Background Harris Hip Score (HHS) is the most commonly used instrument in the assessment of total hip arthroplasty (THA). Clinically meaningful thresholds for HHS have not been defined; limited data exist on responsiveness.
Objectives To examine the clinically meaningful change thresholds, responsiveness and predictive ability of the Harris Hip Score (HHS) questionnaire.
Methods We included a cohort of patients who underwent primary total hip arthroplasty (THA) and responded to HHS preoperatively and/or at 2- or 5-year post-THA to examine the clinically meaningful change thresholds (Minimal clinically important improvement, MCII; and moderate improvement), responsiveness (effect size (ES) and standardized response mean (SRM)) based on pre- to post-operative change and its predictive ability at 2- and 5-years post-THA for future revision.
Results 2,667 patients with mean age of 64 years completed baseline HHS; 1,036 completed both baseline and 2-year and 669 both baseline and 5-year HHS. MCII and moderate improvement thresholds ranged 15.9–18 points and 39.6–40.1 points, respectively. ES was 3.12 and 3.02 at 2- and 5-years; respective SRM was 2.73 and 2.52. Compared to patients with HHS scores of 81–100 (score range, 0–100), patients with scores <55 at 2- and 5-years had higher hazards (95% confidence interval) of subsequent revision, 4.34 (2.14, 7.95; p<0.001) and 3.08 (1.45, 5.84; p=0.002), respectively. Compared to HHS score improvement >50 points from preoperative to 2-years post-THA, lack of improvement/worsening or 1–20 point improvement were associated with increased hazards of revision, 18.10 (1.41, 234.83; p=0.02); and 6.21 (0.81, 60.73; p=0.10), respectively.
Conclusions HHS is a valid measure of THA outcomes, is responsive to change and predictive of revision risk post-primary THA. We have defined MCID and moderate improvement thresholds for HHS in this study.
Acknowledgement We thank Youlonda Lochler for assisting data extraction from the Mayo Clinic Total Joint Registry.
Disclosure of Interest J. Singh Grant/research support from: Savient, Takeda, Consultant for: Savient, Takeda, Regeneron, Iroko, Merz, Bioiberica, Crealta, and Allergan pharmaceuticals, C. Schelck: None declared, S. Harmsen: None declared, D. Lewallen Shareholder of: pipeline, Grant/research support from: DePuy, Stryker, Biomet and Zimmer, Consultant for: Zimmer, Orthosonic and Osteotech