Vitamin D, obesity and cutaneous melanoma
In a collaboration with the Cancer Registry of Norway, a protocol was established for prospective studies of 25-hydroxyvitamin D, leptin and body mass index in relation to cutaneous melanoma incidence and survival (Stenehjem et al, 2017), and we have studied anthropometric factors and melanoma risk (Stenehjem et al, 2018) and tumour thickness (Stenehjem et al., 2018); and vitamin D and melanoma risk (Stenehjem et al, 2020) and death (Stenehjem et al, 2022).
Indoor tanning: irradiance and use in teenagers
In collaboration with the Norwegian Radiation and Nuclear Safety Authority, we studied spectral UVB and UVA solarium irradiances and documented that these are 0.5-3.7 and 3-26 times, respectively, higher than from Oslo summer sun (Nilsen et al, 2008; Nilsen et al, 2011; Nilsen et al, 2012) and conducted a systematic review of the literature on UV irradiance from indoor tanning devices (Nilsen et al, 2016). In collaboration with the Cancer Registry of Norway, we studied prevalence of indoor tanning in teenagers (Robsahm et el, 2020).
Previous projects in the Norwegian Women and Cancer (NOWAC) cohort
In NOWAC, we have studied studied meat intake and cooking methods in relation to colorectal cancer risk (Parr et al, 2013). UV exposure, via its effects on vitamin D synthesis, might have beneficial effects on several conditions including cancer, and we studied potential positive aspects of UV exposure (Veierød et al, 2010; Edvardsen et al, 2011; Yang et al, 2011). We also studied the use of skin care products among Norwegian women (Aniasson et al, 2016) and the use of skin care products and risk of cancer of the breast and endometrium (Rylander et al, 2019). Results of our skin cancer research in NOWAC are described in Achievements in ongoing projects.
Nausea and vomiting in pregnancy
The properties of the gestational diet have become increasingly associated with consequences for the future health of the offspring. In the MoBa study, we have assessed dietary intake, as well as demographic profile and lifestyle factors, in relation to nausea and vomiting in pregnancy (Chortatos et al, 2013; Chortatos et al, 2015; Chortatos et al, 2018).
30-day mortality as a quality indicator
In collaboration with the Norwegian Institute of Public Health, we studied 30-day mortality as a quality indicator for Norwegian hospitals (Kristoffersen et al, 2012), and statistical methods for identifying hospitals with low or high mortality (Kristoffersen et al, 2018).
Long-term effects of trans fatty acids intake on risk of cardiovascular diseases and cancer and of body fatness on colon cancer risk
Body mass index is and established risk factor for colon cancer and using data from the Norwegian County Study, we studied whether risk differ between genders and colon subsites, and whether weight change influence colon cancer risk (Laake et al, 2010) and prognosis (Laake et al, 2016). In the same cohort, we also studied trans fatty acid intake and cancer risk and CVD mortality (Laake et al, 2012; Laake et al, 2013).
Applications of path analysis and functional data analysis in a longitudinal, clinical cohort study of pregnant women and their neonates
Oral glucose tolerance tests (OGTT) are important in medical care/research, and often studied by simple summary measures. We extracted information inherent in the shape of OGTT curves, compared it with the information from simple summary measures, and explored the clinical usefulness of such information (Frøslie et al, 2013; Frøslie et al, 2014). In this project, we found an unexpectedly increase in glucose values during a 7-year period, likely due to bias during long-term use of a glucose measurement system, and concluded that biologically implausible trends in data can be corrected by using independent control values (Frøslie et al, 2011). We also investigated the potential mediating roles of Interleukin 6 and Interleukin 1 Respetor anatagonist in the association between maternal body mass index and birth weight (Frøslie et al, 2010), and revisited the general statistical advice to keep continuous exposure variables as continuous in the analyses (Frøslie et al, 2010).
NORRISK - a cardiovascular disease risk model
In collaboration with National Institute of Public Health, we applied the Systematic Coronary Risk Evaluation (SCORE) risk model to Norwegian population surveys (Lindman et al, 2006; Lindman et al, 2007). Adjustments were required before implementation in clinical practice, thus we developed a cardiovascular disease (CVD) risk model, NORRISK (Selmer et al, 2008), that was implemented in the Norwegian guidelines for CVD prevention (Norwegian Directorate of Health, 2009 (in Norwegian)) and available as a risk calculator (in Norwegian).