High preoperative CONUT score is associated with treatment failure and mortality after surgery for acute periprosthetic joint infection: a single-centre retrospective cohort study

Introduction: Acute periprosthetic joint infection (PJI) is associated with substantial morbidity and mortality. The controlling nutritional status (CONUT) score combines serum albumin, total lymphocyte count, and total cholesterol, and may reflect host vulnerability. This study evaluated whether preoperative CONUT is associated with failure and mortality after surgery for acute PJI. Methods: We performed a single-centre retrospective cohort study of patients surgically treated for acute postoperative or acute haematogenous hip or knee PJI between 1 January 2013 and 30 November 2024. PJI was defined according to EBJIS criteria. CONUT was calculated from preoperative blood tests and dichotomised as low (< 5; normal to mild) or high (≥ 5; moderate to severe). Outcomes were defined using an adapted MSIS-ORT classification as failure, total failure including death within 1 year, and overall mortality. Results: Of 169 screened patients, 59 were excluded for missing CONUT data and 90 were included; 42/90 (46.7 %) had high CONUT. High CONUT was associated with higher failure (35.7 % vs. 10.4 %; p =0.004), total failure (57.1 % vs. 12.5 %; p <0.001), and overall mortality (61.9 % vs. 22.9 %; p <0.001). Adjusted analyses confirmed independent associations with failure (odds ratio (OR) 4.24, 95 % confidence interval (CI) 1.34–13.46; p =0.014), total failure (OR 9.57, 95 % CI 2.91–31.50; p <0.001), and overall mortality (hazard ratio (HR) 2.73, 95 % CI 1.29–5.74; p =0.008). Conclusions: High preoperative CONUT was associated with failure, total failure, and overall mortality after surgery for acute PJI. It may support risk stratification but should not be viewed solely as a nutritional marker, as its components may reflect systemic inflammation, bacteraemia, and infection severity.