Risk Factors and Mortality of Elderly Patients with Hospital-Acquired Pneumonia of Carbapenem-Resistant Klebsiella pneumoniae Infection

Abstract

Purpose: Hospital-acquired pneumonia (HAP) caused by carbapenem-resistant K. pneumoniae (CRKP), especially in elderly patients, results in high morbidity and mortality. Studies on risk factors, mortality, and antimicrobial susceptibility of CRKP pulmonary infection among elderly patients are lacking.

Patients and methods: A retrospective case-control study was conducted from January 2019 to December 2021. The elderly inpatients (≥65 years) who were diagnosed with HAP caused by K. pneumoniae were enrolled. Clinical data were collected. Univariate and multivariate logistic regression analyses were used to identify risk factors. Propensity score matching was used to minimize the effect of potential confounding variables. Kaplan-Meier analysis was used to compare survival.

Results: A total of 115 patients with CRKP infection and 78 patients with carbapenem-susceptible K. pneumoniae (CSKP) infection were recruited. There were four independent risk factors for CRKP infection: history of intensive care unit (ICU) stays from hospital admission to positive respiratory specimen culture for K. pneumoniae (odds ratio (OR)=2.530), Charlson comorbidity index score ≥3 (OR = 2.420), prior exposure to carbapenems (OR = 5.280), and prior K. pneumoniae infection or colonization in the preceding 3 years (OR = 18.529). The all-cause 30-day mortality was 22.3%, the mortality of CRKP and CSKP infection was 28.7% and 12.8%, respectively. Independent risk factors for mortality included: older age (OR = 1.107), immunocompromised patients (OR = 8.632), severe pneumonia (OR = 51.244), quick Sepsis-related Organ Failure Assessment (qSOFA) score ≥2 (OR = 6.187), exposure to tigecycline before infection (OR = 24.702), and prolonged ICU stay (OR = 0.987). Thirty-day mortality was significantly lower in patients receiving ceftazidime-avibactam (CAZ-AVI) containing regimens than patients receiving polymyxin B sulfate (PB) containing regimens (P = 0.048). qSOFA score had a good prognostic effect [area under receiver operating characteristic curve (AUROC) of 0.838].

Conclusion: Active screening of CRKP for the high-risk populations, especially elderly patients, is significant for early detection and successful management of CRKP infection.

Keywords: CRKP; CSKP; ceftazidime-avibactam; elderly; hospital-acquired pneumonia; qSOFA.

Figure 1

Flowchart outlining of the patients included in this study.

Figure 2

The results of antimicrobial susceptibility test of K. pneumoniae strains.

Figure 3

The clinical outcomes of patients with CRKP and CSKP infection.

Figure 4

Kaplan–Meier analysis was used to compare the 30-day survival rate for (A) CRKP vs CSKP infection; (B) severe pneumonia vs non-severe pneumonia; (C) immunocompromised vs immunocompetent patients, and (D) patients receiving CAZ-AVI containing regimes vs polymyxin B sulfate (PB) containing regimes. The data were analyzed using SPSS 26 to obtain p-values (SPSS 26_analyze_survival_Kaplan-Meier_log-rank_p value), and the drawing was made using Prism 8 app.

Figure 5

Distribution and mortality of patients by qSOFA score. (A) Distribution of qSOFA score (0–3) and its association with 30-day mortality (the x axis indicated the specific value of the qSOFA score when the patient developed K. pneumoniae infection) (B) the area under receiver operating characteristic curve (AUROC) predicted the prognosis of patients using qSOFA score. The (A) was made using Prism 8 app., the (B) was made using SPSS 26 analysis (SPSS 26_analyze_category_ROC curve).