Derivation and Validation of an Algorithm To Identify Helicobacter pylori Infected Patients Using Administrative Data
Bibliographic record
Abstract
Purpose: To validate VA administrative data for the diagnosis of H. pylori infected patients. Methods: National pharmacy, inpatient and outpatient administrative databases identified patients with an ICD-9 code for H. pylori (041.86) and those with prescriptions for eradication therapy from 01/01/03 to 12/31/03. Primary chart abstraction was used to confirm diagnosis of H. pylori based on antibody serology, urease breath testing, histopathology, or progress notes. Multivariable regression assessed predictors of H. pylori infection considering: prescription of eradication drug therapy, ICD-9 code, EGD procedure code, source of diagnostic code (inpatient or outpatient), age, gender and race. The c-statistic was calculated to assess the discriminant ability of the algorithm. Once derived this algorithm was validated in a cohort of patients from calendar year 2005 (N = 312). Results: The test cohort consisted of 581 patients (378 potential cases; 203 random controls) who were primarily male (94%), Caucasian (59%) and elderly (67 years [SD 10]). ICD-9 code 041.86 had the greatest positive predictive value (PPV) for H. pylori (PPV 100% if from an inpatient encounter; PPV 97.4% if from an outpatient encounter). Evidence of eradication drug therapy was associated with a PPV of 73.7% (triple therapy) and 97.7% (quadruple therapy). Multivariable regression revealed the strongest predictors to be outpatient ICD-9 code 041.86 (OR 8.1; 95% CI: 7.0–9.1); eradication drug therapy (OR 7.4; 95% CI: 6.6–8.3); EGD (OR 3.5; 95% CI: 3.3–3.6); and age ≥ 70 (OR 1.2; 95% CI: 1.1–1.4). A diagnostic algorithm including eradication drug therapy, ICD-9 diagnostic code 041.86 and age ≥ 70 yielded a c-statistic of 0.93, suggesting excellent discriminant ability. When this algorithm was tested in a validation cohort from calendar year 2005, the PPV was 97.9% with a NPV of 98.8%. Conclusion: Administrative data can be used to accurately diagnose H. pylori infected patients. The optimal diagnostic algorithm includes presence of eradication drug therapy overlapping with an outpatient ICD-9 code 041.86 among elderly adults.
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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 | 0.019 | 0.068 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".