Low serum creatinine levels are associated with major post-operative complications in patients undergoing surgery with gynecologic oncologists.

ABSTRACT

OBJECTIVE: Serum creatinine is a byproduct of muscle metabolism, and low creatinine is postulated to be associated with diminished muscle mass. This study examined the association between low pre-operative serum creatinine and post-operative outcomes. METHODS: This retrospective cohort study utilized the 2014-2021 National Surgical Quality Improvement Program to identify patients undergoing surgery with gynecologic oncologists. Patients with missing pre-operative creatinine, end-stage renal disease, sepsis, septic shock, dialysis, or pregnancy were excluded. Pre-operative creatinine was categorized into markedly low (≤0.44 mg/dL), mildly low (0.45-0.64 mg/dL), normal (0.65-0.84 mg/dL), and four categories of elevated levels (0.85-1.04, 1.05-1.24, 1.25-1.44, and ≥1.45 mg/dL). Outcomes included major (≥Grade 3) 30-day complications, categorized into any complications, wound, cardiovascular and pulmonary, renal, infectious, and thromboembolic complications. Also examined were 30-day readmissions, reoperations, and mortality. Logistic regressions assessed the association between creatinine and complications, with stratification by albumin and sensitivity analysis with propensity score matching. RESULTS: Among 84 786 patients, 0.8% had markedly low, 19.6% mildly low, and 50.2% normal creatinine; the remainder had elevated creatinine. As creatinine decreased, the risks of major complications increased in a dose-dependent manner on univariable and multivariable analyses. A total of 9.6% (n=63) markedly low patients experienced major complications, second to creatinine ≥1.45 mg/dL (9.9%, n=141). On multivariable models, both markedly and mildly low creatinine were associated with higher odds of major complications (OR 1.715, 95% CI 1.299 to 2.264 and OR 1.093, 95% CI 1.001 to 1.193) and infections (OR 1.575, 95% CI 1.118 to 2.218 and OR 1.165, 95% CI 1.048 to 1.296) versus normal. Markedly low creatinine had similar ORs to creatinine ≥1.45 mg/dL and was further associated with higher odds of cardiovascular and pulmonary complications (OR 2.301, 95% CI 1.300 to 4.071), readmissions (OR 1.403, 95% CI 1.045 to 1.884), and mortality (OR 2.718, 95% CI 1.050 to 7.031). After albumin stratification, associations persisted for markedly low creatinine. Propensity-weighted analyses demonstrated congruent findings. CONCLUSIONS: Low creatinine levels are associated with major post-operative complications in gynecologic oncology in a dose-dependent manner. Low creatinine can offer useful information for pre-operative risk stratification, surgical counseling, and peri-operative management.