A comparative study of intravenous polymyxin B and colistimethate sodium on efficacy, safety, and cost comparison in treating pulmonary infections: a retrospective cohort study.

Pulmonary infections have become a major global health challenge due to their high incidence, and the escalating bacterial resistance has further increased the difficulty of clinical treatment. As a pivotal agent for treating infections caused by multidrug-resistant Gram-negative bacteria, polymyxins hold a critical position in the management of pulmonary infection. This retrospective cohort study aimed to compare the efficacy, safety, and cost comparison of polymyxin B sulfate (PMB) and colistimethate sodium (CMS) in the treatment of pulmonary infections, providing real-world evidence to support clinical decision-making. A total of 527 inpatients diagnosed with pulmonary infections were included. Univariate and multivariate logistic regression analyses were performed to assess treatment outcomes and identify risk factors associated with all-cause mortality and nephrotoxicity. The results showed that there were no statistically significant differences between the two groups in 28-day and 42-day all-cause mortality or clinical response rate, whereas the PMB group was associated with a significantly shorter length of hospital stay. Univariate and multivariate logistic regression analyses on the factors influencing 28-day all-cause mortality revealed that concomitant extracorporeal membrane oxygenation (ECMO) (OR = 5.312, 95% CI: 1.412-22.893, P = 0.018), hypoalbuminemia (OR = 2.641, 95% CI: 1.549-4.613, P < 0.001), intensive care unit (ICU) admission (OR = 2.579, 95% CI: 1.273-5.330, P = 0.009), central nervous system infection (OR = 8.577, 95% CI: 3.198-24.254, P < 0.001) and concomitant use of immunosuppressants (OR = 4.113, 95% CI: 2.498-6.925, P < 0.001) significantly increased the risk of death in patients. In contrast, adjuvant inhaled polymyxin E therapy and prolonged duration of polymyxin administration exhibited a protective effect. Regarding safety, the incidence of hepatotoxicity was similar between the two groups. Although the difference in nephrotoxicity incidence was not statistically significant, the CMS group showed a numerically higher trend. In addition, the incidence of hematologic toxicity was significantly higher in the CMS group than in the PMB group. Univariate and multivariate logistic regression analyses identified the factors influencing nephrotoxicity, indicating that concomitant dialysis (OR = 2.539, 95% CI: 1.461-4.442, P = 0.001), hypoalbuminemia (OR = 2.620, 95% CI: 1.542-4.596, P = 0.001) and concomitant use of diuretics (OR = 3.022, 95% CI: 1.921-4.837, P < 0.001) were independent risk factors for nephrotoxicity. Regarding economic aspects, following the implementation of the national volume-based procurement (VBP) policy, the procurement cost of PMB was significantly lower than that of CMS (P < 0.05), indicating a clear economic advantage for PMB. No significant difference was observed in total hospitalization costs between the two groups. In conclusion, in the treatment of pulmonary infections in adults, PMB and CMS show comparable overall efficacy, while PMB is associated with a significantly shorter length of hospital stay and presents advantages in safety and cost outcomes. Limited by the retrospective observational design, the above conclusions still require further validation in prospective studies.