Development and Validation of Crosswalks Between the Western Ontario & McMaster Universities Osteoarthritis Index and Hip Disability and Osteoarthritis Outcome Score Joint Replacement/Knee Injury and Osteoarthritis Outcome Score Joint Replacement.

BACKGROUND: The wide variety of patient-reported outcome measures used to assess outcomes following total joint arthroplasty can present a substantial methodological obstacle when attempting to compare information across studies or between institutions. A simple solution is to create crosswalks that reliably convert scores between patient-reported outcome measures. Our goal is to create and validate crosswalks between the commonly used Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) and short-form versions of the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR)/Knee Injury and Osteoarthritis Outcome Score (KOOS JR.). METHODS: Patients in our joint replacement registry were included if they underwent primary total hip arthroplasty (n = 4649) or total knee arthroplasty (n = 3750) for osteoarthritis between May 2007 and February 2012. We used their preoperative and 2-year postoperative HOOS scores (n = 6351) or KOOS scores (n = 4688) to generate the patients' WOMAC and HOOS JR/KOOS JR scores. The equipercentile equating method was applied to create 10 crosswalks: HOOS JR/KOOS JR to WOMAC Total (WOMAC-T), and WOMAC-T, WOMAC Pain (WOMAC-P), WOMAC Stiffness (WOMAC-S), and WOMAC Function (WOMAC-F) to HOOS JR/KOOS JR. Crosswalk validity was assessed by comparing actual and derived scores using Spearman's rank correlation coefficients in a bootstrapped cohort. RESULTS: All 10 crosswalks showed strong positive correlations ranging from 0.846 (WOMAC-S to KOOS JR) to 0.981 (HOOS JR to WOMAC-T). CONCLUSION: We created and validated 10 crosswalks between WOMAC and HOOS JR/KOOS JR. We recommend using the crosswalks between WOMAC-T and HOOS JR/KOOS JR when possible, as they demonstrated the highest correlation. WOMAC-F or WOMAC-P should be used in favor of WOMAC-S if only subscores are available. The HOOS JR/KOOS JR should only be converted to a WOMAC-T. LEVEL OF EVIDENCE: Level III.

Crosswalks Between Knee and Hip Arthroplasty Short Forms: HOOS/KOOS JR and Oxford.

BACKGROUND: The Oxford Knee Score (OKS); Oxford Hip Score (OHS); Knee injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS JR); and Hip disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS JR) are well-validated and widely used short-form patient-reported outcome measures (PROMs) for assessing outcomes after total knee arthroplasty (TKA) and total hip arthroplasty (THA). We are not aware of the existence of any crosswalks to convert scores between these PROMs. We aimed to develop and validate crosswalks that will permit the comparison of scores between studies using different PROMs and the pooling of results for meta-analyses. METHODS: We retrospectively analyzed scores from patients (486 in the knee cohort and 340 in the hip cohort) from the Syracuse Orthopedic Specialists Joint Registry who had completed the appropriate PROMs (OKS and KOOS JR in the knee cohort and OHS and HOOS JR in the hip cohort) as the standard of care before undergoing primary TKA or unicompartmental knee arthroplasty (UKA) between January 9, 2016, and June 19, 2017, or primary THA or hip resurfacing between November 29, 2010, and October 30, 2017, or when returning for postoperative care. Using the equipercentile equating method, we created 4 crosswalks: OKS to KOOS JR, KOOS JR to OKS, OHS to HOOS JR, and HOOS JR to OHS. To assess validity, Spearman coefficients were calculated using bootstrapping methods, and means for actual and crosswalk-derived scores were compared. RESULTS: There were minimal differences between the means of the known and crosswalk-derived scores. As calculated with the use of bootstrapping methods, Spearman coefficients between the actual and derived scores were strong and positive for both knee arthroplasty crosswalks (0.888 to 0.889; 95% confidence interval [CI], 0.887 to 0.891) and hip arthroplasty crosswalks (0.916 to 0.918; 95% CI, 0.914 to 0.919). CONCLUSIONS: We successfully created 4 crosswalks that allow conversion of Oxford scores to KOOS and HOOS JR scores and vice versa. These crosswalks will allow harmonization of PROMs assessment regardless of which of the short forms are used, which may facilitate multicenter collaboration or allow sites to switch PROMs without loss of historic comparison data. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.