrift for Den norske legeforening. ISSN 0029-2001. 126(11), s. 1475–1477.
• Fosen, Johan; Borgan, Ørnulf; Weedon-Fekjaer, H & Aalen, Odd Olai (2006). Dynamic analysis of recurrent event data using the additive hazard model. Biometrical Journal. ISSN 0323-3847. 48, s. 381–398.
• Fosen, Johan; Ferkingstad, Egil; Borgan, Ørnulf & Aalen, Odd O. (2006). Dynamic path analysis - a new approach to analyzing time-dependent covariates. Lifetime Data Analysis. ISSN 1380-7870. 12, s. 143–167.
• Svensson, Elisabeth; Moger, TA; Tretli, Steinar; Aalen, Odd & Grotmol, Tom (2006). Frailty modelling of colorectal cancer incidence in Norway: Indications that individual heterogeneity in risk is related to birth cohort. European Journal of Epidemiology (EJE). ISSN 0393-2990. 21, s. 587–593.
• Moger, Tron Anders & Aalen, Odd Olai (2005). A distribution for multivariate frailty based on the compound Poisson distribution with random scale. Lifetime Data Analysis. ISSN 1380-7870. 11(1), s. 41–59.
• Weedon-Fekjær, Harald; Vatten, L; Aalen, Odd Olai; Lindqvist, B & Tretli, S (2005). Estimating mean sojourn time and screening test sensitivity in breast cancer mammography screening; New results. Journal of Medical Screening. ISSN 0969-1413. 12(4), s. 172–178.
• Weedon-Fekjær, Harald; Vatten, Lars Johan; Aalen, Odd; Lindqvist, Bo Henry & Tretli, Steinar (2005). Estimating mean sojourn time and screening test sensitivity in breast cancer mammography screening: new results. Journal of Medical Screening. ISSN 0969-1413. 12(4), s. 172–178.
• Sweeting, MJ; De Angelis, Daniela & Aalen, Odd O. (2005). Bayesian back-calculation using a multi-state model with application to HIV. Statistics in Medicine. ISSN 0277-6715. 24(24), s. 3991–4007. Vis sammendrag

  Back-calculation is a method of obtaining estimates of the number of infections of a disease over time. Data on an endpoint of the disease, together with knowledge of the time from infection to endpoint, allows reconstruction of the incidence of infection. The technique has had much success when applied to the HIV epidemic, using incidence of AIDS diagnoses to inform past HIV infections. In recent years, the period from infection to AIDS has changed considerably due to new regimes of anti-viral therapies. This has led to attempts to use incidence of first positive HIV test as an alternative basis for back-calculation. Developing on earlier work, this paper explores the feasibility of a multi-state formulation of the back-calculation method that models the disease and diagnosis processes and uses HIV diagnoses as an endpoint. Estimation is carried out in a Bayesian framework, which naturally allows incorporation of external information to inform the diagnosis probabilities. The idea is illustrated on data from the HIV epidemic in homosexuals in England and Wales.

• Moger, Tron Anders; Aalen, Odd Olai; Heimdal, K & Gjessing, Håkon K (2004). Analysis of testicular cancer data using a frailty model with familial dependence. Statistics in Medicine. ISSN 0277-6715. 23(4), s. 617–632.
• Moger, Tron Anders; Aalen, Odd Olai; Halvorsen, TO; Storm, HH; Tretli, S & Halvorsen, Tarje Onsøien (2004). Frailty modelling of testicular cancer incidence using Scandinavian data. Biostatistics. ISSN 1465-4644. 5(1), s. 1–14.
• Aalen, Odd Olai; Fosen, Johan; Weedon-Fekjær, Harald; Borgan, Ørnulf & Husebye, Einar (2004). Dynamic analysis of multivariate failure time data. Biometrics. ISSN 0006-341X. 60, s. 764–773.
• Amundsen, Ellen J; Stigum, Hein; Røttingen, John-Arne & Aalen, Odd Olai (2004). Definition and estimation of an actual reproduction number describing past infectious disease transmission: application to HIV epidemics among homosexual men in Denmark, Norway and Sweden. Epidemiology and Infection. ISSN 0950-2688. 132, s. 1139–1149. Vis sammendrag

  Prevalence and incidence measures are the common way to describe epidemics. The reproduction number supplies information on the potential for epidemical growth or decline. We define an actual reproduction number for infectious disease transmission that has taken place. An estimator is suggested, based on the number of new infections observed in a given time interval, the number of those infected at the start of the interval, and the length of the infectious period. That estimator is applied to HIV among men having sex with other men over the period, 1977-1995, in Scandinavia. The actual reproduction number was estimated with acceptable certainty from the period, 1981-82, yielding a value of 15 secondary cases. A value of less than one secondary case was assessed for the period, 1988-1995, in Denmark and Sweden. The actual reproduction number gives us some additional understanding of the dynamics of epidemics, compared with prevalence and incidence curves.

Se alle arbeider i Cristin

• Aalen, Odd O.; Frigessi, Arnoldo; Moger, Tron Anders; Scheel, Ida; Skovlund, Eva & Veierød, Marit Bragelien (2018). Statistiske metoder i medisin og helsefag. 2. utgave. Gyldendal Akademisk. ISBN 978-82-05-50764-7. 351 s.
• Aalen, Odd O.; Borgan, Ørnulf & Gjessing, Håkon K. (2008). Survival and Event History Analysis: A Process Point of View. Springer. ISBN 978-0-387-20287-7. 539 s.
• Aalen, Odd O.; Borgan, Ørnulf & Gjessing, Håkon K (2008). Event history analysis: A process point of view. Springer Science+Business Media B.V.. ISBN 978-0-387-20287-7. 539 s.
• Aalen, Odd O.; Borgan, Ørnulf & Gjessing, Håkon K. (2008). Survival and event history analysis: a process point of view. Springer Science+Business Media B.V.. ISBN 978-0-387-20287-7. 539 s.
• Aalen, Odd O.; Frigessi, Arnoldo; Moger, Tron Anders; Scheel, Ida; Skovlund, Eva & Veierød, Marit Bragelien (2006). Statistiske metoder i medisin og helsefag. Gyldendal Akademisk. ISBN 978-82-05-34685-7. 335 s.

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• Rimal, Raju; Robsahm, Trude Eid; Green, Adèle C.; Ghiasvand, Reza; Rueegg, Corina Silvia & Bassarova, Assia Vassileva [Vis alle 11 forfattere av denne artikkelen] (2021). Long-term trends in melanoma tumour thickness in Norway.
• Gran, Jon Michael & Aalen, Odd O. (2019). Letter to the Editor: Comparison of statistical approaches dealing with time-dependent confounding in drug effectiveness studies (SMMR, Vol. 27, Issue 6, 2018). Statistical Methods in Medical Research. ISSN 0962-2802. 28(1), s. 321–322. doi: 10.1177/0962280218811177.
• Stensrud, Mats Julius; Valberg, Morten & Aalen, Odd O. (2017). Can collider bias explain paradoxical associations? Epidemiology. ISSN 1044-3983. 28(4), s. e39–e40. doi: 10.1097/EDE.0000000000000653.
• Aalen, Odd O.; Valberg, Morten; Grotmol, Tom & Tretli, Steinar (2015). Authors' response: Understanding variation in disease risk. International Journal of Epidemiology. ISSN 0300-5771. 44(4), s. 1426–1428. doi: 10.1093/ije/dyv047.
• Stensrud, Mats Julius & Aalen, Odd O. (2015). Hva kan vi si om kausalitet? Tidsskrift for Den norske legeforening. ISSN 0029-2001. 135(16), s. 1465–1467. doi: 10.4045/tidsskr.15.0347.
• Kristensen, Petter & Aalen, Odd O. (2013). Understanding mechanisms: opening the "black box" in observational studies. Scandinavian Journal of Work, Environment and Health. ISSN 0355-3140. 39(2), s. 121–124. doi: 10.5271/sjweh.3343.
• Aalen, Odd O.; Borgan, Ørnulf & Kvaløy, Jan Terje (2013). Medical statistics - a subject of increasing breadth and importance Preface. Statistics in Medicine. ISSN 0277-6715. 32(30), s. 5221–5221. doi: 10.1002/sim.6035.
• Wisløff, Torbjørn; Aalen, Odd O. & Kristiansen, Ivar Sønbø (2012). Regarding adequate methods for comparison of effect measures - Reply. Journal of Clinical Epidemiology. ISSN 0895-4356. 65(4), s. 462–463. doi: 10.1016/j.jclinepi.2011.10.005.
• Corbett, Karina; Mehlum, Ingrid Alethe Sivesind; Aalen, Odd O. & Kristensen, Petter (2011). Is risk of sickness absence associated with sibling sickness absence?
• Frigessi, Arnoldo; Holden, Lars & Aalen, Odd O. (2011). Klima og statistikk. Forskning.no. ISSN 1891-635X.
• Aalen, Odd O. (2010). Survival analysis, longitudinal analysis and causal inference. Lifetime Data Analysis. ISSN 1380-7870. 16(1), s. 1–2. doi: 10.1007/s10985-009-9147-z.
• Aalen, Odd O. (2010). Understanding disease processes. Statistics in Medicine. ISSN 0277-6715. 29(11), s. 1159–1160. doi: 10.1002/sim.3851.
• Aalen, Odd O. (2008). What hides behind the data?
• Aalen, Odd O. (2008). Dynamic path analysis.
• Aalen, Odd O. (2008). Statistics, causality and dynamic path modelling.
• Haugen, Marion; Bray, Freddie Ian; Grotmol, Tom; Tretli, Steinar; Aalen, Odd O. & Moger, Tron Anders (2008). Frailty modelling of bimodal age-incidence curves of nasopharyngeal carcinoma in low-risk populations.
• Gravseth, Hans Magne Ulrik; Kristensen, Petter; Bjerkedal, Tor; Irgens, Lorentz M; Aalen, Odd O. & Selmer, Randi (2008). Social inequalities in disability pension in a life course perspective.
• Aalen, Odd O. (2007). Discussion to: Analysis of longitudinal data with drop-out: objectives, assumptions and a proposal. The Journal of the Royal Statistical Society, Series C (Applied Statistics). ISSN 0035-9254. 56, s. 538–539.
• Aalen, Odd O. (2007). Discussion to: Maximum likelihood estimation in semiparametric regression models with censored data. Journal of The Royal Statistical Society Series B-statistical Methodology. ISSN 1369-7412. 69, s. 537–539.
• Aalen, Odd O. & De Blasio, Birgitte Freiesleben (2007). Mathematical Modelling of infectious disease.
• Senn, S; Keiding, N; Andrews, N; Musonda, P; Hocine, M & Moreau, T [Vis alle 16 forfattere av denne artikkelen] (2006). Semiparametric analysis of case series data - Discussion. The Journal of the Royal Statistical Society, Series C (Applied Statistics). ISSN 0035-9254. 55, s. 581–594.
• Aalen, Odd O. (2006). What hides behind the data?
• Aalen, Odd O. (2005). Fugleinfluensa til mennesker? Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116.
• Borgan, Ørnulf; Aalen, Odd O. & Røsjø, Bjarne (2005). Bedre statistikk kan redde flere liv. [Avis]. Informasjonsblad nr 2/2005. Senter for grunnforskning.
• Aalen, Odd O. (2005). Understanding the structure of event histories: A process point of view.
• Aalen, Odd O. (2005). Understanding the shape of the hazard rate: An application of quasi-stationarity.
• Aalen, Odd O. (2005). Dynamic path analysis and Granger-Schweder causality.
• Aalen, Odd Olai (2004). Discussion on causality. Scandinavian Journal of Statistics. ISSN 0303-6898. 31, s. 193–195.
• Moger, Tron Anders & Aalen, Odd O. (2006). Hierarchical Lévy Frailty Models and a Frailty Analysis of Data on Infant Mortality in Norwegian Siblings. Biostatistics Working Paper Series, no. 290. Department of Biostatistics.
• Alquist, R.; Grøgaard, Jens; Hellenes, Kaja; Myr, Rachel; Rognum, Torleiv Ole & Nilsen, Anne Britt Vika [Vis alle 9 forfattere av denne artikkelen] (2005). Samsoving, smokk, amming og krybbedød - finnes det en sammenheng? Kunnskapssenteret. ISSN 82-8121-049-4.

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