Office of Research & Development

VA CSP Diuretic Comparison Project (DCP): Information for VA Providers

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The Diuretic Comparison Project (DCP) is the first national study to implement the Point of Care (POC) Clinical Trial design, which embeds trials into routine medical care. This methodology is uniquely positioned to compare two or more approved treatments when clinical equipoise exists. The goal of the DCP is to compare the effects of two thiazide-type diuretics, hydrochlorothiazide and chlorthalidone, on cardiovascular outcomes in older Veterans with hypertension. Both diuretics have been on the market for over 50 years, but have never been directly compared with a randomized trial. Nationally, more than one million Veterans are prescribed a thiazide-type diuretic with 95% receiving hydrochlorothiazide. Indirect evidence suggests that chlorthalidone may be more effective than hydrochlorothiazide at preventing cardiovascular events. Possible mechanisms for such an effect include longer duration of action, better nighttime blood pressure control and pleiotropic effects.

The DCP aims to enroll 13,500 patients over 65 years old who are receiving hydrochlorothiazide 25 or 50 mg daily from VA pharmacies. Participants will be randomly assigned to continue their hydrochlorothiazide or to be switched to chlorthalidone at a suggested equipotent dose of 2:1.

The key feature of this pragmatic design is that, instead of employing local investigators, we substitute centralized study processes and rely on usual primary care. Specifically this involves:

1. Identification of eligible patients using the VA electronic medical record system (by the study team)

2. Centralized recruitment and enrollment, involving permission from the patient's primary care provider (PCP) via a View Alert order (by the study team and the primary care provider)

3. Informed consent obtained from the patient by study personnel via telephone

4. Centralized placement of notes and orders using View Alerts in the VA EMR (by the study team)

5. All patient care including the diuretic to be managed by the primary care provider

6. Centralized passive collection of outcomes and process variables using the VA EMR, Medicare, and other national VA and non-VA databases. (by the study team)

How the DCP will be "embedded" into Primary Care?
Although patients will be recruited, consented, and enrolled centrally by the Boston CSP Coordinating Center, VA Providers will consent to participate as study subjects themselves and allow the DCP to contact their eligible patient panel. Participating providers will approve each patient's enrollment and randomization, and then continue to care for the patient as usual. DCP will use the electronic medical record to collect outcome data. Additionally, the DCP will attempt to enroll patients 3-4 months before a scheduled visit allowing PCPs to assess their patients in a timely manner.

PCP Participation:
DCP is requesting provider participation for three key purposes:

1. Allow the DCP to contact potentially eligible patients in the primary care provider's patient panel (via CPRS)

2. Provide approval to randomize specific patients once the patient has consented to participate (via CPRS)

3. Allow the DCP to track your patient's health status, including diuretic management (via the electronic medical record)

All information regarding participation will be kept confidential.

How is VA uniquely positioned to conduct this research?
POC capitalizes on the VA's unique electronic medical record system to perform study activities traditionally conducted by a study team such as enrollment, randomization, and longitudinal data collection. By integrating clinical research into clinical care, the VA aims to create a 'learning healthcare system' that delivers the most beneficial treatment to Veterans by answering research questions directly from patient data.

For more detailed information, please visit ClinicalTrials.gov


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