Validation of the RAPID score in a Danish population with pleural infection

INTRODUCTION: The incidence of pleural infection, a condition associated with increased mortality, is rising internationally. The RAPID (renal, age, purulence, infection source and dietary factor) score is a prognostic tool designed to stratify patients into risk categories based on five clinical baseline parameters. The aim of the study was to validate the RAPID score as a tool for assessment of prognosis, in the form of mortality, in patients with pleural infection in a Danish setting.

METHODS: This was a retrospective observational cohort study including all patients coded with an International Classification of Diseases, version 10 (ICD-10) code for pleural infection (DJ86 Pyothorax) at a regional University Hospital in a five-year period. Medical records were reviewed retrospectively, RAPID scores were calculated and study participants were stratified into risk groups: low (RAPID scores: 0-2), medium (RAPID scores: 3-4) and high (RAPID scores: 5-7). The primary outcome was three-month mortality. Secondary outcomes were 12-month mortality, length of hospital stay, failure of initial medical treatment and surgical intervention.

RESULTS: Overall mortality at three months was 18.0%. Mortality according to RAPID risk category was as follows: Low risk 2.4% (95% confidence interval (CI): 0.1-12.6), medium risk 17.0% (95% CI: 7.7-30.8) and high risk 39.4% (95% CI 22.9-57.9). Hazard ratios for three-month mortality, with low risk as reference, were 7.5 (95% CI: 0.9-60.1; p = 0.057) for medium risk and 20.6 (95% CI: 2.7-157.6; p = 0.004) for high risk.

CONCLUSION: The findings of this study support the use of the RAPID score as a prognostic tool for assessment of mortality risk in patients with pleural infection in Danish healthcare.