The changing demographics of our society will lead to an increasing number of patients presenting for orthopedic surgery with increasing comorbidity. We investigated the association between comorbidity and both the risks (complications) and benefits (improved function) of total hip arthroplasty (THA) for primary hip osteoarthritis, whilst controlling for potential confounders including age.
One thousand five hundred and eighty-four patients (67.1 ± 10.6 years; 54% men) in our tertiary care orthopedic hospital completed the Oxford Hip Score before and 12 months after THA. Comorbidity was assessed using the American Society of Anesthesiologists (ASA) grade and Charlson Comorbidity Index (CCI). Details regarding perioperative complications (hospital stay plus 18 days after discharge; mean 27 ± 3 days) were extracted from the clinic information system and graded for severity.
For ASA1, 2, and ≥3, respectively, there were 3.1%, 3.0%, and 6.6% surgical/orthopedic complications; 3.7%, 12.5%, and 27.4% general medical complications; and 6.7%, 14.5%, and 29.8% complications of either type. ASA was associated with complication severity (P < .001). In multiple regression, increasing ASA grade (OR 1.74; 95% CI, 1.33-2.29) and age (OR 1.06; 95% CI, 1.05-1.08), both showed an independent association with increased risk of a complication; CCI explained no further significant variance. CCI, but not age, was associated with the 12-month Oxford Hip Score (beta coefficient, -0.742; 95% CI, -1.130 to -0.355; P = .002) while ASA grade explained no further variance.
Greater comorbidity was associated with increased odds of a complication and (independently) slightly worse patient-rated outcome 12 months after THA. Comorbidity indices can be easily obtained for all surgical patients and may assist with preoperative counseling regarding individual risks and benefits of THA.