Responsiveness of the Harris Hip Score and the SF-36: Five years after total hip arthroplasty

Purpose: Comparing the responsiveness over time of the Harris Hip Score (HHS) and the SF-36 in patients who underwent total hip arthroplasty (THA) and assessing variation in the responsiveness of these measures by the number of co-morbidities. Methods: This prospective study analyzed 335 THA patients treated at two southern Taiwan hospitals from 1997 to 2000. Magnitude of change in HRQoL was compared by generalized estimating equation. Bias-corrected and accelerated bootstrapping was used to measure magnitude of change in HHS and SF-36 subscale scores for five different time intervals spanning a 5-year period. Results: The analytical results indicated that the pain and physical function subscales of the HHS are more responsive than those of the SF-36 for short-term (within 1 year post-surgery) measurements but are less responsive for long-term measurements. At various follow-up intervals, the HHS and the SF-36 significantly differed in ES of changes in pain and physical function subscale scores for patients with one co-morbidity and for patients with two or more co-morbidities. Conclusion: For long-term evaluation of THA patients, clinicians and health researchers should weight both measures equally and should also consider co-morbidities.