Self-report questionnaires are still considered to be a useful instrument for disease screening and for epidemiological studies. Few questionnaires have been developed for the purpose of screening for knee osteoarthritis (KOA). The aim of this study was to develop a KOA screening tool that is useful for health and exercise professionals who do not have access to advanced and costly diagnostic instruments.
This study comprised five steps: content validity, reliability, criterion validity, construct validity and responsiveness. Internal consistency was verified using Cronbach's alpha and the intraclass correlation coefficient (ICC). Reproducibility was analyzed using the ICC (1 week). Criterion validity was assessed by comparing the Knee OA Pre-Screening Questionnaire (KOPS) score with the Short Form (SF)-12, the Knee Injury and Osteoarthritis Outcome Scores questionnaire and the 6 min walk test. Construct validity was verified using the receiver operating characteristic (ROC) curve (American College of Rheumatology clinical criteria and X-ray). Responsiveness was analyzed over 3 months of an aquatic exercise program using the pooled effect size.
The overall KOPS score yielded a Cronbach's alpha of 0.747 and an ICC of 0.646. KOPS was considered reproducible (ICC: 0.895-0.992; Cronbach's alpha: 0.894-0.979). The ROC curve revealed a sensitivity of 86.96 and a specificity of 75.82. The KOPS demonstrated medium responsiveness in terms of the total score and the pain and symptoms components.
The KOPS questionnaire is valid for the purposes for which it was created, and its translation into English should be considered.