Abstract 125: Natural Language Processing Identifies an Association Between Canadian Cardiovascular Society Angina Severity and Mortality Within the Department of Veterans Affairs
Bibliographic record
Abstract
Background: Stable angina is estimated to affect more than 10 million Americans and is the presenting symptom in half of patients diagnosed with coronary disease. Documentation of angina severity resides as unstructured data and is often unavailable in large datasets. We used natural language processing (NLP) to identify Canadian Cardiovascular Society (CCS) angina class and determine the association with all-cause mortality in an integrated health system’s electronic records (EHR). Methods: We performed a historic cohort study using national Veterans Health Administration data between 1/1/06 and 12/31/13. Veterans with incident stable angina were identified by ICD-9-CM codes. We developed an NLP tool to extract CCS class from free text notes. Risk ratios (RR) for all-cause mortality at one year associated with CCS class were calculated using Poisson regression. Results: There were 299,577 Veterans with angina, of which 14,216 had at least one CCS class extracted via NLP. Mean age was 66.6 years, 98% were male sex, and 82% were white. Diabetes increased with CCS class, but other comorbidities were stable (Table). There were 719 deaths at one year follow-up. The adjusted RR for all-cause mortality at one-year comparing Class III to Class I and Class IV to Class I was 1.40 (95% CI 1.16 - 1.68) and 1.52 (95% CI 1.13 - 2.04), respectively. Conclusion: NLP-derived CCS class was independently associated with one year all-cause mortality. Its application may be limited by inadequate EHR documentation of angina severity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.021 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".