Retrospective cohort study on prognostic factors of malignant pleural effusion secondary to pleural mesothelioma

Malignant pleural effusion (MPE) frequently complicates pleural mesothelioma; however, prognostic determinants for this condition, particularly pleural fluid biomarkers, have yet to be comprehensively characterized. This study sought to assess the prognostic utility of clinical profiles and laboratory findings, with a specific focus on pleural fluid parameters, in patients with mesothelioma-associated MPE.

This retrospective cohort study included patients diagnosed with MPE secondary to pleural mesothelioma at Tianjin Chest Hospital from January 2015 to May 2025. Inclusion criteria: age ≥18 years, confirmed diagnosis. Exclusion criteria: active infection, incomplete baseline clinical/laboratory data, or prior anti-tumor therapy. Follow-up was conducted via telephone at monthly intervals for 6 months then every 3 months. The primary outcome was overall survival (OS), defined as time from diagnosis to death or last follow-up. Univariable and multivariable Cox regression analyses were performed to identify independent prognostic factors.

Seventy‑one eligible patients were analyzed. Median OS was 30 months (range, 16-44 months). Four factors were independently associated with OS in multivariable analysis: pleural fluid lactate dehydrogenase (LDH) ≥361 U/L [hazard ratio (HR) 4.373, 95% confidence interval (CI): 1.903-10.049, P=0.001], fibrinogen (FIB) ≥3.82 g/L (HR 3.592, 95% CI: 1.683-7.666, P=0.001), mean platelet volume (MPV) ≥12.50 fL (HR 2.507, 95% CI: 1.125-5.586, P=0.03), and absolute lymphocyte count ≥1.48×10⁹/L (HR 0.423, 95% CI: 0.204-0.877, P=0.02).

These four routinely available baseline parameters-pleural fluid LDH, FIB, MPV, and absolute lymphocyte count-may serve as potential prognostic indicators in patients with MPE secondary to pleural mesothelioma. Prospective, multicenter studies with external validation are required to confirm these findings.