Background: Individuals with schizophrenia tend to have low levels of physical activity (PA) which contributes to high rates of physical comorbidities. Valid and reliable methods of assessing PA are essential for advancing health research. Ten years after initial validation of the Short-Form International Physical Activity Questionnaire (IPAQ), this study expands on the initial validation study by examining retest reliability over a 4-week period, assessing validity with a larger sample, and comparing validity of the IPAQ to a 24-hour recall alternative.
Methods: Participants completed the IPAQ at baseline and 4weeks later, along with a 24-hour PA recall at week 4. At week 3 participants wore waist accelerometers for 7days. Spearman's correlation coefficients and Bland-Altman plots were calculated based on weekly minutes of moderate to vigorous PA (MVPA).
Results: Test-retest reliability for the self-administered IPAQ was ρ=0.47, p<0.001 for MVPA. Correlation between IPAQ assessment and accelerometer-determined MVPA was ρ=0.30, p=0.003. The 24-hour recall correlated significantly with MVPA on the previous day ρ=0.27, p=0.012. A Bland-Altman plot indicated the IPAQ-SF underreported by -119.2min (-72%) on average compared to accelerometry (95% limits of agreement -1017.1 to 778.7min, -292% to 147%).
Conclusion: Compared to previous IPAQ validation work in this population, criterion validity was similar, but reliability was lower over a 4-week period. MVPA criterion validity of the 24-hour recall was comparable to the 7-day self-report IPAQ. Findings further support that the IPAQ is a suitable assessment tool for epidemiological studies. Objective measures of physical activity are recommended for intervention assessment.
Keywords: Measurement; Physical activity; Validation.
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