The cohorts at the Research Centre for Prevention and Health, formerly 'The Glostrup Population Studies'

Public attitudes towards personal health data sharing in long-term epidemiological research: a Citizen Science approach in the KORA study

BACKGROUND

Loss to follow-up in long-term epidemiological studies is well-known and often substantial. Consequently, there is a risk of bias to the results. The motivation to take part in an epidemiological study can change over time, but the ways to minimize loss to follow-up are not well studied. The Citizen Science approach offers researchers to engage in direct discussions with study participants and to integrate their opinions and requirements into cohort management.

METHODS

Guided group discussions were conducted with study participants from the KORA cohort in the Augsburg Region in Germany, established 40 years ago, as well as a group of independently selected citizens. The aim was to look at the relevant aspects of health studies with a focus on long-term participation. A two-sided questionnaire was developed subsequently in a co-creation process and presented to 500 KORA participants and 2,400 employees of the research facility Helmholtz Munich.

RESULTS

The discussions revealed that altruistic motivations, (i.e. supporting research and public health), personal benefits (i.e. a health check-up during a study examination), data protection, and information about research results in layman's terms were crucial to ensure interest and long-term study participation. The results of the questionnaire confirmed these aspects and showed that exclusively digital information channels may be an obstacle for older and less educated people. Thus, paper-based media such as newsletters are still important.

CONCLUSIONS

The findings shed light on cohort management and long-term engagement with study participants. A long-term health study needs to benefit public and individual health; the institution needs to be trustworthy; and the results and their impact need to be disseminated in widely understandable terms and by the right means of communication back to the participants.

Six decades of longitudinal health knowledge production: a systematic review on Nordic birth cohort studies

This systematic review (a) identifies birth cohort studies (BCSs) established in the Nordic countries, (b) describes their basic characteristics, and (c) explores how these characteristics have evolved over time, discussing their implications to knowledge production. To identify Nordic BCSs, cohort databases and relevant scientific articles were systematically searched and screened.The review shows that since 1959, more than 600,000 index children have participated in the 79 Nordic BCSs (22 Danish, 20 Finnish, 12 Norwegian, 24 Swedish, one Icelandic), over half of them still ongoing. The Nordic BCSs cover a wide geographical area including the Nordic Arctic. The topics of BCSs have varied over time but most have focused on examining the developmental origins of diseases. A quarter of them had a general scope, while the rest started with a specific focus, commonly atopic diseases. All BCSs collected questionnaire and/or interview data and over 60% of the BCSs announced exclusion criteria for participants, typically insufficient language proficiency.NBCSs have produced crucial scientific knowledge for over six decades, but there are underutilised opportunities including systematic interdisciplinary collaboration, inclusion of children's own views of their health and well-being, intergenerational data collection, and specific knowledge of Arctic indigenous peoples and other minorities.

Tracking and Cumulative Lifetime Exposure to IGF-I in 6459 Healthy Individuals and in SGA Children Treated With GH

CONTEXT

Supraphysiological serum insulin-like growth factor-I (IGF-I) concentrations have been a matter of concern in children treated with GH because high IGF-I levels were associated with risk of later disease in former epidemiological studies.

OBJECTIVE

To determine whether a single IGF-I measurement reliably reflects lifetime IGF-I exposure we evaluated intraindividual longitudinal tracking of IGF-I and IGF-binding protein-3 (IGFBP-3) levels and we estimated cumulative lifetime exposure to IGF-I in healthy and GH-treated individuals.

METHODS

We included 6459 healthy participants (cross-sectional = 5326; longitudinal = 1133) aged 0-76 years (9963 serum samples) and 9 patients born small-for-gestational-age (SGA) with 238 serum samples during GH treatment. Intraindividual tracking of IGF-I and IGFBP-3 (SD score [SDS]) was determined by intraclass correlation coefficients (ICCs). Cumulative lifetime IGF-I exposure was estimated by area under the curve of the predicted SDS trajectory from 0 to 76 years.

RESULTS

For IGF-I (SDS), ICCs were 0.50 (95% CI, 0.47-0.53) for male and 0.53 (0.50-0.56) for female participants. Lifetime IGF-I exposure was significantly higher in female (mean 12 723 ± 3691 SD) than in male participants (12 563 ± 3393); P = 0.02. In SGA children, treatment with GH increased the lifetime exposure to IGF-I from 9512 ± 1889 to 11 271 ± 1689, corresponding to an increase in lifetime IGF-I trajectory from -0.89 SD ± 0.57 to -0.35 SD ± 0.49.

CONCLUSION

Because IGF-I and IGFBP-3 levels track throughout life, a single measurement reliably reflects lifetime exposure. GH therapy increased the lifetime exposure to IGF-I only slightly and it remained below the average lifetime exposure in the reference population.

Population-based epidemiology: The Glostrup Population Studies 1964–2021

The Glostrup Population Studies are population-based cohorts undertaken in the south-western part of Greater Copenhagen since 1964. The participants were randomly selected from the adult general population. The first cohort was established to assess cardiovascular risk factors and, since, the objectives have been broadened to describe and analyse the health of the general population. The studies are health-examination studies with clinical and biochemical data in addition to data from self-administered questionnaires and, in some studies, interviews. Fasting blood and urine samples were collected and stored in our biobank for further studies. Several of the cohorts were performed according to standardized methods in international consortia, hence data have been pooled with other, both Danish and international, cohorts. To date more than 30,000 individuals, both men and women, aged 15–85 years, have participated in The Glostrup Population Studies and participants have been re-examined up to eight times. The data can be used for disease-specific epidemiology, social epidemiology, genetic epidemiology, ageing, lifestyle and health interventions nested within the cohorts. The Glostrup Population Studies represent a great resource; the possibility of merging the different cohorts enables large datasets, as well as trends over time. Furthermore, the long follow-up in both the national registers and with follow-up examinations is unique. The purpose of this commentary is to inform about The Glostrup Population Studies and to invite collaborations to continue utilizing this great resource to combat current and future challenges within health promotion and disease prevention.

Risk Factors, Subsequent Disease Onset, and Prognostic Impact of Myocardial Infarction and Atrial Fibrillation

Background Although myocardial infarction (MI) and atrial fibrillation (AF) are frequent comorbidities and share common cardiovascular risk factors, the direction and strength of the association of the risk factors with disease onset, subsequent disease incidence, and mortality are not completely understood. Methods and Results In pooled multivariable Cox regression analyses, we examined temporal relations of disease onset and identified predictors of MI, AF, and all-cause mortality in 108 363 individuals (median age, 46.0 years; 48.2% men) free of MI and AF at baseline from 6 European population-based cohorts. During a maximum follow-up of 10.0 years, 3558 (3.3%) individuals were diagnosed exclusively with MI, 1922 (1.8%) with AF but no MI, and 491 (0.5%) individuals developed both MI and AF. Association of sex, systolic blood pressure, antihypertensive treatment, and diabetes appeared to be stronger with incident MI than with AF, whereas increasing age and body mass index showed a higher risk for incident AF. Total cholesterol and daily smoking were significantly related to incident MI but not AF. Combined population attributable fraction of cardiovascular risk factors was >70% for incident MI, whereas it was only 27% for AF. Subsequent MI after AF (hazard ratio [HR], 1.68; 95% CI, 1.03-2.74) and subsequent AF after MI (HR, 1.75; 95% CI, 1.31-2.34) both significantly increased overall mortality risk. Conclusions We observed different associations of cardiovascular risk factors with both diseases indicating distinct pathophysiological pathways. Subsequent diagnoses of MI and AF significantly increased mortality risk.

Educational attainment and trajectories of cognitive decline during four decades-The Glostrup 1914 cohort

BACKGROUND

The potential association between level of education and age-related cognitive decline remains an open question, partly because of a lack of studies including large subsamples with low education and follow-up intervals covering a substantial part of the adult lifespan.

OBJECTIVES

To examine cognitive decline assessed by a comprehensive clinical test of intelligence over a 35-year period of follow-up from ages 50 to 85 and to analyze the effect of education on trajectories of cognitive decline, including the effects of selective attrition.

METHODS

A longitudinal cohort study with a 35-year follow-up of community dwelling members of the Glostrup 1914 cohort. The study sample comprised 697 men and women at the 50-year baseline assessment and additional participants recruited at later follow-ups. Verbal, Performance, and Full Scale IQs were assessed using the Wechsler Adult Intelligence Scale at ages 50, 60, 70, 80, and 85. To be able to track cognitive changes between successive WAIS assessments, all IQs were based on the Danish 50-year norms. Information on school education was self-reported. The association between education and cognitive decline over time was examined in growth curve models. Selective attrition was investigated in subsamples of participants who dropped out at early or later follow-ups.

RESULTS

The trajectories for Verbal, Performance, and Full Scale IQ showed higher initial cognitive performance, but also revealed steeper decline among participants with a formal school exam compared to participants without a formal exam. Verbal IQ showed the largest difference in level between the two educational groups, whereas the interaction between education and age was stronger for Performance IQ than for Verbal IQ. In spite of the difference in trajectories, higher mean IQ was observed among participants with a formal school exam compared to those without across all ages, including the 85-year follow-up. Further analyses revealed that early dropout was associated with steeper decline, but that this effect was unrelated to education.

CONCLUSION

Comprehensive cognitive assessment over a 35-year period suggests that higher education is associated with steeper decline in IQ, but also higher mean IQ at all follow-ups. These findings are unlikely to reflect regression towards the mean, other characteristics of the employed test battery or associations between educational level and study dropout.

Hemoglobin A1c-levels and subsequent risk of depression in individuals with and without diabetes

BACKGROUND

It has been suggested that long-term glycemic load as reflected in plasma levels of Glycosylated Hemoglobin, Type A1C (HbA1c) is associated with higher risk of depression, however results have been conflicting. We examined the potential association between HbA1c and risk of depression in a large population-based cohort without baseline diabetes (the Glostrup cohort) defined by either self-reported diabetes, registry diagnosis of diabetes or use of antidiabetic medication at baseline and in a national diabetes cohort (the Danish Adult Diabetes Database).

METHODS

A total of 16,124 middle-aged individuals from the Glostrup cohort and 93,544 patients registered in the Danish Adult Diabetes Database were followed from the first registered HbA1c measurement (1999-2014) for subsequent diagnosis of depression or use of antidepressant medication in nation-wide Danish registers. The association was analyzed using a Cox proportional hazards regression model with HbA1c on both a continuous scale using restricted cubic splines and categorized based on the groups found in the spline model. We adjusted for relevant sociodemographic and clinical variables including previous depression and tested for interaction of both gender, insulin use and diabetes type.

RESULTS

During follow-up, 2694 (17%) in the Glostrup cohort and 29,234 (31%) in the diabetes cohort developed depression. In the Glostrup cohort, we found an indication of a positive linear association between HbA1c and depression in women, while no clear association was found in men. In patients with diabetes, we found a U-shaped association between HbA1c and depression in both men and women with the lowest risk estimates for HbA1c levels of 58 mmol/mol (7.5%) in men and of 60 mmol/mol (7.6%) in women. When HbA1c was categorized, men with the highest HbA1c-levels had significantly elevated risk of depression (HR_HbA1c>9.4 1.16 (95%CI 1.10-1.23)) after multifactorial adjustment compared to the reference group with HbA1c of 42.1-56.2 mmol/mol (6.0-7.3%). Women in the lowest and highest category of HbA1c had significantly higher risk of depression HR_HbA1c<6.0 1.15 (95% CI 1.09-1.22) and HR_HbA1c>9.3 1.10 (95% CI 1.04-1.16), respectively, compared to the reference group with HbA1c 42.1-55.0 mmol/mol (7.2-9.3%). There was a significant interaction with gender, but no interaction for insulin use or diabetes type.

CONCLUSIONS

In a population without baseline diabetes, higher HbA1c levels seemed associated with higher depression risk in women, whereas a U-shaped association was found in patients with known diabetes.

The impact of the Covid-19 pandemic on mental and physical health in Denmark - a longitudinal population-based study before and during the first wave

BACKGROUND

In the continuation of the first wave of the Covid-19 outbreak in Denmark, unprecedented restrictions with great impact on the citizen's everyday life were implemented. The objectives of this study were to investigate the influence of the Covid-19 pandemic on mental and physical health in the Danish population during the spring 2020 first wave outbreak and lockdown.

METHODS

A sample from the adult Danish population (n = 2190) were included. Self-reported measures of illness worry (Whiteley-6-R), emotional distress (SCL-90), and physical symptom load (SLC-90) were obtained before and during the first wave of the pandemic and compared with Wilcoxon signed-rank tests. Impact of covariates on physical and mental health was evaluated with ordinal regression analyses. Results from a tailored questionnaire regarding the Covid-19 pandemic were presented to explore the direct impact of the pandemic.

RESULTS

We only found minor increases in illness worry, emotional distress and physical symptom load (0-1 points difference, p ≤ 0.007) during the Covid-19 pandemic compared to before the pandemic. Sex, age, education, and physical disease were not associated with illness worry, emotional distress, or physical symptom load. Overall, the participants were trustful in the authorities' recommendations and felt that they managed the pandemic and the restrictions to a great extent despite that some expected great/major future consequences of the pandemic.

CONCLUSIONS

This study suggested that the first wave of the Covid-19 pandemic only had minor impact on mental and physical health in the Danish general population. Future studies should address the impact of the second wave of the pandemic and the renewed implementation of the concomitant restrictions.

Ten-year trends in DMF-S and DMF-T in a northeast German adult population

OBJECTIVE

The aim of this study was to assess 10-year trends in coronal caries in adults aged 20-83 years using data from the two-representative population-based Studies of Health in Pomerania (SHIP-0/SHIP-Trend-0).

METHODS

Repeated cross-sectional data from 4,286 SHIP-0 and 3,913 SHIP-Trend-0 participants were analysed. Carious, filled and missing teeth/surfaces were recorded in a half-mouth design and the DMF-T/S scores and sound surfaces/teeth were calculated according to WHO criteria. Trends in DMF-T/S scores and its single components were presented stratified by age group and sex.

RESULTS

A statistically significant decline in coronal caries experience (DMF-T and DMF-S) in adults aged 20 to 83 years as well as for D-T/S components was observed. The proportion of edentulous participants was almost halved from 8.7% (SHIP-0) to 5.1% (SHIP-Trend-0), while the number of M-T declined from 4.4 to 3.5 revealing an overall clear shift to a higher retention rate of teeth. In younger adults (25-34 years) 3.8 more sound teeth (17.2 sound surfaces) were found in average in the mouth and in elderly (65-74 years) a clear shift from extracted to filled teeth was observed (M-T reduced by 5.4, while F-T increased by 4). Regarding sex differences, females had consistently on average higher MF-T/S values, but lower D-T/S values than males.

CONCLUSION

A clinically relevant drop in the severity of coronal caries experience in all adult age groups in Northeast Germany shows that not only reductions in caries experience in adolescence translated into adulthood but also later improvements led to long-term oral health.

Longitudinal course of GDF15 levels before acute hospitalization and death in the general population

Growth differentiation 15 (GDF15) is a potential novel biomarker of biological aging. To separate the effects of chronological age and birth cohort from biological age, longitudinal studies investigating the associations of GDF15 levels with adverse health outcomes are needed. We investigated changes in GDF15 levels over 10 years in an age-stratified sample of the general population and their relation to the risk of acute hospitalization and death. Serum levels of GDF15 were measured three times in 5-year intervals in 2176 participants aged 30, 40, 50, or 60 years from the Danish population-based DAN-MONICA cohort. We assessed the association of single and repeated GDF15 measurements with the risk of non-traumatic acute hospitalizations. We tested whether changes in GDF15 levels over 10 years differed according to the frequency of hospitalizations within 2 years or survival within 20 years, after the last GDF15 measurement. The change in GDF15 levels over time was dependent on age and sex. Higher GDF15 levels and a greater increase in GDF15 levels were associated with an increased risk of acute hospitalization in adjusted Cox regression analyses. Participants with more frequent admissions within 2 years, and those who died within 20 years, after the last GDF15 measurement already had elevated GDF15 levels at baseline and experienced greater increases in GDF15 levels during the study. The change in GDF15 levels was associated with changes in C-reactive protein and biomarkers of kidney, liver, and cardiac function. Monitoring of GDF15 starting in middle-aged could be valuable for the prediction of adverse health outcomes.

Association of fatal myocardial infarction with past level of physical activity: a pooled analysis of cohort studies

AIMS

To assess the association between past level of physical activity (PA) and risk for death during the acute phase of myocardial infarction (MI) in a pooled analysis of cohort studies.

METHODS AND RESULTS

European cohorts including participants with a baseline assessment of PA, conventional cardiovascular (CV) risk factors, and available follow-up on MI and death were eligible. Patients with an incident MI were included. Leisure-time PA was grouped as sedentary (<7 MET-hours), low (7-16 MET-hours), moderate (16.1-32 MET-hours), or high (>32 MET-hours) based on calculated net weekly energy expenditure. The main outcome measures were instant and 28-day case fatality of MI. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using multivariate random-effects models. Adjustments for age, sex, CV risk factors, alcohol consumption, and socioeconomic status were made. From 10 cohorts including a total of 1 495 254 participants, 28 140 patients with an incident MI comprised the study population. A total of 4976 (17.7%) died within 28 days-of these 3101 (62.3%) were classified as instant fatal MI. Compared with sedentary individuals, those with a higher level of PA had lower adjusted odds of instant fatal MI: low PA [OR, 0.79 (95% CI, 0.60-1.04)], moderate PA [0.67 (0.51-0.89)], and high PA [0.55 (0.40-0.76)]. Similar results were found for 28-day fatal MI: low PA [0.85 (0.71-1.03)], moderate PA [0.64 (0.51-0.80)], and high PA [0.72 (0.51-1.00)]. A low-to-moderate degree of heterogeneity was detected in the analysis of instant fatal MI (I2 = 47.3%), but not in that of 28-day fatal MI (I2 = 0.0%).

CONCLUSION

A moderate-to-high level of PA was associated with a lower risk of instant and 28-day death in relation to a MI.

Free testosterone and cardiometabolic parameters in men: comparison of algorithms

OBJECTIVE

Calculating the free testosterone level has gained increasing interest and different indirect algorithms have been suggested. The objective was to compare free androgen index (FAI), free testosterone estimated using the linear binding model (Vermeulen: cFTV) and the binding framework accounting for allosterically coupled SHBG monomers (Zakharov: cFTZ) in relation to cardiometabolic conditions.

DESIGN

A prospective cohort study including 5350 men, aged 30-70 years, participating in population-based surveys (MONICA I-III and Inter99) from 1982 to 2001 and followed until December 2012 with baseline and follow-up information on cardiometabolic parameters and vital status.

RESULTS

Using age-standardized hormone levels, FAI was higher among men with baseline cardiometabolic conditions, whereas cFTV and cFTZ levels were lower compared to men without these conditions as also seen for total testosterone. Men in highest quartiles of cFTV or cFTZ had lower risk of developing type 2 diabetes (cFTV: HR = 0.74 (0.49-1.10), cFTZ: HR = 0.59 (0.39-0.91)) than men in lowest quartile. In contrast, men with highest levels of FAI had a 74% (1.17-2.59) increased risk of developing type 2 diabetes compared to men in lowest quartile.

CONCLUSION

The association of estimated free testosterone and the studied outcomes differ depending on algorithm used. cFTV and cFTZ showed similar associations to baseline and long-term cardiometabolic parameters. In contrast, an empiric ratio, FAI, showed opposite associations to several of the examined parameters and may reflect limited clinical utility.

An attempt to explain the bidirectional association between ischaemic heart disease, stroke and depression: a cohort and meta-analytic approach

BACKGROUND

Depression and cardiovascular diseases (CVDs) are common diseases and associated in a bidirectional manner.

AIMS

To examine whether a bidirectional association between CVD and depression could be explained by shared risk factors, misclassification of disease measures or non-response.

METHOD

A total of 10 population-based cohorts including 93 076 men and women (mean age 54.4 years, s.d. = 9.2) and an additional 10 510 men (mean age 51.2 years, s.d. = 0.3) were followed for subsequent depression, ischaemic heart disease (IHD) and stroke in the Danish National Patient Registry from health examinations between 1982 and 2015 and until end of follow-up in 2017-2018. Exposures were physicians' diagnoses of IHD, stroke, depression or self-reported chest pain, depression, use of antidepressant medication and the Major Depression Inventory at the time of study entry in the Metropolit study. Associations were analysed using Cox proportional hazard regression with disease as time-dependent variables.

RESULTS

IHD and stroke were associated with subsequent depression (hazard ratio (HR) for IHD: 1.79, 95% CI 1.43-2.23 and HR for stroke: 2.62, 95% CI 2.09-3.29) and the associations were present in both men and women. Adjustment for the shared risk factors socioeconomic status, lifestyle, body mass index, statin use and serum lipids did not change the risk estimates. Furthermore, depression was associated with higher risk of subsequent IHD (HR = 1.63, 95% CI 1.36-1.95) and stroke (HR = 1.94, 95% CI 1.63-2.30). The associations were also present when the analyses were based on self-reported disease measures or restricted to include non-responders.

CONCLUSIONS

The bidirectional association between CVD and depression was not explained by shared risk factors, misclassification or non-response.

Possible Modifiers of the Association Between Change in Weight Status From Child Through Adult Ages and Later Risk of Type 2 Diabetes

OBJECTIVE

We investigated the association between changes in weight status from childhood through adulthood and subsequent type 2 diabetes risks and whether educational attainment, smoking, and leisure time physical activity (LTPA) modify this association.

RESEARCH DESIGN AND METHODS

Using data from 10 Danish and Finnish cohorts including 25,283 individuals, childhood BMI at 7 and 12 years was categorized as normal or high using age- and sex-specific cutoffs (<85th or ≥85th percentile). Adult BMI (20-71 years) was categorized as nonobese or obese (<30.0 or ≥30.0 kg/m², respectively). Associations between BMI patterns and type 2 diabetes (989 women and 1,370 men) were analyzed using Cox proportional hazards regressions and meta-analysis techniques.

RESULTS

Compared with individuals with a normal BMI at 7 years and without adult obesity, those with a high BMI at 7 years and adult obesity had higher type 2 diabetes risks (hazard ratio [HR]_girls 5.04 [95% CI 3.92-6.48]; HR_boys 3.78 [95% CI 2.68-5.33]). Individuals with a high BMI at 7 years but without adult obesity did not have a higher risk (HR_girls 0.74 [95% CI 0.52-1.06]; HR_boys 0.93 [95% CI 0.65-1.33]). Education, smoking, and LTPA were associated with diabetes risks but did not modify or confound the associations with BMI changes. Results for 12 years of age were similar.

CONCLUSIONS

A high BMI in childhood was associated with higher type 2 diabetes risks only if individuals also had obesity in adulthood. These associations were not influenced by educational and lifestyle factors, indicating that BMI is similarly related to the risk across all levels of these factors.

The association of thyroid stimulation hormone levels with incident ischemic heart disease, incident stroke, and all-cause mortality

PURPOSE

Thyroid dysfunction may affect the risk of cardiovascular disease and mortality through effects on myocardial and vascular tissue and metabolism. Levels of thyroid stimulating hormone (TSH) indicates thyroid function. We aimed to assess the association between TSH-levels and incident ischemic heart disease (IHD), incident stroke, and all-cause mortality.

METHODS

We included 13,865 participants (18-71 years, 51.6% women) from five cohort studies conducted during 1974-2008 were included. TSH was measured at the baseline examination and classified as <0.4; 0.4-2.5 (ref.); 2.5-5.0; 5.0-10, or >10 mU/l. Incident IHD, incident stroke, and all-cause mortality were identified in registries until ultimo 2013. Data were analysed by multivariate Cox regression with age as underlying time axis. Results from the individual cohorts were pooled by random-effects meta-analysis.

RESULTS

The crude incidence rate was for IHD 7.8 cases/1000 person years (PY); stroke 5.4 cases/1000 PY; and all-cause mortality 11.3 deaths/1000 PY (mean follow-up: 14 years). Analyses showed no statistically significant associations between TSH-levels and incident IHD or incident stroke in the partly or fully adjusted models. There was a statistically significant association between TSH of 2.5-5 mU/l and all-cause mortality (hazard ratio 1.145 (95% CI 1.004-1.306) compared with TSH of 0.4-2.5 mU/l in the fully adjusted model.

CONCLUSION

The results do not provide evidence of a harmful effect of decreased or increased TSH on IHD or stroke in the general population. However, there is some indication of an elevated risk for all-cause mortality with TSH 2.5-5 mU/l compared with 0.4-2.5 mU/l.

The impact of mental vulnerability on the relationship between cardiovascular disease and depression

Background.

The mechanisms linking cardiovascular disease (CVD) and depression are still not established. We investigated the impact of mental vulnerability on the relationship between CVD and depression.

Methods.

A total of 19,856 individuals from five cohorts of random samples of the background population in Copenhagen were followed from baseline (1983–2011) until 2017 in Danish registries. Additive hazard and Cox proportional hazard models were used to analyze the effects of confounding by mental vulnerability as well as interactions between mental vulnerability and CVD on the risk of depression.

Results.

During follow-up, 15.3% developed CVD, while 18.1% experienced depression. A strong positive association between CVD and depression (hazard ratio: 3.60 [95% confidence intervals (CI): 3.30; 3.92]) corresponding to 35.4 (95% CI: 31.7; 39.1) additional cases per 1,000 person-years was only slightly attenuated after adjustment for mental vulnerability in addition to other confounders. Synergistic interaction between CVD and mental vulnerability was identified in the additive hazard model. Due to interaction between CVD and mental vulnerability, CVD was associated with 50.9 more cases of depression per 1,000 person-years among individuals with high mental vulnerability compared with individuals with low mental vulnerability.

Conclusions.

Mental vulnerability did not explain the strong relationship between CVD and depression. CVD was associated with additional cases of depression among individuals with higher mental vulnerability indicating that this group holds the greatest potential for intervention, for example, in rehabilitation settings.

Changes and correlations in height from 7 to 69 years of age across the birth years of 1930 to 1989

OBJECTIVES

The aims of this study were to describe changes in height during childhood and to investigate potential changes in the proportion of children attaining final height in childhood and in correlations between child and adult height across birth cohorts.

METHODS

We included 363 059 children (179 906 girls) from the Copenhagen School Health Records Register, who were born between 1930 and 1989, with height measurements at ages 7, 10, or 13 years. Linkages to data resources containing adult height values between ages 18 and 69 years were possible for a subpopulation of 96 133 individuals (23 051 women). Birth years were categorized as 1930 to 1939, 1940 to 1949, and 1950 to 1989. Descriptive height statistics were estimated by birth years and birth cohorts. Height correlations were examined using sex- and age-specific partial Pearson correlation analyses and meta-regression techniques.

RESULTS

Across 60 birth years, mean child heights at age 7 increased by 2.9 cm in girls and 3.0 cm in boys, and adult heights increased as well. The proportions of children attaining final height by age 13 remained low across the birth cohorts; nonetheless, there was a significant increase from 0.7% to 1.5% in girls only (P < .0001). Both child-child and child-adult height correlations were strong and remained relatively stable across birth cohorts.

CONCLUSIONS

Mean child and adult height increased during the study period, but the proportion of children attaining final height at age 13 remained low. Child-child and child-adult height correlations were largely unchanged across birth cohorts.

Risk of dementia and cognitive dysfunction in individuals with diabetes or elevated blood glucose

AIMS

To determine the risk of dementia in patients with type 1 or type 2 diabetes and in individuals with glycosylated haemoglobin, type A1C (HbA1c) of ⩾48 mmol/mol, which is the diagnostic limit for diabetes.

METHODS

We included the following cohorts: all incident diabetes cases aged 15 or above registered in the National Diabetes Registry (NDR) from January 2000 through December 2012 (n = 148 036) and a reference population, adult participants from the Glostrup cohort (n = 16 801), the ADDITION Study (n = 26 586) and Copenhagen Aging and Midlife Biobank (CAMB) (n = 5408). Using these cohorts, we analysed if a diagnosis of type 1 or type 2 diabetes in the NDR or HbA1c level of ⩾ 6.5% (48 mmol/mol) in the cohorts increased risk of dementia in the Danish National Patient Registry or cognitive performance assessed by the Intelligenz-Struktur-Test 2000R (IST2000R).

RESULTS

A diagnosis of type 1 or type 2 diabetes in the NDR was associated with increased risk of dementia diagnosed both before or after age 65 as well as across different subtypes of dementia. Self-reported diabetes or high HbA1c levels were associated with lower cognitive performance (p = 0.004), while high HbA1c was associated with increased risk of dementia (HR 1.94 (1.10-3.44) in the Glostrup cohort but not in the ADDITION Study (HR 0.96 (0.57-1.61)).

CONCLUSIONS

Both type 1 and type 2 diabetes are associated with an increased risk of dementia, while the importance of screening-detected elevated HbA1c remains less clear.

The Danish health care system and epidemiological research: from health care contacts to database records

Denmark has a large network of population-based medical databases, which routinely collect high-quality data as a by-product of health care provision. The Danish medical databases include administrative, health, and clinical quality databases. Understanding the full research potential of these data sources requires insight into the underlying health care system. This review describes key elements of the Danish health care system from planning and delivery to record generation. First, it presents the history of the health care system, its overall organization and financing. Second, it details delivery of primary, hospital, psychiatric, and elderly care. Third, the path from a health care contact to a database record is followed. Finally, an overview of the available data sources is presented. This review discusses the data quality of each type of medical database and describes the relative technical ease and cost-effectiveness of exact individual-level linkage among them. It is shown, from an epidemiological point of view, how Denmark’s population represents an open dynamic cohort with complete long-term follow-up, censored only at emigration or death. It is concluded that Denmark’s constellation of universal health care, long-standing routine registration of most health and life events, and the possibility of exact individual-level data linkage provides unlimited possibilities for epidemiological research.

More Frequent Intake of Regular Meals and Less Frequent Snacking Are Weakly Associated with Lower Long-Term Gains in Body Mass Index and Fat Mass in Middle-Aged Men and Women

BACKGROUND

Few studies have examined the relationship between eating frequency and long-term change in body weight, and the results have been inconsistent.

OBJECTIVE

We examined the associations between eating frequency and 6-y changes in body mass index (BMI; in kg/m2), fat mass, fat-free mass, body fat percentage, and waist circumference.

METHODS

The study consisted of Danish men (n = 1080) and women (n = 1044) aged 35-67 y with repeated measures of eating frequency, adiposity, and covariates during 11 y. Multiple linear regression was used to assess the associations between baseline eating frequency and subsequent change in BMI, fat mass, fat-free mass, fat percentage, and waist circumference, as well as the association between initial change in eating frequency and subsequent change in the same outcomes.

RESULTS

Total baseline eating frequency was not associated with change in outcomes. However, when separately examining regular meals and snacks, each additional daily meal was associated with a subsequent 6-y change in BMI of -0.14 (95% CI: -0.27, -0.00). Similar tendencies of inverse associations were found for change in fat mass (P = 0.04), fat-free mass (P = 0.07), and waist circumference (P = 0.05). We found no association between initial change in total eating frequency and subsequent change in outcomes. However, each additional daily regular meal after 5 y was associated with a subsequent 6-y change in BMI of -0.16 (95% CI: -0.30, -0.01). Inverse associations were also seen for fat (P = 0.04) and fat-free mass (P = 0.05). In contrast, an increase in daily frequency of snacking was associated with an increase in fat mass (P = 0.04) and fat percentage (P = 0.02).

CONCLUSIONS

Our results indicate that total frequency of eating has little or no influence on adiposity among middle-aged Danish men and women. Consumption of regular meals, but not snack consumption, showed a weak inverse association with longitudinal gains in BMI.

Irritable bowel syndrome, mental health, and quality of life: Data from a population-based survey in Germany (SHIP-Trend-0)

BACKGROUND

Irritable bowel syndrome (IBS) is associated with reduced quality of life and high healthcare costs. This study aimed to assess the prevalence and risk factors for IBS in a general adult population.

METHODS

The Study of Health in Pomerania (SHIP) is a population-based cohort study in northeastern Germany. SHIP-Trend-0 participants enrolled from 2008 to 2012 were grouped according to Rome III criteria (main criteria: abdominal discomfort or crampy or bloating pain for at least six months plus 2/3 additional criteria). Factors associated with IBS were assessed using survey-weighted backward stepwise logistic regression.

KEY RESULTS

The final data set included 4194 records. IBS prevalence was 3.5% (3.0%-4.2%). Unemployment (OR: 2.02, 1.26-3.21), headaches (OR: 2.37, 1.59-3.52), mental quality of life (OR: 0.95 per unit increase, 0.93-0.97), and interactions between gender and physical quality of life (P = 0.004) and gender and alexithymia (P = 0.002) predicted IBS probability. The model resulted in a good discrimination (area under the curve = 75.4%) and model fit (F = 0.72, P = 0.69). History of depression (OR: 2.77, 1.94-3.95), back pain (OR: 2.38, 1.69-3.35), early trauma (OR: 1.03, 1.02-1.04), and duration of inpatient treatment within the last twelve months (OR: 1.02, 1.01-1.04) lost their significance in multivariable analysis.

CONCLUSIONS & INFERENCES

IBS prevalence was relatively low compared to other studies. Factors predicting IBS were of biological, psychological, and social nature. The association between IBS and pain in different areas of the body indicates a potential underlying complex somatic symptom disorder.

Association of alcohol consumption with allergic disease and asthma: a multi-centre Mendelian randomization analysis

AIMS

To use the rs1229984 variant associated with alcohol consumption as an instrument for alcohol consumption to test the causality of the association of alcohol consumption with hay fever, asthma, allergic sensitization and serum total immunoglobulin (Ig)E.

DESIGN

Observational and Mendelian randomization analyses using genetic variants as unbiased markers of exposure to estimate causal effects, subject to certain assumptions.

SETTING

Europe.

PARTICIPANTS

We included a total of 466 434 people aged 15-82 years from 17 population-based studies conducted from 1997 to 2015.

MEASUREMENTS

The rs1229984 (ADH1B) was genotyped; alcohol consumption, hay fever and asthma were self-reported. Specific and total IgE were measured from serum samples.

FINDINGS

Observational analyses showed that ever-drinking versus non-drinking, but not amount of alcohol intake, was positively associated with hay fever and inversely associated with asthma but not with allergic sensitization or serum total immunoglobulin (Ig)E. However, Mendelian randomization analyses did not suggest that the observational associations are causal. The causal odds ratio (OR) per genetically assessed unit of alcohol/week was an OR = 0.907 [95% confidence interval (CI) = 0.806, 1.019; P = 0.101] for hay fever, an OR = 0.897 (95% CI = 0.790, 1.019; P = 0.095) for asthma, an OR = 0.971 (95% CI =  0.804, 1.174; P = 0.763) for allergic sensitization and a 4.7% change (95% CI = -5.5%, 14.9%; P = 0.366) for total IgE.

CONCLUSIONS

In observational analyses, ever-drinking versus not drinking was positively associated with hay fever and negatively associated with asthma. However, the Mendelian randomization results were not consistent with these associations being causal.

Predictive value of long-term changes of growth differentiation factor-15 over a 27-year-period for heart failure and death due to coronary heart disease

BACKGROUND

Growth differentiation factor-15 (GDF-15), Cystatin C and C-reactive protein (CRP) have been discussed as biomarkers for prediction of cardiac diseases. The aim of this study was to investigate the predictive value of single and repeated measurements of GDF-15 compared to Cystatin C and CRP for incidence of heart failure (HF) and death due to coronary heart disease (CHD) in the general population.

METHODS AND RESULTS

Levels of GDF-15, CRP and Cystatin C were determined in three repeated measurements collected 5 years apart in the DAN-MONICA (Danish-Multinational MONitoring of trends and determinants in Cardiovascular disease) cohort (participants at baseline n = 3785). Cox regression models adjusted for cardiovascular risk factors revealed significantly increased hazard ratios (HR) for GDF-15 for incident HF 1.36 (HR per interquartile range (IQR) increase, 95% confidence interval (CI): 1.16; 1.59) and for death from CHD 1.51 (HR per IQR increase, 95% CI: 1.31, 1.75) (both with p<0.001). Joint modeling of time-to-event and longitudinal GDF-15 over a median 27-year follow-up period showed that the marker evolution was positively associated with death of CHD (HR per IQR increase 3.02 95% CI: (2.26, 4.04), p < 0.001) and HF (HR per IQR increase 2.12 95% CI: (1.54, 2.92), p<0.001). However using Cox models with follow-up time starting at the time of the third examination, serial measurement of GDF-15, modeled as changes between the measurements, did not improve prediction over that of the most recent measurement.

CONCLUSIONS

GDF-15 is a promising biomarker for prediction of HF and death due to CHD in the general population, which may provide prognostic information to already established clinical biomarkers. Repeated measurements of GDF-15 displayed only a slight improvement in the prediction of these endpoints compared to a single measurement.

Effects of invitation to participate in health surveys on the incidence of cardiovascular disease: a randomized general population study

Background

The effects of health checks on reducing cardiovascular disease morbidity and mortality in the general population have been questioned. There are few randomized studies with long-term follow-up. We used a cohort randomly selected from a general population as a randomized trial to study the effect of repeated general health checks on the 30-year incidence of ischaemic heart disease (IHD), stroke and all-cause mortality.

Methods

The study included all persons ( n = 17 845) aged 30, 40, 50 and 60 years living in 11 municipalities in Copenhagen, the capital of Denmark. An age- and gender-stratified random sample ( n = 4789) was invited to up to three health checks, from 1982 to 1994 (intervention group). The remaining 12 994 persons were defined as the control group. Complete follow-up on mortality, emigration and fatal and non-fatal IHD and stroke until 31 December 2012 was obtained by linkage to registries.

Results

There were 3209 and 2190 incident cases of IHD and stroke, respectively, and a total of 6432 deaths during follow-up (mean = 25.2 years). The hazard ratios (HRs) (95% confidence intervals, CIs) for persons in the intervention group versus persons in the control group were as follows: IHD (HR: 0.99, 95% CI: 0.92, 1.07), stroke (HR: 1.14, 95% CI: 1.04, 1.25) and all-cause mortality (HR: 1.03, 95% CI: 0.98, 1.09).

Conclusions

Repeated general health checks offered to the general population had no beneficial effects on the development of IHD, stroke or all-cause mortality during 30 years of follow-up. An increased incidence of stroke was observed in the group offered health checks.

Explaining trends in coronary heart disease mortality in different socioeconomic groups in Denmark 1991-2007 using the IMPACTSEC model

AIM

To quantify the contribution of changes in different risk factors population levels and treatment uptake on the decline in CHD mortality in Denmark from 1991 to 2007 in different socioeconomic groups.

DESIGN

We used IMPACTSEC, a previously validated policy model using data from different population registries.

PARTICIPANTS

All adults aged 25-84 years living in Denmark in 1991 and 2007.

MAIN OUTCOME MEASURE

Deaths prevented or postponed (DPP).

RESULTS

There were approximately 11,000 fewer CHD deaths in Denmark in 2007 than would be expected if the 1991 mortality rates had persisted. Higher mortality rates were observed in the lowest socioeconomic quintile. The highest absolute reduction in CHD mortality was seen in this group but the highest relative reduction was in the most affluent socioeconomic quintile. Overall, the IMPACTSEC model explained nearly two thirds of the decline in. Improved treatments accounted for approximately 25% with the least relative mortality reduction in the most deprived quintile. Risk factor improvements accounted for approximately 40% of the mortality decrease with similar gains across all socio-economic groups. The 36% gap in explaining all DPPs may reflect inaccurate data or risk factors not quantified in the current model.

CONCLUSIONS

According to the IMPACTSEC model, the largest contribution to the CHD mortality decline in Denmark from 1991 to 2007 was from improvements in risk factors, with similar gains across all socio-economic groups. However, we found a clear socioeconomic trend for the treatment contribution favouring the most affluent groups.

A randomized general population study of the effects of repeated health checks on incident diabetes

BACKGROUND

It is not clear whether offering health checks to the general population can be used to prevent diabetes. Few randomized studies have had a long-term follow-up. We used a randomly selected population cohort as a randomized trial to examine the effect of repeated health checks on the 30-year incidence of diabetes.

METHODS

The study included all persons from 11 municipalities in Copenhagen aged 30, 40, 50, and 60 years (n = 17845). An age-stratified and gender-stratified random sample (N = 4789) was invited to participate in a maximum of three health checks between 1982 and 1994 ('intervention group'). The remaining 12994 persons were defined as the 'control group'. The health checks included a questionnaire, a physical examination including assessment of overweight and blood pressure, and blood sampling with determination of serum lipid levels. Based on the person's answers and test results, the participants were given individual information about the results, disease risk and lifestyle. Their general practitioner, too, was provided with written information on the test results. Both groups were followed in the Danish Civil Registration System, the Danish National Diabetes Register, the Cause of Death Registry, and the National Patient Registry until 31 December 2012.

FINDINGS

There were 2636 incident cases of diabetes and a mean follow-up time of 24.1 years. The age-adjusted and gender-adjusted hazard ratio (HR) (95% confidence interval, CI) for the intervention group versus the control group was HR = 1.07 (95% CI: 0.98, 1.16, p = 0.153).

INTERPRETATION

Offering repeated general health checks to the general population had no preventive effect on the development of diabetes during 30 years of follow-up.

Impact of red and processed meat and fibre intake on treatment outcomes among patients with chronic inflammatory diseases: protocol for a prospective cohort study of prognostic factors and personalised medicine

INTRODUCTION

Chronic inflammatory diseases (CIDs) are frequently treated with biological medications, specifically tumour necrosis factor inhibitors (TNFi)). These medications inhibit the pro-inflammatory molecule TNF alpha, which has been strongly implicated in the aetiology of these diseases. Up to one-third of patients do not, however, respond to biologics, and lifestyle factors are assumed to affect treatment outcomes. Little is known about the effects of dietary lifestyle as a prognostic factor that may enable personalised medicine. The primary outcome of this multidisciplinary collaborative study will be to identify dietary lifestyle factors that support optimal treatment outcomes.

METHODS AND ANALYSIS

This prospective cohort study will enrol 320 patients with CID who are prescribed a TNFi between June 2017 and March 2019. Included among the patients with CID will be patients with inflammatory bowel disease (Crohn's disease and ulcerative colitis), rheumatic disorders (rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis), inflammatory skin diseases (psoriasis, hidradenitis suppurativa) and non-infectious uveitis. At baseline (pretreatment), patient characteristics will be assessed using patient-reported outcome measures, clinical assessments of disease activity, quality of life and lifestyle, in addition to registry data on comorbidity and concomitant medication(s). In accordance with current Danish standards, follow-up will be conducted 14-16 weeks after treatment initiation. For each disease, evaluation of successful treatment response will be based on established primary and secondary endpoints, including disease-specific core outcome sets. The major outcome of the analyses will be to detect variability in treatment effectiveness between patients with different lifestyle characteristics.

ETHICS AND DISSEMINATION

The principle goal of this project is to improve the quality of life of patients suffering from CID by providing evidence to support dietary and other lifestyle recommendations that may improve clinical outcomes. The study is approved by the Ethics Committee (S-20160124) and the Danish Data Protecting Agency (2008-58-035). Study findings will be disseminated through peer-reviewed journals, patient associations and presentations at international conferences.

TRIAL REGISTRATION NUMBER

NCT03173144; Pre-results.

Individual testosterone decline and future mortality risk in men

OBJECTIVE

Male aging is characterized by a decline in testosterone (TS) levels with a substantial variability between subjects. However, it is unclear whether differences in age-related changes in TS are associated with general health. We investigated associations between mortality and intra-individual changes in serum levels of total TS, SHBG, free TS and LH during a ten-year period with up to 18 years of registry follow-up.

DESIGN

1167 men aged 30-60 years participating in the Danish Monitoring Trends and Determinants of Cardiovascular Disease (MONICA1) study and who had a follow-up examination ten years later (MONICA10) were included. From MONICA10, the men were followed up to 18 years (mean: 15.2 years) based on the information from national mortality registries via their unique personal ID numbers.

METHODS

Cox proportional hazard models were used to investigate the association between intra-individual hormone changes and all-cause, CVD and cancer mortalities.

RESULTS

A total of 421 men (36.1%) died during the follow-up period. Men with most pronounced decline in total TS (<10th percentile) had a higher all-cause mortality risk compared to men within the 10th to 90th percentile (hazard ratio (HR): 1.60; 95% confidence interval (CI): 1.08-2.36). No consistent associations were seen in cause-specific mortality analyses.

CONCLUSION

Our study showed that higher mortality rates were seen among the men who had the most pronounced age-related decline in TS, independent of their baseline TS levels.

Associations of genetic determinants of serum vitamin B12 and folate concentrations with hay fever and asthma: a Mendelian randomization meta-analysis

BACKGROUND/OBJECTIVES

Studies of the effect of vitamin B12 and folate on the risk of asthma and hay fever have shown inconsistent results that may be biased by reverse causation and confounding. We used a Mendelian randomization approach to examine a potential causal effect of vitamin B12 and folate on hay fever, asthma, and selected biomarkers of allergy by using 11 vitamin B12-associated single-nucleotide polymorphisms (SNPs) and 2 folate-associated SNPs as unconfounded markers.

SUBJECTS/METHODS

We included 162,736 participants from 9 population-based studies including the UK Biobank. Results were combined in instrumental variable and meta-analyses and effects expressed as odds ratios (ORs) or estimates with 95% confidence interval (CI).

RESULTS

Using genetic proxies for B12 and folate, instrumental variable analyses did not show evidence for associations between serum B12 and hay fever: OR = 1.02 (95% CI: 0.98, 1.05), asthma: OR = 0.99 (95% CI: 0.95, 1.04), allergic sensitization: OR = 1.02 (95% CI: 0.74, 1.40), or change in serum IgE: 10.0% (95% CI: -9.6%, 29.6%) per 100 pg/ml B12. Similarly, there was no evidence for association between serum folate and hay fever: OR = 0.74 (95% CI: 0.45, 1.21), asthma: OR = 0.80 (95% CI: 0.43, 1.49), or allergic sensitization: OR = 1.92 (95% CI: 0.11, 33.45), but there was a statistically significant association with change in serum IgE: 2.0% (95% CI: 0.43%, 3.58%) per 0.1 ng/ml serum folate.

CONCLUSIONS

Our results did not support the hypothesis that levels of vitamin B12 and folate are causally related to hay fever, asthma, or biomarkers of allergy, but we found evidence of a positive association between serum folate and serum total IgE.

Current European guidelines for management of cardiovascular disease: Is medical treatment in nearly half a population realistic?

Background Health checks of the general population are widely used to prevent cardiovascular diseases, but are the current clinical guidelines from the European Society of Cardiology (ESC) suitable for screening the general population? Design A cross-sectional, population-based study of 978 men and women aged 40-65 years examined in 2010-2011 was used to estimate the proportion of the general Danish population fulfilling the criteria from the clinical guidelines from the ESC on medical treatment and lifestyle intervention to prevent cardiovascular disease. Methods The ESC criteria for medical treatment and lifestyle intervention were applied to a general population using information on previous cardiovascular diseases, known diabetes, urinalbumin, smoking, total cholesterol, systolic and diabolic blood pressure, low-density lipoprotein cholesterol and a multifactor risk score (SCORE). Results A total of 12.5% fulfilled the criteria for immediate medical treatment to prevent cardiovascular diseases. Furthermore, 30.4% are recommended for medical treatment if an initial lifestyle intervention fails summing to 42.9% eligible for medical treatment. The majority (79%) of persons aged 60-65 years are eligible for medical treatment, while close to half (44.9%) of all persons aged 50-59 years are recommended for medical treatment. Conclusion If ESC's guidelines were followed in Denmark, a conservative estimate shows that medical preventive treatment would involve nearly half the general population aged 40-65 years. The use of these guidelines in screening of the general population can be questioned as realistic and suitable.

Influence of marital status on testosterone levels-A ten year follow-up of 1113 men

Based on a large population of 1113 men aged 30-60 at baseline (mean: 44.1 years, standard deviation: 10.5), we investigated whether intra-individual changes in testosterone (T) and related reproductive hormones during a ten year period were dependent of marital status at baseline and follow-up. The studied men were part of a health survey in Denmark, conducted between 1982 and 1984 with a follow-up examination approximately ten years later. Data on reproductive hormones, measured in serum, and lifestyle and marital status were obtained at both time points. As expected, an age-related decline in testosterone was observed. However, independent of age and lifestyle, we observed that men who went from unmarried to married (n=81) during the study period experienced an accelerated age-related decline in testosterone (-6.6nmol/L) whereas men who went from married to unmarried (n=67) experienced an attenuated age-related decline (-2.3nmol/L). Men who were either married or unmarried at both time points (n=167, n=798, respectively) had a testosterone decline in between (-3.7nmol/L and -4.6nmol/L, respectively). Changes in T/LH ratio did not differ according to marital status indicating that the lowered T level is not compensated by increasing LH levels. This could suggest a modification of the gonadostat due to an adaptation to changing life circumstances.

A Proposal for a Study on Treatment Selection and Lifestyle Recommendations in Chronic Inflammatory Diseases: A Danish Multidisciplinary Collaboration on Prognostic Factors and Personalised Medicine

Chronic inflammatory diseases (CIDs), including Crohn’s disease and ulcerative colitis (inflammatory bowel diseases, IBD), rheumatoid arthritis, psoriasis, psoriatic arthritis, spondyloarthritides, hidradenitis suppurativa, and immune-mediated uveitis, are treated with biologics targeting the pro-inflammatory molecule tumour necrosis factor-α (TNF) (i.e., TNF inhibitors). Approximately one-third of the patients do not respond to the treatment. Genetics and lifestyle may affect the treatment results. The aims of this multidisciplinary collaboration are to identify (1) molecular signatures of prognostic value to help tailor treatment decisions to an individual likely to initiate TNF inhibitor therapy, followed by (2) lifestyle factors that support achievement of optimised treatment outcome. This report describes the establishment of a cohort that aims to obtain this information. Clinical data including lifestyle and treatment response and biological specimens (blood, faeces, urine, and, in IBD patients, intestinal biopsies) are sampled prior to and while on TNF inhibitor therapy. Both hypothesis-driven and data-driven analyses will be performed according to pre-specified protocols including pathway analyses resulting from candidate gene expression analyses and global approaches (e.g., metabolomics, metagenomics, proteomics). The final purpose is to improve the lives of patients suffering from CIDs, by providing tools facilitating treatment selection and dietary recommendations likely to improve the clinical outcome.

Cohort description: The Danish study of Functional Disorders

The Danish study of Functional Disorders (DanFunD) cohort was initiated to outline the epidemiology of functional somatic syndromes (FSS) and is the first larger coordinated epidemiological study focusing exclusively on FSS. FSS are prevalent in all medical settings and can be defined as syndromes that, after appropriate medical assessment, cannot be explained in terms of a conventional medical or surgical disease. FSS are frequent and the clinical importance varies from vague symptoms to extreme disability. No well-described medical explanations exist for FSS, and how to delimit FSS remains a controversial topic. The specific aims with the cohort were to test delimitations of FSS, estimate prevalence and incidence rates, identify risk factors, delimitate the pathogenic pathways, and explore the consequences of FSS. The study population comprises a random sample of 9,656 men and women aged 18–76 years from the general population examined from 2011 to 2015. The survey comprises screening questionnaires for five types of FSS, ie, fibromyalgia, whiplash-associated disorder, multiple chemical sensitivity, irritable bowel syndrome, and chronic fatigue syndrome, and for the unifying diagnostic category of bodily distress syndrome. Additional data included a telephone-based diagnostic interview assessment for FSS, questionnaires on physical and mental health, personality traits, lifestyle, use of health care services and social factors, and a physical examination with measures of cardiorespiratory and morphological fitness, metabolic fitness, neck mobility, heart rate variability, and pain sensitivity. A biobank including serum, plasma, urine, DNA, and microbiome has been established, and central registry data from both responders and nonresponders are similarly available on morbidity, mortality, reimbursement of medicine, heath care use, and social factors. A complete 5-year follow-up is scheduled to take place from year 2017 to 2020, and further reexaminations will be planned. Several projects using the DanFunD data are ongoing, and findings will be published in the coming years.

IgE sensitization to inhalant allergens and the risk of airway infection and disease: A population-based study

BACKGROUND

Immunoglobulin E (IgE) sensitization, which is the propensity to develop IgE antibodies against common environmental allergens, is associated with a lymphocyte T-helper type 2 (Th2) skewed immune response and a high risk of allergic respiratory disease. Little is known about whether IgE sensitization confers an increased risk of respiratory infections in adults. We investigated the association between IgE sensitization and the incidence of acute airway infections, other infections and chronic lower airway disease events as recorded in nation-wide registries.

METHODS

We included 14,849 persons from five population-based studies with measurements of serum specific IgE positivity against inhalant allergens. Participants were followed by linkage to Danish national registries (median follow-up time 11.3 years). The study-specific relative risks were estimated by Cox regression analysis, meta-analysed, and expressed as hazard ratios, HRs (95% confidence intervals, CIs).

RESULTS

The relative risks for IgE sensitized vs. non-sensitized were: for pneumonia (HR = 1.20, 95% CI: 1.01, 1.41), other acute airway infection (HR = 0.86, 95% CI: 0.60, 1.22), infection (HR = 1.06, 95% CI: 0.90, 1.24), asthma (HR = 2.26, 95% CI: 1.79, 2.86), and other chronic lower airway disease (HR = 1.31, 95% CI: 1.08, 1.58). In never smokers, the higher risk of pneumonia (HR = 1.73, 95% CI: 1.23, 2.44) and asthma (HR = 3.17, 95% CI: 2.10, 4.76) among IgE sensitized was more pronounced.

CONCLUSIONS

IgE sensitization was associated with a higher risk of asthma, other chronic lower airway diseases, and pneumonia. However, the association between IgE sensitization and pneumonia may be explained by undiagnosed asthma causing the pneumonia. Further studies are needed for confirmation.

Association of Repeatedly Measured High-Sensitivity-Assayed Troponin I with Cardiovascular Disease Events in a General Population from the MORGAM/BiomarCaRE Study

BACKGROUND

High-sensitivity troponin I (hs-cTnI) concentrations reflect myocardial stress. The role of hs-cTnI in predicting long-term changes in the risk of cardiovascular disease (CVD) in general populations is not clearly defined.

METHODS

We investigated whether the change in 3 repeated measures of hs-cTnI collected 5 years apart in a prospective Danish study (3875 participants, initially aged 30-60 years, 51% female, disease free at baseline) improves 10-year prediction of incident CVD compared to using a single most recent hs-cTnI measurement. The change process was modelled using a joint (longitudinal and survival) model and compared to a Cox model using a single hs-cTnI measure adjusted for classic CVD risk factors, and evaluated using discrimination statistics.

RESULTS

Median hs-cTnI concentrations changed from 2.6 ng/L to 3.4 ng/L over 10 years. The change in hs-cTnI predicts 10-year risk of CVD (581 events); the joint model gave a hazard ratio of 1.31 per interquartile difference in hs-cTnI (95% CI 1.15-1.48) after adjustment for CVD risk factors. However, the joint model performed only marginally better (c-index improvement 0.0041, P = 0.03) than using a single hs-cTnI measure (c-index improvement 0.0052, P = 0.04) for prediction of CVD, compared to a model incorporating CVD risk factors without hs-cTnI (c-index 0.744).

CONCLUSIONS

The change in hs-cTnI in 5-year intervals better predicts risk of CVD in the general population, but the most recent measure of hs-cTnI, (at 10 years) is as effective in predicting CVD risk. This simplifies the use of hs-cTnI as a prognostic marker for primary prevention of CVD in the general population.

Midlife Cognitive Ability, Education, and Tooth Loss in Older Danes

OBJECTIVE

To examine the possible influence of cognitive ability and education at age 50 or 60 on number of teeth at age 70.

SETTING

Community-dwelling population in Copenhagen, Denmark.

PARTICIPANTS

Men and women born in 1914 (N = 302).

MEASUREMENTS

Cognitive ability was assessed using the Wechsler Adult Intelligence Scale at age 50 or 60. A global cognitive ability measure was used as a continuous measure and according to tertile. Information on education was gathered using a questionnaire at age 50 or 60. A clinical oral examination took place at age 70, and oral health was measured according to number of teeth (<6 vs ≥6). Baseline covariates were smoking, alcohol, sex, and income.

RESULTS

Logistic regression analyses revealed that greater cognitive ability and educational attainment had a protective effect against risk of tooth loss. The associations were significant and persisted after adjusting for confounders and a two-way interaction between cognitive ability and education.

CONCLUSION

Higher education level and cognitive ability measured at age 50 or 60 were associated with having more teeth at age 70. Whether these findings are due to the interaction of these factors with oral health, related socioeconomic factors, or other factors remains to be studied.

Natriuretic peptides and integrated risk assessment for cardiovascular disease: an individual-participant-data meta-analysis

BACKGROUND

Guidelines for primary prevention of cardiovascular diseases focus on prediction of coronary heart disease and stroke. We assessed whether or not measurement of N-terminal-pro-B-type natriuretic peptide (NT-proBNP) concentration could enable a more integrated approach than at present by predicting heart failure and enhancing coronary heart disease and stroke risk assessment.

METHODS

In this individual-participant-data meta-analysis, we generated and harmonised individual-participant data from relevant prospective studies via both de-novo NT-proBNP concentration measurement of stored samples and collection of data from studies identified through a systematic search of the literature (PubMed, Scientific Citation Index Expanded, and Embase) for articles published up to Sept 4, 2014, using search terms related to natriuretic peptide family members and the primary outcomes, with no language restrictions. We calculated risk ratios and measures of risk discrimination and reclassification across predicted 10 year risk categories (ie, <5%, 5% to <7·5%, and ≥7·5%), adding assessment of NT-proBNP concentration to that of conventional risk factors (ie, age, sex, smoking status, systolic blood pressure, history of diabetes, and total and HDL cholesterol concentrations). Primary outcomes were the combination of coronary heart disease and stroke, and the combination of coronary heart disease, stroke, and heart failure.

FINDINGS

We recorded 5500 coronary heart disease, 4002 stroke, and 2212 heart failure outcomes among 95 617 participants without a history of cardiovascular disease in 40 prospective studies. Risk ratios (for a comparison of the top third vs bottom third of NT-proBNP concentrations, adjusted for conventional risk factors) were 1·76 (95% CI 1·56-1·98) for the combination of coronary heart disease and stroke and 2·00 (1·77-2·26) for the combination of coronary heart disease, stroke, and heart failure. Addition of information about NT-proBNP concentration to a model containing conventional risk factors was associated with a C-index increase of 0·012 (0·010-0·014) and a net reclassification improvement of 0·027 (0·019-0·036) for the combination of coronary heart disease and stroke and a C-index increase of 0·019 (0·016-0·022) and a net reclassification improvement of 0·028 (0·019-0·038) for the combination of coronary heart disease, stroke, and heart failure.

INTERPRETATION

In people without baseline cardiovascular disease, NT-proBNP concentration assessment strongly predicted first-onset heart failure and augmented coronary heart disease and stroke prediction, suggesting that NT-proBNP concentration assessment could be used to integrate heart failure into cardiovascular disease primary prevention.

FUNDING

British Heart Foundation, Austrian Science Fund, UK Medical Research Council, National Institute for Health Research, European Research Council, and European Commission Framework Programme 7.

Social resources and cognitive ageing across 30 years: the Glostrup 1914 Cohort

BACKGROUND

to examine associations between social resources and cognitive ageing over 30 years.

METHODS

participants in the Glostrup 1914 Cohort, a year of birth sample, completed a standardarised battery of cognitive ability tests every 10 years from age 50 to 80, summarised as general cognitive ability. Participants also provided information concerning a range of social resources, including marital status and living arrangements from age 50, and from age 70, details regarding social support, social contact and loneliness.

RESULTS

across the follow-up, participants were less likely to be married, falling from 85.0 to 40.4% between ages 50 and 80, while the proportion of those living alone increased from 13.1 to 54.2%. In separate growth curve models, being married, living with others and not feeling lonely were all associated with higher cognitive ability level, while more telephone contact had a negative association. Marital status (at ages 50 and 60) and loneliness at age 70 were the only social resources associated with cognitive change; married individuals and those not feeling lonely experienced less cognitive decline. When the social resources showing significant associations were considered together (and accounting for sex, education and social class), loneliness was associated with lower cognitive ability level and greater cognitive decline, while married individuals experienced less decline.

CONCLUSIONS

in a relatively large cohort followed for up to 30 years, marital status and loneliness were associated with cognitive ability or change. Interventions designed to reduce loneliness in older adults might be supported as one avenue to reduce cognitive ageing.

Effect of major lifestyle risk factors, independent and jointly, on life expectancy with and without cardiovascular disease: results from the Consortium on Health and Ageing Network of Cohorts in Europe and the United States (CHANCES)

Seldom have studies taken account of changes in lifestyle habits in the elderly, or investigated their impact on disease-free life expectancy (LE) and LE with cardiovascular disease (CVD). Using data on subjects aged 50+ years from three European cohorts (RCPH, ESTHER and Tromsø), we used multi-state Markov models to calculate the independent and joint effects of smoking, physical activity, obesity and alcohol consumption on LE with and without CVD. Men and women aged 50 years who have a favourable lifestyle (overweight but not obese, light/moderate drinker, non-smoker and participates in vigorous physical activity) lived between 7.4 (in Tromsø men) and 15.7 (in ESTHER women) years longer than those with an unfavourable lifestyle (overweight but not obese, light/moderate drinker, smoker and does not participate in physical activity). The greater part of the extra life years was in terms of “disease-free” years, though a healthy lifestyle was also associated with extra years lived after a CVD event. There are sizeable benefits to LE without CVD and also for survival after CVD onset when people favour a lifestyle characterized by salutary behaviours. Remaining a non-smoker yielded the greatest extra years in overall LE, when compared to the effects of routinely taking physical activity, being overweight but not obese, and drinking in moderation. The majority of the overall LE benefit is in disease free years. Therefore, it is important for policy makers and the public to know that prevention through maintaining a favourable lifestyle is “never too late”.

Leucocyte Telomere Length and Risk of Cardiovascular Disease in a Cohort of 1,397 Danish Men and Women

OBJECTIVES

Short leucocyte telomere length (LTL) might be a risk factor for cardiovascular diseases (CVD). The present study examines the relation between LTL and incident fatal or non-fatal CVD, ischaemic heart disease (IHD) and stroke in a Danish cohort followed for 29 years.

METHODS

In total, 1,397 men and women who participated in health examinations with blood sampling in 1981-1984 were followed for CVD outcomes until the end of 2012 by linkage to national registers. Cox proportional hazard regression models were used to analyse the relation between LTL and CVD adjusting for potential confounding CVD risk factors.

RESULTS

During the follow-up, 603 participants experienced an incident fatal or non-fatal CVD. The survival analysis showed that baseline LTL was not associated with CVD outcomes. In the subanalysis with IHD as outcome, those with middle and short LTL had an increased hazard rate ratio of 1.97 (95% CI 1.31-2.93) and 1.55 (95% CI 1.02-2.35), respectively, which was attenuated when confounding factors were adjusted for. For stroke, the pattern of associations was similar but less precisely estimated.

CONCLUSIONS

In this study short, LTL was not associated with an increased risk of CVD, but modestly associated with an increased risk of IHD.

The Association of Reproductive Hormone Levels and All-Cause, Cancer, and Cardiovascular Disease Mortality in Men

CONTEXT

Testosterone (T) levels have been associated with mortality, but controversy exists.

OBJECTIVE

Our objective was to investigate associations between serum levels of total T, SHBG, free T, estradiol, LH and FSH, and subsequent mortality with up to 30 years of follow-up.

DESIGN

This was a prospective cohort study consisting of men participating in four independent population-based surveys (MONICA I-III and Inter99) from 1982 to 2001 and followed until December 2012 with complete registry follow-up.

SETTING AND PARTICIPANTS

A total of 5350 randomly selected men from the general population aged 30, 40, 50, 60, or 70 years at baseline participated.

MAIN OUTCOMES AND MEASURES

All-cause mortality, cardiovascular disease (CVD) mortality, and cancer mortality were the main outcomes.

RESULTS

A total of 1533 men died during the follow-up period; 428 from CVD and 480 from cancer. Cox proportional hazard models revealed that men in highest LH quartile had an increased all-cause mortality compared to lowest quartile (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.14-1.53). Likewise, increased quartiles of LH/T and estradiol increased the risk of all-cause mortality (HR, 1.23; 95% CI, 1.06-1.43; HR, 1.23; 95% CI 1.06-1.43). No association to T levels was found. Higher LH levels were associated with increased cancer mortality (HR, 1.42; 95% CI, 1.10-1.84) independently of smoking status. Lower CVD mortality was seen for men with T in the highest quartile compared to lowest (HR, 0.72; 95% CI, 0.53-0.98). Furthermore, negative trends were seen for SHBG and free T in relation to CVD mortality, however insignificant.

CONCLUSION

The observed positive association of LH and LH/T, but not T, with all-cause mortality suggests that a compensated impaired Leydig cell function may be a risk factor for death by all causes in men. Our findings underpin the clinical importance of including LH measurement in the diagnostic work-up of male patients seeking help for possible androgen insufficiency.

The Danish National Patient Registry: a review of content, data quality, and research potential

Background

The Danish National Patient Registry (DNPR) is one of the world’s oldest nationwide hospital registries and is used extensively for research. Many studies have validated algorithms for identifying health events in the DNPR, but the reports are fragmented and no overview exists.

Objectives

To review the content, data quality, and research potential of the DNPR.

Methods

We examined the setting, history, aims, content, and classification systems of the DNPR. We searched PubMed and the Danish Medical Journal to create a bibliography of validation studies. We included also studies that were referenced in retrieved papers or known to us beforehand. Methodological considerations related to DNPR data were reviewed.

Results

During 1977–2012, the DNPR registered 8,085,603 persons, accounting for 7,268,857 inpatient, 5,953,405 outpatient, and 5,097,300 emergency department contacts. The DNPR provides nationwide longitudinal registration of detailed administrative and clinical data. It has recorded information on all patients discharged from Danish nonpsychiatric hospitals since 1977 and on psychiatric inpatients and emergency department and outpatient specialty clinic contacts since 1995. For each patient contact, one primary and optional secondary diagnoses are recorded according to the International Classification of Diseases. The DNPR provides a data source to identify diseases, examinations, certain in-hospital medical treatments, and surgical procedures. Long-term temporal trends in hospitalization and treatment rates can be studied. The positive predictive values of diseases and treatments vary widely (<15%–100%). The DNPR data are linkable at the patient level with data from other Danish administrative registries, clinical registries, randomized controlled trials, population surveys, and epidemiologic field studies – enabling researchers to reconstruct individual life and health trajectories for an entire population.

Conclusion

The DNPR is a valuable tool for epidemiological research. However, both its strengths and limitations must be considered when interpreting research results, and continuous validation of its clinical data is essential.

A new, accurate predictive model for incident hypertension

OBJECTIVE

Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures.

METHODS

The primary study population consisted of 1605 normotensive individuals aged 20-79 years with 5-year follow-up from the population-based study, that is the Study of Health in Pomerania (SHIP). The initial set was randomly split into a training and a testing set. We used a probabilistic graphical model applying a Bayesian network to create a predictive model for incident hypertension and compared the predictive performance with the established Framingham risk score for hypertension. Finally, the model was validated in 2887 participants from INTER99, a Danish community-based intervention study.

RESULTS

In the training set of SHIP data, the Bayesian network used a small subset of relevant baseline features including age, mean arterial pressure, rs16998073, serum glucose and urinary albumin concentrations. Furthermore, we detected relevant interactions between age and serum glucose as well as between rs16998073 and urinary albumin concentrations [area under the receiver operating characteristic (AUC 0.76)]. The model was confirmed in the SHIP validation set (AUC 0.78) and externally replicated in INTER99 (AUC 0.77). Compared to the established Framingham risk score for hypertension, the predictive performance of the new model was similar in the SHIP validation set and moderately better in INTER99.

CONCLUSION

Data mining procedures identified a predictive model for incident hypertension, which included innovative and easy-to-measure variables. The findings promise great applicability in screening settings and clinical practice.

Lifestyle-Related Factors and Atopy in Seven Danish Population-Based Studies from Different Time Periods

BACKGROUND

The prevalence of allergic respiratory disease tends to increase in populations that adopt the so-called Westernized lifestyle. We investigated the association between atopy and several possible lifestyle-related factors in seven Danish population-based studies.

METHODS

A total of 20048 persons participated in the seven studies. We used logistic regression to analyse the associations between possible determinants and atopy defined as serum specific IgE or skin prick test positivity against inhalant allergens. Associations were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs). In addition, individual participant data meta-analyses were performed.

RESULTS

Atopy was significantly associated with younger age (OR per 1 year increase in age: 0.97; 95% CI: 0.97, 0.98); male sex (OR for males versus females: 1.34; 95% CI: 1.24, 1.45), heavy drinking (OR for heavy drinkers versus light drinkers: 1.15; 95% CI: 1.04, 1.27), never smoking (OR for current versus never smokers: 0.73; 95% CI: 0.67, 0.80), and higher educational level (OR for educated versus uneducated: 1.27; 95% CI: 1.15, 1.41). Atopy was not associated with blood pressure, serum total cholesterol, physical activity or body mass except in women only, where we found a positive association (OR for obese vs. normal weight: 1.18; 95% CI: 1.00, 1.39) with ptrend = 0.032.

CONCLUSIONS

Of interest for preventive purposes, we found that atopy was associated with some of the reversible lifestyle-related factors that characterize a Westernized lifestyle.

Atopy and cause-specific mortality

BACKGROUND

Atopy is the familial or personal propensity to develop immunoglobulin E (IgE) antibodies against common environmental allergens and is associated with high risk of allergic disease. It has been proposed that atopy may have effects on risk of cardiovascular disease and cancer.

OBJECTIVES

We investigated the association of atopy with all-cause and cause-specific mortality.

METHODS

We included a total of 14 849 individuals from five Danish population-based cohorts with measurements of atopy defined as serum-specific IgE positivity against inhalant allergens. Participants were followed by linkage to the Danish Registry of Causes of Death to obtain information on mortality status and cause of death (median follow-up time 11.3 years). The relative mortality risk was estimated by Cox regression and expressed as hazard ratios, HRs (95% confidence intervals, CIs).

RESULTS

A total of 1776 person died during follow-up. The mortality risk for atopics vs. non-atopics was: for all-cause mortality (HR = 1.03, 95% CI: 0.90, 1.17); neoplasms (HR = 0.86, 95% CI: 0.69, 1.06); endocrine, nutritional and metabolic disorders (HR = 1.48, 95% CI: 0.71, 3.08); mental and behavioural disorders (HR = 2.26, 95% CI: 1.18, 4.30); diseases of the nervous system (HR = 1.36, 95% CI: 0.65, 2.87); diseases of the circulatory system (HR = 1.00, 95% CI: 0.78, 1.29); diseases of the respiratory system (HR = 0.94, 95% CI: 0.55, 1.60); and diseases of the digestive system (HR = 1.75, 95% CI: 1.03, 2.98).

CONCLUSIONS & CLINICAL RELEVANCE

We found no statistically significant association between atopy and all-cause mortality. However, atopy was associated with a significantly higher risk of dying from mental and behavioural disorders and gastrointestinal diseases, particularly liver diseases, and a lower risk of dying from breast cancer, but these associations were not statistically significant when applying the Bonferroni adjusted significance level. Further studies are needed to confirm our findings.

Neighborhood deprivation is strongly associated with participation in a population-based health check

Background

We sought to examine whether neighborhood deprivation is associated with participation in a large population-based health check. Such analyses will help answer the question whether health checks, which are designed to meet the needs of residents in deprived neighborhoods, may increase participation and prove to be more effective in preventing disease. In Europe, no study has previously looked at the association between neighborhood deprivation and participation in a population-based health check.

Methods

The study population comprised 12,768 persons invited for a health check including screening for ischemic heart disease and lifestyle counseling. The study population was randomly drawn from a population of 179,097 persons living in 73 neighborhoods in Denmark. Data on neighborhood deprivation (percentage with basic education, with low income and not in work) and individual socioeconomic position were retrieved from national administrative registers. Multilevel regression analyses with log links and binary distributions were conducted to obtain relative risks, intraclass correlation coefficients and proportional change in variance.

Results

Large differences between neighborhoods existed in both deprivation levels and neighborhood health check participation rate (mean 53%; range 35-84%). In multilevel analyses adjusted for age and sex, higher levels of all three indicators of neighborhood deprivation and a deprivation score were associated with lower participation in a dose-response fashion. Persons living in the most deprived neighborhoods had up to 37% decreased probability of participating compared to those living in the least deprived neighborhoods. Inclusion of individual socioeconomic position in the model attenuated the neighborhood deprivation coefficients, but all except for income deprivation remained statistically significant.

Conclusion

Neighborhood deprivation was associated with participation in a population-based health check in a dose-response manner, in which increasing neighborhood deprivation was associated with decreasing participation. This suggests the need to develop preventive health checks tailored to deprived neighborhoods.

Socioeconomic inequality and mortality--a regional Danish cohort study

Background

Socioeconomic inequalities in mortality pose a serious impediment to enhance public health even in highly developed welfare states. This study aimed to improve the understanding of socioeconomic disparities in all-cause mortality by using a comprehensive approach including a range of behavioural, psychological, material and social determinants in the analysis.

Methods

Data from The North Denmark Region Health Survey 2007 among residents in Northern Jutland, Denmark, were linked with data from nationwide administrative registries to obtain information on death in a 5.8-year follow-up period (1^stFebruary 2007- 31^stDecember 2012). Socioeconomic position was assessed using educational status as a proxy. The study population was assigned to one of five groups according to highest achieved educational level. The sample size was 8,837 after participants with missing values or aged below 30 years were excluded. Cox regression models were used to assess the risk of death from all causes according to educational level, with a step-wise inclusion of explanatory covariates.

Results

Participants’ mean age at baseline was 54.1 years (SD 12.6); 3,999 were men (45.3%). In the follow-up period, 395 died (4.5%). With adjustment for age and gender, the risk of all-cause mortality was significantly higher in the two least-educated levels (HR = 1.5, 95%, CI = 1.2-1.8 and HR = 3.7, 95% CI = 2.4-5.9, respectively) compared to the middle educational level. After adjustment for the effect of subjective and objective health, similar results were obtained (HR = 1.4, 95% CI = 1.1-1.7 and HR = 3.5, 95% CI = 2.0-6.3, respectively). Further adjustment for the effect of behavioural, psychological, material and social determinants also failed to eliminate inequalities found among groups, the risk remaining significantly higher for the least educated levels (HR = 1.4, 95% CI = 1.1-1.9 and HR = 4.0, 95% CI = 2.3-6.8, respectively). In comparison with the middle level, the two highest educated levels remained statistically insignificant throughout the entire analysis.

Conclusion

Socioeconomic inequality influenced mortality substantially even when adjusted for a range of determinants that might explain the association. Further studies are needed to understand this important relationship.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1813-3) contains supplementary material, which is available to authorized users.