Efficacy and safety of colistin monotherapy versus colistin-based combination therapy in pediatric patients with multidrug-resistant gram-negative infections: A propensity score analysis

Objectives: To compare the efficacy and safety of colistin monotherapy versus colistin-based combination therapy in pediatric patients with multidrug-resistant Gram-negative bacteria (MDR-GNB) infections. Methods: This retrospective cohort analysis encompassed patients under the age of 18 years diagnosed with MDR-GNB infections who were administered intravenous colistin at Chiang Mai University Hospital during the period from 2010 to 2024. Inverse probability weighting (IPW) utilizing propensity scores was employed to equilibrate baseline characteristics. The primary endpoint was defined as 30-day mortality. Secondary endpoints comprised end-of-treatment mortality, clinical response, microbiologic response, and nephrotoxicity. Both univariable and multivariable logistic regression analyses were conducted subsequent to the implementation of propensity score weighting via IPW. Results: Colistin alone and combination therapy did not substantially affect 30-day mortality among 218 patients (74 monotherapy and 144 combination therapy) (adjusted odds ratio [aOR], 2.50; 95% confidence interval [CI], 0.69–9.15; p = 0.165). Clinical response (aOR, 1.27; 95% CI, 0.52–3.10; p = 0.595), end-of-treatment mortality (aOR, 0.79; 95% CI, 0.32–1.91; p = 0.595), and nephrotoxicity rate (aOR, 0.93; 95% CI, 0.40–2.17; p = 0.867) did not show any significant differences. When compared to monotherapy, patients receiving colistin-based combination therapy had a significantly greater microbiologic response rate (aOR, 3.62; 95% CI, 1.08–12.10; p = 0.037). Conclusions: Colistin-based combination therapy improved microbiologic response but showed no mortality or safety advantage over monotherapy in pediatric patients with MDR-GNB. Colistin monotherapy may provide comparable clinical outcomes without increased toxicity.