Comparative nephrotoxicity of polymyxin B versus colistin: evidence from ensemble learning and propensity score matching.

BACKGROUND

Polymyxins are last-resort antibiotics for multidrug-resistant Gram-negative infections, but their nephrotoxicity limits clinical use.

OBJECTIVES

To compare the nephrotoxicity of colistin versus polymyxin B and identify risk factors for acute kidney injury (AKI).

METHODS

We retrospectively analysed 258 patients (132 colistin, 126 polymyxin B) with normal to moderately impaired renal function. Machine learning (ML) algorithms predicted AKI risk, and propensity score matching was used to evaluate the risk of colistin preference over polymyxin B.

RESULTS

Colistin nephrotoxicity (defined as at least stage II KDIGO AKI) was significantly more frequent with colistin than polymyxin B in both unmatched (for colistin 31% versus for polymyxin B 19%, P = 0.04) and matched cohorts (34.4% for colistin versus 14.1% for polymyxin B, P = 0.01). ML identified lower baseline eGFR, higher uric acid, hypalbuminaemia, higher age, concomitant nephrotoxic drug use, weight, vasopressor use and polymyxin type as top predictors. Colistin preference over polymyxin B resulted in significant nephrotoxicity risk in both unmatched (OR: 2.08, 95% CI [1.14-3.79]) and matched cohorts (OR: 3.42, 95% CI [1.38-8.5]). Complete renal recovery occurred in only 41% of AKI cases within 30 days.

CONCLUSIONS

Colistin demonstrates significantly higher nephrotoxicity than polymyxin B. The complex relationship between baseline renal function and AKI risk suggests careful monitoring for patients with moderate renal impairment, regardless of polymyxin choice.