Clinical identification of malignant pleural effusions

ImportancePleural effusions frequently signal disseminated cancer. Diagnostic markers of pleural malignancy at presentation that would assess cancer risk and would streamline diagnostic decisions remain unidentified.ObjectiveThe present study aimed at identifying and validating predictors of malignant pleural effusion at patient presentation.DESIGN, SETTING, AND PARTICIPANTSA consecutive cohort of 323 patients with pleural effusion (PE) from different etiologies were recruited between 2013-2017 and was retrospectively analyzed. Data included history, chest X-ray, and blood/pleural fluid cell counts and biochemistry. Group comparison, receiver-operator characteristics, unsupervised hierarchical clustering, binary logistic regression, and random forests were used to develop the malignant pleural effusion detection (MAPED) score. MAPED was validated in an independent retrospective UK cohort (n= 238).Main Outcomes and MeasuresThe outcome was diagnostic of pleural effusion in patients, and the clinical and laboratory indicators available of the patient were measured.ResultsFive variables showed significant diagnostic power and were incorporated into the 5-point MAPED score. Age > 55 years, effusion size > 50% of the most affected lung field, pleural neutrophil count < 2,500/mm3, effusion protein > 3.5 g/dL, and effusion lactate dehydrogenase > 250 U/L, each scoring one point, predicted underlying cancer with the area under curve(AUC) = 0.819 (sensitivity=82%, specificity=74%,P< 10-15) in the derivation cohort. The AUC and net reclassification improvement (NRI) of MAPED score and cytology were not significantly different. However, the integrated discrimination improvement (IDI) of The MAPED score displayed a slight increment(PConclusionsThe MAPED score identifies malignant pleural effusions with satisfactory accuracy and can be used complementary to cytology to streamline diagnostic procedures.