Author Affiliations: Sydney School of Public Health, University of Sydney, Sydney, Australia (Drs van der Ploeg and Bauman); Department of Public and Occupational Health, VU University Medical Center Amsterdam, the Netherlands (Dr van der Ploeg); and National Centre for Epidemiology and Population Health, Australian National University, Acton, Australia and The Sax Institute, Sydney (Dr Banks).
The responses to our recent article on sitting time and mortality1 highlight the interest in, and potential importance of, sedentary behaviors and health. Our original article found that prolonged sitting was associated with increased all-cause mortality risk, independent of physical activity.1 A study limitation was the relatively short follow-up time (mean, 2.8 years), potentially leading to confounding by occult disease. However, findings persisted after adjustments (for demographic variables, physical activity, body mass index, smoking, self-rated health, and disability), chronic disease stratification, and sensitivity analyses excluding deaths in the first year. Nevertheless, neither reverse causality due to occult disease nor residual confounding could be completely excluded.1
van der Ploeg HP, Banks E, Bauman A. Is Sitting Harmful to Health? It Is Too Early to Say—Reply. Arch Intern Med. 2012;172(16):1272-1273. doi:10.1001/archinternmed.2012.2953