School absence policy and healthcare use: a difference-in-difference cohort analysis.

Background: A national policy in Norway demanding certificates for medical absences in upper secondary school was implemented in 2016, leading to an increase in general practitioner (GP) visits in this age group.

Objectives: To assess the policy's effect on the use of primary and specialist healthcare.

Methods: A cohort study following all Norwegian youth aged 14-21 in the years 2010-2019 using a difference-in-differences approach comparing exposed cohorts expected to attend upper secondary school after the policy change in 2016 with previous unexposed cohorts.

Use of general practitioner services among youth and young adults in Norway from 2006 to 2021.

Objective: To describe the frequency and content of contacts with general practitioners (GPs) among youth and young adults by sex, age and time, emphasizing mental health, sexual health and respiratory tract infections.

Design: Registry-based population-wide cohort study.

Setting: General practice in Norway 2006-2021.

Prescription of potentially addictive medications after a multilevel community intervention in general practice.

Objective: To evaluate the long-term effects of a multilevel community intervention to improve the quality of prescription practice of potentially addictive medications (PAMs).

Design: We conducted a retrospective study, using anonymized data from the Norwegian prescription registry.

Setting: Based on an initiative from the GPs in Molde Municipality in Norway, a multilevel community intervention was initiated by the municipal chief physician in 2018.

Impact of altering referral threshold from out-of-hours primary care to hospital on patient safety and further health service use: a cohort study.

Objectives: To estimate the impact of altering referral thresholds from out-of-hours services on older patients' further use of health services and risk of death.

Design: Cohort study using patient data from primary and specialised health services and demographic data from Statistics Norway and the Norwegian Cause of Death Registry.

Setting: Norway PARTICIPANTS: 491 653 patients aged 65 years and older contacting Norwegian out-of-hours services between 2008 and 2016.

Do they cope or mope? A survey of GPs' experiences with the changes in the Norwegian Cervical Cancer Screening Programme.

Objective: To explore Norwegian general practitioners' (GPs) experiences with the changes in the cervical cancer screening programme and to uncover which aspects of the programme they find most challenging.

Design: We conducted an electronic cross-sectional survey.

Setting: Norwegian GPs were invited to participate in the survey between February and September in 2020.

Cervical cancer mortality in Norway according to screening attendance and age.

Introduction: The association between cervical cancer screening and reduction of cervical cancer has been dealt with in much research. However, little has been published on the association between screening and cervical cancer mortality. We assessed cervical cancer deaths according to screening history, histopathology, and age among women in, under, and above screening age.

Body mass index and healthcare costs: using genetic variants from the HUNT study as instrumental variables.

Background: Past studies have found associations between obesity and healthcare costs, however, these studies have suffered from bias due to omitted variables, reverse causality, and measurement error.

Methods: We used genetic variants related to body mass index (BMI) as instruments for BMI; thereby exploiting the natural randomization of genetic variants that occurs at conception. We used data on measured height and weight, genetic information, and sociodemographic factors from the Nord-Trøndelag Health Studies (HUNT), and individual-level registry data on healthcare costs, educational level, registration status, and biological relatives.

Effects of GP characteristics on unplanned hospital admissions and patient safety. A 9-year follow-up of all Norwegian out-of-hours contacts.

Background: There are substantial differences in hospital referrals between general practitioners (GPs); however, there is little research on the consequences for patient safety and further healthcare use.

Objective: To investigate associations between out-of-hours GP characteristics, unplanned hospital admissions, and patient safety.

Methods: This cohort study included all Norwegian out-of-hours services contacts from 2008 to 2016, linked to registry data on patient characteristics, healthcare use and death, and GP age, sex, specialist status, out-of-hours service experience, and prior admission proportion.

Intergenerational polygenic obesity risk throughout adolescence in a cross-sectional study design: The HUNT study, Norway.

Objective: This study examined the relationship between parental obesity polygenic risk and children's BMI throughout adolescence. Additionally, from a smaller subsample, the objective was to assess whether parental polygenic risk score (PRS) may act as a proxy for offspring PRS in studies lacking offspring genetic data.

Methods: A total of 8,561 parent-offspring (age 13-19 years) trios from the Trøndelag Health Study (the HUNT Study) were included, of which, 1,286 adolescents had available genetic data.

Genetic associations with temporal shifts in obesity and severe obesity during the obesity epidemic in Norway: A longitudinal population-based cohort (the HUNT Study).

Background: Obesity has tripled worldwide since 1975 as environments are becoming more obesogenic. Our study investigates how changes in population weight and obesity over time are associated with genetic predisposition in the context of an obesogenic environment over 6 decades and examines the robustness of the findings using sibling design.

Methods And Findings: A total of 67,110 individuals aged 13-80 years in the Nord-Trøndelag region of Norway participated with repeated standardized body mass index (BMI) measurements from 1966 to 2019 and were genotyped in a longitudinal population-based health study, the Trøndelag Health Study (the HUNT Study).

Separating the genetics of childhood and adult obesity: a validation study of genetic scores for body mass index in adolescence and adulthood in the HUNT Study.

From a life-course perspective, genetic and environmental factors driving childhood obesity may have a lasting influence on health later in life. However, how obesity trajectories vary throughout the life-course remains unknown. Recently, Richardson et al.

Avoiding dynastic, assortative mating, and population stratification biases in Mendelian randomization through within-family analyses.

Estimates from Mendelian randomization studies of unrelated individuals can be biased due to uncontrolled confounding from familial effects. Here we describe methods for within-family Mendelian randomization analyses and use simulation studies to show that family-based analyses can reduce such biases. We illustrate empirically how familial effects can affect estimates using data from 61,008 siblings from the Nord-Trøndelag Health Study and UK Biobank and replicated our findings using 222,368 siblings from 23andMe.

Quantifying the impact of genes on body mass index during the obesity epidemic: longitudinal findings from the HUNT Study.

Objectives: To study the trajectories of body mass index (BMI) in Norway over five decades and to assess the differential influence of the obesogenic environment on BMI according to genetic predisposition.

Design: Longitudinal study.

Setting: General population of Nord-Trøndelag County, Norway.

The effect of smoking intensity on all-cause and cause-specific mortality-a Mendelian randomization analysis.

Background: Smoking is an important cause of mortality and recent studies have suggested that even low-intensity smoking might be associated with increased mortality. Still, smoking is associated with lower socio-economic status as well as other potential risk factors, and disease onset might motivate smoking cessation, thus residual confounding and reverse causality might bias results. We aimed to assess the evidence of a causal relationship between smoking intensity and cause-specific as well as all-cause-mortality using Mendelian randomization analyses.

Body mass index and all cause mortality in HUNT and UK Biobank studies: linear and non-linear mendelian randomisation analyses.

Editor's Note: Please see the Editor's Note (doi: https://doi.org/10.1136/bmj.

Evidence of a causal relationship between body mass index and psoriasis: A mendelian randomization study.

Background: Psoriasis is a common inflammatory skin disease that has been reported to be associated with obesity. We aimed to investigate a possible causal relationship between body mass index (BMI) and psoriasis.

Methods And Findings: Following a review of published epidemiological evidence of the association between obesity and psoriasis, mendelian randomization (MR) was used to test for a causal relationship with BMI.

Temporal changes in health within 5 years before and after disability pension-the HUNT Study.

Background: Health status has been reported to change before, during and after disability pension receipt. These associations might be subject to temporal changes according to changes in policy, incidence of disability pensions and other contextual factors. We compared the perceived health around time of disability retirement among persons receiving disability pension in the 1990 s and 2000 s in Norway.

Cardiovascular mortality - Comparing risk factor associations within couples and in the total population - The HUNT Study.

Background: To compare associations of conventional risk factors with cardiovascular death within couples and in the population as a whole.

Methods: We analysed baseline data (1995-97) from the HUNT2 Study in Norway linked to the national Causes of Death Registry. We compared risk within couples using stratified Cox regression.

Health and unemployment: 14 years of follow-up on job loss in the Norwegian HUNT Study.

Background: Many studies have investigated how unemployment influences health, less attention has been paid to the reverse causal direction; how health may influence the risk of becoming unemployed. We prospectively investigated a wide range of health measures and subsequent risk of unemployment during 14 years of follow-up.

Methods: Self-reported health data from 36 249 participants in the Norwegian HUNT2 Study (1995-1997) was linked by a personal identification number to the National Insurance Database (1992-2008).

Mortality and work disability in a cohort of Norwegian couples--the HUNT study.

Background: Poor health is clustered in families, and partners might influence each other. We studied possible consequences of living with a spouse with poor health or unhealthy lifestyle on mortality and work disability.

Methods: In total, 18 943 couples from the HUNT2 Study (1995-97) were linked to national registries and followed until December 2007, identifying deaths and disability pension retirements.

The Health Hazards of Marriage. A cohort study of work related disability within 12,500 Norwegian couples - the HUNT Study.

Aims: Work disability and sickness absence increase following partner's retirement, which similarities in spouses' health could explain. We therefore studied the risk of work disability within couples, taking account of baseline health, lifestyle and socioeconomic factors.

Methods: A cohort of 12,511 couples from the HUNT Study (aged 20-67 years in HUNT2, 1995-1997) was linked to national registries, identifying all new cases of disability pension up until December 2007.