Healthcare utilization and costs associated with S. aureus and P. aeruginosa pneumonia in the intensive care unit: a retrospective observational cohort study in a US claims database

Abstract

Background: Staphylococcus aureus and Pseudomonas aeruginosa are major causes of pneumonia in intensive care unit (ICU) patients. Limited data exist regarding the health economic impact of S. aureus and P. aeruginosa pneumonias in the ICU setting.

Methods: We conducted a retrospective observational cohort study using a 29.6 million enrollee US medical and pharmacy administrative claims database. ICU patients with S. aureus or P. aeruginosa infection per International Classification of Diseases, 9th ed. coding between 01/01/2007-8/31/2012 were compared with ICU patients without any pneumonia or infections of interest. Primary outcomes were costs in 2012 US dollars, healthcare utilization and all-cause mortality associated with hospital-acquired S. aureus or P. aeruginosa pneumonia, and the relative odds of incurring higher costs due to a comorbid condition.

Results: Patients with S. aureus or P. aeruginosa pneumonia had longer mean hospital (37.9 or 55.4 vs 7.2 days, P < .001) and ICU stays (6.9 or 14.8 vs 1.1 days, P < .001), a higher rate of mechanical ventilation (62.6 % or 62.3 % vs 7.4 %, P < .001), higher mortality (16.0 % or 20.2 % vs 3.1 %, P < .001), and higher total mean hospitalization costs ($146,978 or $213,104 vs $33,851, P < .001) vs controls. Pneumonia survivors had significantly increased risk of rehospitalization within 30 days (27.2 % or 31.1 % vs 15.3 %, P < .001). Comorbid conditions were not associated with increased cost in the pneumonia cohorts.

Conclusions: Healthcare costs and resource utilization were high among ICU patients with S. aureus or P. aeruginosa pneumonia. Reducing the incidence of these infections could lead to substantial cost savings in the United States.

Fig. 1

Inclusion/exclusion criteria, cohort definition, and patient counts. Cohort 1: Controls (no pneumonia); excluded the following conditions and Cohort 2 and Cohort 3: Viral pneumonia (ICD-9 dx 480.xx); Other pneumonia with specified bacteria: Pneumococcal pneumonia (481.xx), Other specified bacterial pneumonia (482.0x, 482.2x, 482.3x, 482.8x), Bronchopneumonia (485.xx); Pneumonia due to unspecified bacteria: Unspecified bacterial pneumonia (482.9x), Pneumonia, organism unspecified [bacterial or viral] (486.xx), Ventilator associated pneumonia (VAP) (997.31); Other pneumonias: Aspiration Pneumonia (507.0x), Post-procedural pneumonia (997.32); Septicemia due to staphylococcus or pseudomonas: Staphylococcal septicemia, unspecified (038.10), Methicillin susceptible Staphylococcus aureus septicemia (038.11), Methicillin resistant Staphylococcus aureus septicemia (038.12), Septicemia due to pseudomonas (038.43); Other bacterial infections due to staphylococcus or pseudomonas: Staphylococcus, unspecified (041.10), Methicillin susceptible Staphylococcus aureus (041.11), Methicillin resistant Staphylococcus aureus (041.12), Pseudomonas (041.7); Staphylococcal meningitis (320.3x); Bacteremia (790.7x). Cohort 2: Pneumonia due to staphylococcus (ICD-9 diagnosis: 482.4x). Cohort 3: Pneumonia due to pseudomonas (ICD-9 diagnosis: 482.1x). Cohort 2 and Cohort 3 are not necessarily mutually exclusive. Patients with diagnosis codes for both pneumonia due to staphylococcus and pneumonia due to pseudomonas during the index hospitalization visit are included in both cohorts (N = 132)