An aggregate score to predict the risk of large pleural effusion after pulmonary lobectomy

Abstract

OBJECTIVES: The volume of pleural effusion is one of the determinants of chest drain removal following pulmonary resection. Recent research suggests that values up to 400 ml/day are safe. The objective of this study was to develop an aggregate risk score to identify patients at higher risk of developing a large pleural effusion (LPE) (>400 ml/day) on postoperative day 2 (POD2) after pulmonary lobectomy. METHODS: An observational study on 229 consecutive patients was conducted prospectively in two European centres (June 2012-September 2013). All patients underwent pulmonary lobectomy for lung cancer (thoracotomy: 131, video-assisted thoracic surgery: 98) and managed by single chest tube connected to an electronic-regulated suction device. Exclusion criteria were chest wall or diaphragm resection and postoperative-assisted mechanical ventilation. To build the aggregate score, variables were initially screened by univariable analysis, and then used in stepwise logistic regression analysis (validated by bootstrap). The scoring system was developed by proportional weighing of the significant predictor estimates, and patients were grouped in classes of incremental risk according to their total score. RESULTS: The incidence of LPE on POD2 was 23% (53 of 229 patients). The independent risk factors associated with LPE on POD2 were age greater than 70 years (P = 0.01, bootstrap frequency 71%), a lower lobectomy (P = 0.03, bootstrap frequency 59%) and presence of COPD (P = 0.02, bootstrap frequency 63%). Each predictor received a weighted score of 1, and patients were grouped into three risk classes showing an incremental risk of LPE (P < 0.001): Class A (Score 0) 5 LPE in 66 patients, 7.5%; Class B (Score 1) 19 LPE in 88 patients, 22%; Class C (Score >1) 29 LPE in 75 patients, 39%. CONCLUSIONS: The aggregate score is a reliable tool for identifying high-risk patients for LPE and assists in the selection of patients that can safely proceed to chest drain removal early after surgery.