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Potential impact of exclusion criteria on results of hypertension trials
1Department of Preventive Medicine and Environmental Health, University of Iowa, Iowa City 52242.
Insights
Excluding participants in antihypertensive trials can lower mortality event rates, potentially reducing the study
Area of Science:
- Cardiovascular Medicine
- Clinical Trials Methodology
- Public Health
Background:
- Numerous large-scale antihypertensive therapy trials have been conducted, including the Veterans Administration trials, Hypertension Detection and Follow-up Program, Multiple Risk Factor Intervention Trial, Australian Mild Hypertension Trial, and British Medical Research Council Trial.
- Participant selection criteria in these trials significantly influence the characteristics of the study population.
Purpose of the Study:
- To review recent antihypertensive therapy trials, focusing on participant exclusion criteria.
- To assess the impact of participant exclusion on the general applicability and statistical power of trial results.
Main Methods:
- Review of participant selection and exclusion criteria in major antihypertensive therapy trials.
- Analysis of all-cause and cause-specific mortality rates in selected trial populations.
- Evaluation of the relationship between end-point event rates and trial power.
Main Results:
- Participant exclusion criteria can substantially reduce end-point event rates in clinical trials.
- Low end-point event rates may compromise the statistical power to detect meaningful treatment effects.
- The observed mortality rates in selected participants serve as an indicator of the generalizability of trial findings.
Conclusions:
- Trial designs must account for the reduction in end-point rates caused by patient exclusion.
- Future antihypertensive trials should consider the impact of exclusion criteria on statistical power during the design phase.
- Careful consideration of participant eligibility is crucial for ensuring the relevance and robustness of clinical trial outcomes.
Abstract:
Recent trials of antihypertensive therapy, including the Veterans Administration trials, the Hypertension Detection and Follow-up Program, the Multiple Risk Factor Intervention Trial, the Australian Mild Hypertension Trial, and the British Medical Research Council Trial, are reviewed with a particular emphasis on the criteria leading to the exclusion of potentially eligible participants. The observation of all-cause and cause-specific mortality rates in the group ultimately selected to participate in the trial is suggested as an index to the general applicability of trial results. Because end-point rates are fundamental for determining sample size, substantial reduction in these end-point rates by patient exclusion should be taken into account by the trial design. Some recent trials may have generated end-point-event rates so low that the power of the trial to detect reasonable treatment effects was substantially reduced. Future trials should attempt to take this important factor into account at the design stage.