The Pain Disability Questionnaire (PDQ): Evaluating the efficacy of the psychosocial and functional subscales for 12-month post-treatment outcomes after total knee arthroplasty

Background: The Patient Disability Questionnaire (PDQ) has been shown to have good predictive validity for outcomes after total hip arthroplasty (TKA). However, the PDQ subscales (psychosocial and functional disability) have not been assessed independently. This study assesses 1-year surgical outcomes based on the PDQ's psychosocial and functional disability subscale scores. Methods: The sample included 130 participants undergoing TKA. Physical and psychosocial measures included the PDQ, Knee Society Score (KSS), Western Ontario McMaster Arthritic Index (WOMAC), and the Short Form-36 Health Inventory (SF-36). Univariate correlations were used to cross-validate all subscales. Multivariate gamma and linear regressions were used to associate PDQ functional and psychosocial disability subscale scores with WOMAC and SF-36, 1 yr after TKA. Results: Poorer PDQ psychosocial scores were associated with being younger, black or Hispanic, and using Medicaid. Poorer functional disability scores were associated with being younger, female, black or Hispanic, and using Medicaid or without insurance. Multivariate regressions revealed that baseline PDQ psychosocial and functional disability were both significantly associated with 1-year WOMAC total scores and 1-year SF-36 Mental Composite Scores. Conclusions: The PDQ is useful in predicting 1-year outcomes for patients undergoing TKA. Worse baseline PDQ subscale scores indicated worse quality of life, more pain and stiffness of the joints, as determined by comparative WOMAC and SF-36 scores. Clinical implications from this study suggest screening patients before surgery to identify factors that could hinder recovery time or cause pain or function remission in adults undergoing TKA.