How Is Surgical Risk Best Assessed? A Cohort Comparison of Measures in Total Joint Arthroplasty

We designed this study to determine whether a Frailty Deficit Index (FI) confers added risk stratification beyond more traditional methods. The associations of preoperative scores on FI, American Society of Anesthesiologists (ASA) physical status, and Charlson Comorbidity Index (CCI) with complications after total joint arthroplasty (TJA) were compared.

Using a single institution cohort of adult patients ≥50 years undergoing primary or revision TJA from 2005 to 2016, we assessed how well the FI, CCI, and ASA scores predicted risk of mortality, infection, and reoperation. We performed 7 models for each outcome: FI, ASA, and CCI alone, FI + ASA, FI + CCI, ASA + CCI, and FI + ASA + CCI. Cox proportional hazards regression methods were used to calculate the concordance (C-) statistic, a measure of discrimination.

Of 18,397 TJAs included, 98.9% were alive 1 year postoperatively. For mortality, all models had concordance between 0.76 and 0.79, with the FI + ASA + CCI model performing highest (C-statistic 0.79; 95% confidence interval [CI] 0.76-0.82). Unadjusted, FI had the strongest concordance (C-statistic 0.77). In FI + ASA + CCI, each increase in 1 comorbidity (of 32 total comorbidities) in the FI was significantly associated with a 12% increase in the rate of mortality (hazard ratio [HR] 1.12, 95% CI 1.07-1.17, P < .001), 10% increase in infection (HR 1.10, 95% CI 1.06-1.14; P < .001), and 6% increase in reoperation (HR 1.06, 95% CI 1.05-1.08, P < .001).

Identifying at-risk patients preoperatively is crucial and may result in adjustment of postoperative care. FI was independently associated with risk of adverse outcomes following TJA even after taking into account other predictive measures.