Microbial aetiology, outcomes, and costs of hospitalisation for community-acquired pneumonia; an observational analysis

BACKGROUND: The aim of this study was to investigate the clinical outcome and especially costs of hospitalisation for community-acquired pneumonia (CAP) in relation to microbial aetiology. This knowledge is indispensable to estimate cost-effectiveness of new strategies aiming to prevent and/or improve clinical outcome of CAP. METHODS: We performed our observational analysis in a cohort of 505 patients hospitalised with confirmed CAP between 2004 and 2010. Hospital administrative databases were extracted for all resource utilisation on a patient level. Resource items were grouped in seven categories: general ward nursing, nursing on ICU, clinical chemistry laboratory tests, microbiology exams, radiology exams, medication drugs, and other.linear regression analyses were conducted to identify variables predicting costs of hospitalisation for CAP. RESULTS: Streptococcus pneumoniae was the most identified causative pathogen (25%), followed by Coxiella burnetii (6%) and Haemophilus influenzae (5%). Overall median length of hospital stay was 8.5 days, in-hospital mortality rate was 4.8%. Total median hospital costs per patient were €3,899 (IQR 2,911-5,684). General ward nursing costs represented the largest share (57%), followed by nursing on the intensive care unit (16%) and diagnostic microbiological tests (9%). In multivariate regression analysis, class IV-V Pneumonia Severity Index (indicative for severe disease), Staphylococcus aureus, or Streptococcus pneumonia as causative pathogen, were independent cost driving factors. Coxiella burnetii was a cost-limiting factor. CONCLUSIONS: Median costs of hospitalisation for CAP are almost €4,000 per patient. Nursing costs are the main cause of these costs.. Apart from prevention, low-cost interventions aimed at reducing length of hospital stay therefore will most likely be cost-effective.