title: Association between education and future leisure-time physical inactivity: a study of Finnish twins over a 35-year follow-up.
abstract: Education is associated with health related lifestyle choices including leisure-time physical inactivity. However, the longitudinal associations between education and inactivity merit further studies. We investigated the association between education and leisure-time physical inactivity over a 35-year follow-up with four time points controlling for multiple covariates including familial confounding.
  
  
  
  This study of the population-based Finnish Twin Cohort consisted of 5254 twin individuals born in 1945-1957 (59 % women), of which 1604 were complete same-sexed twin pairs. Data on leisure-time physical activity and multiple covariates was available from four surveys conducted in 1975, 1981, 1990 and 2011 (response rates 72 to 89 %). The association between years of education and leisure-time physical inactivity (<1.5 metabolic equivalent hours/day) was first analysed for each survey. Then, the role of education was investigated for 15-year and 35-year inactivity periods in the longitudinal analyses. The co-twin control design was used to analyse the potential familial confounding of the effects. All analyses were conducted with and without multiple covariates. Odds Ratios (OR) with 95 % Confidence Intervals (CI) were calculated using logistic and conditional (fixed-effects) regression models.
  
  
  
  Each additional year of education was associated with less inactivity (OR 0.94 to 0.95, 95 % CI 0.92, 0.99) in the cross-sectional age- and sex-adjusted analyses. The associations of education with inactivity in the 15- and 35-year follow-ups showed a similar trend: OR 0.97 (95 % CI 0.93, 1.00) and OR 0.94 (95 % CI 0.91, 0.98), respectively. In all co-twin control analyses, each year of higher education was associated with a reduced likelihood of inactivity suggesting direct effect (i.e. independent from familial confounding) of education on inactivity. However, the point estimates were lower than in the individual-level analyses. Adjustment for multiple covariates did not change these associations.
  
  
  
  Higher education is associated with lower odds of leisure-time physical inactivity during the three-decade follow-up. The association was found after adjusting for several confounders, including familial factors. Hence, the results point to the conclusion that education has an independent role in the development of long-term physical inactivity and tailored efforts to promote physical activity among lower educated people would be needed throughout adulthood.
authors: Department of Public Health, University of Helsinki, PO Box 41 (Tukholmankatu 8, 2B), FI-00014, Helsinki, Finland. maarit.piirtola@helsinki.fi.
authors: Maarit
authors: 0000-0001-7270-6676
authors: M
authors: Piirtola
authors: Department of Public Health, University of Helsinki, PO Box 41 (Tukholmankatu 8, 2B), FI-00014, Helsinki, Finland.|Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.|Department of Health, National Institute for Health and Welfare, Helsinki, Finland.
authors: Jaakko
authors: J
authors: Kaprio
authors: Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
authors: Urho M
authors: UM
authors: Kujala
authors: Department of Public Health, University of Helsinki, PO Box 41 (Tukholmankatu 8, 2B), FI-00014, Helsinki, Finland.|Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.
authors: Kauko
authors: K
authors: Heikkilä
authors: Department of Public Health, University of Helsinki, PO Box 41 (Tukholmankatu 8, 2B), FI-00014, Helsinki, Finland.
authors: Markku
authors: M
authors: Koskenvuo
authors: Department of Clinical Neuroscience, Division of Insurance Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: Pia
authors: P
authors: Svedberg
authors: Department of Social Research, Population Research Unit, University of Helsinki, Helsinki, Finland.
authors: Karri
authors: K
authors: Silventoinen
authors: Finnish Institute of Occupational Health, Helsinki, Finland.
authors: Annina
authors: A
authors: Ropponen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D004522:Educational Status; D004777:Environment; D015444:Exercise; D005190:Family; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D015438:Health Behavior; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D057185:Sedentary Behavior; D012931:Social Environment; D011795:Surveys and Questionnaires; D014427:Twins; D055815:Young Adult
keywords: Adult; Behavioral genetics; Cohort studies; Educational status; Exercise; Follow-Up studies; Twins