Evaluation of the construct validity of the Questionnaire to Identify Knee Symptoms among individuals across Canada with chronic knee pain

The primary purpose of this study was to evaluate the construct validity of the Questionnaire to Identify Knee Symptoms (QuIKS) measurement scale among individuals with chronic knee symptoms consistent with osteoarthritis. Construct validity was assessed using tests of convergent and discriminative validity on 15 pre-specified hypotheses. The secondary objective was to determine the internal consistency reliability of the QuIKS. One hundred and five individuals recruited in select physiotherapy clinics from across Canada were mailed the QuIKS and five other health questionnaires. Fiftyfive individuals completed the questionnaire package. While none of the pre-specified construct validity hypotheses were met, nine of the validity analyses supported the construct validity of the QuIKS. The results also supported the internal consistency reliability of the QuIKS, as Cronbach’s alpha for the scale was 0.81. Overall, the QuIKS appears to be a valid tool to quantify illness behaviour in individuals with chronic knee symptoms.