Abstract 2118: A Population-based Comparison of the Cardiovascular Protective Effects of Hydrochlorothiazide and Chlorthalidone
Bibliographic record
Abstract
Background Clinical practice guidelines for the treatment of hypertension recommend a thiazide diuretic as initial therapy for the majority of patients. Most clinicians consider chlorthalidone (CHL) and hydrochlorothiazide (HCTZ), the two most commonly prescribed thiazides, to be interchangeable, despite evidence suggesting these drugs are not equivalent. Methods We constructed a population-based retrospective cohort study by linking the health records of 1.4 million residents of Ontario, Canada aged 66 or older between July 1, 1993 and March 1, 2002. The index event for entry into the cohort was a new prescription for either HCTZ or CHL. The primary outcome was the time from the index event to a composite outcome of acute myocardial infarction (AMI), stroke, or all-cause mortality. Secondary analyses explored each outcome individually. Analysis was done using Cox proportional hazards regression with the HCTZ group as the reference. Results During 218,360 person-years of follow-up in the HCTZ group, there were 10 025 events (death, AMI or stroke), compared to 113 events during 4,214 person-years of follow-up in the CHL group. The unadjusted hazard ratio for the primary outcome was 0.73 (95% confidence interval 0.61 to 0.88), suggesting a substantially lower risk of events during CHL therapy. After adjustment for differences in baseline demographic and clinical characteristics, there was no statistically significant difference between the groups for the primary outcome (adjusted hazard ratio 0.85; 95% confidence interval 0.71 to 1.03). The hazard ratios for each component of the primary composite outcome all trended in the direction of a lower risk of events in users of CHL. Conclusion In a large cohort of older patients treated with thiazide diuretics, the use of CHL was not associated with a statistically significant reduction in the risk of AMI, stroke, or death. However, treatment effects favored CHL for every outcome, raising the hypothesis that CHL is superior to HCTZ. Further research is needed to confirm or refute this hypothesis.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".