Disability pension due to musculoskeletal diagnoses: importance of work-related factors in a prospective cohort study of Finnish twins.

OBJECTIVES: The aim of this study was to investigate the impact of work-related risk factors for future disability pension (DP) due to musculoskeletal diagnoses and for a subgroup of these, namely, DP due to osteoarthritis. METHODS: For this prospective study of 16,028 Finnish twins born in 1911-1957 and employed at baseline, a postal questionnaire collected information in 1975 on work-related factors; follow-up data on DP was gathered through register linkages up to 2004. A series of proportional hazards (Cox) regression models were used to analyze the associations between work-related factors and the incidence of DP. RESULTS: During the 30-year follow-up, 1297 participants (8%) were granted DP due to musculoskeletal diagnoses, 376 of which were due to osteoarthritis. High stress of daily activities, monotonous work, physical workload (namely work including lifting and carrying or physically heavy work), several workplace changes, and unemployment displayed a strong association with DP due to musculoskeletal diagnoses that was not affected by familial factors, including genetics and shared environment. Additionally, standing work increased the risk for DP due to osteoarthritis. CONCLUSIONS: Uninfluenced by family background or other confounding factors, several work-related factors were identified as being strong and direct risk factors for DP due to musculoskeletal diagnoses.

Effect of smoking on use of antibacterials: a 9-year follow-up study of 24 000 working-aged Finns.

BACKGROUND: Previous studies indicate an association between tobacco smoking and infectious diseases. However, large population-based follow-up studies including both accurate measurements of smoking behaviour and confounders and a reliable register-based follow-up of infections are lacking. OBJECTIVE: To examine the effect of smoking on use of antibacterials as an indicator of infections among working-aged population. METHODS: The participants of the population-based Health and Social Support Study (24,283 working-aged Finns) were followed up for 9 years. Information on smoking behaviour and confounders was obtained from a questionnaire in 1998. Number of antibacterial purchases was obtained from the National-Drug-Prescription-Register. The association between smoking and use of antibacterials was analysed using multinomial regression models. RESULTS: A graded association between lifetime smoking as measured by pack-years and use of antibacterials was found. Compared with never-smokers, the age-adjusted OR for multiple use of antibacterials among smokers with 12 or more pack-years was 2.32 (95% CI 1.91 to 2.82) in women and 1.45 (95% CI 1.23 to 1.71) in men. The associations remained after adjustment for the following confounding factors: use of alcohol, body mass index, physical activity, socioeconomic status, hard physical work, life satisfaction, disability pension and dyspnoea. CONCLUSIONS: Smoking is associated with increased use of antibacterials. Infectious periods experienced by patients should be used as an opportunity to encourage smoking cessation.

Effects of work and lifestyle on risk for future disability pension due to low back diagnoses: a 30-year prospective study of Finnish twins.

OBJECTIVE: To investigate work and lifestyle factors as predictors for disability pension (DP) due to low back diagnoses (LBDs) during a 30-year follow-up. METHODS: Baseline survey data were obtained in 1975 for 16,028 working-age twins followed with register data on DP, emigration, old-age pension, and death until end of 2004; analyzed by Cox proportional hazards regression. RESULTS: Among those at work at baseline, 470 DPs due to LBDs were granted during the follow-up. Monotonous work, lifting and carrying at work or physically heavy work, and unemployment at least once before baseline were significant predictors for DP. A healthy lifestyle was a protective factor for DP. Family background played a role in all these associations. CONCLUSION: The factors shared by family members seemed to influence both work and lifestyle factors, which then influenced the incidence of DP due to LBDs.

Personality traits and life dissatisfaction as risk factors for disability pension due to low back diagnoses: a 30-year longitudinal cohort study of Finnish twins.

OBJECTIVE: Little is known about the association of mild symptoms and mental well-being with risk of disability pension (DP) due to somatic diagnoses, even less for DP due to low back diagnoses (LBD). Moderate genetic influences on personality traits, life dissatisfaction and DP exist suggesting that shared genetic influences may underlie these associations. One can control for familial confounding (genetics and family environment) by examining twins. This twin study aimed to investigate personality traits and life dissatisfaction as predictors for DP due to LBD accounting for familial confounding. METHODS: Data on 24043 twins aged 18-65year in a baseline survey in 1975 was followed up from national DP register data until 2004. Personality traits were assessed using the short version of the Eysenck Personality Inventory and life dissatisfaction was measured with a four item scale on levels of interest, happiness, easiness, and loneliness of life. Cox proportional hazards regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI). RESULTS: DP due to LBD was granted to 537 individuals during the follow-up. Each one unit increase in life dissatisfaction (HR 1.06; 95%CI 1.03, 1.10) and neuroticism (1.07; 1.03, 1.10) but not extroversion was significantly associated with an elevated risk for DP due to LBD. These associations with life dissatisfaction and neuroticism remained when socioeconomic status, education, and marital status were taken into account, and demonstrated an independence from familial confounding. CONCLUSION: Life dissatisfaction and neuroticism seems to be early, perhaps causal risk factors for DP due to LBD.

Health-related risk factors for disability pensions due to musculoskeletal diagnoses: a 30-year Finnish twin cohort study.

AIMS: There is a need to better understand work incapacity due to musculoskeletal disorders (MSD) and the factors that contribute to being granted disability pension (DP) with such disorders. A twin cohort study would serve a powerful tool responding to this knowledge gap by providing information on factors affecting DP when controlling for family background. The purpose was to investigate the incidence of and risk factors for DP due to any MSD (n=1,819) and specifically due to osteoarthritis (OA, n=677) in a twin cohort of 24,043 people over a 30-year follow-up. METHODS: Data on twin pairs from a mailed questionnaire during the baseline year of 1975 were followed up with register data regarding DP, emigration, old-age pension, and death. For statistical analysis, univariate and multivariate Cox proportional hazard ratios were estimated. RESULTS: Baseline musculoskeletal pain, frequency of use of analgesics, body mass index, and chronic diseases, as well as education and social class were significant risk factors for DP due to MSD at follow-up in both sexes. These factors were also the significant predictors of DP due to OA in men. In women, DP due to OA was best predicted by baseline musculoskeletal pain and lower social class. CONCLUSIONS: The risk of DP due to MSD and OA seemed to be influenced by comorbidities, educational level and social class. Analyses of twin pairs discordant for DP confirmed the results. Accumulated health problems and chronic conditions during the life course may lead to permanent work incapacity.

Health-related and sociodemographic risk factors for disability pension due to low back disorders: a 30-year prospective Finnish Twin Cohort Study.

OBJECTIVES: To investigate health-related and sociodemographic risk factors for disability pensions (DP) due to low back disorders (LBD). METHODS: Questionnaire data in 1975 of the Finnish Twin Cohort Study with record linkage to information on DP due to LBD from the official pension registers during follow-up 1975 to 2004 was analyzed with Cox proportional hazard models. RESULTS: Musculoskeletal pain (Hazards Ratio [HR] = 2.36 to 2.39; 95% CI 1.97 to 2.88), smoking (HR = 1.82; 1.49 to 2.22), frequent analgesics use (HR = 1.67; 1.38 to 2.02), and presence of other chronic disease (HR = 1.44; 1.22 to 1.70) increased the risk for DP due to LBD. Years of education decreased the risk (HR = 0.81; 0.77 to 0.85). Associations remained significant when adjusted for familial background. CONCLUSIONS: Health-related and sociodemographic risk factors for DP due to LBD can be identified early in life, and they seem independent from familial effects.

The burden of symptoms predicts early retirement: a twin cohort study on fibromyalgia-associated symptoms.

OBJECTIVE: To assess whether symptoms of fibromyalgia (FM) predict disability retirement or mortality. METHODS: All Finnish Twin Cohort members and diagnosed FM-patients who had answered the same health questionnaire in 1990-1992 were studied. A sample of 10,608 working aged individuals of the cohort was classified in homogenous groups based on symptom profile with latent class analysis, using a battery of questions addressing FM-associated symptoms validated between FM-patients and twins. This resulted in three classes: no or few symptoms (LC1), some symptoms (LC2), and high load of FM-symptoms (LC3). In a 14-year follow-up, 1990-2004, information on disability retirement was obtained from official pension registers. Further linkage with Population Register Centre data for 1990-2009 yielded information on the vital status of the cohort subjects. Those with malignancies or inflammatory rheumatic diseases were excluded. RESULTS: Cumulative incidence of early disability retirement was 9.5% among all 8448 individuals (after exclusions), and 26% in LC3. Adjusted hrs for early retirement were 1.0 (reference class) in LC1, 1.5 (95%CI 1.2-1.7) in LC2, and 2.9 (2.4-3.6) in LC3 for all causes and 1.8 (1.4-2.5) in LC2 and 5.0 (3.6-6.9) in LC3 for musculoskeletal disorders. In 173,675 person-years, the high symptom class (LC3) had a 43% (95% CI 17-75%) increased overall mortality risk, which was fully accounted for by adjustment for lifestyle factors, mainly smoking. CONCLUSION: Symptoms associated with FM strongly correlate with early disability retirement. Lifestyle problems associated with high symptom load need prompt management to avoid increased risk of mortality.

The genetic liability to disability retirement: a 30-year follow-up study of 24,000 Finnish twins.

BACKGROUND: No previous studies on the effect of genetic factors on the liability to disability retirement have been carried out. The main aim of this study was to investigate the contribution of genetic factors on disability retirement due to the most common medical causes, including depressive disorders. METHODS: The study sample consisted of 24,043 participants (49.7% women) consisting of 11,186 complete same-sex twin pairs including 3519 monozygotic (MZ) and 7667dizygotic (DZ) pairs. Information on retirement events during 1.1.1975-31.12.2004, including disability pensions (DPs) with diagnoses, was obtained from the Finnish nationwide official pension registers. Correlations in liability for MZ and DZ twins and discrete time correlated frailty model were used to investigate the genetic liability to age at disability retirement. RESULTS: The 30 year cumulative incidence of disability retirement was 20%. Under the best fitting genetic models, the heritability estimate for DPs due to any medical cause was 0.36 (95% CI 0.32-0.40), due to musculoskeletal disorders 0.37 (0.30-0.43), cardiovascular diseases 0.48 (0.39-0.57), mental disorders 0.42 (0.35-0.49) and all other reasons 0.24 (0.17-0.31). The effect of genetic factors decreased with increasing age of retirement. For DP due to depressive disorders, 28% of the variance was explained by environmental factors shared by family members (95% CI 21-36) and 58% of the variance by the age interval specific environmental factors (95% CI 44-71). CONCLUSIONS: A moderate genetic contribution to the variation of disability retirement due to any medical cause was found. The genetic effects appeared to be stronger at younger ages of disability retirement suggesting the increasing influence of environmental factors not shared with family members with increasing age. Familial aggregation in DPs due to depressive disorders was best explained by the common environmental factors and genetic factors were not needed to account for the pattern of familial aggregation.