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VA Cooperative Studies Program (CSP)

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

Diuretic Comparison Project Home PageInformation for Veterans | Information for VA ProvidersStudy Team and Contact Information |

The Diuretic Comparison Project (DCP) is the first national study to implement the Point of Care Clinical Trial (POC-CT) 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
  2. Centralized recruitment and enrollment, involving permission from the patient’s primary care provider (PCP) via a View Alert order and informed consent obtained from the patient by study personnel via telephone
  3. Centralized placement of notes and orders using View Alerts in the VA EMR
  4. All patient care including the diuretic to be managed by the primary care provider
  5. Centralized passive collection of outcomes and process variables using the VA EMR, Medicare, and other national VA and non-VA databases.

How the DCP will be embedded in Primary Care? Although patients will be recruited and enrolled centrally by the Boston CSP Coordinating Center, PCPs will consent to participate as study subjects themselves and allow the DCP to contact their eligible patient panel. Participating PCPs approve each patient’s enrollment and continue to care for the patient as usual. The DCP will leverage the EMR to integrate study processes within the usual primary care workflow eliminating extra study visits or procedures. Additionally, the DCP will attempt to enroll patients before a scheduled visit allowing PCPs to assess their patients in a timely manner.

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

  1. Allow the DCP to contact potentially eligible patients in the primary care provider’s patient panel
  2. Provide approval to randomize specific patients once the patient has consented to participate
  3. Allow the DCP to track your patient’s health status, including diuretic management

All information regarding participation will be kept confidential.

Why should this research be conducted at the VA? The POC Program capitalizes on the VA’s unique electronic medical record (EMR) 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 best practice medicine to Veterans.

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Updated September 2018

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