Association of Sitting Time and Physical Activity With CKD: A Cross-sectional Study in Family Practices

Background: Chronic kidney disease (CKD) represents a significant and growing health care burden globally. Lifestyle factors, such as physical activity and sitting-related sedentary behavior, have been hypothesized to be directly associated with CKD; however, epidemiologic research is limited. Study Design: Cross-sectional analysis. Setting & Participants: A population-level diabetes screening program conducted across 20 family practices in Leicester, United Kingdom, August 2004 to December 2007. Predictors: Self-reported sitting time and physical activity, obtained using the International Physical Activity Questionnaire. Outcomes & Measurements: CKD, defined using NKF-KDOQI (National Kidney Foundation's Kidney Disease Outcomes Quality Initiative) criteria. Results: 6,379 (52% women) individuals were included. Lower levels of sitting time were associated with lower risk of CKD after controlling for physical activity, body mass index, and other potential confounding variables (OR, 0.74 [95% CI, 0.62-0.92] for lowest vs highest tertile). Interaction analysis showed that women trended toward a significantly higher risk of CKD with higher levels of sitting time compared with men. Participating in levels of physical activity that were at least consistent with the minimum recommendations for health was associated with lower risk of CKD. A significant interaction with sex was observed, with men showing a lower risk of CKD with high levels of physical activity compared with women. Limitations: Cross-sectional design, self-reported lifestyle data, CKD defined at a single time, and estimated glomerular filtration rate and microalbuminuria were the only measures used to define CKD. Conclusions: This study suggests that higher levels of physical activity and lower levels of sitting time are associated with a lower prevalence of CKD independently of each other and other risk factors. However, results may vary by sex, with sitting time being the more important factor in women and physical activity the more important factor in men. These results have important implications for future research. Am J Kidney Dis. 60(4):583-590. (C) 2012 by the National Kidney Foundation, Inc.