Study objective: To find the clinical and laboratory criteria that best predict a prolonged fever in children with parapneumonic effusion-associated pneumonia treated conservatively.
Design: Retrospective, cohort study.
Patients: Children admitted to the Shaare Zedek Medical Center between January 1, 1997, and December 31, 2006, and who had been discharged with a diagnosis of empyema and pleurisy.
Measurements and results: One hundred-twenty children were included, all of whom were treated with antibiotics; in 80 patients, a thoracic drain was introduced; in 23, pleural tap was performed; and in 17 patients, no special procedure was performed. In no case was video-assisted thoracic surgery performed. The mean total days of fever was 12.8 +/- 5.9 (2-29 days), and the mean length of stay at the hospital was 11.5 +/- 4.9 (3-25) days. In 44 patients (37%), a bacterial culture was positive either in blood or in pleural fluid or both. A positive blood or a positive pleural fluid culture was significantly associated with a prolonged fever as was a history of an underlying disease. Platelet counts, serum Na, serum protein, pleural lactate dehydrogenase (LDH), pleural glucose, pleural/serum LDH ratio, pleural/serum glucose ratio, and pleural fluid pH were the only factors significantly but weakly correlated with the total duration of fever or duration of fever after admission. A "fever duration" score using platelet count, pleural fluid pH, pleural/serum LDH ratio, and pleural/serum glucose ratio predicted a prolonged course of fever (>7 days) with a sensitivity of 91% (95% confidence interval: 60%-100%) and a specificity of 47% (95% confidence interval: 25%-71%).
Conclusions: In children with parapneumonic effusion-associated pneumonia, a positive bacterial culture and an underlying disease are associated with prolonged fever. A low score based on platelet count, pH pleural fluid and glucose, and LDH pleural/serum ratio is associated with a prolonged fever. We speculate that children with the risk factors mentioned earlier may be the best candidates for an early aggressive approach.