Abstract: BACKGROUND: COPD is a major cause of morbidity and mortality across the world and new estimates of prevalence and trend are of great importance. We aimed to estimate the prevalence and trend of COPD from 1995-1997 to 2006-2008 in Norwegian adults >/=40 years from the Nord-Trondelag Health Study. MATERIAL AND METHODS: COPD was assessed using a fixed-ratio and lower limit of normal (LLN) criteria. Pre-bronchodilator spirometry was performed during 1995-1997 (n=7158) and 2006-2008 (n=8788). The prevalence of COPD was weighted using the inverse probability of selection and predicted probability of response. RESULTS: The prevalence of pre-bronchodilator COPD was 16.7% in 1995-1997 and 14.8% in 2006-2008 using fixed-ratio criteria, and 10.4% in 1995-1997 and 7.3% in 2006-2008 using LLN criteria. The prevalence of LLN COPD was higher among men (13.0% in 1995-1997, 7.7% in 2006-2008) than women (8.0% in 1995-1997, 6.9% in 2006-2008). From 1995-1997 to 2006-2008, the prevalence decreased among men but remained relatively stable among women. Over the 11-year period, the cumulative incidence of pre-bronchodilator COPD using LLN criteria was 3.3% and 2.7% among men and women respectively. The prevalence of self-reported asthma and respiratory symptoms increased. CONCLUSIONS: The prevalence declined in men but not in women from 1995-1997 to 2006-2008, and was consistently higher among men than women.

Abstract: BACKGROUND: There is little knowledge about how factors early in life affect the development of migraine and tension-type headache. We aimed to examine whether growth restriction in utero is associated with development of migraine and frequent tension-type headache in adults. METHODS: The population-based Nord-Trondelag Health Study (HUNT 3) contained a validated headache questionnaire, which differentiated between migraine and tension-type headache. These data were linked to information on weight and gestational age at birth from the Norwegian Medical Birth Registry. In total 4557 females and 2789 males, aged 19-41 years, were included in this registry-based study. Participants were categorized as appropriate for gestational age (AGA, 10th-90th percentile), small for gestational age (SGA, 3rd-10th percentile) or very small for gestational age (VSGA, < 3rd percentile). Logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI) for migraine and tension-type headache, with exposure being growth restriction at birth. RESULTS: The effect of growth restriction on migraine was modified by sex, with a significant association in males (p<0.001), but not in females (p = 0.20). In particular, males born VSGA were at increased risk of developing migraine (OR 2.73, 95% CI 1.63-4.58, p<0.001), with an intermediate risk among those born SGA (OR 1.50, 95% CI 0.96-2.35, p = 0.08) compared to those born AGA. There was no significant association between growth restriction and frequent TTH (p = 0.051). CONCLUSION: Growth restriction was associated with increased risk of migraine in adulthood among males, but not among females. This suggests that migraine might, in part, be influenced by early life events, and that males seem to be particularly vulnerable.

Abstract: The aim of this paper was to investigate whether psychosocial functioning in adulthood (e.g., friends support, cohabitation, community connectedness and work satisfaction) could be predicted by mental health, subjective well-being, social relations and behavior problems in adolescence, and whether gender was a moderator in these associations. Data were obtained from a major population-based Norwegian study, the Nord-Trondelag Health Study (HUNT), in which 517 men and 819 women completed an extensive self-report questionnaires at baseline (mean age 14.4 years) and at follow-up (mean age 26.9 years). Community connectedness as well as work satisfaction were predicted by subjective well-being. Cohabitation was predicted by male gender and frequency of meeting friends in adolescence, and friends support was predicted by frequency of meeting friends. Gender had a minor effect as a moderator. Frequency of meeting friends and subjective well-being seemed to be the strongest adolescent predictors of psychosocial functioning in young adulthood. These findings may have implications both for prevention and intervention in adolescence, as well as for future research.

Abstract: BACKGROUND: The magnitude of participation bias due to non-participation should be considered for cancer patients invited to population-based surveys. We studied participation rates among persons with and without cancer in a large population based study, the Nord-Trondelag Health Study (HUNT). METHODS: Citizens 20 years or above living in the Nord-Trondelag County of Norway have been invited three times to comprehensive health surveys. The invitation files with data on sex, invitation date and participation were linked to the Cancer Registry of Norway. In a first step unadjusted crude participation rates (participants/invited persons) were estimated for cancer patients (CaPts) and non-cancer persons (NonCaPers), followed by logistic regression analyses with adjustment for age and sex. To evaluate the “practical” significance of the estimated odds ratios in the cancer diagnosis group, relative risks were also estimated comparing the observed rates to the estimated rates under the counterfactual assumption of no earlier cancer diagnosis among CaPts. RESULTS: Overall 3 % of the participants in the three HUNT studies were CaPts and 59 % of them had been diagnosed with their first life-time cancer >5 years prior to each survey. In each of the three HUNT surveys crude participation rates were similar for CaPts and NonCaPers. Adjusted for sex and age, CaPts' likelihood to participate in HUNT1 (1984-86) and HUNT2 (1995-97), but not in HUNT3 (2006-2008), was statistically significantly reduced compared to NonCaPers, equaling a relative risk of 0.98 and 0.96, respectively. The lowest odds ratio emerged for CaPts diagnosed during the last 2 years preceding a HUNT invitation. Only one-third of CaPts participating in a survey also participated in the subsequent survey compared to approximately two-thirds of NonCaPers, and 11 % of CaPts participated in all three HUNT surveys compared to 37 % of NonCaPers. CONCLUSION: In the three HUNT surveys no or only minor participation bias exist as to CaPts' participation rates. In longitudinal studies selection bias as to long-term cancer survivorship should be taken into account, the percentage of repeatedly participating CaPts diminishing more strongly than among NonCaPers.

Abstract: BACKGROUND: Lowered physical activity levels may partially explain changes in metabolic risk factors in women after menopause. OBJECTIVES: To evaluate the association between physical activity and metabolic risk factors at baseline and after 11 years, as well as the change in that association over time in women who were premenopausal and >/= 40 years at baseline. METHODS: Subjects in a Norwegian population-based health survey answered questionnaires and had body and serum measurements during 1995-1997 (HUNT 2) and in a follow-up study during 2006-2008 (HUNT 3). Repeated-measures analyses were used to estimate the association between physical activity and metabolic factors, adjusting for age, smoking status, education, alcohol intake, and parity. Adjustment for hormonal treatment and medication was made, as appropriate. RESULTS: In women remaining premenopausal, a higher physical activity score in HUNT 3 was associated with lower weight (p < 0.01) and waist-hip ratio (p < 0.01) and higher high density lipoprotein (HDL) cholesterol in HUNT 3 (p < 0.01). In women that were postmenopausal by the time of follow-up, a higher physical activity score in HUNT 3 was associated with lower weight (p < 0.01), waist-hip ratio (p < 0.01), triglycerides (p < 0.01), and higher total cholesterol (p < 0.05), HDL cholesterol (p < 0.01), and diastolic blood pressure (p < 0.05) in HUNT 3. The association of total physical activity score with weight and waist-hip ratio was stronger in HUNT 3 than in HUNT 2 (p < 0.01). CONCLUSION: Increased physical activity may reduce the risk of adverse outcomes and use of pharmacological management in women of menopausal age.

Abstract: BACKGROUND: People with a lower socioeconomic position have a higher the prevalence of most self-rated health problems. In this article we ask whether this may be attributed to self-rated health not reflecting actual health, understood as mortality, in different socioeconomic groups. MATERIAL AND METHOD: For the study we used data from the Nord-Trondelag Health Study 1984-86 (HUNT1), in which the county's entire adult population aged 20 years and above were invited to participate. The association between self-rated health and mortality in different occupational classes and income groups was analysed. The analysis corrected for age, chronic disease, functional impairment and lifestyle factors. RESULTS: The association between self-rated health and mortality was of the same order of magnitude for the occupational classes and income groups, but persons without work/income and with poor self-rated health stood out. Compared with persons in the highest socioeconomic class, unemployed men had a hazard ratio for death that was three times higher in the follow-up period. For women with no income, the ratio was twice as high. INTERPRETATION Self-rated health and mortality largely conform to the different socioeconomic strata. This supports the perception that socioeconomic differences in health are a reality and represent a significant challenge nationally. Our results also increase the credibility of findings from other studies that use self-reported health in surveys to measure differences and identify the mechanisms that create them.

Abstract: BACKGROUND: Studies have shown an independent association between poor self-rated health (SRH) and increased mortality. Few studies, however, have investigated any possible impact on SRH of diagnostic labelling. OBJECTIVE: To test whether SRH differed in persons with known and unknown hypothyroidism, diabetes mellitus (DM) or hypertension, opposed to persons without these conditions, after 11-year follow-up. METHODS: Prospective population-based cohort study in North-Trondelag County, Norway, HUNT2 (1995-97) to HUNT3 (2006-08). All inhabitants aged 20 years and older were invited. The response rate was 69.5% in HUNT2 and 54.1% in HUNT3. In total, 34144 persons aged 20-70 years were included in the study population. The outcome was poor SRH. RESULTS: Persons with known disease had an increased odds ratio (OR) to report poor SRH at follow-up; figures ranging from 1.11 (0.68-1.79) to 2.52 (1.46-4.34) (men with hypothyroidism kept out owing to too few numbers). However, in persons not reporting, but having laboratory results indicating these diseases (unknown disease), no corresponding associations with SRH were found. Contrary, the OR for poor SRH in women with unknown hypothyroidism and unknown hypertension was 0.64 (0.38-1.06) and 0.89 (0.79-1.01), respectively. CONCLUSIONS: Awareness opposed to ignorance of hypothyroidism, DM and hypertension seemed to be associated with poor perceived health, suggesting that diagnostic labelling could have a negative effect on SRH. This relationship needs to be tested more thoroughly in future research but should be kept in mind regarding the benefits of early diagnosing of diseases.

Abstract: BACKGROUND: Aggregated measures are often employed when prevalence, risk factors and consequences of alcohol use in the population are monitored. In order to avoid time-dependent bias in aggregated measures, reference periods which assess alcohol use over longer time-periods or measures assessing typical alcohol use are considered superior to reference periods assessing recent or current alcohol consumption. Alcohol consumption in the population is found to vary through the months of the year, but it is not known whether monthly variations in actual alcohol use affects self-reports of long-term or typical alcohol consumption. Using data from a large, population-based study with data-collection over two years, the aim of the present study was to examine whether self-reported measures of alcohol use with different reference periods fluctuated across the months of the year. METHODS: Participants in the third wave of the Nord-Trondelag Health Survey (HUNT3) answered questions regarding alcohol use in the last 4 weeks, weekly alcohol consumption last twelve months, typical weekly binge drinking and typical number of alcoholic drinks consumed in a 14 day period. For each of the alcohol measures, monthly variations in reporting were estimated and compared to the overall average. RESULTS: Monthly variations in self-reported alcohol use were found across all alcohol measures regardless of reference period. A general tendency was found for highest level of alcohol use being reported during the summer season, however, the highest number of individuals who reported alcohol use in the last 4 weeks was found in January. Women reported substantially larger increase in weekly binge drinking during the summer months than men. CONCLUSIONS: Self-reports of alcohol use over longer time and typical alcohol use varies according to the month the respondents are assessed. Monthly variations should therefore be taken into account when designing, analyzing and interpreting data from population-based studies aimed to examine descriptive and analytical characteristics of alcohol use in the population.

Abstract: BACKGROUND AND PURPOSE: Despite the absence of robust scientific evidence, it is today generally accepted that the acute headache typical for intracranial infections can develop into permanent headache complaints. This widespread concept was explored in the first, large, longitudinal, population-based study. METHODS: Data on confirmed exposure to intracranial infections amongst all adult inhabitants in a geographical area during a 20-year period were assembled from hospital records. Surviving individuals were later invited to the third Nord-Trondelag Health Survey (HUNT 3), where 39,690 (42%) of 94,194 invited inhabitants aged >/=20 years responded to a validated headache questionnaire. Using logistic regression, the 1-year prevalence of headache and its subtypes according to the diagnostic criteria of the International Headache Society was assessed and compared between those with and without previous confirmed intracranial infection. Age and sex were used as covariates. RESULTS: Overall, 43 participants were identified with earlier intracranial infection, whereof three had more than one infection: bacterial meningitis (n=19), lymphocytic meningitis (n=18), encephalitis (n=9), and brain abscess (n=1).The mean interval from infection to participation in HUNT 3 was 11.2 (range 1.5-19.7) years. There was no significant increase in the prevalence of headache (OR 1.10, 95% CI 0.58-2.07), its subtypes (migraine, or tension-type headache), or chronic daily headache (OR 1.85, 95% CI 0.45-7.68) amongst participants with previous intracranial infection compared with the surrounding population. CONCLUSIONS: This study challenges the existence of chronic post-bacterial meningitis headache and does not indicate the presence of other long-term headaches induced by intracranial infection.

Abstract: Experimental studies suggest that vitamin D modulates the activity of adipocytes. The authors examined baseline serum 25-hydroxyvitamin D (25(OH)D) level in relation to prevalent and cumulative incident obesity in Norway. A cohort of 25,616 adults aged 19-55 years participated in both the second and third surveys of the Nord-Trondelag Health Study (HUNT 2 (1995-1997) and HUNT 3 (2006-2008)). Serum 25(OH)D levels measured at baseline and anthropometric measurements taken at both baseline and follow-up were available for a random sample of 2,460 subjects. Overall, 40% of the 2,460 subjects had a serum 25(OH)D level less than 50.0 nmol/L, and 37% had a level of 50.0-74.9 nmol/L. The prevalence and cumulative incidence of obesity, defined as body mass index (weight (kg)/height (m)(2)) >/=30, were 12% and 15%, respectively. Lower serum 25(OH)D level was associated with a higher prevalence of obesity. In the 2,165 subjects with baseline BMI less than 30, a serum 25(OH)D level less than 50.0 nmol/L was associated with a significantly increased odds ratio for incident obesity during follow-up (adjusted odds ratio = 1.73, 95% confidence interval: 1.24, 2.41). When prevalent and incident obesity were classified according to waist circumference (>/=88 cm for women, >/=102 cm for men), similar results were obtained. In addition to prevalent obesity, a serum 25(OH)D level less than 50.0 nmol/L was significantly associated with new-onset obesity in adults.

Abstract: AIMS: To examine whether physical activity and adiposity modify the increased risk of cancer associated with diabetes. METHODS: We prospectively examined the association of diabetes and risk of cancer among 73,726 persons stratified by physical activity and body mass index (BMI). Adjusted hazard ratios (HRs) with 95% confidence intervals (CI) were estimated from Cox regression. RESULTS: During a median follow-up of 22.0 years, 9572 people were diagnosed with incident cancer. There was no clear association between diabetes and cancer risk in those reporting high levels of physical activity (>/=2.0h per week) (HR 0.93; 95% CI: 0.70-1.24) or those with a normal weight (BMI

Abstract: OBJECTIVE: Most individuals experiencing whiplash accidents recover rapidly. A considerable proportion, however, develop chronic symptoms. Psychological factors may slow recovery, possibly by increasing the likelihood of other symptoms being misattributed to, and amplified by the whiplash injury. We aimed to investigate how pre-injury mental and somatic symptoms, self-rated health, use of health-services and medications, health-behavior and socio-demographics predict the development of chronic whiplash. METHODS: Data from two waves of a large, population based study (HUNT2 (baseline) and HUNT3) were used. Individuals reporting no whiplash at baseline were identified in HUNT3. Characteristics reported at baseline were compared between those who had developed chronic whiplash in HUNT3 (n=199) and those who had not (n=20,600), using Pearson's chi-squared tests, independent sample t-tests and logistic regression analyses. RESULTS: Individuals developing chronic whiplash reported worse baseline health than those reporting no chronic whiplash. Poor self-rated health was a strong risk factor for subsequent chronic whiplash (OR=2.26, 95%CI: 1.68-3.04). Musculoskeletal pain also increased the risk (OR=1.21, 95%CI: 1.15-1.26), as did diffuse somatic symptoms (OR=2.09, 95%CI: 1.47-2.96), use of different health services (OR=1.31, 95%CI: 1.19-1.45), high use of medications (OR=1.28, 95%CI: 1.14-1.43) and symptoms of anxiety (OR=1.93, 95%CI: 1.39-2.68). Physical activity was protective (OR=0.67, 95%CI: 0.49-0.91). Most socio-demographic variables were not significantly associated with chronic whiplash. CONCLUSION: Poor somatic and mental pre-injury health increased the risk of subsequent chronic whiplash. This suggests that chronic whiplash is not merely an organic disorder, and highlights the importance of individual expectations, symptom reattribution and amplification in development of chronic whiplash.

Abstract: OBJECTIVE: Changes in the occurrence of gastro-oesophageal reflux symptoms (GORS) in the population remain uncertain. This study aimed to determine the prevalence changes, the incidence and the spontaneous loss of GORS. DESIGN: This population-based cohort study was conducted within the Nord-Trondelag Health Study (the HUNT study), a longitudinal series of population-based health surveys in Nord-Trondelag County, Norway. The study base encompassed all adult residents in the county, and the participants reported the degree of GORS during the previous 12 months. The number of participants included were 58,869 (64% response rate) in 1995-7 and 44,997 (49%) in 2006-9. Of these, 29,610 persons (61%) were prospectively followed up for an average of 11 years. RESULTS: Between 1995-7 and 2006-9, the prevalence of any, severe and at least weekly GORS increased by 30% (from 31.4% to 40.9%), 24% (from 5.4% to 6.7%) and 47% (from 11.6% to 17.1%), respectively. The average annual incidence of any and severe GORS was 3.07% and 0.23%, respectively. In women, but not men, the incidence of GORS increased with increasing age. The average annual spontaneous loss (not due to antireflux medication) of any and severe GORS was 2.32% and 1.22%, respectively. The spontaneous loss of GORS decreased with increasing age. CONCLUSION: Between 1995-7 and 2006-9 the prevalence of GORS increased substantially. At least weekly GORS increased by 47%. The average annual incidence of severe GORS was 0.23%, and the corresponding spontaneous loss was 1.22%. The incidence and spontaneous loss of GORS were influenced by sex and age.