Prospective evaluation of pneumonia severity index in hospitalised patients with community-acquired pneumonia

Abstract

The aim of the present study was to investigate whether the pneumonia severity index (PSI) could adequately predict the severity of community-acquired pneumonia (CAP) and could be used as a severity of illness classification system. Furthermore, reasons that may influence the decision to admit low risk patients were analysed. In a prospective study 260 patients with CAP were included. Stratification in five risk classes according to the PSI was compared with parameters that are closely related to severity of CAP. A significant difference in severity parameters, such as length of stay ( P<0.001) and simplified acute physiologic score and acute physiologic and chronic health evaluation II score ( P<0.001) was found between the five risk classes. Furthermore, a positive British Thoracic Society (BTS) rule and modified BTS rule score was significantly more prevalent in the higher risk classes ( P<0.001). The patient population had an average 30-day mortality of 10% and a mean Intensive Care Unit (ICU) admission rate of 8%. The mortality rate and ICU admission rate significantly differed between the five risk classes ( P<0.001), in which the highest ICU admission rate (40.9%) and the highest mortality percentage (40.9%) were both found in risk class V. Several clinical factors ( n=64), such as an exacerbation of chronic obstructive pulmonary disease in 17 patients and clinical appearance of being ill in 16 patients, lack of improvement on outpatient antibiotic therapy ( n=15) and social circumstances ( n=3) were reasons that influenced the decision to hospitalise low risk patients ( n=82). The results show that the PSI adequately predicted the severity of CAP and can be used as a severity of illness classification in CAP. Clinical and social factors other than those mentioned in the PSI have to be considered when making the decision to hospitalise patients with CAP.