Objective: To investigate the reliability, validity, and responsiveness to change of the Human Activity Profile (HAP), a questionnaire measuring physical activity, in persons with arthritis.
Methods: Twenty-eight subjects completed the following self-report questionnaires: HAP, Modified Health Assessment Questionnaire, Medical Outcomes Study 36-Item Short Form Health Survey, and Arthritis Impact Measurement Scale 2. Subjects also completed a submaximal treadmill test, Timed-Stands Test, and 50-Foot Walk Test. Responses on the HAP resulted in 2 scores: the maximum activity score (MAS) and the adjusted activity score (AAS). These scores were correlated with the other tests and examined for test-retest reliability. A subset of subjects participated in a 12-week exercise program, repeating the same tests when finished.
Results: For all subjects, the intraclass correlation coefficient (ICC) was 0.76 for the MAS and 0.87 for the AAS. Significant correlations were found between the HAP scores and the questionnaires, submaximal treadmill test, Timed-Stands Test, and 50-Foot Walk Test. In response to 12 weeks of exercise, both HAP scores had an effect size of 0.5, similar to that of the other questionnaires.
Conclusion: The ICCs demonstrate that the HAP is reliable, and the correlations between the HAP and other questionnaires, Timed-Stands Test, and 50-Foot Walk Test demonstrate that the HAP is a valid measure of physical function in persons with arthritis. The HAP's correlation with maximum oxygen consumption estimated by the treadmill test validates it as a measure of physical activity. The medium effect size (0.5) demonstrates that the HAP is moderately responsive to change. Its ease of use and broad scope make it a valuable assessment tool for persons with arthritis.