Class I Obesity Delays Achievement of Patient-Acceptable Symptom State but Not Minimum Clinically Important Difference or Substantial Clinical Benefit After Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome

Purpose: To identify differences in the time taken to achieve the minimum clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) following primary hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS) among patients of different body mass index (BMI) categories. Methods: We conducted a retrospective comparative study of hip arthroscopy patients with minimum 2-year follow-up. BMI categories were defined as normal (18.5 <= BMI < 25.0), overweight (25.0 <= BMI <30.0), or class I obese (30.0 <= BMI<35.0). All subjects completed the modified Harris Hip Score (mHHS) prior to surgery and at 6 months, 1 year, and 2 years postoperative. MCID and SCB cutoffs were defined as pre-to-postoperative increases in mHHS by >= 8.2 and >= 19.8, respectively. PASS cutoff was set at postoperative mHHS >= 74. Time to achievement of each milestone was compared using the interval-censored EMICM algorithm. The effect of BMI was adjusted for age and sex using an interval-censored proportional hazards model. Results: 285 patients were included in the analysis: 150 (52.6%) normal BMI, 99 (34.7%) overweight, and 36 (12.6%) obese. Obese patients had lower mHHS at baseline (P =.006) and at 2-year follow-up (P =.008). There were no significant intergroup differences in time to achievement for MCID (P =.92) or SCB (P =.69), but obese patients had longer time to PASS than normal BMI patients (P =.047). Multivariable analysis found obesity to be predictive of longer time to PASS (HR =.55; P =.007) but not MCID (HR = 0.91; P =.68) or SCB (HR = 1.06; P =.30). Conclusions: Class I obesity is associated with delays in achieving a literature- defined PASS threshold after primary hip arthroscopy for FAIS.