Comparison of bacterial pneumonia etiology in dialysis versus non-dialysis patients

Purpose: There are limited data to characterize pneumonia pathogens among patients on chronic hemodialysis (HD).   The primary objective of this study was to compare the incidence of selected pneumonia pathogens (methicillin-resistant Staphylococcus aureus [MRSA], Pseudomonas, and Streptococcus pneumoniae) between chronic HD patients and non-HD patients.

Methods: Data from 2009-10 were collected from the U.S. CDC National Hospital Discharge Survey, an annual survey of short-stay, non-federal hospitals.  Pneumonia, comorbidities, and pathogens were determined using ICD-9-CM codes.  Data weights were used to provide population estimates. Pneumonia cases were required to have been admitted from a community setting and have a principal ICD-9-CM diagnosis of pneumonia or a secondary diagnosis of pneumonia if accompanied by a primary diagnosis of sepsis or respiratory failure.  Cases were excluded if patient age was <18 or hospital length-of-stay (LOS) was <1 day.  Statistical significance was defined as p<0.0001.  Dichotomous variables were compared using chi-square tests.  LOS was compared using the Wilcoxon rank-sum test.

Results: There were 2,217,040 community-dwelling pneumonia cases identified; 72,334 cases (3.3%) had end-stage renal disease requiring chronic HD.  Median age was 71 (inter-quartile range 57-82).  MRSA accounted for 64% of all Staphylococcus aureus cases.  Pseudomonas pneumonia was more common in HD vs. non-HD cases (33.6 Pseudomonas pneumonias per 1,000 pneumonia cases vs. 16.8 per 1,000 cases; p<0.0001), while MRSA pneumonia was increased in the non-HD cohort (32.2 per 1,000 cases vs. 15.5 per 1,000 cases, p<0.0001).  S. pneumoniae rates were lower in HD vs. non-HD cases (9.6 per 1,000 cases vs. 33.6 per 1,000 cases; p<0.0001).    Compared to non-HD patients, HD patients had increased in-hospital mortality (9.7 vs. 6.9%; P <0.0001) and median LOS (6 vs. 5 days; P <0.0001).

Conclusion: Chronic HD in community-dwelling pneumonia patients is associated with an increased incidence of Pseudomonas pneumonia and significantly worse health outcomes vs. non-HD patients.