Clinical features associated with risk category 4 in pleural infection: an application of the ACCP classification

Introduction: In pleural infection, including parapneumonic effusion and empyema, the risk category classification proposed by the American College of Chest Physicians (ACCP) is a useful tool to guide treatment. However, limited information is available on how different clinical characteristics of patients may influence this classification. Objective: To identify clinical, biochemical, and radiological factors associated with risk category 4 (poor prognosis) in patients with pleural infection, according to the ACCP classification. Method: Secondary analysis of a database from a cohort study of consecutive patients with confirmed pleural infection. Clinical, laboratory, and imaging variables were compared between patients classified as risk category 4 vs. categories 1, 2, and 3. Multivariate logistic regression was performed to identify factors independently associated with risk category 4. Results: A total of 208 patients were included, of whom 100 (48.1%) were classified as risk category 4. Independent factors associated with category 4 were: > 15 days between symptom onset and hospital admission (OR: 4.13; 95% CI: 2.01-8.48), glucose > 200 mg/dl (OR: 2.93; 95% CI: 1.21-7.11), presence of two or more loculations (OR: 2.42; 95% CI: 1.25-4.67), pleural thickening (OR: 4.82; 95% CI: 1.42-16.32) and positive microbiological identification (OR: 3.02; 95% CI: 1.55-5.86). Conclusions: Delayed medical care, hyperglycemia, extensive loculated involvement, pleural thickening, and positive microbiological identification were associated with a higher clinical risk. These findings may inform strategies for early evaluation and timely management of patients with parapneumonic effusion or empyema.