Early predictors of prolonged pleural effusion after lobectomy: a prospective study

Introduction. To identify early clinical, functional and pleural predictors of prolonged pleural effusion (PPE) after lobectomy and to assess their prognostic value. Materials and methods. This prospective single-centre study included 168 patients who underwent lobectomy with systematic mediastinal lymph node dissection at the Ulyanovsk Regional Oncology Dispensary between 1 June 2024 and 1 November 2025. Clinical and demographic data, pulmonary function parameters, complete blood count and biochemical markers, as well as pleural fluid characteristics on postoperative days 2 and 4–5 were analysed. PPE was defined as the need to maintain a pleural drain for more than 5 days in the absence of purulent complications. Logistic regression and ROC analysis were used for statistical assessment. Results. The incidence of PPE was 29,2 % (49/168). In univariate analysis, taller height (p=0,012), smoking (p=0,002), higher peak expiratory flow (PEF) and forced vital capacity (FVC, % predicted), as well as increased pleural protein, neutrophil and lymphocyte counts and higher pleural fluid volume on day 2 (all p<0,001) were associated with PPE. In multivariable logistic regression, independent predictors of PPE were pleural neutrophil count on day 2 (AOR=1,94), pleural protein concentration (AOR=1,082), smoking (AOR=2,92) and FVC (% predicted) (AOR=1,021), whereas peripheral lower limb atherosclerosis was associated with a reduced risk of PPE (AOR=0,34). The resulting model demonstrated high discriminative ability (AUC=0,832; 95 % CI: 0,756–0,908; sensitivity 70,8 %; specificity 83,6 %). Conclusion. Prolonged pleural effusion after lobectomy occurs in nearly one-third of patients and is strongly related to early markers of inflammatory exudative response in the pleural space, smoking status and functional respiratory characteristics. Early assessment of pleural fluid composition and key clinical parameters on postoperative day 2 allows reliable risk stratification for PPE and may guide individualized postoperative drainage management and clinical surveillance.