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Rimal, Raju; Robsahm, Trude Eid; Green, Adele C.; Ghiasvand, Reza; Rueegg, Corina Silvia & Bassarova, Assia Vassileva
[Show all 12 contributors for this article]
(2023).
Melanoma survival by tumour thickness in Norway, 1983–2019.
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Veierød, Marit Bragelien & Jelmini, Maria
(2023).
Forskare: Teorin att vänja huden långsamt vid solen stämmer inte.
[Newspaper].
Svenska Dagbladet.
-
Veierød, Marit Bragelien & Jelmini, Maria
(2023).
Solkrämsanvändare tycks få hudcancer oftare - varför?
[Newspaper].
Svenska Dagbladet.
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Veierød, Marit Bragelien
(2023).
Melanoma risk factors.
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Veierød, Marit Bragelien
(2022).
Epidemiological melanoma research.
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Stenehjem, Jo Steinson; Grimsrud, Tom Kristian & Veierød, Marit Bragelien
(2022).
Vi kan fortsatt lære av Kielland-ulykken.
Dagens medisin.
ISSN 1501-4290.
-
Veierød, Marit Bragelien
(2022).
Epidemiologisk hudkreftforskning.
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Rimal, Raju; Robsahm, Trude Eid; Green, Adèle C.; Ghiasvand, Reza; Rueegg, Corina Silvia & Bassarova, Assia Vassileva
[Show all 11 contributors for this article]
(2022).
Trends in melanoma tumour thickness in Norway, 1983–2019.
Show summary
Aim: Describe the trends in melanoma tumour thickness in Norway by T category, overall and in important subgroups such as sex, age, anatomic site, and histopathological subtype, over 35-year.
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Marjerrison, Niki; Jakobsen, Jarle; Grimsrud, Tom Kristian; Hansen, Johnnie; Martinsen, Jan Ivar & Nordby, Karl-Christian
[Show all 8 contributors for this article]
(2022).
Cancer incidence and mortality in the Norwegian Fire Departments Cohort, 1960-2018.
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Marjerrison, Niki; Grimsrud, Tom Kristian; Hansen, Johnnie; Martinsen, Jan Ivar; Nordby, Karl-Christian & Veierød, Marit Bragelien
[Show all 7 contributors for this article]
(2022).
Cancer incidence and mortality in the Norwegian Fire Departments cohort: Are incidence versus mortality outcome measures contributing to variability in risk estimates?
-
Veierød, Marit Bragelien
(2022).
Lifestyle and melanoma risk: what do we know, what do we counsel our patients?
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Christensen, Jacob Juel; Bogsrud, Martin Prøven; Holven, Kirsten Bjørklund; Retterstøl, Kjetil; Veierød, Marit Bragelien & Nordeng, Hedvig Marie Egeland
(2021).
Maternal use of statins in pregnancy: a population based registry study.
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Støer, Nathalie Charlotte; Botteri, Edoardo; Busund, Marit Katinka; Ghiasvand, Reza; Vangen, Siri & Lund, Eiliv
[Show all 8 contributors for this article]
(2021).
Menopausal hormone therapy and risk of melanoma: a population-based cohort study.
British Journal of Dermatology.
ISSN 0007-0963.
doi:
10.1111/bjd.20640.
-
Perrier, Flavie; Ghiasvand, Reza; Lergenmuller, Simon; Robsahm, Trude Eid; Green, Adele C. & Borch, Kristin Benjaminsen
[Show all 10 contributors for this article]
(2021).
Physical activity and melanoma risk: a Norwegian population-based cohort study.
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Perrier, Flavie; Ghiasvand, Reza; Lergenmuller, Simon; Robsahm, Trude Eid; Green, Adele C & Borch, Kristin Benjaminsen
[Show all 10 contributors for this article]
(2021).
Physical activity and cutaneous melanoma risk: A Norwegian population-based cohort study.
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Veierød, Marit Bragelien & Perrier, Flavie
(2021).
Physical activity does not increase the risk of melanoma/ aktivitet øker ikke risikoen for melanom (føflekkreft).
[Internet].
https://www.med.uio.no/imb/english/research/news-and-events/.
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Rimal, Raju; Robsahm, Trude Eid; Green, Adèle C.; Ghiasvand, Reza; Rueegg, Corina Silvia & Bassarova, Assia Vassileva
[Show all 11 contributors for this article]
(2021).
Long-term trends in melanoma tumour thickness in Norway.
Show summary
Norway has the second-highest mortality rate of cutaneous melanoma worldwide and ranks fifth in incidence. Tumour (Breslow) thickness at diagnosis is the primary determinant of the T category in the tumour, nodes, metastasis staging system, and the most important prognostic factor for survival after localized melanoma. This ongoing study investigates long-term trends in tumour thickness, and the corresponding T categories, overall and in important subgroups, in a nationwide case series over a 40-year time period.
The population-based Cancer Registry of Norway (CRN) provided all first primary invasive melanoma cases for 1980-2019. Tumour thickness was available from the Norwegian Melanoma Registry (within the CRN) for all cases diagnosed in 2008-2019 and was manually extracted from the paper notifications archived in the CRN for the cases diagnosed in 1980-2007. Covariates include sex, age, residential geographical region, anatomic site, histopathological subtype, clinical stage, and ulceration.
Descriptive summaries are presented as frequencies (numbers, %) and medians with interquartile ranges (IQR).
In total, 47,439 morphologically verified first primary invasive melanoma cases were diagnosed in Norway in 1980-2019. In both men and women, median age at diagnosis increased from 1980-2000 to 2008-2019 (Table 1). Trunk was the most common anatomic site in men (59.5%), and trunk (32.3%) and lower extremities (35.9%) the most common sites in women. The dominant subtype was superficial spreading melanoma (54.8%), followed by nodular melanoma (18.4%). In total, 90.0% of the cases were diagnosed in a local stage, whereas 5.6% had regional metastases and 4.4% had distant metastases.
Women were diagnosed at a thinner stage than men. In men, median (IQR) tumour thickness decreased from 1.4 mm (0.75–3) in 1980-1999 to 1 mm (0.6–2.3) in 2008-2019, and in women from 1 mm (0.6–2) to 0.9 mm (0.5–1.8) (Table 1).
Tumour thickness was missing in the pathology reports for more than 25% of the cases until 1990. Reporting of ulceration started in 2000, but with a large proportion of missing values. After the Norwegian Melanoma Registry was established in 2008, the proportions of missing ulceration decreased dramatically.
This unique time series of national melanoma tumour thickness data will identify trends in tumour thickness, overall and in subgroups of the population, as well as identify potential effects of changing exposure patterns and earlier detection.
-
Veierød, Marit Bragelien
(2021).
Sunscreen use, indoor tanning and skin cancer.
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Robsahm, Trude Eid; Stenehjem, Jo S.; Berge, Leon Alexander & Veierød, Marit Bragelien
(2020).
Prevalence of Indoor Tanning Among Teenagers in Norway Before and After Enforcement of Ban for Ages Under 18 Years.
Acta Dermato-Venereologica.
ISSN 0001-5555.
100(8).
doi:
10.2340/00015555-3482.
-
Veierød, Marit Bragelien
(2020).
Risikofaktorer for melanom i hud.
-
Veierød, Marit Bragelien & Lergenmuller, Simon
(2019).
https://www.med.uio.no/imb/forskning/aktuelt/aktuelle-saker/2019/risiko-hudkreft-oker-solariumsbruk.html.
[Internet].
https://www.med.uio.no/imb/forskning/aktuelt/aktuelle-saker/.
-
Veierød, Marit Bragelien
(2019).
Føflekkreft - bedre forståelse av føflekkreft gir bedre forebygging.
-
Veierød, Marit Bragelien
(2019).
Risikofaktorer for melanom.
-
Øyri, Linn Kristin Lie; Bogsrud, Martin Prøven; Christensen, Jacob J.; Ulven, Stine Marie; Brantsæter, Anne Lise & Retterstøl, Kjetil
[Show all 12 contributors for this article]
(2019).
Novel and comprehensive metabolite profiling in cord blood reveal sex differences: A sub-study from the Norwegian Mother, Father and Child Cohort study.
-
Mundal, Liv; Igland, Jannicke; Veierød, Marit Bragelien & Retterstøl, Kjetil
(2018).
THE IMPACT OF AGE AND SEX ON EXCESS RISK OF CORONARY HEART DISEASE IN PATIENTS WITH FAMILIAL HYPERCHOLESTEROLEMIA: A REGISTRY STUDY.
Atherosclerosis.
ISSN 0021-9150.
275 ,
p. E175–E175.
-
Kristoffersen, Doris Tove; Helgeland, Jon; Laake, Petter & Veierød, Marit Bragelien
(2018).
Hospitals with high or low 30-day mortality - which method should we use to identify outliers?
-
Øyri, Linn Kristin Lie; Narverud, Ingunn; Bogsrud, Martin P.; Hansson, Patrik; Leder, Lena & Byfuglien, Marte G.
[Show all 9 contributors for this article]
(2018).
LOWER POSTPRANDIAL LDL RECEPTOR GENE EXPRESSION IN PBMC
AFTER INTAKE OF SATURATED COMPARED TO POLYUNSATURATED FAT
IN SUBJECTS WITH AND WITHOUT FH.
-
Øyri, Linn Kristin Lie; Narverud, Ingunn; Bogsrud, Martin P.; Hansson, Patrik; Leder, Lena & Byfuglien, Marte G.
[Show all 9 contributors for this article]
(2018).
LOWER POSTPRANDIAL LDL RECEPTOR GENE EXPRESSION IN PBMC
AFTER INTAKE OF SATURATED COMPARED TO POLYUNSATURATED FAT
IN SUBJECTS WITH AND WITHOUT FH.
-
Øyri, Linn Kristin Lie; Narverud, Ingunn; Bogsrud, Martin P.; Hansson, Patrik; Leder, Lena & Byfuglien, Marte G.
[Show all 9 contributors for this article]
(2018).
LOWER POSTPRANDIAL LDL RECEPTOR GENE EXPRESSION IN PBMC
AFTER INTAKE OF SATURATED COMPARED TO POLYUNSATURATED FAT
IN SUBJECTS WITH AND WITHOUT FH.
-
Øyri, Linn Kristin Lie; Narverud, Ingunn; Bogsrud, Martin P.; Hansson, Patrik; Leder, Lena & Byfuglien, Marte G.
[Show all 9 contributors for this article]
(2018).
LOWER POSTPRANDIAL LDL RECEPTOR GENE EXPRESSION IN PBMC
AFTER INTAKE OF SATURATED COMPARED TO POLYUNSATURATED FAT
IN SUBJECTS WITH AND WITHOUT FH.
-
Halvorsen, Jon Anders; Løberg, Magnus; Gjersvik, Petter; Roscher, Ingrid; Veierød, Marit Bragelien & Robsahm, Trude Eid
[Show all 9 contributors for this article]
(2018).
Why a randomized melanoma screening trial is not a good idea.
British Journal of Dermatology.
ISSN 0007-0963.
179,
p. 532–533.
doi:
10.1111/bjd.16784.
-
Skodje, Gry Irene; Henriksen, Christine; Veierød, Marit Bragelien; Gibson, Peter R. & Lundin, Knut Erik Aslaksen
(2018).
Reply.
Gastroenterology.
ISSN 0016-5085.
155(1).
doi:
10.1053/j.gastro.2018.06.032.
-
Mundal, Liv; Igland, Jannicke; Tell, Grethe S.; Veierød, Marit Bragelien; Holven, Kirsten Bjørklund & Retterstøl, Kjetil
(2017).
Incidence of acute myocardial infarction and coronary heart disease in patients with genotyped familial hypercholesterolemia in Norway during
2001-2009.
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Mundal, Liv; Igland, Jannicke; Veierød, Marit Bragelien; Tell, Grethe S.; Holven, Kirsten Bjørklund & Leren, Trond Paul
[Show all 7 contributors for this article]
(2017).
Standardized incidence ratio of peripheral arterial disease and aortic stenosis in genotyped familial hypercholesterolemia in Norway during 2001-2009.
-
Retterstøl, Kjetil; Mundal, Liv; Igland, Jannicke; Tell, Grethe S.; Tell, Grethe Seppola & Veierød, Marit Bragelien
[Show all 9 contributors for this article]
(2017).
Incidence of various types of atherosclerotic disease in patients with genotyped familial hypercholesterolemia.
-
Veierød, Marit Bragelien
(2017).
Studies of ultraviolet exposure and pigmentary characteristics in the Norwegian Women and Cancer cohort.
ISM Skriftsserie.
184.
-
Øyri, Linn Kristin Lie; Hansson, Patrik; Bogsrud, Martin P.; Narverud, Ingunn; Florholmen, Geir & Leder, Lena
[Show all 10 contributors for this article]
(2017).
DIFFERENT POSTPRANDIAL TRIGLYCERIDE PEAK AFTER INTAKE OF SATURATED FAT COMPARED TO POLYUNSATURATED FAT IN SUBJECTS WITH AND WITHOUT FAMILIAL HYPERCHOLESTEROLEMIA.
-
Øyri, Linn Kristin Lie; Hansson, Patrik; Bogsrud, Martin P.; Narverud, Ingunn; Florholmen, Geir & Leder, Lena
[Show all 10 contributors for this article]
(2017).
DIFFERENT POSTPRANDIAL TRIGLYCERIDE PEAK AFTER
INTAKE OF SATURATED FAT COMPARED TO POLYUNSATURATED FAT IN SUBJECTS WITH AND WITHOUT FAMILIAL HYPERCHOLESTEROLEMIA.
-
Robsahm, Trude Eid; Stenehjem, Jo Steinson & Veierød, Marit Bragelien
(2017).
18-årsgrensen for solariebruk skal håndheves :.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
137(9),
p. 608–608.
doi:
10.4045/tidsskr.17.0130.
-
Øyri, Linn Kristin Lie; Hansson, Patrik; Bogsrud, Martin Prøven; Narverud, Ingunn; Florholmen, Geir & Leder, Lena
[Show all 10 contributors for this article]
(2017).
DIFFERENT POSTPRANDIAL TRIGLYCERIDE PEAK AFTER
INTAKE OF SATURATED FAT COMPARED TO POLYUNSATURATED FAT IN SUBJECTS WITH AND WITHOUT FAMILIAL HYPERCHOLESTEROLEMIA.
-
-
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Mundal, Liv; Veierød, Marit Bragelien; Halvorsen, Thomas; Holven, Kirsten Bjørklund; Ose, Leiv & Iversen, Per Ole
[Show all 9 contributors for this article]
(2016).
CARDIOVASCULAR DISEASE IN PATIENTS WITH FAMILIAL HYPERCHOLESTEROLEMIA IN NORWAY.
-
Mundal, Liv; Igland, Jannicke; Veierød, Marit Bragelien; Holven, Kirsten Bjørklund; Selmer, Randi & Wisløff, Torbjørn
[Show all 8 contributors for this article]
(2016).
INCIDENCE OF ACUTE MYOCARDIAL INFARCTION IN PATIENTS WITH GENOTYPED FAMILIAL HYPERCHOLESTEROLEMIA IN NORWAY DURING 2001-2009.
Circulation.
ISSN 0009-7322.
134 (25),
p. E711–E711.
-
Mundal, Liv; Igland, Jannicke; Ose, Leiv; Holven, Kirsten Bjørklund; Veierød, Marit Bragelien & Leren, Trond Paul
[Show all 7 contributors for this article]
(2016).
MORTALITY OF CARDIOVASCULAR DISEASE IN PATIENTS WITH GENETICALLY VERIFIED FAMILIAL HYPERCHOLESTEROLEMIA.
Atherosclerosis.
ISSN 0021-9150.
252,
p. E38–E38.
-
Mundal, Liv; Igland, Jannicke; Ose, Leiv; Holven, Kirsten Bjørklund; Veierød, Marit Bragelien & Leren, Trond Paul
[Show all 7 contributors for this article]
(2016).
MORTALITY OF CARDIOVASCULAR DISEASE IN PATIENTS WITH GENETICALLY VERIFIED FAMILIAL HYPERCHOLESTEROLEMIA.
-
Kristoffersen, Doris Tove; Helgeland, Jon; Clench-Aas, Jocelyne; Laake, Petter & Veierød, Marit Bragelien
(2016).
Type I error and power for detecting hospitals with high or low 30-day mortality.
-
Mansoor, Nadia; Vinknes, Kathrine; Veierød, Marit Bragelien & Retterstøl, Kjetil
(2016).
Low-carbohydrate diets increase LDL-cholesterol, and thereby indicate increased risk of CVD.
British Journal of Nutrition.
ISSN 0007-1145.
115(12),
p. 2264–2266.
doi:
10.1017/S0007114516001343.
-
Skodje, Gry Irene; Sarna, Vikas Kumar; Rolfsen, Kjersti Langballe; Hillestad Minelle, Ingunn; Muir, JG & Gibson, Peter R.
[Show all 9 contributors for this article]
(2016).
A double-blind cross-over challenge in individuals with self-reported gluten sensitivity points towards fructans as symptom trigger.
-
Narverud, Ingunn; van Lennep, Jeanine Roeters; Christensen, Jacob J.; Versmissen, Jorie; Gran, Jon Michael & Iversen, Per Ole
[Show all 14 contributors for this article]
(2016).
What is the impact of maternal inheritance of FH
on lipids and CRP in children with FH?
-
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Chortatos, Arthur; Haugen, Margaretha; Iversen, Per Ole; Vikanes, Åse Vigdis; Eberhard-Gran, Malin & Bjelland, Elisabeth Krefting
[Show all 8 contributors for this article]
(2015).
Erratum to Pregnancy complications and birth outcomes among women experiencing nausea only or nausea and vomiting during pregnancy in the Norwegian Mother and Child Cohort Study. [BMC Pregnancy Childbirth, 15, (2015), 138] doi: 10.1186/s12884-015-0580-6.
BMC Pregnancy and Childbirth.
ISSN 1471-2393.
15:167.
doi:
10.1186/s12884-015-0596-y.
-
Veierød, Marit Bragelien
(2015).
Forekomsten av føflekkreft øker igjen.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
135(5),
p. 450–452.
doi:
10.4045/tidsskr.14.1109.
-
Narverud, Ingunn; van Lennep, Jeanine Roeters; Christensen, Jacob Juel; Versmissen, Jorie; Gran, Jon Michael & Iversen, Per Ole
[Show all 15 contributors for this article]
(2014).
Cardiovascular risk markers in a large cohort of children and adolescents with genetically verified familial hypercholestelemia show no inheritance-related but LDL receptor mutation type- and family history of cardiovascular disease-related variance.
-
Torvik, Krstin; Narverud, Ingunn; Retterstøl, Kjetil; Svilaas, Arne B; Andersen, Lene Frost & Veierød, Marit Bragelien
[Show all 12 contributors for this article]
(2014).
Relation between diet and lipids in children with familial hypercholesterolemia (FH).
-
Moltu, Sissel; Blakstad, Elin Wahl; Strømmen, Kenneth; Almaas, Astrid; Nakstad, Britt & Rønnestad, Arild Erlend
[Show all 11 contributors for this article]
(2013).
Enhanced nutritional support enables postnatal growth similar to normal in utero growth in very low birth weight infants.
-
Blakstad, Elin Wahl; Strømmen, Kenneth; Moltu, Sissel; Wattam-Bell, J; Nordheim, Trond & Almaas, Astrid
[Show all 14 contributors for this article]
(2013).
Enhanced feeding improved global motion visual event-related potentials in very low birth weight infants.
-
Strømmen, Kenneth; Blakstad, Elin Wahl; Moltu, Sissel; Almaas, Astrid; Amlien, Inge & Rønnestad, Arild Erlend
[Show all 13 contributors for this article]
(2013).
Enhanced Nutrition to very low birth weight infants improves nutrition of cerebral connective tracts.
-
-
Veierød, Marit Bragelien & Nilsen, Lill Tove
(2012).
Solarium is not healthy.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
132(11),
p. 1320–1320.
doi:
10.4045/tidsskr.12.0401.
-
Parr, Christine Louise; Hjartåker, Anette; Lund, E & Veierød, Marit Bragelien
(2012).
Meat intake and colorectal cancer risk before and after measurement error correction in the Norwegain Women and Cancer study (NOWAC).
Norsk Epidemiologi, Supplement.
ISSN 0803-4206.
21.
-
Parr, Christine Louise; Hjartåker, Anette; Lund, Eiliv & Veierød, Marit Bragelien
(2012).
Meat intake and colorectal cancer risk before and after measurement error correction in the Norwegian Women and Cancer study (NOWAC).
The 8th International Conference on Diet and Activity Methods, Rome, Italy, May 14-17, 2012, Abstract Book PP032.
-
Moltu, Sissel; Blakstad, Elin Wahl; Strømmen, Kenneth; Almaas, Astrid; Nakstad, Britt & Rønnestad, Arild Erlend
[Show all 11 contributors for this article]
(2012).
Økt tilførsel av næring-stoffer gir bedret vekst hos svært premature barn.
-
Strømmen, Kenneth; Blakstad, Elin Wahl; Moltu, Sissel; Almaas, Astrid; Westerberg, Ane Cecilie & Amlien, Inge
[Show all 16 contributors for this article]
(2012).
Enhanced Nutrition to Very Low Birth Weight Infants Improves Maturation of Cerebral Connective Tracts.
-
-
Weiderpass, Elisabete & Veierød, Marit Bragelien
(2011).
Ultraviolet exposure and women's health.
Maturitas.
ISSN 0378-5122.
70(3),
p. 208–209.
-
Robsahm, Trude Eid; Nilsen, Lill Tove Norvang & Veierød, Marit Bragelien
(2011).
Solariebruk er kreftfremkallende.
Dagbladet.
ISSN 0805-3766.
p. 50–50.
-
Veierød, Marit Bragelien; Nilsen, Lill Tove Norvang & Robsahm, Trude Eid
(2011).
Oslo kommune etablerer solarier – hvorfor?
Aftenposten (morgenutg. : trykt utg.).
ISSN 0804-3116.
p. 37–37.
-
Veierød, Marit Bragelien; Nilsen, Lill Tove Norvang & Robsahm, Trude Eid
(2011).
M.B. Veierød og medarbeidere svarer.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
131,
p. 333–334.
-
Parr, Christine Louise; Hjartåker, Anette; Laake, Petter; Lund, Eiliv & Veierød, Marit Bragelien
(2009).
Recall bias in melanoma risk factors and measurement error effects: a nested case-control study within the Norwegian Women and Cancer Study.
Norsk Epidemiologi, Supplement.
ISSN 0803-4206.
19,
p. 8–8.
-
Selmer, Randi Marie; Lindman, Anja Schou; Tverdal, Aage; Pedersen, Jan I; Veierød, Marit B & Njølstad, Inger
(2009).
Begrensninger ved datagrunnlaget for NORRISK.
Tidsskrift for Den norske legeforening.
ISSN 0029-2001.
129(8).
doi:
10.4045/tidsskr.09.0203.
-
Veierød, Marit Bragelien; Veierod, MB; Parr, CL; Lund, Eiliv & Hjartaker, A
(2009).
Response: errors in assessing risk factors for melanoma.
Melanoma research.
ISSN 0960-8931.
19(1),
p. 61–61.
doi:
10.1097/CMR.0b013e3283199576.
-
-
Veierød, MB; Adami, HO; Lund, E; Armstrong, B & Weiderpass, E
(2009).
Indoor tanning and melanoma risk in a Norwegian-Swedish cohort study.
-
Veierød, MB; Adami, HO; Lund, E; Armstrong, B & Weiderpass, E
(2009).
Ultraviolet exposure in five life decades and risk of cutaneous malignant melanoma.
-
Lindman, Anja Schou; Selmer, Randi Marie; Tverdal, Aage; Pedersen, Jan I.; Njølstad, Inger & Veierød, Marit B.
(2006).
Norsk SCORE-diagram for estimering av kardiovaskulær risiko.
-
Lindman, Anja Schou; Veierød, Marit B.; Pedersen, Jan I.; Tverdal, Aage; Njølstad, Inger & Selmer, Randi Marie
(2006).
The ability of the score risk model to predict 10-year CVD mortality in Norway.
-
Parr, Christine Louise; Hjartåker, Anette; Scheel, Ida; Laake, Petter; Lund, Eiliv & Veierød, Marit Bragelien
(2006).
Substituting missing values in food frequency questionnaires (FFQs): effects on energy intake in the Norwegian Women and Cancer Study (NOWAC).
Show summary
Objective: Missing values are common in FFQs used in large epidemiological studies and must be handled when calculating energy intake. We compare results from different methods for substituting/imputing missing values using NOWAC data.
Methods: A FFQ was mailed twice (test-retest) to 1995 women aged 46-75 y from the NOWAC cohort in a reproducibility study (75% response). Missing answers in the test were imputed as follows:
1. Frequencies=0 (null intake) and portion sizes=smallest
2. Mode values
3. Median values
4. Retest values. Remaining missing values were treated as in method 1
5. K-nearest neighbors imputation using a weighted average of the values for the same question from the K=10 most similar respondents within the same dataset.
Results: After imputation of the test FFQ (17% missing data) with the different methods, estimated mean energy intake (MJ/day) with 95% CI was:
1. 6.43 (6.34, 6.53)
2. 6.92 (6.83, 7.01)
3. 7.16 (7.06, 7.25)
4. 6.93 (6.84, 7.03)
5. 7.52 (7.42, 7.62)
Conclusion: Exclusion is not practical when most respondents have missing values. However, the calculated energy intake is influenced by the imputation method. Treating missing as null intake may not be correct for all foods and may lead to underestimation of energy intake.
-
Lindman, AS; Selmer, R; Tverdal, A; Eggen, Anne Elise; Pedersen, IJ & Veierød, MB
(2005).
The SCORE risk function applied on population surveys in Norway.
Prevention and control.
1,
p. 85–86.
Show summary
Sixth International Conference on Preventive Cardiology, Brazil 2005
-
Parr, Christine Louise; Hjartåker, Anette; Scheel, Ida; Laake, Petter; Lund, Eiliv & Veierød, Marit Bragelien
(2005).
Substituting missing values in food frequency questionnaires (FFQs): effects on energy intake in the Norwegian Women and Cancer Study.
Show summary
Objective: Missing values are common in self-administered FFQs used in large epidemiological studies and must be handled when calculating energy and nutrient intake. We compare results from different methods for substituting/imputing missing values using data from the Norwegian Women and Cancer study (NOWAC). We include K-nearest neighbors imputation (KNNimpute). This is a widely used method for missing entries in cDNA microarray data, but is here extended and adapted to FFQ data, which is new to our knowledge.
Methods: A FFQ designed to assess habitual diet was mailed twice (test-retest 3 months apart) to a random sample of 1995 women aged 46-75 y from the NOWAC cohort as part of a reproducibility study (75% response). A total of 126 questions were included in the dietary intake calculations. Missing answers to consumption frequencies and portion sizes in the test FFQ were imputed before the calculations using the following methods:
1. Frequencies=0 (null intake) and portion sizes=smallest for a conservative estimate
2. The mode value
3. The median value
4. Non-missing values in the retest. Remaining missing values were treated as in method 1
5. KNNimpute using a weighted average of the values for the same question from the K=10 most similar respondents within the same dataset (test). Similarity is evaluated from the closeness of responses to the other FFQ questions.
Results: In the test FFQ 17% of the data matrix was missing. Among respondents (n=1495) 95% had ≥1 missing answer. After imputation with retest values (method 4), 10% of the data was still missing and treated as in method 1. The estimated mean energy intake (MJ/day) with 95% CI after imputation according to the different methods was:
1. 6.43 (6.34, 6.53) for null intake and the smallest portion
2. 6.92 (6.83, 7.01) for mode
3. 7.16 (7.06, 7.25) for median
4. 6.93 (6.84, 7.03) for retest
5. 7.52 (7.42, 7.62) for KNNimpute
Conclusion: Exclusion is not practical when most respondents have missing values. However, the calculated energy intake is influenced by the imputation method used. Missing is frequently handled as null intake, but this may not be correct for all foods. This is indicated by the increase in energy when missing is imputed by the other methods, including the retest values from the same respondents 3 months later. KNNimpute gave the highest energy intake, and will be investigated further.
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Parr, Christine Louise; Veierød, Marit Bragelien; Laake, Petter; Lund, Eiliv & Hjartåker, Anette
(2005).
Effects of replacing missing values in food frequency questionnaires (FFQs) in the Norwegian Women and Cancer Study (NOWAC).
Show summary
Objective: Missing values are common in self-administered FFQs. Since exclusion of all respondents with missing values is usually not practical when calculating energy and nutrient intake, missing values must be handled. We compare dietary intake calculated using two different methods for replacing missing values.
Methods: A FFQ was mailed twice (test-retest 3 months apart) to a random sample of 1995 women aged 46-75 y from the NOWAC cohort as part of a reproducibility study (75% response). All women had some missing values in the test FFQ. Energy and nutrient intake from the test was first calculated by treating missing frequencies as no consumption and missing portions as the smallest portion size. In the second calculation we replaced missing values in the test by non-missing values in the retest. Remaining missing values were treated as in the first calculation.
Results: The mean energy intake in the test was 6.4 MJ (SD=1.9) before and 6.9 MJ (SD=1.9) after the imputation with retest values. The mean change in individual intake was +10% for energy and ranged from +9% (iron) to +27% (vitamin D) for nutrients. The mean change in % energy from macronutrients was <2%, but larger for sugar (+5%) and alcohol (+11%).
Conclusion: The increase in energy intake after imputation with retest values indicates that missing values in FFQs should not always be interpreted as no consumption. In the absence of better estimates, using null intake in nutrient calculation programs may lead to underestimation of dietary intake.
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Veierod, MB; Veierød, Marit Bragelien; Weiderpass, E; Lund, Eiliv; Armstrong, B & Adami, HO
(2004).
Re: A prospective study of pigmentation, sun exposure, and risk of cutaneous malignant melanoma in women - Response.
Journal of the National Cancer Institute.
ISSN 0027-8874.
96,
p. 337–338.