Investigation of the ability of the Pneumonia Severity Index to accurately predict clinically relevant outcomes: a European study

In order to confirm the validity of the Pneumonia Severity Index (PSI) for patients in Europe, data from adults with pneumonia who were enrolled in two prospective multicentre studies, conducted in France (Pneumocom-1, n = 925) and Spain (Pneumocom-2, n = 853), were compared with data from the original North American study (Pneumonia PORT, n = 2287). The primary outcome was 28-day mortality; secondary outcomes were subsequent hospitalisation for outpatients, and intensive care unit admission and length of stay for inpatients. All outcomes within individual risk classes, and mortality rates in low-risk (PSI I-III) and higher-risk patients, were compared across the three cohorts. Overall mortality rates were 4.7% in Pneumonia PORT, 6.3% in Pneumocom-2 and 10.6% in Pneumocom-1 (p <0.01), ranging from 0.4% to 1.6% (p 0.06) for low-risk patients and from 13.0% to 19.1% (p 0.24) for high-risk patients. Despite significant differences in baseline patient characteristics, none of the study outcomes differed within the low-risk classes. The sensitivity and negative predictive value of low-risk classification for mortality exceeded 93% and 98%, respectively. Thus, in two independent European cohorts, the PSI predicted patient outcomes accurately and reliably, particularly for low-risk patients. These findings confirm the validity of the PSI when applied to patients from Europe.