Clinical identification of malignant pleural effusions

ABSTRACT Importance Pleural effusions frequently signal disseminated cancer. Diagnostic markers of pleural malignancy at presentation that would assess cancer risk and would streamline diagnostic decisions remain unidentified. Objective The present study aimed at identifying and validating predictors of malignant pleural effusion at patient presentation. DESIGN, SETTING, AND PARTICIPANTS A 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 Measures The outcome was diagnostic of pleural effusion in patients, and the clinical and laboratory indicators available of the patient were measured. Results Five 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 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 (P <0.001). The calibration curves of the cytology model were slightly better than The MAPED score. Decision curve analysis (DCA) indicated that The MAPED score generated net clinical benefit. In the validation dataset, the results were generally consistent with the above findings, with an AUC of 0.723 (sensitivity=76%, specificity=62%, P =3*10-9) for The MAPED score. Interestingly, MAPED correctly identified 33/42(79%) of cytology-negative patients that indeed had cancer. The MAPED score is used to create nomogram so clinicians can predict the probability of malignant pleural effusions. Conclusions The MAPED score identifies malignant pleural effusions with satisfactory accuracy and can be used complementary to cytology to streamline diagnostic procedures.