Association of 12-year trajectories of sitting time with frailty in middle-aged women

Prolonged sitting time is associated with several health outcomes; with limited evidence reporting associations with frailty. The aims of this study were to identify patterns of sitting time over 12 years in middle-aged women and examine associations of these patterns with frailty in older age. Our study examined 5,462 women born in 1946-1951 from the Australian Longitudinal Study on Women's Health who self-reported socio-demographic attributes, daily sitting time and frailty in 2001, and then every three years until 2013. Frailty was assessed using the FRAIL scale (score 0\ua0=\ua0healthy; 1-2\ua0=\ua0pre-frail; 3-5\ua0=\ua0frail) and group-based trajectory analyses identified trajectories of sitting time. We identified five sitting time trajectories: low (27.5%); medium (41.5%; reference); increasing (8.2%); decreasing (18.0%); and high (4.9%). In adjusted models, the likelihoods (odds ratio: 95% confidence interval) of being frail were statistically higher for those in the increasing (1.29: 1.03, 1.61) and high (1.42: 1.10, 1.84) trajectories. In contrast, the low (0.86: 0.75, 0.98) trajectory group was less likely to be frail, with no difference in likelihood of frailty in the decreasing trajectory group. Our study suggests that patterns of sitting time over 12 years in middle-aged women predict frailty in older age