Relationships between weight, physical activity, and back pain in young adult women

Background: Back pain is a major global health problem, causing greater disability worldwide than any other condition. It is associated with a significant economic burden and major disability, as therapeutic options have limited efficacy. Given limited treatment options, clarifying predictors of back pain is important in order to optimize preventive strategies. Furthermore, as previous episodes of back pain are predictive of future recurrence, understanding risk factors associated with back pain in early adulthood is particularly important.  Objectives: The study aims were to identify whether modifiable risk factors, weight and physical activity, are predictive of back pain in young adult women.  Methods: Community dwelling women born between 1973 and 1978 were randomly selected from the Australian national health insurance scheme database to participate in the Australian Longitudinal Study of Women's Health. Women were recruited nationally with intentional oversampling from rural and remote areas. Self-reported data on back pain in the last 12 months, age, weight, physical activity, depression and other socio-demographic factors were collected in 2000, 2003, 2006, 2009 and 2012. In 2000, 9,688 women completed the questionnaire and 83% completed follow up 12 years later.  Results: At baseline, median age was 24.6 years and 41% had self-reported back pain. For every 5kg higher weight at baseline, there was a 5% (95% CI 4% - 6%) increased risk of back pain over the next 12 years, after adjusting for age, height, education status, physical activity and depression. Higher weight also predicted back pain risk over each 3 year survey interval (p<0.001). The effects of weight on back pain were most significant in those with body mass index ≥25 kg/m2 and were observed at all levels of physical activity. Inadequate physical activity and depression were independent predictors of back pain over the following 12 years (both p<0.001), after adjusting for above confounders.  Conclusions: Back pain is common in community-based young adult women. Higher weight, inadequate levels of physical activity and depression were all independent predictors of back pain over the following decade. Furthermore, the adverse effects of weight on back pain were not mitigated by physical activity. Our findings highlight the role of both higher weight and physical inactivity in back pain among young adult women and suggest potential opportunities for future prevention.