A score before a model

Most clinical ML projects start by throwing raw measurements at a model and seeing what sticks. This one started differently: before touching machine learning at all, the first step was clinical exploratory data analysis, followed by hand-engineering a composite feature called the Heart Clinical Abnormality Score (HCAS) — a single number that summarizes cardiovascular severity from routine measurements a nurse or clinician would already have on hand (blood pressure, heart rate, BNP, creatinine, sodium, and related vitals). The reasoning: a model built on a clinically meaningful summary is easier to trust and easier to explain than one built purely on whatever raw columns happened to be in the spreadsheet.

Only after HCAS existed as a feature did model-building start. Eight independent classifiers were trained and compared on identical data and metrics, deliberately spanning very different mathematical approaches so that any agreement between them couldn't be explained by shared assumptions: Logistic Regression, Random Forest, CatBoost, SVM, XGBoost, an Explainable Boosting Machine, LightGBM, and a Stacking Ensemble that combines several of the others.

The finding that mattered: all eight models, despite spanning linear, tree-based, kernel, boosting, and ensemble methods, independently converged on the same five top predictors of 30-day readmission: medication adherence, BNP, HCAS, age, and distance to hospital. Eight different ways of looking at the same data reaching the same conclusion is a stronger signal than any single model's leaderboard score — it reads as the models corroborating clinical reasoning, not discovering something clinicians didn't already suspect.

Eight models, one conclusion

ModelFamilyRole in this project
Logistic RegressionLinearBaseline, interpretable coefficients
Random ForestTree ensembleSelected as the production model
CatBoostGradient boostingConvergence check
SVMKernel methodConvergence check
XGBoostGradient boostingConvergence check
Explainable Boosting MachineGeneralized additiveConvergence check
LightGBMGradient boostingConvergence check
Stacking EnsembleMeta-ensembleConvergence check

This project deliberately reports on agreement across models rather than a single accuracy/ROC-AUC leaderboard number — the clinical claim being tested was "do independent methods agree," not "which model scores highest."

From score to system

Random Forest was carried forward into a working prototype — the AEGIS Clinical Decision Support System, a desktop application that takes a patient's routine measurements as input, computes HCAS internally without ever surfacing it to the user, and returns an interpretable readmission-risk score. The clinician never needs to know a composite score is running underneath; they see the inputs they'd already collect and a risk assessment they can act on.

Because this sits inside a broader research programme rather than a one-off script, the project also carries a five-stage IP protection plan (ownership, invention disclosure, separating what's patentable from what's a trade secret from what's copyrightable, an innovation blueprint, and a commercialization step) and four possible paths to real-world use: a SaaS offering for hospital systems, licensing to nursing homes, a government/public-health deployment, and a direct-to-consumer version. None of these are built yet — they're the deliberate next steps once the clinical case for the model is solid, which is exactly the order this project did things in: score first, model second, product last.

Update (July 2026): a browser-based version of this tool is now live — try it here — running three of the eight models from the convergence analysis: the production Random Forest, LightGBM, and Logistic Regression, selectable side-by-side. The other five (CatBoost, SVM, XGBoost, the Explainable Boosting Machine, and the Stacking Ensemble) were part of the original convergence study but aren't wired into this demo. The HCAS composite score is computed internally using a faithful reconstruction of the original methodology — the exact original scoring script no longer exists among the project files, so this is disclosed rather than presented as ground truth. This remains an exploratory tool, not a validated clinical device: it has not gone through clinical trial or regulatory review, and should not be used for real patient care decisions.