Benzene exposure and risk of lung cancer in the Norwegian Offshore Petroleum Worker cohort: a prospective case-cohort study.

Objective: The objective of our study was to examine whether occupational exposure to benzene is associated with lung cancer among males in the Norwegian Offshore Petroleum Workers cohort.

Methods: Among 25 347 male offshore workers employed during 1965-1998, we conducted a case-cohort study with 399 lung cancer cases diagnosed between 1999 and 2021, and 2035 non-cases sampled randomly by 5-year birth cohorts. Individual work histories were coupled to study-specific job-exposure matrices for benzene and other known lung carcinogens.

Exposure to benzene and other hydrocarbons and risk of bladder cancer among male offshore petroleum workers.

Background: Occupational exposures constitute the second leading cause of urinary bladder cancer after tobacco smoking. Increased risks have been found in the petroleum industry, but high-quality exposure data are needed to explain these observations.

Methods: Using a prospective case-cohort design, we analysed 189 bladder cancer cases (1999-2017) and 2065 randomly drawn non-cases from the Norwegian Offshore Petroleum Workers cohort.

Night shift work and risk of aggressive prostate cancer in the Norwegian Offshore Petroleum Workers (NOPW) cohort.

Background: Night shift work may acutely disrupt the circadian rhythm, with possible carcinogenic effects. Prostate cancer has few established risk factors though night shift work, a probable human carcinogen, may increase the risk. We aimed to study the association between night shift work and chlorinated degreasing agents (CDAs) as possible endocrine disrupters in relation to aggressive prostate cancer as verified malignancies.

Sexual Debut Ages in Heterosexual Norwegians Across Six Birth Cohorts.

This study aims to estimate six different sexual debut ages in heterosexual Norwegians in six birth cohorts of the general population in Norway. The results are based on a 2020 national web panel survey of 18-89-year-olds in Norway (n = 4160). There was a general decline in the median debut age from those aged 70+ to those 18-29 (born 1991-2002).

Cox regression can be collapsible and Aalen regression can be non-collapsible.

It is well-known that the additive hazards model is collapsible, in the sense that when omitting one covariate from a model with two independent covariates, the marginal model is still an additive hazards model with the same regression coefficient or function for the remaining covariate. In contrast, for the proportional hazards model under the same covariate assumption, the marginal model is no longer a proportional hazards model and is not collapsible. These results, however, relate to the model specification and not to the regression parameter estimators.

Maternal and paternal anxiety during pregnancy: Comparing the effects on behavioral problems in offspring.

Prenatal maternal anxiety has been associated with both short and long-term mental health problems in the child. The current study aims to examine the association between maternal and paternal prenatal anxiety and behaviour problems in the child at 1.5 and 5 years, using three different approaches; (1) adjusting for covariates, (2) using fathers' anxiety during pregnancy as a negative control, and (3) using a sibling-comparison design, controlling for unmeasured family factors.

The blood microbiome and its association to cardiovascular disease mortality: case-cohort study.

Background: Little is known about the association between bacterial DNA in human blood and the risk of cardiovascular disease (CVD) mortality.

Methods: A case-cohort study was performed based on a 9 ½ year follow-up of the Oslo II study from 2000. Eligible for this analysis were men born in 1923 and from 1926 to 1932.

Night shift work, chemical coexposures and risk of female breast cancer in the Norwegian Offshore Petroleum Workers (NOPW) cohort: a prospectively recruited case-cohort study.

Objectives: This study examined the association between night shift work and risk of breast cancer, overall and by hormone receptor subtype, among females in the Norwegian Offshore Petroleum Workers (NOPW) cohort. We also examined the association of coexposure (chlorinated degreasers and benzene) and breast cancer risk, and possible interaction with work schedule.

Design: Prospectively recruited case-cohort study within the NOPW cohort.

Maternal Anxiety and Infants Birthweight and Length of Gestation. A sibling design.

Background: The overall aim of this study is to examine the effect of prenatal maternal anxiety on birthweight and gestational age, controlling for shared family confounding using a sibling comparison design.

Methods: The data on 77,970 mothers and their 91,165 children from the population-based Mother, Father and Child Cohort Study and data on 12,480 pairs of siblings were used in this study. The mothers filled out questionnaires for each unique pregnancy, at 17 and 30 week in pregnancy.

Socio-economic differences in all-cause mortality in people with alcohol use disorder: a prospective cohort study.

Background And Aims: While alcohol-attributable mortality rates are higher in low socio-economic status (SES) groups, less is known about SES differences in all-cause mortality in alcohol use disorder (AUD). The aim of this study was to explore whether there are SES differences in people with AUD, regarding (i) treatment admission, (ii) all-cause mortality risk and (iii) relative mortality risk.

Design And Setting: A prospective cohort study in Norway, follow-up period from 2009-10 to 2013.

The cure model in perinatal epidemiology.

In the statistical literature, the class of survival analysis models known as cure models has received much attention in recent years. Cure models seem not, however, to be part of the statistical toolbox of perinatal epidemiologists. In this paper, we demonstrate that in perinatal epidemiological studies where one investigates the relation between a gestational exposure and a condition that can only be ascertained after several years, cure models may provide the correct statistical framework.

Seasonal and pandemic influenza during pregnancy and risk of fetal death: A Norwegian registry-based cohort study.

Previous studies of fetal death with maternal influenza have been inconsistent. We explored the effect of maternal influenza-like illness (ILI) in pregnancy on the risk of fetal death, distinguishing between diagnoses during regular influenza seasons and the 2009/2010 pandemic and between trimesters of ILI. We used birth records from the Medical Birth Registry of Norway to identify fetal deaths after the first trimester in singleton pregnancies (2006-2013).

Adjusting for unmeasured confounding using validation data: Simplified two-stage calibration for survival and dichotomous outcomes.

In epidemiology, one typically wants to estimate the risk of an outcome associated with an exposure after adjusting for confounders. Sometimes, outcome and exposure and maybe some confounders are available in a large data set, whereas some important confounders are only available in a validation data set that is typically a subset of the main data set. A generally applicable method in this situation is the two-stage calibration (TSC) method.

Re-examining the link between prenatal maternal anxiety and child emotional difficulties, using a sibling design.

Background: Prenatal exposure to maternal anxiety has been associated with child emotional difficulties in a number of epidemiological studies. One key concern, however, is that this link is vulnerable to confounding by pleiotropic genes or environmental family factors.

Methods: Data on 82 383 mothers and children from the population-based Mother and Child Cohort Study and data on 21 980 siblings were used in this study.

Aromatic hydrocarbons and risk of skin cancer by anatomical site in 25 000 male offshore petroleum workers.

Background: We prospectively examined skin cancer risk according to occupational exposure to aromatic hydrocarbons with adjustment for ultraviolet radiation exposure, in a cohort of 24 917 male offshore petroleum workers.

Methods: Hazard ratios (HRs) and 95% confidence intervals were estimated with Cox regression adapted to a stratified case-cohort design.

Results: During 13.

Long Term Association between Serum 25-Hydroxyvitamin D and Mortality in a Cohort of 4379 Men.

Objective: A number of observational studies have shown an inverse association between circulating 25-hydroxyvitamin D and total mortality, but a reverse J-shaped association has also been reported. In a large nested case-control study, serum-25-hydroxyvitamin D (s-25(OH)D) was positively associated with incident prostate cancer. Based on the same study population, the primary aim of the present study was to investigate the association between s-25(OH)D and total mortality.

No increase in risk of hip fracture at high serum retinol concentrations in community-dwelling older Norwegians: the Norwegian Epidemiologic Osteoporosis Studies.

Background: Norway has the highest hip fracture rates worldwide and a relatively high vitamin A intake. Increased fracture risk at high intakes and serum concentrations of retinol (s-retinol) have been observed in epidemiologic studies.

Objective: We aimed to study the association between s-retinol and hip fracture and whether high s-retinol may counteract a preventive effect of vitamin D.

Inverse probability weighting in nested case-control studies with additional matching--a simulation study.

Nested case-control designs are inevitably less efficient than full cohort designs, and it is important to use available information as efficiently as possible. Reuse of controls by inverse probability weighting may be one way to obtain efficiency improvements, and it can be particularly advantageous when two or more endpoints are analyzed in the same cohort. The controls in a nested case-control design are often matched on additional factors than at risk status, and this should be taken into account when reusing controls.

Low serum levels of 25-hydroxyvitamin D predict hip fracture in the elderly: a NOREPOS study.

Background: Despite considerable interest, the relationship between circulating 25-hydroxyvitamin D and the risk of hip fracture is not fully established.

Objective: The objective of the study was to study the association between serum 25-hydroxyvitamin D concentrations [s-25(OH)D] and the risk of hip fracture in Norway, a high-latitude country that has some of the highest hip fracture rates worldwide.

Methods: A total of 21 774 men and women aged 65-79 years attended 4 community-based health studies during 1994-2001.

Fetal death and placental weight/birthweight ratio: a population study.

Objective: To study the association of placental weight and placental weight/birthweight ratio with gestational age-specific fetal death.

Design: Population-based study.

Setting: Medical Birth Registry of Norway.

Risk of fetal death after pandemic influenza virus infection or vaccination.

Background: During the 2009 influenza A (H1N1) pandemic, pregnant women were at risk for severe influenza illness. This concern was complicated by questions about vaccine safety in pregnant women that were raised by anecdotal reports of fetal deaths after vaccination.

Methods: We explored the safety of influenza vaccination of pregnant women by linking Norwegian national registries and medical consultation data to determine influenza diagnosis, vaccination status, birth outcomes, and background information for pregnant women before, during, and after the pandemic.