Comparison of short and full-length international physical activity questionnaires

Background: Our study aims to compare the short and full-length International Physical Activity Questionnaires (IPAQ). Methods: Both versions were completed by 186 subjects >14 y living in southern Brazil. Half answered the short and then the long version; the remaining subjects followed the reverse order. Physical inactivity (PI) was defined as <150 min/wk spent in moderate or vigorous activities. The Bland and Altman method and the kappa statistic were used to assess agreement between the continuous and categorical outcomes, respectively. Results: The prevalence of PI was 50% higher with the short IPAQ (42% vs. 28%). The kappa value was 53.7%. Although the correlation coefficient was moderately high (r=0.61), agreement between methods was low. Conclusions: Both analyses used show that the short and full-length IPAQ versions have poor agreement. Utilization of inappropriate statistics would lead to misinterpretation. Researchers should exercise care before comparing studies using different IPAQ versions.