Real-time automated billing for tobacco treatment: performance evaluation of the CigStopper machine learning framework.

Objective: To evaluate CigStopper, a machine learning algorithm designed to predict billing eligibility for tobacco cessation counseling (CPT 99406/99407), addressing persistent underbilling and documentation gaps in health systems. Materials and Methods: We trained CigStopper on a 40,000-note corpus comprising real-world de-identified clinical notes, synthetically generated notes, and a blended dataset. Notes were categorized by billing eligibility and smoking documentation. Random Forest models were trained and evaluated using both flat multiclass and hierarchical classification approaches. Performance was assessed on a 20% holdout set of real notes using standard metrics (accuracy, precision, recall, F1). Results: Models trained on real or blended datasets achieved high performance for billing eligibility (F1 ≥ 0.97) and 99406 prediction (F1 ≥ 0.90). Prediction for intensive counseling (99407) remained limited (F1 ≤ 0.56). Synthetic-only training resulted in overfitting, with poor generalization to real-world data. Hierarchical classification improved eligibility detection and CPT code prediction compared with flat multiclass models. Discussion: Findings demonstrate that blended datasets mitigate class imbalance and improve generalizability, while hierarchical architectures enhance performance on billing tasks. Persistent gaps in 99407 prediction were related to low training volume, likely reflecting documentation and coding culture rather than model limitations, underscoring systemic issues in clinical note content. Conclusion: CigStopper demonstrates feasibility as a scalable NLP-based billing validation tool. By automating tobacco cessation CPT coding, the algorithm can improve data integrity, reduce missed reimbursement, and support health systems in aligning clinical care with financial and population health priorities.