Development and preliminary evaluation of the CHARUSAT patellofemoral arthritis questionnaire: A psychometric study

Background: Knee osteoarthritis is one of the leading causes of the increasing global burden of musculoskeletal disorders. The prevalence rate of patellofemoral arthritis is 39% in South Asia in >40 years of age. The census on early osteoarthritis recommends focusing on the prediagnostic stage. However, none of the tools is available to screen the early symptoms of patellofemoral arthritis. Purpose of the Study: The purpose of this study was to develop and evaluate the psychometric properties of the CHARUSAT Patellofemoral Arthritis Questionnaire. Methods: The questionnaire was developed using a mixed method stepwise approach. The participant with early patellofemoral arthritis (n = 14) was interviewed. We conducted scoping review and in-depth interviews to develop a conceptual framework. Initial content validation was completed through community consultation and expert opinion. Final psychometric validation was conducted on n = 310 individuals with early patellofemoral arthritis. Participants were recruited from tertiary hospitals' outpatient units and regional communities in India. Results: Conceptual framework was developed based on the current literature review, and qualitative data obtained from participants finalized the 4 domains and 12 content versions: crepitus (2 items), stiffness (2 items), pain (2 items), and difficulty in functional activity (6 items). The psychometric measurement demonstrated good internal consistency, Cronbach's alpha a was 0.90 and an acceptable level of inter-item redundancy. The intraclass correlation coefficient (ICC) value for the test and retest assessment was 0.93 (ICC:2,1; 95% confidence interval = 0.880-0.936; P < 0.000). Principal component analysis demonstrates a four-factor solution with 56.83% total variance. Conclusions: It is an acceptable, reliable, and valid self-administered questionnaire that can identify the early symptoms of patellofemoral arthritis. The questionnaire provides an excellent opportunity for self-analysis of the symptoms at the community level.