External validation of the LENT and PROMISE prognostic scores for malignant pleural effusion.

Background: Accurate survival estimation in malignant pleural effusion is essential to guide clinical management strategies and inform patient discussion. The LENT and PROMISE scores were developed to aid prognostication in malignant pleural effusion; however their uptake in practice has been limited. We aimed to conduct a detailed external validation of the LENT and PROMISE scores to develop recommendations regarding clinical utility, and to highlight factors limiting performance. Methods: Medical records of patients diagnosed with malignant pleural effusion between 2015-2023 at Oxford University Hospitals were retrospectively reviewed to determine length of survival and the LENT and PROMISE scores at diagnosis. Performance of the scores in predicting overall survival and chance of survival at 3, 6 and 12 months was assessed using measures of discrimination, calibration and overall model performance. Kaplan-Meier analysis and Cox models were utilised to further investigate individual score variables. Results: 773 patients with malignant pleural effusion were included. Both scores showed predictive ability for overall survival; however median survival estimates lacked precision. Score performance in predicting survival at 3, 6 and 12 months was stronger, with C-indices around 0.8 for both at each time point, and the models appearing well calibrated. Limited stratification of tumour types and lack of consideration of sensitising mutations were demonstrated to be potential factors restricting performance. Conclusions: Both scores have the ability to prognosticate in malignant pleural effusion, and greater use in practice should be considered. However, areas to improve score performance were also highlighted, and these may aid future model development.