Sitting Time, Fidgeting, and All-Cause Mortality in the UK Women's Cohort Study

Introduction: Sedentary behaviors (including sitting) may increase mortality risk independently of physical activity level. Little is known about how fidgeting behaviors might modify the association. Methods: Data were from the United Kingdom(UK) Women's Cohort Study. In 1999-2002, a total of 12,778 women (aged 37-78 years) provided data on average daily sitting time, overall fidgeting (irrespective of posture), and a range of relevant covariates including physical activity, diet, smoking status, and alcohol consumption. Participants were followed for mortality over a mean of 12 years. Proportional hazards Cox regression models estimated the relative risk of mortality in high (versus low) and medium (versus low) sitting time groups. Results: Fidgeting modified the risk associated with sitting time (p = 0.04 for interaction), leading us to separate groups for analysis. Adjusting for covariates, sitting for >= 7 hours/day (versus <5 hours/day) was associated with 30% increased all-cause mortality risk (hazard ratio [HR] = 1.30, 95% CI = 1.02, 1.66) only among women in the low fidgeting group. Among women in the high fidgeting group, sitting for 5-6 hours/day (versuso5 hours/day) was associated with decreased mortality risk (HR = 0.63, 95% CI = 0.43, 0.91), adjusting for a range of covariates. There was no increased mortality risk from longer sitting time in the middle and high fidgeting groups. Conclusions: Fidgeting may reduce the risk of all-cause mortality associated with excessive sitting time. More detailed and better-validated measures of fidgeting should be identified in other studies to replicate these findings and identity mechanisms, particularly measures that distinguish fidgeting in a seated from standing posture. (C) 2016 American Journal of Preventive Medicine