Cohort Profile: The INTERGENE Study

Comparison of associations between alcohol consumption and metabolic syndrome according to three definitions: The Swedish INTERGENE study

Background

While prevalence estimates differ by definition of metabolic syndrome (MetS), it is less clear how different definitions affect associations with alcohol consumption.

Methods

We included 3051 adults aged 25-77 from the baseline examination of the Swedish INTERGENE cohort (2001-2004). Using multiple logistic regression, we investigated cross-sectional associations between ethanol intake and MetS defined according to the Adult Treatment Panel III (ATP III), the International Diabetes Federation (IDF), and the Joint Interim Statement (JIS). Alcohol exposure categories comprised abstinence, and low, medium, and high consumption defined via sex-specific tertiles of ethanol intake among current consumers. Covariates included sociodemographics, health, and lifestyle factors.

Results

MetS prevalence estimates varied between 13.9 % (ATP III) and 25.3 % (JIS), with higher prevalence in men than women. Adjusted for age and sex, medium-high alcohol consumption was associated with lower odds of MetS compared to low consumption, while no difference was observed for abstainers. Only the most specific (and thus severe) definition of MetS (ATP III) showed decreasing odds for ethanol intake when adjusted for all covariates.

Conclusion

Our study shows that alcohol-related associations differ by definition of MetS. The finding that individuals with the most stringently defined MetS may benefit from alcohol consumption calls for further well-controlled studies.

Domain-Specific Physical Activity and Stroke in Sweden

Importance

Associations of domain-specific physical activity with stroke incidence and poststroke outcomes have not been extensively studied using long-term, population-based data.

Objective

To investigate associations of leisure time, work time, transport, and household physical activity with stroke incidence and death or dependency in activities of daily living (ADL) 3 months after stroke.

Design, Setting, and Participants

The prospective, population-based Interplay Between Genetic Susceptibility and External Factors (INTERGENE) cohort study was conducted among a random sample of individuals from an urban-rural area covering western Sweden; 3614 individuals aged 24 to 77 years were examined in 2001 to 2004, and 1394 individuals were reexamined in 2014 to 2016. The median (range) follow-up was 20.0 years (56 days to 21.9 years). Data were analyzed from September through October 2023.

Exposure

Physical activity levels were self-reported for leisure time, work time, transportation, and household domains. The mean number of steps taken over a 6-day period was collected in a subgroup of participants using a sealed pedometer.

Main Outcomes and Measures

Follow-up for stroke incidence and mortality rates continued until December 31, 2022. The composite outcome of death or ADL dependency was assessed at 3 months after stroke.

Results

Among 3614 individuals (mean [SD] age, 51.4 [13.1] years; 1910 female [52.9%]); 269 individuals (7.4%) developed stroke, of whom 120 individuals (44.6%) were dead or ADL dependent at 3 months. Intermediate (adjusted hazard ratio [aHR], 0.54; 95% CI, 0.38-0.77) and high (aHR, 0.47; 95% CI, 0.31-0.73) levels of leisure time physical activity were associated with a reduced incidence of stroke compared with low levels, as was an intermediate level of physical activity in transportation (aHR, 0.69; 95% CI, 0.52-0.93). High levels of leisure time physical activity were also associated with a reduced risk of poststroke death or ADL dependency (adjusted odds ratio, 0.34; 95% CI, 0.16-0.71) compared with low levels. Work time and household physical activity were not associated with stroke incidence or stroke outcomes. In exploratory subgroup analyses, there were interactions between physical activity and smoking (current smoking or smoking in the past year associated with stroke risk only in participants with low or intermediate physical activity: aHR, 2.33; 95% CI, 1.72-3.15) and family history of stroke (first-degree relative with a history of stroke associated with stroke risk only in participants with low or intermediate physical activity: aHR, 1.73; 95% CI, 1.27-2.38).

Conclusions and Relevance

In this study, leisure time and transport-related physical activities were associated with a reduced risk of stroke. A high level of leisure time physical activity was also associated with a lower risk of death or ADL dependency 3 months after stroke.

Genetic susceptibility to airway inflammation and exposure to short-term outdoor air pollution

BACKGROUND

Air pollution is a large environmental health hazard whose exposure and health effects are unequally distributed among individuals. This is, at least in part, due to gene-environment interactions, but few studies exist. Thus, the current study aimed to explore genetic susceptibility to airway inflammation from short-term air pollution exposure through mechanisms of gene-environment interaction involving the SFTPA, GST and NOS genes.

METHODS

Five thousand seven hundred two adults were included. The outcome measure was fraction of exhaled nitric oxide (FeNO), at 50 and 270 ml/s. Exposures were ozone (O₃), particulate matter < 10 µm (PM₁₀), and nitrogen dioxide (NO₂) 3, 24, or 120-h prior to FeNO measurement. In the SFTPA, GST and NOS genes, 24 single nucleotide polymorphisms (SNPs) were analyzed for interaction effects. The data were analyzed using quantile regression in both single-and multipollutant models.

RESULTS

Significant interactions between SNPs and air pollution were found for six SNPs (p < 0.05): rs4253527 (SFTPA1) with O₃ and NO_x, rs2266637 (GSTT1) with NO₂, rs4795051 (NOS2) with PM₁₀, NO₂ and NO_x, rs4796017 (NOS2) with PM₁₀, rs2248814 (NOS2) with PM₁₀ and rs7830 (NOS3) with NO₂. The marginal effects on FeNO for three of these SNPs were significant (per increase of 10 µg/m³):rs4253527 (SFTPA1) with O₃ (β: 0.155, 95%CI: 0.013-0.297), rs4795051 (NOS2) with PM₁₀ (β: 0.073, 95%CI: 0.00-0.147 (single pollutant), β: 0.081, 95%CI: 0.004-0.159 (multipollutant)) and NO₂ (β: -0.084, 95%CI: -0.147; -0.020 (3 h), β: -0.188, 95%CI: -0.359; -0.018 (120 h)) and rs4796017 (NOS2) with PM₁₀ (β: 0.396, 95%CI: 0.003-0.790).

CONCLUSIONS

Increased inflammatory response from air pollution exposure was observed among subjects with polymorphisms in SFTPA1, GSTT1, and NOS genes, where O₃ interacted with SFTPA1 and PM10 and NO₂/NO_x with the GSTT1 and NOS genes. This provides a basis for the further exploration of biological mechanisms as well as the identification of individuals susceptible to the effects of outdoor air pollution.

Echocardiographic diagnosis of heart failure with preserved ejection fraction in elderly patients with hypertension

Objectives. The aim of this study is to evaluate the diagnostic performance of echocardiography for the diagnosis of heart failure with preserved ejection fraction (HFpEF) in the elderly and to validate the Heart Failure Association diagnostic algorithm (HFA-PEFF). Design. A case-control study was conducted in patients with hypertension with or without HFpEF who were matched for age (n = 33; 78.4 ± 5.3 years) and sex. Participants underwent echocardiography including assessment of left atrial (LA) volume index (LAVI), early mitral filling to early diastolic mitral annulus velocity ratio (E/e'), LA reservoir strain (LASr), tissue Doppler LA contraction (a'), right ventricular isovolumic relaxation time (RVIVRT), and a 6-minute walk test (6-MWT). The filling pressure algorithm from the European association of cardiovascular imaging (EACVI) 2021 was applied. The HFA-PEFF score was also applied, using echocardiography parameters and the value of NT pro-BNP, without considering symptomatic status. Results. Echocardiographic parameters identified patients with HFpEF with an area under the curve (AUC) >0.9 for E/e', RVIVRT, LASr, a', and the ratio of LAVI/a'. LASr correlated with 6-MWT (r = 0.59, p = .0003). The EACVI algorithm classified all controls with normal filling pressure and 94% of patients with HFpEF with increased filling pressure. When the HFA-PEFF diagnostic algorithm was validated, a high score (≥5 points) had 100% sensitivity for HFpEF, while 88% of controls had intermediate scores (2-4 points). Conclusion. The EACVI filling pressure algorithm, RVIVRT, LASr, and the ratio LAVI/a' were accurate for diagnosing HFpEF in elderly patients with hypertension. The HFA-PEFF score had high sensitivity but limited ability to exclude HFpEF.

Secular trends in diet-related greenhouse gas emission estimates since 2000 - a shift towards sustainable diets in Sweden

Objective:

This study examines secular changes in diet-related greenhouse gas emissions (GHGE) in younger and older Swedish adults, since the turn of this century.

Design:

Two cross-sectional health examination surveys were conducted in 2001–2004 (T₁) and 2014–2018 (T₂). At both times, an eighty-six-item FFQ was embedded in the survey. From the food frequencies and age-standardised portion sizes, GHGE estimates (kg CO₂e/year) were calculated. GHGE was modelled as a function of time period and covariates, for five distinct age groups.

Setting:

The municipality of Gothenburg, in western Sweden.

Participants:

Women and men aged 25–34, 35–44, 45–54, 55–64 and 65–75 years were randomly selected from the population registry and recruited for examinations. After exclusion of participants with incomplete dietary data, the analytic sample consisted of 2569 individuals at T₁ and 2119 at T₂.

Results:

Lower dietary GHGE scores were observed at T₂ compared with T₁, in each age group, adjusting for sex, BMI and education. The largest differences in GHGE were observed in the youngest age group (approximately 30 % reduction). Decreasing trends in GHGE from animal-based foods were observed at all ages and were accompanied by smaller increases from plant-based sources in younger groups only. At all ages, GHGE from discretionary foods decreased, and prevalence of overweight remained stable.

Conclusions:

Optimal dietary trends should support both human health and planetary health. Our results suggest that Swedish adults have moved in this direction, e.g. through less intake of red meat products and stable weight status.

Current smoking alters phospholipid- and surfactant protein A levels in small airway lining fluid: An explorative study on exhaled breath

Small airways are difficult to access. Exhaled droplets, also referred to as particles, provide a sample of small airway lining fluid and may reflect inflammatory responses. We aimed to explore the effect of smoking on the composition and number of exhaled particles in a smoker-enriched study population. We collected and chemically analyzed exhaled particles from 102 subjects (29 never smokers, 36 former smokers and 37 current smokers) aged 39 to 83 years (median 63). A breathing maneuver maximized the number exhaled particles, which were quantified with a particle counter. The contents of surfactant protein A and albumin in exhaled particles was quantified with immunoassays and the contents of the phospholipids dipalmitoyl- and palmitoyl-oleoyl- phosphatidylcholine with mass spectrometry. Subjects also performed spirometry and nitrogen single breath washout. Associations between smoking status and the distribution of contents in exhaled particles and particle number concentration were tested with quantile regression, after adjusting for potential confounders. Current smokers, compared to never smokers, had higher number exhaled particles and more surfactant protein A in the particles. The magnitude of the effects of current smoking varied along the distribution of each PEx-variable. Among subjects with normal lung function, phospholipid levels were elevated in current smokers, in comparison to no effect of smoking on these lipids at abnormal lung function. Smoking increased exhaled number of particles and the contents of lipids and surfactant protein A in the particles. These findings might reflect early inflammatory responses to smoking in small airway lining fluid, also when lung function is within normal limits.

Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden

OBJECTIVES

To investigate the long-term effects of source-specific particle matter (PM) on lung function, effects of Surfactant Protein A (SP-A) and glutathione S-transferase (GST) genes GSTP1 and GSTT1 gene variants and effect modification by single-nucleotide polymorphism (SNP) genotype.

DESIGN

Cohort study with address-based annual PM exposure assigned from annual estimates of size (PM₁₀, PM_2.5 and PM_BC) and source-specific (traffic, industry, marine traffic and wood burning) dispersion modelling.

SETTING

Gothenburg, Sweden.

PARTICIPANTS

The ADult-Onset asthma and NItric oXide Study had 6685 participants recruited from the general population, of which 5216 (78%) were included in the current study with information on all variables of interest. Mean age at the time of enrolment was 51.4 years (range 24-76) and 2427 (46.5%) were men.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁). Secondary outcome measures were effects and gene-environment interactions of SP-A and GSTT1 and GSTP1 genotypes.

RESULTS

Exposure to traffic-related PM₁₀ and PM_2.5 was associated with decreases in percent-predicted (% predicted) FEV₁ by -0.48% (95% CI -0.89% to -0.07%) and -0.47% (95% CI -0.88% to -0.07%) per IQR 3.05 and 2.47 µg/m³, respectively, and with decreases in % predicted FVC by -0.46% (95% CI -0.83% to -0.08%) and -0.47% (95% CI -0.83% to -0.10%). Total and traffic-related PM_BC was strongly associated with both FEV₁ and FVC by -0.53 (95% CI -0.94 to -0.13%) and -0.43% (95% CI -0.77 to -0.09%) per IQR, respectively, for FVC, and similarly for FEV₁. Minor allele carrier status for two GSTP1 SNPs and the GSTT1 null genotype were associated with decreases in % predicted lung function. Three SP-A SNPs showed effect modification with exposure to PM_2.5 from industry and marine traffic.

CONCLUSIONS

PM exposure, specifically traffic related, was associated with FVC and FEV₁ reductions and not modified by genotype. Genetic effect modification was suggested for industry and marine traffic PM_2.5.

Negative life events predict weight gain in a 13-year follow-up of an adult Swedish population

BACKGROUND

Increasing psychosocial stress may underlie contemporary obesity trends. We investigate cross-sectional and prospective associations between negative life events (NLEs) and anthropometric indicators, and whether these are explained by lifestyle, depression and sleeping problems.

METHODS

Participants in the Swedish INTERGENE cohort answered questions about ten types of NLE, and indicated whether they occurred during the last year or earlier (2001-04, n = 2706). Body mass index (BMI) and waist-to-hip ratio (WHR) were measured at baseline, and at follow-up (2014-16, n = 974). Numbers of recent and distant NLE were related to anthropometric variables using linear models including age, sex, and education, and further adjusted for lifestyle, and psychological problems. Prospective models were adjusted for baseline anthropometric values.

RESULTS

Participants reported on average 3.6 types of NLEs, of which 70% were experienced more than one year ago. At baseline, distant but not recent NLEs were associated with higher values of both BMI and WHR. These associations were explained in part by lifestyle and depression assessed at baseline. Recent but not distant NLEs predicted gain in BMI, 0.19 (0.07, 0.30) kg/m², and WHR, 0.005 (0.002, 0.007), per event and independent of baseline covariates. The largest associations were seen for job insecurity and financial worries, with 0.35 (0.17, 0.52) kg/m² increase in BMI corresponding to approximately 1.2 kg per event, in both sexes.

CONCLUSION

We observed positive associations between NLEs and weight gain over 13 years including signs of latency and recovery regarding adverse weight development.

Negative emotional states and negative life events: Consequences for cardiovascular health in a general population

OBJECTIVE

The contemporary increase in psychological distress observed in many countries is, by itself, a public health issue of great concern. The present study aims to investigate associations between self-reported negative emotional states and negative life events, and cardiovascular disease (CVD).

METHODS

Prospective cohort study based on the Swedish INTERGENE cohort comprising 3614 men and women, aged 25 to 75. Baseline examinations during 2001-2004 included self-rating depression and anxiety scales, life stress, as well as a wide range of physiological and behavioral parameters, which allowed for relevant adjustments. Cox proportion hazard was used to predict incident CVD, CVD mortality as well as all-cause mortality.

RESULTS

The results showed a dose-response relationship between depressiveness, anxiety and negative life events on the one hand, and increased risk of CVD. Most of these associations persisted in the fully adjusted models. Furthermore, the youngest age group (25-44 years) generally showed the highest prevalence of psychosocial distress, and also had the highest risks of incident CVD with regard to depression and anxiety.

CONCLUSION

The associations between psychological distress and later life cardiovascular disease calls for enhanced public health efforts aiming at ameliorating psychological health, not least in younger age groups.