Objectives: To assess the usefulness of the British Thoracic Society guidelines for severity assessment of community-acquired pneumonia (CAP) in predicting mortality and to explore alternative criteria which could be more useful in older patients.
Design: Compilation study of two prospective observational cohorts.
Setting and participants: A University hospital in Norfolk, UK with a catchment population of 568,000. Subjects were 195 patients (median age = 77 years) who were included in two prospective studies of CAP.
Main outcome measure: All-cause mortality occurring within the 6 week follow-up.
Results: sensitivity, specificity, positive and negative predictive values for study outcome using CURB and CURB-65 were assessed in 189 patients, and CRB-65 in 192 patients out of a total of 195 patients. Our results were comparable with the original study by Lim et al. Although CURB-65 and CRB-65 included age criteria, in effect they did not materially improve the specificity in predicting high-risk patients in both studies. We found that oxygenation measured by ventilation perfusion mismatch (PaO2:FiO2) was the best predictor of outcome in this slightly older cohort [odds ratio (OR) = 0.99 (0.98-0.99), P = 0.0001]. We derived a new set of criteria; SOAR (systolic blood pressure, oxygenation, age and respiratory rate) based on our findings. Their sensitivity, specificity, positive and negative predictive values were 81.0% (58.1-94.6), 59.3% (49.6-68.4), 27.0% (16.6-39.7) and 94.4% (86.2-98.4), respectively, confirming their comparability with existing criteria.
Conclusions: Our Study confirms the usefulness of currently recommended severity rules for CAP in this older cohort. SOAR criteria may be useful as alternative criteria for a better identification of severe CAP in advanced age where both raised urea level above 7 mmol/l and confusion are common.