title: Stability and change of body mass index as a predictor of disability pension.
abstract: OBJECTIVE
  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.
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland annina.ropponen@ttl.fi.
authors.forename: Annina
authors.initials: A
authors.lastname: Ropponen
authors.affiliation: Population Research Unit, Department of Sociology, University of Helsinki, Finland.
authors.forename: Karri
authors.initials: K
authors.lastname: Silventoinen
authors.affiliation: Department of Public Health, University of Helsinki, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Sweden.
authors.forename: Pia
authors.initials: P
authors.lastname: Svedberg
authors.affiliation: Department of Public Health, University of Helsinki, Finland Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Finland Institute for Molecular Medicine, University of Helsinki, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D006233:Persons with Disabilities / Q000706:statistics & numerical data*; D005260:Female; D005387:Finland; D006801:Humans; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000175:diagnosis* / Q000235:genetics; D010415:Pensions / Q000706:statistics & numerical data*; D012306:Risk
keywords: Sickness absence; body mass index; disability pension; musculoskeletal disorders; prospective design