Are there non-linear relationships between alcohol consumption and long-term health?: a systematic review of observational studies employing approaches to improve causal inference

Background

Research has long found ‘J-shaped’ relationships between alcohol consumption and certain health outcomes, indicating a protective effect of moderate consumption. However, methodological limitations in most studies hinder causal inference. This review aimed to identify all observational studies employing improved approaches to mitigate confounding in characterizing alcohol–long-term health relationships, and to qualitatively synthesize their findings.

Methods

Eligible studies met the above description, were longitudinal (with pre-defined exceptions), discretized alcohol consumption, and were conducted with human populations. MEDLINE, PsycINFO, Embase and SCOPUS were searched in May 2020, yielding 16 published manuscripts reporting on cancer, diabetes, dementia, mental health, cardiovascular health, mortality, HIV seroconversion, and musculoskeletal health. Risk of bias of cohort studies was evaluated using the Newcastle-Ottawa Scale, and a recently developed tool was used for Mendelian Randomization studies.

Results

A variety of functional forms were found, including reverse J/J-shaped relationships for prostate cancer and related mortality, dementia risk, mental health, and certain lipids. However, most outcomes were only evaluated by a single study, and few studies provided information on the role of alcohol consumption pattern.

Conclusions

More research employing enhanced causal inference methods is urgently required to accurately characterize alcohol–long-term health relationships. Those studies that have been conducted find a variety of linear and non-linear functional forms, with results tending to be discrepant even within specific health outcomes.

Trial registration

PROSPERO registration number CRD42020185861.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01486-5.

The role of familial confounding in the associations of physical activity, smoking and alcohol consumption with early exit from the labour market

We investigated the associations between health behaviors and sustainable working life outcomes including all-cause disability pension, disability pensions due to musculoskeletal and mental diagnoses and unemployment. The role of familial factors behind these associations was studied by analysing discordant twin pairs. Our data included Swedish twins born in 1925-1986 (51891 twin individuals). Baseline data based on two independent surveys in 1998-2003 and 2005-2006 for health behaviors were linked to national registers on disability pension and unemployment until 2016. Cox proportional hazards models for hazard ratios (HR) with 95% confidence intervals (CI) were estimated for the whole sample adjusting for covariates. Analyses of health behavior discordant twin pairs (n = 5903 pairs) were conducted using conditional Cox models. In the whole cohort, the combination of healthy behaviors was associated with lower risk for all-cause disability pension, disability pension due to musculoskeletal diagnoses or mental diagnoses, and for unemployment (HRs 0.56-0.86, 95% CIs 0.51-0.92) as did being physically active (HRs 0.69-0.87, 95% CI 0.65-0.92). The discordant pair analyses confirmed the lower risk among those having healthy behaviors (HR 0.70-0.86) or being physically active (HR 0.86-0.87) for all-cause disability pension, disability pension due to musculoskeletal diagnoses, and for unemployment. To conclude, controlling the effects of covariates or familial confounding (i.e. discordant twin pair analyses) shows that being physically active or having several healthy behaviors predict better working life outcomes. This points towards independent association between healthy behavior and longer working life.

Sustainable Working Life in a Swedish Twin Cohort-A Definition Paper with Sample Overview

Background: A unified or consensus definition of “sustainable working life” remains lacking, although studies investigating risk factors for labour market exit are numerous. In this study, we aimed (1) to update the information and to explore a definition of “sustainable working life” via a systematic literature review and (2) to describe the working life trajectories via the prevalence of sickness absence (SA), disability pension (DP), and unemployment in a Swedish twin cohort to provide a sample overview in our Sustainable Working Life-project. Methods: A systematic literature review was conducted to explore the studies with the search phrase “sustainable working life” in PubMed, PsycInfo, and the Web of Science Database of Social Sciences in January 2021, resulting in a total of 51 references. A qualitative synthesis was performed for the definitions and the measures of “sustainable working life.” Based on the Swedish Twin project Of Disability pension and Sickness absence (STODS), the current dataset to address sustainable working life includes 108 280 twin individuals born between 1925 and 1990. Comprehensive register data until 2016 for unemployment, SA and DP were linked to all individuals. Using STODS, we analysed the annual prevalence of SA, DP, and unemployment as working life trajectories over time across education and age groups. Results: The reviewed 16 full articles described several distinct definitions for sustainable working life between 2007 and 2020 from various perspectives, i.e., considering workplaces or employees, the individual, organizational or enterprise level, and the society level. The definition of “sustainable working life” appearing most often was the swAge-model including a broad range of factors, e.g., health, physical/mental/psychosocial work environment, work motivation/satisfaction, and the family situation and leisure activities. Our dataset comprised of 81%–94% of individuals who did not meet SA, DP, or unemployment during the follow-up in 1994–2016, being indicative for “sustainable working life.” The annual prevalence across years had a decreasing trend of unemployment over time, whereas the prevalence of SA had more variation, with DP being rather stable. Both unemployment and DP had the highest prevalence among those with a lower level of education, whereas in SA, the differences in prevalence between education levels were minor. Unemployment was highest across the years in the youngest age group (18–27 years), the age group differences for SA were minor, and for DP, the oldest age group (58–65 years) had the highest prevalence. Conclusions: No consensus exists for a “sustainable working life,” hence meriting further studies, and we intend to contribute by utilising the STODS database for the Sustainable Working Life project. In the upcoming studies, the existing knowledge of available definitions and frameworks will be utilised. The dataset containing both register data and self-reports enables detailed follow-up for labour market participation for sustainable working life.

The role of sickness absence diagnosis for the risk of future inpatient- or specialized outpatient care in a Swedish population-based twin sample

BACKGROUND

Studies of consequences of sickness absence such as health and well-being have been rare whereas risk factors for sickness absence have been studied extensively. This study assumed the consequences of sickness absence would differ by diagnostic group or by patient care type. The aim was to investigate sickness absence due to various diagnosis groups as a predictor for subsequent inpatient- and specialized outpatient care while controlling for familial confounding.

METHODS

We utilized the register data of 69,552 twin individuals between 16 and 80 years of age (48% women). The first incident sickness absence spell, from baseline year 2005, including diagnosis of sickness absence was our primary exposure of interest and we followed them until the first incident inpatient- and specialized outpatient care episode with main diagnosis code or until 31.12.2013.

RESULTS

A total of 7464 incident sickness absence spells took place (11%), 42% had inpatient care and 83% specialized outpatient care (mean follow-up time 3.2 years, SD 3.1 years). All the main sickness absence diagnosis groups were associated with increased risk of future care in comparison to no sickness absence. Controlling for confounders attenuated the associations in magnitude but with retaining direction, and we could not confirm an effect of familial factors.

CONCLUSIONS

Sickness absence predicts both inpatient- and specialized outpatient care and the association is universal across diagnosis groups. The lower survival time and incidence rates of inpatient than specialized outpatient care point towards severity of diseases assumption. This finding was also universal across sickness absence diagnosis groups.

Number of Pain Locations as a Predictor of Cause-Specific Disability Pension in Sweden-Do Common Mental Disorders Play a Role?

OBJECTIVE

The aim of this study was to investigate the associations between number of pain locations, common mental disorders (CMDs), and disability pension (DP).

METHODS

Survey data in 1998 to 2003 for 27,165 Swedish twins born in 1935 to 1958 were linked to national DP data until 2013. Pain locations were evaluated for back, low back, sciatica, shoulder, or neck pain, and CMDs for lifetime major depression and 1-month anxiety.

RESULTS

The number of pain locations was associated with DP in a dose-response manner. One pain location had a hazard ratio of 1.50 (95% confidence interval 1.35 to 1.68) and five pain locations hazard ratio 4.67 (95% confidence interval 4.11 to 5.30) for DP. Also, CMDs were associated with DP.

CONCLUSION

The number of pain locations has a dose-response association with the risk of DP. CMDs predict DP. In strategies to prevent DP, early signs of pain or CMDs should be taken into consideration.

Education differences in sickness absence and the role of health behaviors: a prospective twin study

BACKGROUND

Long-term sickness absences burden the economy in many industrialized countries. Both educational attainment and health behaviors are well-known predictors of sickness absence. It remains, however, unclear whether these associations are causal or due to confounding factors. The co-twin control method allows examining causal hypotheses by controlling for familial confounding (shared genes and environment). In this study, we applied this design to study the role of education and health behaviors in sickness absence, taking sex and cohort differences into account.

METHODS

Participants were two cohorts of in total 8806 Norwegian twins born 1948 to 1960 (older cohort, mean age at questionnaire = 40.3, 55.8% women), and 1967 to 1979 (younger cohort, mean age at questionnaire = 25.6, 58.9% women). Both cohorts had reported their health behaviors (smoking, physical activity and body mass index (BMI)) through a questionnaire during the 1990s. Data on the twins' educational attainment and long-term sickness absences between 2000 and 2014 were retrieved from Norwegian national registries. Random (individual-level) and fixed (within-twin pair) effects regression models were used to measure the associations between educational attainment, health behaviours and sickness absence and to test the effects of possible familial confounding.

RESULTS

Low education and poor health behaviors were associated with a higher proportion of sickness absence at the individual level. There were stronger effects of health behaviors on sickness absence in women, and in the older cohort, whereas the effect of educational attainment was similar across sex and cohorts. After adjustment for unobserved familial factors (genetic and environmental factors shared by twin pairs), the associations were strongly attenuated and non-significant, with the exception of health behaviors and sickness absence among men in the older cohort.

CONCLUSIONS

The associations between educational attainment, health behaviors, and sickness absence seem to be confounded by unobserved familial factors shared by co-twins. However, the association between health behaviors and sickness absence was consistent with a causal effect among men in the older cohort. Future studies should consider familial confounding, as well as sex and age/cohort differences, when assessing associations between education, health behaviors and sickness absence.

Health behaviours and psychosocial working conditions as predictors of disability pension due to different diagnoses: a population-based study

BACKGROUND

To investigate whether the clustering of different health behaviours (i.e. physical activity, tobacco use and alcohol consumption) influences the associations between psychosocial working conditions and disability pension due to different diagnoses.

METHODS

A population-based sample of 24,987 Swedish twins born before 1958 were followed from national registers for disability pension until 2013. Baseline survey data in 1998-2003 were used to assess health behaviours and psychosocial Job Exposure Matrix for job control, job demands and social support. Cox proportional hazards models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

During follow-up, 1252 disability pensions due to musculoskeletal disorders (5%), 601 due to mental diagnoses (2%) and 1162 due to other diagnoses (5%) occurred. In the models controlling for covariates, each one-unit increase in job demands was associated with higher (HR 1.16, 95%CI 1.01-1.33) and in job control with lower (HR 0.87, 95%CI 0.80-0.94) risk of disability pension due to musculoskeletal disorders among those with unhealthy behaviours. Among those with healthy behaviours, one-unit increase of social support was associated with a higher risk of disability pension due to mental and due to other diagnoses (HRs 1.29-1.30, 95%CI 1.04-1.63).

CONCLUSIONS

Job control and job demands were associated with the risk of disability pension due to musculoskeletal disorders only among those with unhealthy behaviours. Social support was a risk factor for disability pension due to mental or other diagnoses among those with healthy behaviours. Workplaces and occupational health care should acknowledge these simultaneous circumstances in order to prevent disability pension.

The influence of unhealthy behaviours on early exit from paid employment among workers with a chronic disease: A prospective study using the Lifelines cohort

OBJECTIVES

This study examined the risk of unhealthy behaviours and the additive effects of multiple unhealthy behaviours on exit from paid employment among workers with a chronic disease and investigated effect modification by gender and educational level.

METHODS

Data from the Lifelines cohort, collected between 2006 and 2013, were enriched with registry data from Statistics Netherlands with up to 11 years follow-up. Workers with a chronic disease were selected (n = 11,467). The influence of unhealthy behaviours (physical inactivity, smoking, unhealthy diet, high alcohol intake, and obesity) on exit from paid employment (unemployment, disability benefits, early retirement, and economic inactivity) was examined using competing risk models. To examine effect modification by gender and educational level, interaction terms were added.

RESULTS

Smoking and low fruit intake increased the risk to exit paid employment through unemployment and disability benefits. Low vegetable intake increased the risk of unemployment, obesity the risk of receiving disability benefits, and high alcohol intake the risk of early retirement. Physical inactivity was not associated with any exit from paid employment. Having multiple unhealthy behaviours increased the risk of both unemployment and of receiving disability. No consistent effect modification for gender or educational level was found.

CONCLUSIONS

Unhealthy behaviours increased the risk to exit paid employment through unemployment and disability benefits among workers with a chronic disease, and this risk increased when having multiple unhealthy behaviours. Health promotion to support workers with chronic diseases to make healthier choices may help to extend their working life.

Smoking and disability pension: a systematic review and meta-analysis

OBJECTIVES

Smoking has negative consequences on occupational health. The current meta-analysis was conducted with the aim to pool the studies about smoking and increased disability pension.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Articles were found in the scientific literature using keywords, and searching was limited to prospective cohort studies that had been published before August 2018. Based on the inclusion and exclusion criteria, 23 prospective cohort studies were selected. The analyses were carried out on the basis of the random-effects method. Subgroup analysis was also carried out. Finally, the bias of publication was examined using Begg's test, the Egger test, the trim-and-fill method, and the funnel plot.

RESULTS

Twenty-three studies were included. The results showed a positive association between smoking and disability pension, with a risk ratio (RR) of 1.41 and 95% confidence interval (95% CI) of 1.30-1.53 (P < 0.001). In men, the RR was equal to 1.48 and 95% CI was equal to 1.30-1.68 (P < 0.001). In women, the RR was equal to 1.23 and 95% CI was equal to 1.09-1.37 (P = 0.001). In current smokers, the RR was equal to 1.41 and 95% CI was equal to 1.26-1.57 (P < 0.001). In former smokers, the RR was equal to 1.16 and 95% CI was equal to 1.05-1.29 (P = 0.003). Qualitative evaluation showed that the studies had a low level of selection bias, data collection bias, and withdrawal and dropout bias.

CONCLUSIONS

Smoking is a risk factor for increasing disability pension, and men are at higher risk of disability pension. In addition, both current and former smokers are in high risk of disability pension. Overall, it can be concluded that smoking is a risk factor for occupational health.

Transitioning from sickness absence to disability pension-the impact of poor health behaviours: a prospective Swedish twin cohort study

OBJECTIVES

To investigate the association between three poor health behaviours (current smoker, high consumption of alcohol and low physical activity levels) and the transition to disability pension (DP) among individuals who have recently been sickness absent. Furthermore, we aimed to explore whether having multiple poor health behaviours increased the risk of transitioning from sickness absence (SA) to DP.

DESIGN

Prospective twin cohort study.

SETTING

Sweden.

PARTICIPANTS

Twins aged 20-46 who had participated in a survey and been on SA (>14 days) in the year preceding baseline (date of answering the questionnaire).

MAIN OUTCOME MEASURE

Incident DP during the follow-up which ended on 31 December 2012 (mean 5.2 years). A national register with full coverage provided data on DP.

RESULTS

The Cox proportional-hazards regression analyses showed that current smokers had a higher risk of transitioning from SA to DP compared with never smokers (HR 1.76; 95% CI 1.08 to 2.84). Alcohol use and lack of physical activity as well as poor health behaviour sum score showed no significant associations.

CONCLUSIONS

Being a current smoker influences the transition from SA to DP. Although non-significant, there were indications that more physical activity and fewer poor health behaviours could reduce the risk of exiting the labour market through DP. Improving health behaviours among people on SA could be a valuable tool for preventing the transition to DP.

Changes in prescription of antidepressants and disability pension due to back pain, compared with other musculoskeletal and other somatic diagnoses: a cohort study in Sweden

OBJECTIVES

The aim was to investigate differences in the prescription of antidepressants during the transition to disability pension (DP) comparing DP due to back pain with DP due to other musculoskeletal and DP due to other somatic diagnoses.

DESIGN

A population-based cohort study with follow-up 3 years before and after the event. Estimated prevalence and adjusted ORs with 95% CIs for antidepressant prescription were computed for the 7-year window (ie, t-3 to t+3) around the DP by generalised estimating equations for repeated measures.

SETTING AND PARTICIPANTS

This Swedish population-based nationwide study with registry data included individuals aged 18-64 years, with DP due to back pain (n=2011), DP due to other musculoskeletal (n=3548) or DP due to other somatic diagnoses (n=11 809).

PRIMARY OUTCOME MEASURES

Prescription of antidepressants.

RESULTS

Before DP, the prevalence of prescription of antidepressants was stable in DP due to back pain, but increased for the other DP groups. Similarly, the likelihood of prescription increased only marginally before DP due to back pain (ORs from 0.86 at t-3 to 1.10 at t-1), but clearly in DP due to musculoskeletal (from 0.42 to 1.15) and somatic diagnoses (from 0.29 to 0.98). Both prevalence measures and risks remained at the elevated levels after DP.

CONCLUSIONS

Pathways to DP due to musculoskeletal and somatic diagnoses seem to be partly driven by adverse mental health, which remains at a higher level after DP. The increasing prescription of antidepressants prior to DP suggests that special attention should be paid to mental health for prevention of DP. The period after DP needs attention to avoid deterioration of mental health.

Childhood adversities, parental education and disability retirement among Finnish municipal employees

Background

There is increasing evidence that childhood socioeconomic position and childhood adversities influence adult health. However, the potential contribution of these factors to disability retirement is poorly understood. This study aimed to examine the associations between childhood adversities, parental education and disability retirement.

Methods

Data on parental education and childhood adversities were derived from the Helsinki Health Study baseline survey, conducted in 2000–02 among 40- to 60-year old employees of the City of Helsinki, Finland. Data on disability retirement and their diagnoses were obtained from the Finnish Centre of Pensions and followed until the end of 2016. The analyses included 5992 employees. The associations of parental education and childhood adversities with disability retirement due to any cause, musculoskeletal diseases and mental disorders were analysed using Cox regression analysis.

Results

Low parental education was associated with an increased risk of disability retirement due to any cause (maternal education: HR 1.74, 95% CI 1.16–2.62; paternal education: 1.86, 1.38–2.51) and due to musculoskeletal diseases (maternal education: 4.44, 1.66–11.92; paternal education: 3.81, 2.02–7.17). However, adjustment for own education mainly abolished the associations. Economic difficulties in the childhood family, parental alcohol problems and having been bullied at school or by peers increased the risk of disability retirement due to all studied diagnostic groups, whereas parental death or divorce had no effect. Childhood illness (1.53, 1.20–1.95) and parental mental illness (1.68, 1.28–2.20) were associated with disability retirement due to any cause and due to mental disorders (1.65, 1.05–2.59; 3.60, 2.46–5.26). The associations between childhood adversities and disability retirement remained after adjustment for own education, whereas working conditions, and weight and health behaviours somewhat attenuated the associations.

Conclusions

Parental education and childhood adversities contributed to disability retirement even in midlife. Policy actions investing in children’s well-being might promote work ability in midlife.

Association between midlife health behaviours and transitions out of employment from midlife to early old age: Whitehall II cohort study

Background

It is important to determine whether unhealthy behaviours might influence transitions out of employment from midlife to old age, given the anticipated need for adults to work for longer. Our aim was to determine the association between repeated assessments of cigarette smoking, heavy/problem alcohol drinking, low physical activity and poor diet at midlife, in relation to work exit from midlife to old age.

Methods

Data from 7704 participants (5392 men) from the Whitehall II cohort study in employment at midlife were used to evaluate the association between unhealthy behaviours and a subsequent transition out of work during 22 years follow-up, using logistic regression models.

Results

Men who smoked cigarettes, consistently drank alcohol heavily, or reported problem drinking, were more likely to leave employment over follow-up. Women with a consistently poor diet were more likely to leave employment. Associations were stronger when the reason for leaving was health grounds, and stronger among those with persistently unhealthy behaviours over follow-up. The size of the effects were broadly equivalent to one advancing year of age on employment. Physical health functioning over follow-up only partly accounted for the associations with work exit, whereas physical and mental functioning accounted for most of the associations with work exit on health grounds.

Conclusions

Unhealthy behaviours in midlife are associated with transitions out of employment into old age. Promoting healthy behaviours at midlife might support current policy initiatives aimed at extending working life. Future research should consider possible mechanisms that link behaviours to transitions out of employment, and consider sex differences in larger cohorts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3970-4) contains supplementary material, which is available to authorized users.

Labour market participation and sick leave among patients diagnosed with myasthenia gravis in Denmark 1997-2011: a Danish nationwide cohort study

Background

To examine labour market participation and long-term sick leave following a diagnosis with myasthenia gravis (MG) compared with the general Danish population and for specific subgroups of MG patients.

Methods

A nationwide matched cohort study from 1997 to 2011 using data from population-based medical and social registries. The study includes 330 MG patients aged 18 to 65 years old identified from hospital diagnoses and dispensed prescriptions, and twenty references from the Danish population matching each MG patient on age, gender, and profession. Main outcome measures are labour market participation (yes/no) and long-term sick leave ≥9 weeks (yes/no) with follow-up at 1- and 2 years after the time of MG diagnosis or match. Based on complete person-level information on all public transfer payments in Denmark, persons having no labour market participation are defined as individuals receiving social benefits for severely reduced workability, flexijob, and disability pension.

Results

MG is consistently associated with higher odds of having no labour market participation and long-term sick leave compared with the general Danish population (no labour market participation & ≥9 weeks sick leave at 2-year follow-up, adjusted OR (95% CI): 5.76 (4.13 to 8.04) & 8.60 (6.60 to 11.23)). Among MG patients, females and patients treated with both acetylcholinesterase inhibitors and immunosuppression have higher odds of lost labour market participation and long-term sick leave.

Conclusions

This study suggests that MG patients have almost 6 times higher odds of no labour market participation and almost 9 times higher odds of long-term sick leave 2 years after diagnosis compared with the general Danish population. In particular female MG patients and patients treated with both acetylcholinesterase and immunosuppression have high odds of a negative labour market outcome. Future research should focus on predictors in workplace and labour market policy of labour market participation among MG patients.

High Job Demands, Job Strain, and Iso-Strain are Risk Factors for Sick Leave due to Mental Disorders: A Prospective Swedish Twin Study With a 5-Year Follow-Up

OBJECTIVE

To investigate whether psychosocial work environment and health behaviors are risk factors for sick leave due to mental disorders, and whether familial confounding (genetics and shared environment) explains the associations.

METHODS

Respondents (n = 11,729), given to complete a questionnaire in 2004 to 2006, were followed up approximately 5 years for sick leave spells due to mental disorders, using national registry data. Data were analyzed using logistic regression, and conditional logistic regression for twin pairs discordant for sick leave (cotwin control).

RESULTS

High job demands, job strain, and iso-strain were independent risk factors for sick leave due to mental disorders. Familial factors seem to be of importance in the associations between job support, smoking, a combination of unhealthy behaviors and sick leave.

CONCLUSIONS

Improving the psychosocial work environment may be effective in preventing sick leave due to mental disorders.

Stability and change of body mass index as a predictor of disability pension

AIMS

To investigate whether stability or change in body mass index (BMI) predict disability pension (DP) due to musculoskeletal diagnosis (MSD) when controlling for familial confounding.

METHODS

Our study cohort consisted of 17,169 Finnish twins born before 1958. Data on BMI and multiple covariates from questionnaires in 1975 and 1981 were included and DPs were collected from the national pension registers until the end of 2004. Cox proportional hazards regression models with Hazard Ratios (HR) and 95% Confidence Intervals (CI) were used for statistical analyses.

RESULTS

General DP was granted to 2853 individuals and DP due to MSD to 1143 individuals during the 23-year follow-up. A one-unit increase in BMI in both 1975 (HR 1.08, 95% CI 1.05, 1.10) and 1981 (HR 1.06, 95% CI 1.04, 1.07), as well as the stability of and change in BMI from 1975 to 1981 were all associated with an increased risk of DP. These associations held in the analyses controlling for multiple covariates (age, sex, socioeconomic status, education, marital status, leisure-time physical activity, and musculoskeletal pain), and mainly also familial confounding, that is, genetics and shared environment. HR for stable obesity was 2.28 (95% CI 1.69, 3.08) for DP due to MSD, and 1.91 (95% CI 1.56, 2.34) for general DP in the fully adjusted models. CONCLUSIONS BMI IS AN EARLY PREDICTOR OF GENERAL DP AND ALSO OF DP DUE TO MSD OWING TO THE INDEPENDENCY OF VARIOUS COVARIATES AND POTENTIALLY ALSO FAMILIAL CONFOUNDING, BMI MAY POSSIBLY HAVE A DIRECT EFFECT ON THE RISK OF DP.

Cigarette smoking and alcohol use as predictors of disability retirement: A population-based cohort study

BACKGROUND

This study investigated how cigarette smoking and alcohol use predict disability retirement.

METHODS

Data from the longitudinal nationwide Finnish Twin Cohort study were analyzed, with clustered study design applied when computing 95% confidence intervals (CI). The sample included 21,719 individuals. Smoking and alcohol use were assessed with a questionnaire in 1975. Registry data on retirement events up till end of 2004 were obtained from the Social Insurance Institution and the Finnish Centre for Pensions.

RESULTS

Disability pension was granted to 4251 participants. Among men, adjusted for age and alcohol use, former (HR=1.45, 95%CI 1.28, 1.65, p<.001) and daily smokers (HR=1.93, 95%CI 1.71, 2.17, p<.001) showed elevated disability pension risk compared to never smokers. Among women, daily smokers (HR=1.25, 95%CI 1.11, 1.40, <.001) had elevated risk. The age and smoking adjusted risk estimates for alcohol were elevated among abstainers (men HR=1.41, 95%CI 1.21, 1.65, p<.001; women HR=1.36, 95%CI 1.23, 1.52, p<.001) and heavy drinkers (men HR=1.30, 95%CI 1.18, 1.43, p<.001; women HR=1.34, 95%CI 1.04, 1.72, p=.026). Those being persistent smokers and binge drinkers had over three-fold disability risk compared to those who were binge drinkers but had only a few smoking years (men: HR=3.32, 95%CI 2.43, 4.54, p<.001; women: HR=4.05, 95%CI 2.05, 8.00, p<.001). Among men and women who were not binge drinkers, longer smoking duration was needed for elevated disability risk.

CONCLUSIONS

Both smoking and excess alcohol use significantly predict disability retirement. In order to extend working careers, more attention should be paid to health behaviors, in addition to working conditions.

Joint associations of smoking and physical activity with disability retirement: a register-linked cohort study

OBJECTIVES

We examined the risk of disability retirement by smoking and physical activity, and particularly whether the risk due to smoking is affected by the level of physical activity. Additionally, the contribution of baseline health, sociodemographic and work-related factors to the joint associations of smoking and physical activity with disability retirement was considered.

DESIGN

Cohort study.

SETTING

Helsinki, Finland.

PARTICIPANTS

Employees of the City of Helsinki, aged 40-60 years at baseline in 2000-2002, were followed up using complete register data from the Finnish Centre of Pensions until the end of 2010 (n=6390, with a consent to register linkage from 74%).

PRIMARY OUTCOME MEASURE

All-cause disability retirement (ICD-10).

RESULTS

Altogether, 608 employees (9.5%) retired due to disability during the follow-up. Cox regression models were fitted to examine the joint associations of smoking and physical activity with subsequent disability retirement. Never-smokers, ex-smokers and moderate smokers who were inactive or moderately active had an increased risk of disability retirement, but if they were vigorously active, they had no excess risk. Instead, all heavy smokers (15 or more cigarettes per day among women, and 20 or more among men), irrespective of physical activity, had an increased risk of disability retirement. The examined associations attenuated but remained for ex-smokers and heavy smokers after adjustments for gender, age, socioeconomic position, mental and physical workload, problem drinking, body mass index and self-rated health. No gender interactions were found.

CONCLUSIONS

Vigorous physical activity might help prevent disability retirement not only among never-smokers, but even among ex-smokers and moderate smokers. However, among heavy smokers, physical activity is not sufficient to eliminate the adverse effects of smoking on health and work ability.

Associations between childbirth, hospitalization and disability pension: a cohort study of female twins

Background

As the literature on long-term effects of childbirth on risk of morbidity or permanent work incapacity (DP) is limited, we aimed to study associations of childbirth with hospitalization and DP, adjusting for familial factors.

Methods

This cohort study included female twins, i.e. women with twin sister, born 1959–1990 in Sweden (n = 5 118). At least one in the twin pair had their first childbirth 1994–2009. Women were followed regarding all-cause and cause-specific (mental or musculoskeletal diagnoses) DP during year 2–5 after first delivery or equivalent. Associations between childbirth, hospitalization and DP were calculated as hazard ratios (HR) with 95% confidence intervals (CI).

Results

Women who did not give birth had markedly higher number of DP days/year compared to those giving birth. Hospitalization after first childbirth was associated with a higher HR of DP. Those hospitalized at least once after their first childbirth had a three-fold DP risk (HR: 3.2; 95% CI 1.1–9.6), DP due to mental diagnoses (HR: 3.2; 1.2–8.8), and of DP due to musculoskeletal diagnoses (HR: 6.1; 1.6–22.9). Lower HRs in the discordant twin pair analyses indicated that familial factors may influence the studied associations.

Conclusions

Women who did not give birth had a much higher risk for DP than those who did. Among those who gave birth, the risk for DP was markedly higher among those with a previous hospitalization, and especially in women with repeated hospitalizations. The results indicate a health selection into giving birth as well as the importance of morbidity for DP.