Higher pleural fluid lactate dehydrogenase is associated with shorter overall survival in lung cancer patients with malignant pleural effusion: a retrospective cohort study

To explore the association between lactate dehydrogenase (LDH) levels in pleural effusion and prognosis of lung cancer patients with malignant pleural effusion (MPE). A nomogram model was established to predict the survival of the target patients. The clinical data of lung cancer patients with MPE who were diagnosed at The First Affiliated Hospital of Guilin Medical University from December 1, 2017, to December 31, 2019, were retrospectively analyzed. A nomogram was built based on the independent predictors identified using univariate and Cox multivariate analyses. The discrimination, calibration, and performance of the nomogram were evaluated using the Concordance Index(C-index), calibration plots, and decision curves. This study included 71 lung cancer patients with MPE, with a median survival time of 10 months. Univariate analysis showed that a neutrophil-to-lymphocyte ratio≥3.55, pleural fluid LDH ≥ 292 U/L, non-chemotherapy, and non-targeted therapy were associated with shorter overall survival ( P < 0.05). In multivariable Cox analysis, receipt of targeted therapy was associated with a lower hazard of death (HR 0.503, 95% CI 0.274–0.925), whereas pleural-fluid LDH ≥ 292 U/L was associated with a higher hazard of death (HR 2.449, 95% CI 1.238–4.843). The C-index of the nomogram is 0.703. Calibration and decision curves revealed the moderate discrimination of the nomogram model. Higher pleural-fluid LDH was associated with shorter overall survival. The treatment association may be affected by residual confounding. The internally validated two-variable model is exploratory and requires external validation before clinical use.