Excess mortality and long-term disability from healthcare-associated carbapenem-resistant Acinetobacter baumannii infections: A nationwide population-based matched cohort study

Abstract

Background: Carbapenem resistance is perceived as a clinical challenge in the management of debilitated and immunocompromised patients who eventually will die from underlying diseases. We aimed to examine whether carbapenem resistance per se, rather than the underlying diseases, negatively affect outcomes, by comparing the excess mortality and morbidity from healthcare-associated infections (HAIs) caused by carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-susceptible A. baumannii (CSAB).

Methods: This was a nationwide retrospective matched cohort study of hospitalized patients in 96 hospitals which participated in Taiwan Nosocomial Infection Surveillance (TNIS). A total of 2,213 patients with A. baumannii HAIs were individually matched to 4,426 patients without HAIs. Main outcomes were excess risks for one-year all-cause mortality and one-year new-onset chronic ventilator dependence or dialysis-dependent end-stage renal disease.

Results: Excess one-year mortality was 27.2% in CRAB patients, compared with their matched uninfected inpatients, as well as 15.4% in CSAB patients (also compared with their matched uninfected inpatients), resulting in an attributable mortality of 11.8% (P <0.001) associated with carbapenem resistance. The excess risk associated with carbapenem resistance for new-onset chronic ventilator dependence was 5.2% (P <0.001). Carbapenem resistance was also associated with an extra cost of $2,511 per case of A. baumannii HAIs (P <0.001).

Conclusion: Carbapenem resistance is associated with a significant disease burden in terms of excess mortality, long-term ventilator dependence, and medical cost. Further studies on effects of antimicrobial stewardship programs in decreasing this burden are warranted.

Fig 1. Enrollment of study subjects.

Flow chart showed study design and patient selection for matching. Note: HAI, healthcare-associated infection; CRAB, carbapenem-resistant Acinetobacter baumannii; CSAB, carbapenem-susceptible A. baumannii.

Fig 2. Kaplan-Meier survival curves.

(A) CSAB patients (n = 1,177) and their matched uninfected patients (n = 2,354). (B) CRAB patients (n = 1,036) and their matched uninfected patients (n = 2,072). Note: CSAB HAI, carbapenem-susceptible Acinetobacter baumannii healthcare-associated infection; CRAB HAI, carbapenem-resistant A. baumannii healthcare-associated infection.