THORAXJNL134072 1..7

Background Several scoring systems have been used to predict mortality in patients with community-acquired pneumonia. The properties of commonly used risk stratification scales were systematically reviewed. Methods MEDLINE and EMBASE (January 1999eOctober 2009) were searched for prospective studies that reported mortality at 4e8 weeks in patients with radiographically-confirmed community-acquired pneumonia. The search focused on the Pneumonia Severity Index (PSI) and the three main iterations of the CURB (confusion, urea nitrogen, respiratory rate, blood pressure) scale (CURB-65, CURB, CRB-65), and test performance was evaluated based on ‘higher risk’ categories as follows: PSI class IV/V, CURB-65 (score $3), CURB (score$2) and CRB-65 (score$2). Random effects meta-analysis was used to generate summary statistics of test performance and receiver operating characteristic curves were used for predicting mortality. Results 402 articles were screened and 23 studies involving 22 753 participants (average mortality 7.4%) were retrieved. The respective diagnostic odds ratios for mortality were 10.77 (PSI), 6.40 (CURB-65), 5.97 (CRB65) and 5.75 (CURB). Overall, PSI had the highest sensitivity and lowest specificity for mortality, CRB-65was the most specific (but least sensitive) test and CURB-65/ CURB were between the two. Negative predictive values for mortality were similar among the tests, ranging from 0.94 (CRB-65) to 0.98 (PSI), whereas positive predictive values ranged from 0.14 (PSI) to 0.28 (CRB-65). Conclusions The current risk stratification scales (PSI, CURB-65, CRB-65 and CURB) have different strengths and weaknesses. All four scales had good negative predictive values for mortality in populations with a low prevalence of death but were less useful with regard to positive predictive values. BACKGROUND Community-acquired pneumonia (CAP) is a common cause of hospital admission and a leading cause of death in the UK. The overall mortality of CAP varies, with higher rates of death seen in those judged to have severe pneumonia. A reliable method of assessing the severity of pneumonia may potentially improve the triage or initial management of patients by helping clinicians determine whether close monitoring and aggressive treatment is more appropriate than conservative management. However, accurately assessing the severity of pneumonia can be challenging, so a number of scales based on prognostic factors have been designed to identify patients at high risk of death, as well as those at low risk who may require less of a watchful eye. The most notable scales are the CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, age $65 years) which is recommended by the British Thoracic Society and the Pneumonia Severity Index (PSI) which originates from the USA. Different iterations of the CURB-65 are available, including the CRB-65 which may be particularly suited for community use as it relies on clinical history and examination without requiring blood urea measurements, and the CURB score which excludes age as part of its criteria, thus reducing emphasis on chronological age as a prognostic factor. In this review we aimed to systematically retrieve and appraise the available data on the PSI and the three main iterations of the CURB scoring system (CURB, CRB-65, CURB-65) in order to determine the ability of each test to correctly predict mortality in patients with pneumonia. Although we are aware of a multitude of individual studies in different settings, the comparative performance of these scales has yet to be summarised in a meta-analysis.