Revisiting the International Physical Activity Questionnaire (IPAQ): Assessing sitting time among individuals with schizophrenia

•Mean difference between IPAQ and accelerometry not significant.•Limits of agreement between measures are wide.•Bias appears proportional.•4-week retest reliability indices fair.•Objective measure of sedentary behaviour advisable. While moderate to vigorous physical activity may be one method of addressing common physical morbidities in schizophrenia, reducing sedentary time may be a low intensity adjunct. In order to determine whether sedentary behaviour is associated with health outcomes, valid and reliable tools for assessing sedentary time are necessary. In order to characterize the validity and reliability of the International Physical Activity Questionnaire (IPAQ) for assessing sitting (sedentary) time, participants completed the IPAQ at baseline and 4 weeks later and wore accelerometers for 7 days before the final assessment. Bland-Altman analyses and intraclass correlation coefficients (ICC) were used to compare agreement between measurements. One-hundred thirteen individuals completed the study. Mean difference between the IPAQ and accelerometer was 26.8 min (95% Limits of Agreement: −458.7–512.3) and ICCA,1 was 0.23 (95% CI: 0.06–0.39). Week 1 and Week 4 administrations of the IPAQ differed by an average of 26.6 min, (95% Limits of Agreement: −510.9–564.2) and ICCA,1 was 0.41 (95% CI: 0.21–0.59). The “minutes” of sitting reported by the IPAQ do not reflect objective sedentary behaviour measurements and this current measure may be unsuitable for the population level assessment of sitting time among individuals with schizophrenia.