Association Between the Modified Frailty Index and Short‐Term Total Thyroidectomy Complications

OBJECTIVE: The Modified Frailty Index (mFI-5) is a validated preoperative risk stratification tool across surgical settings. This study evaluated the predictive value of the mFI-5 score for postoperative outcomes following total thyroidectomy. METHODS: This retrospective cohort study utilized the TriNetX U.S. Network to identify adults who underwent total thyroidectomy between 2006 and 2025. Patients were stratified by mFI-5 scores (0, 1, 2, ≥ 3) based on the presence of five ICD-10-coded comorbidities. Propensity score matching was used to control for demographic and clinical covariates. Postoperative complications-hypocalcemia, vocal fold paralysis, surgical-site infection, hematoma, tracheostomy, and mortality-as well as emergency department visits-were assessed within 30 days of surgery. Each mFI-5 group ≥ 1 was compared to the mFI-5 = 0 cohort using logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (α = 0.05). RESULTS: Among 65,866 total thyroidectomy patients, postoperative complications increased significantly with higher frailty. Odds of hypocalcemia rose from mFI-5 = 1 (OR = 1.22 [95% CI, 1.14-1.32]) to mFI-5 ≥ 3 (OR = 1.59 [95% CI, 1.29-1.95]). Vocal fold paralysis was more likely at mFI-5 ≥ 3 (OR = 2.27 [95% CI, 1.49-3.46]). Emergency department visits increased progressively with frailty, from mFI-5 = 1 (OR = 1.36 [95% CI, 1.23-1.51]) to mFI-5 ≥ 3 (OR = 2.28 [95% CI, 1.72-3.03]). Surgical-site infection and tracheostomy were elevated at mFI-5 = 2 (OR = 1.93 [95% CI, 1.20-3.10] and OR = 2.00 [95% CI, 1.08-3.73], respectively), though mFI-5 ≥ 3 groups were limited by sample size. Postprocedural neck hematoma risk was significantly higher at mFI-5 ≥ 3 (OR = 2.60 [95% CI, 1.45-4.64]). Mortality events were rare and precluded reliable estimation. CONCLUSION: Higher mFI-5 scores were associated with increased postoperative complications after total thyroidectomy. Incorporating frailty assessment into preoperative evaluation may improve risk stratification and patient outcomes.