Prognostic Factors for Mortality Due to Pneumonia Among Adults from Different Age Groups in Singapore and Mortality Predictions Based on PSI and CURB-65

Introduction: Pneumonia is associated with considerable mortality. However, there is limited information on age-specific prognostic factors for death from pneumonia.

Methods: Patients hospitalised with a diagnosis of pneumonia through the emergency department were stratified into three age groups: 18-64 years, 65-84 years and ≥ 85 years. Multivariate logistic regression and receiver operating characteristic curve analyses were conducted to evaluate prognostic factors for mortality and the performance of pneumonia severity scoring tools for mortality prediction.

Results: A total of 1,902 patients were enrolled (18-64 years: 614 [32.3%]; 65-84 years: 944 [49.6%]; ≥ 85 years: 344 [18.1%]). Mortality rates increased with age (18-64 years: 7.3%; 65-84 years: 16.1%; ≥ 85 years: 29.7%; p < 0.001). Malignancy and tachycardia were prognostic of mortality among patients aged 18-64 years. Male gender, malignancy, congestive heart failure and eight other parameters reflecting acute disease severity were associated with mortality among patients aged 65-84 years. For patients aged ≥ 85 years, altered mental status, tachycardia, blood urea nitrogen, hypoxaemia, arterial pH and pleural effusion were significantly predictive of mortality. The Pneumonia Severity Index (PSI) was more sensitive than CURB-65 (confusion, uraemia, respiratory rate ≥ 30 per minute, low blood pressure, age ≥ 65 years) for mortality prediction across all age groups.

Conclusion: The predictive effect of prognostic factors for mortality varied among patients with pneumonia from the different age groups. PSI performed significantly better than CURB-65 for mortality prediction, but its discriminative power decreased with advancing age.