Do Functional Patient-reported Outcome Measures Reflect the Activities That Matter Most to Patients After Hip or Knee...

Although there has been increasing focus on patient-centered approaches in outcome evaluation, there is limited information on how well the existing patient-reported outcome measures (PROMs) used to assess function for hip or knee arthroplasty align with patients' perspectives.

(1) To what extent do currently used functional PROMs for hip or knee arthroplasty cover the functional activities that are important to patients at 2, 6, 13, and 26 weeks after surgery? (2) Which functional activities important to patients are either not covered or inadequately covered by PROMs? (3) Which activities not important to patients are covered by PROMs?

We assessed functional key activity coverage and coverage gaps of 47 PROMs at four points. This analysis was based on 22 key activities identified by 953 patients who underwent primary elective hip or knee arthroplasty performed by eight surgeons. These patients were recruited from the Orthopedic Division at The Ottawa Hospital in Ottawa, Ontario, Canada, an academic-affiliated institution in an urban setting. From November 2023 to March 2024 and September 2024 to January 2025, a total of 615 patients who underwent hip arthroplasty and 555 who underwent knee arthroplasty were approached, and 503 and 450, respectively, completed the questionnaire. Patients who underwent hip arthroplasty had a mean ± SD age of 65 ± 11 years; 51.1% (257 of 503) were female, and the mean BMI was 28.3 ± 5.6 kg/m 2 . Patients who underwent knee arthroplasty had a mean age of 68 ± 9 years; 51.3% (231 of 450) were female, and the mean BMI was 31.1 ± 6.4 kg/m 2 . A functional activity was defined as key if at least 75% of patients rated it as important and at least 15% had difficulty doing it.

No PROM adequately addressed all key activities. Within the first 2 weeks after surgery, knee-specific, hip-specific, and combined hip and knee PROMs addressed 86%, 85%, and 79% of key activities, respectively, but this coverage declined for hip and knee PROMs at subsequent follow-up points to fewer than one-half by 26 weeks. The most commonly covered activities were going up and down stairs, rising from a chair, and putting on footwear. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS) demonstrated the widest coverage among knee and hip PROMs, respectively, while the WOMAC provided the widest coverage for combined hip and knee PROMs. Several key functional activities were either inadequately covered or not covered by PROMs. Inadequate coverage often resulted from combining multiple activities into a single item, with the most frequent key activities inadequately addressed being "going up and down stairs" and "doing housework." Five key activities, including washing lower body parts, putting on clothes, taking off clothes, carrying objects, and placing objects on the floor, were not covered by any PROMs. Furthermore, all PROMs included at least one non-key activity.

Given the role of PROMs in evaluating treatment efficacy, their limited comprehensiveness could lead to inaccurate assessments of interventions, potentially contributing to the overuse or underuse of healthcare services. Moreover, including non-key activities in these measures may burden patients and increase the likelihood of nonresponses. To address these issues, future development of PROMs for hip and knee arthroplasty should prioritize engaging patients in the design process.

Our findings showed that the relationship between the length and coverage of current PROMs is often inverse. Selecting between longer and shorter PROMs requires weighing comprehensiveness against burden, with the most efficient PROMs maximizing coverage of key activities while minimizing non-key ones. Clinicians should consider choosing PROMs to specific phases of recovery after hip or knee arthroplasty rather than relying on a single tool across all time periods. This approach can enhance the relevance of follow-up assessments and better support individualized care decisions. The wide variety of available PROMs presents selection challenges, and stakeholders, including clinicians, patients, and decision-makers, should work toward consensus on a core set of outcome measures appropriate for various stages of recovery.