Development and Validation of the COMPLES Score for Differentiating Between Tuberculous Effusions with Low Pleural pH or Glucose and Complicated Parapneumonic Effusions.

Background: The frequency of "complicated" pleural effusions (CPE) (i.e., pleural fluid pH ≤ 7.2 and/or glucose ≤60 mg/dL) of tuberculous origin (CTPE) is not well reported. This study aims to quantify their prevalence, and develop a score to differentiate CTPE from complicated parapneumonic effusions (CPPE).

Methods: Retrospective analysis of databases from three Spanish hospitals which included patients with CTPE and CPPE. Forty percent of the study population served to generate a scoring system (COMPLES, COMplicated PLeural Effusion Score) that was further validated in the remaining 60 %.

Results: During the study period (1992-2015) 549 patients were diagnosed with tuberculous effusions and 434 parapneumonic effusions, of whom 25 and 64 %, respectively, had CPE. COMPLES was based on the combination of pleural fluid adenosine deaminase (ADA), the percentage of mononuclear cells (MNC %), pH, and age. The cutoff values and assigned scores were: ADA (<46 IU/L [0 points], 46-100 IU/L [4 points], ≥100 IU/L [6 points]), MNC % (<10 % [0 points], 10-50 [3 points], >50 [8 points]), pH (<7.07 [0 points], 7.07-7.20 [3 points], >7.20 [5 points]), and age (≥30 [0 points], <30 years [3 points]). A sum of 12 or more points had 97 % sensitivity, 92 % specificity, likelihood ratio positive 12.3, likelihood ratio negative 0.03, and area under the curve of 0.947 for identifying CTPE versus CPPE in the validation set.

Conclusions: CPE is not an unusual presentation of tuberculosis. A simple new scoring system provides a reliable tool for differentiating between CTPE and CPPE.