Prediction of Time to Next Therapeutic Thoracentesis and Identification of Risk Factors of Rapid Pleural Fluid Recurrence: A Prospective Observational Study

Background: The value of pre-booked repeated thoracentesis in patients with recurrent pleural effusion is reliant on the estimation of time to next drainage. Identifying factors associated with rapid pleural fluid recurrence could be supportive. Objective: We aimed to evaluate the ability of the patient and physician to predict the time to next therapeutic thoracentesis and to identify characteristics associated with rapid pleural fluid recurrence. Method: In a prospective, observational study, patients with recurrent unilateral pleural effusion and the physician were to predict the time to next symptom-guided therapeutic thoracentesis. Primary outcome was difference between days to actual thoracentesis and days predicted by the patient and the physician. Factors associated with pleural fluid recurrence within 60-day follow-up were assessed using Cox regression analysis. Results: A total of 98 patients were included, 71% with malignant pleural effusion. Patients’ and physicians’ predictions numerically deviated by 6 days from the actual number of days to re-thoracentesis (IQR 2–12 and 2–13, respectively). On multivariate analyses, factors associated with increased hazard of pleural fluid recurrence included daily fluid production (HR 1.35 [1.16–1.59], p > 0.001) and large effusion size (HR 2.76 [1.23–6.19], p = 0.01). Septations were associated with decreased hazard (HR 0.48 [0.24–0.96], p = 0.04). Conclusion: Patients and physicians were equally unable to predict the time to next therapeutic thoracentesis. Daily fluid production and large effusion size were associated with increased risk of rapid pleural fluid recurrence, while septations were associated with a decreased risk. This may guide patients and physicians in when to expect a need for therapeutic thoracentesis.