Pneumonia Pathogen Characterization Is an Independent Determinant of Hospital Readmission

Abstract

Background: Hospital readmissions for pneumonia occur often and are difficult to predict. For fiscal year 2013, the Centers for Medicare & Medicaid Services readmission penalties have been applied to acute myocardial infarction, heart failure, and pneumonia. However, the overall impact of pneumonia pathogen characterization on hospital readmission is undefined.

Methods: This was a retrospective 6-year cohort study (August 2007 to September 2013).

Results: We evaluated 9,624 patients with a discharge diagnosis of pneumonia. Among these patients, 4,432 (46.1%) were classified as having culture-negative pneumonia, 1,940 (20.2%) as having pneumonia caused by antibiotic-susceptible bacteria, 2,991 (31.1%) as having pneumonia caused by potentially antibiotic-resistant bacteria, and 261 (2.7%) as having viral pneumonia. The 90-day hospital readmission rate for survivors (n = 7,637, 79.4%) was greatest for patients with pneumonia attributed to potentially antibiotic-resistant bacteria (11.4%) followed by viral pneumonia (8.3%), pneumonia attributed to antibiotic-susceptible bacteria (6.6%), and culture-negative pneumonia (5.8%) (P < .001). Multiple logistic regression analysis identified pneumonia attributed to potentially antibiotic-resistant bacteria to be independently associated with 90-day readmission (OR, 1.75; 95% CI, 1.56-1.97; P < .001). Other independent predictors of 90-day readmission were Charlson comorbidity score > 4, cirrhosis, and chronic kidney disease. Culture-negative pneumonia was independently associated with lower risk for 90-day readmission.

Conclusions: Readmission after hospitalization for pneumonia is relatively common and is related to pneumonia pathogen characterization. Pneumonia attributed to potentially antibiotic-resistant bacteria is associated with an increased risk for 90-day readmission, whereas culture-negative pneumonia is associated with lower risk for 90-day readmission.

Figure 1

Bar graph depicting the prevalence of 90-d readmission for hospital survivors with culture-negative pneumonia, pneumonia attributed to antibiotic-susceptible bacteria, pneumonia attributed to potentially antibiotic-resistant bacteria, and viral pneumonia. P < .001 for the trend among groups.

Figure 2

Kaplan-Meier curves for 90-d readmission with censoring of hospital nonsurvivors. Log-rank test: P < .001 comparing potentially antibiotic-resistant pneumonia to culture-negative pneumonia and comparing potentially antibiotic-resistant pneumonia to antibiotic-susceptible pneumonia; P = .004 comparing potentially antibiotic-resistant pneumonia to viral pneumonia; P > .05 for all other combinations of pairings.