Treatment of Hypertension In Adults With ThiaZIDES: Pragmatic Trial Pilot Study (ThiaZIDES)

October 10, 2017 updated by: HealthPartners Institute
This proposed pilot study will test methods and feasibility for a large pragmatic clinical trial comparing two inexpensive, first-line drugs for treating high blood pressure to determine if one is superior in preventing serious cardiovascular events and death. It will develop and test novel approaches to conducting trials that will be faster, less expensive, and more realistic by being embedded in a typical practice setting and using advanced health information technology.

Study Overview

Status

Completed

Conditions

Detailed Description

For several decades, U.S. hypertension treatment guidelines have recommended a low-dose diuretic such as hydrochlorothiazide (HCTZ) or chlorthalidone (CTD) as initial monotherapy in a stepped-care approach or as part of an initial two-drug combination. In numerous large clinical trials, CTD-based regimens have significantly reduced rates of cardiovascular events such as stroke, heart failure, and cardiovascular mortality compared with placebo, usual care, or active comparators. In contrast, few outcome studies have compared HCTZ-based regimens with other treatments, and they have generally found HCTZ to be less effective than non-thiazide comparators in preventing cardiovascular events. The two drugs have never been compared directly in a large trial. Despite the empirical evidence favoring CTD, HCTZ is much more widely used in clinical practice. The proposed R34 is a pilot study conducted in two large integrated health systems to test methods and feasibility for an eventual pragmatic randomized trial comparing the effectiveness of HCTZ and CTD for preventing cardiovascular events and mortality. Using a cluster-randomized design, investigators will allocate 40 primary care physicians and their adult hypertensive patients who currently use HCTZ (N=2,000) to either convert HCTZ users to CTD (intervention group) or to continue HCTZ (usual care group). The pilot study and planned full-scale trial will use existing health care infrastructure and electronic health records to identify eligible study subjects, distribute study medication, and collect operational and outcomes data. For this pilot study, Aim 1 will document that the intervention is delivered as intended. Aim 2 will compare safety in intervention and usual care patients. Aim 3 will refine the pilot study design and identify critical factors for intervention success using a mixed-methods approach. Aim 4 will refine estimates of sample size. Finally, Aim 5 will determine the costs of ascertaining outcomes and estimate per-participant costs for the full-scale trial. The pilot study will produce data that are necessary and sufficient to inform the planning of a full-scale trial comparing CTD and CTZ and will advance the development of methods for pragmatic trials.

Study Type

Interventional

Enrollment (Actual)

2027

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Minnesota
      • Bloomington, Minnesota, United States, 55105
        • HealthPartners Institute for Education and Research
    • Oregon
      • Portland, Oregon, United States, 97227
        • Kaiser Permanente Center For Health Research

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Adults 18 years and older
  • Hypertension diagnosis (ICD-9 401.x)
  • Current prescription for hydrochlorothiazide (HCTZ), 12.5-50 mg/day as a single-agent (not part of a fixed-dose combination drug)
  • No history of intolerance to chlorthalidone (CTD)
  • No known low levels of sodium (<135 mEg/L (milliequivalents per liter)) or potassium (<3.5 mEg/L)
  • English speaking

Exclusion Criteria:

  • Physician deems patient inappropriate for switching HCTZ to CTD
  • Patient refuses the switch prior to intervention

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Intervention
Intervention is HCTZ prescription conversion to chlorthalidone. Intervention patients are defined as patients of physicians randomized to "intervention." All these patients will have their current prescription of hydrochlorothiazide (HCTZ) switched to an equipotent dose of Chlorthalidone. These patients can choose to decline this intervention, and will be followed for 9 months with no other intervention to observe primary and secondary outcomes.
The intervention is simply a prescription conversion and the main outcome is whether or not patients accept the conversion and treatment with chlorthalidone.
No Intervention: Usual Care
Usual care patients are defined as patients of physicians randomized to "usual care." All these patients will keep their current prescription for HCTZ and work with their physician like normal. These patients will be followed for 9 months with no intervention to compare primary and secondary outcomes to the intervention group.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Conversion to chlorthalidone, number of patients with primary fills
Time Frame: 3 months
We will observe pharmacy claims to assess whether intervention patients filled their first prescription for chlorthalidone (primary adherence)
3 months
Conversion to chlorthalidone, number of participants with secondary fills
Time Frame: 9 months
We will observe pharmacy claims to assess whether intervention patients who filled their first chlorthalidone prescription also filled their subsequent prescription (secondary adherence)
9 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Blood pressure
Time Frame: 9 months
Systolic and diastolic blood pressure measures, as documented in electronic health record
9 months
Hypertension drugs
Time Frame: 9 months
Use of anti-hypertensive drugs in addition to hydrochlorothiazide or chlorthalidone, as documented in pharmaceutical claims
9 months
Electrolyte levels
Time Frame: 9 months
Sodium and potassium levels, as documented in electronic health record
9 months
Renal function
Time Frame: 9 months
Kidney function lab values (including epidermal growth factor receptor (eGFR) and creatinine), as documented in electronic health record
9 months
Safety outcomes
Time Frame: 9 months
Hypotension with fainting (over-treatment), hypertensive crisis (under-treatment) and other clinical outcomes related to safety of hypertension treatment
9 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Collaborators

Investigators

  • Principal Investigator: Karen L Margolis, MD, MPH, HealthPartners Institute
  • Principal Investigator: Stephen P Fortmann, MD, Kaiser Permanente

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 2015

Primary Completion (Actual)

July 1, 2017

Study Completion (Actual)

July 1, 2017

Study Registration Dates

First Submitted

September 25, 2015

First Submitted That Met QC Criteria

October 28, 2015

First Posted (Estimate)

October 29, 2015

Study Record Updates

Last Update Posted (Actual)

October 11, 2017

Last Update Submitted That Met QC Criteria

October 10, 2017

Last Verified

January 1, 2017

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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