Health care costs associated with prolonged sitting and inactivity.

BACKGROUND Physical inactivity and prolonged sitting are associated with negative health outcomes. PURPOSE To examine the health-related costs of prolonged sitting and inactivity in middle-aged women. METHODS Australian Longitudinal Study on Women's Health participants (born 1946-1951) answered questions about time spent sitting, walking, and in moderate and vigorous leisure activities in 2001 (n=6108); 2004 (n=5902); 2007 (n=5754); and 2010 (n=5535) surveys. Sitting time was categorized as low (0-4); moderate (5-7); and high (≥8 hours/day). Physical activity was categorized as inactive (<40); low (40-600); moderate (600-1200); and high (≥1200 MET-minutes/week). National health insurance claims data averaged over the survey year ±1 year were used to calculate annual costs (Australian dollars [AU$]). Differences between categories in median costs were estimated using quantile regression over four surveys with bootstrapped 95% CIs. Analyses were performed in 2013. RESULTS In 2010, annual median costs were AU$689 (interquartile range [IQR]=274, 1541) in highly active participants; AU$741 (IQR=279, 1690) in inactive participants; AU$671 (IQR=273, 1551) in participants with low sitting time; and AU$709 (IQR=283, 1575) in participants with high sitting time. The difference in median costs for inactive and highly active participants was AU$94 (CI=57, 131) after adjustment for confounders. No statistically significant associations were found between sitting time and costs. When sitting and physical activity were combined, high sitting time did not add to the inactivity-associated increased costs. Associations were consistent across normal-weight, overweight, and obese subgroups. CONCLUSIONS Physical inactivity, but not prolonged sitting, was associated with higher health-related costs in middle-aged women.