Evaluation of psychometric properties of Walking Impairment Questionnaire in overweight patients with osteoarthritis of knee.

This study tested the psychometric properties of the Walking Impairment Questionnaire (WIQ) in overweight patients with osteoarthritis (OA) of the knee. Internal consistency, test-retest reliability, and concurrent validity of the WIQ were measured. Used in a randomized clinical trial, the WIQ was one of the instruments completed by overweight adults with OA of the knee. A total of 105 patients completed the WIQ. Internal consistency of the WIQ was supported in this population with a Cronbach alpha total score of 0.97. Test-retest reliability scores were not different when subjects completed the WIQ 14 days apart (p > 0.05). The relationships were moderate between the WIQ subscales and other established measures, such as the 6-minute walk distance, stair climb and descend, and the Western Ontario and McMaster Universities (OA Index) questionnaire. After evaluating the psychometric properties of the WIQ, we found that it is a valid and reliable instrument to use in overweight patients with symptomatic OA of the knee.