This study examined the one-year test-re-test reliability and criterion validity of sedentary time survey items in a subset of participants from a large, nationwide prospective cohort.METHODS
Participants included 423 women and 290 men aged 31-72 years in the Cancer Prevention Study-3 (CPS-3). Reliability was assessed by computing Spearman correlation coefficients between responses from pre- and post-study surveys. Validity was assessed by comparing survey-estimated sedentary time with a latent variable representing true sedentary time estimated from the seven-day diaries, accelerometry, and surveys through the method of triads. Sensitivity analyses were restricted to 566 participants with an average of 14+ hours of diary and accelerometer data per day for seven days per quarter.RESULTS
Reliability estimates for total sitting time were moderate or strong across all demographic strata (Spearman ρ≥0.6), with significant differences by race (p=0.01). Reliability estimates were strongest for the TV-related sedentary time item (Spearman ρ=0.74, 95% CI: 0.70, 0.77). The overall validity coefficient (VC) for survey-assessed total sedentary time was 0.62 (95% CI: 0.55, 0.69), although VCs varied by age group and activity level (p<0.05). However, VCs were similar across groups (p<0.05) when restricting to highly compliant participants in a sensitivity analysis.RESULTS
The CPS-3 sedentary behavior questionnaire has acceptable reliability and validity for ranking or categorizing participants according to sedentary time. Acceptable reliability and validity estimates persist across various demographic sub-groups.