Development and Validation of a Practical Model to Identify Patients at Risk of Bleeding After TAVR.

OBJECTIVES: No standardized algorithm exists to identify patients at risk of bleeding after transcatheter aortic valve replacement (TAVR). The aim of this study was to generate and validate a useful predictive model. BACKGROUND: Bleeding events after TAVR influence prognosis and quality of life and may be preventable. METHODS: Using machine learning and multivariate regression, more than 100 clinical variables from 5,185 consecutive patients undergoing TAVR in the prospective multicenter RISPEVA (Registro Italiano GISE sull'Impianto di Valvola Aortica Percutanea; NCT02713932) registry were analyzed in relation to Valve Academic Research Consortium-2 bleeding episodes at 1 month. The model's performance was externally validated in 5,043 TAVR patients from the prospective multicenter POL-TAVI (Polish Registry of Transcatheter Aortic Valve Implantation) database. RESULTS: Derivation analyses generated a 6-item score (PREDICT-TAVR) comprising blood hemoglobin and serum iron concentrations, oral anticoagulation and dual antiplatelet therapy, common femoral artery diameter, and creatinine clearance. The 30-day area under the receiver-operating characteristic curve (AUC) was 0.80 (95% confidence interval [CI]: 0.75-0.83). Internal validation by optimism bootstrap-corrected AUC was 0.79 (95% CI: 0.75-0.83). Score quartiles were in graded relation to 30-day events (0.8%, 1.1%, 2.5%, and 8.5%; overall p <0.001). External validation produced a 30-day AUC of 0.78 (95% CI: 0.72-0.82). A simple nomogram and a web-based calculator were developed to predict individual patient probabilities. Landmark cumulative event analysis showed greatest bleeding risk differences for top versus lower score quartiles in the first 30 days, when most events occurred. Predictivity was maintained when omitting serum iron values. CONCLUSIONS: PREDICT-TAVR is a practical, validated, 6-item tool to identify patients at risk of bleeding post-TAVR that can assist in decision making and event prevention.

A comparison of machine learning techniques for survival prediction in breast cancer.

BACKGROUND: The ability to accurately classify cancer patients into risk classes, i.e. to predict the outcome of the pathology on an individual basis, is a key ingredient in making therapeutic decisions. In recent years gene expression data have been successfully used to complement the clinical and histological criteria traditionally used in such prediction. Many "gene expression signatures" have been developed, i.e. sets of genes whose expression values in a tumor can be used to predict the outcome of the pathology. Here we investigate the use of several machine learning techniques to classify breast cancer patients using one of such signatures, the well established 70-gene signature. RESULTS: We show that Genetic Programming performs significantly better than Support Vector Machines, Multilayered Perceptrons and Random Forests in classifying patients from the NKI breast cancer dataset, and comparably to the scoring-based method originally proposed by the authors of the 70-gene signature. Furthermore, Genetic Programming is able to perform an automatic feature selection. CONCLUSIONS: Since the performance of Genetic Programming is likely to be improvable compared to the out-of-the-box approach used here, and given the biological insight potentially provided by the Genetic Programming solutions, we conclude that Genetic Programming methods are worth further investigation as a tool for cancer patient classification based on gene expression data.