Hemoglobin A1c, BP With Eye Exam for Diabetic Retinopathy

An Expert Interview With David J. Browning, MD, PhD

Troy Brown

February 07, 2012

February 7, 2012 — The Diabetic Retinopathy Clinical Research (DRCR) Network is a network of community- and academic-based ophthalmologists that has been conducting clinical research related to diabetic retinopathy, macular edema, and associated conditions since 2002.

David J. Browning, MD, PhD, from Charlotte Eye, Ear, Nose and Throat Associates PA, in North Carolina, described the history of the DRCR Network and presented the latest information about studies in progress and in the planning stages at the Bascom Palmer Eye Institute 50th Anniversary Scientific Meeting in Miami, Florida. Medscape Medical News interviewed Dr. Browning about the DRCR Network.

Medscape: How did the DRCR Network come about?

Dr. Browning: Lloyd Paul Aiello, MD, PhD, Roy Beck, MD, PhD, and Matthew (Dinny) Davis, MD, conceived it in 2002. It was unique at the time in its openness to include community ophthalmologists, rather than just those affiliated with academic centers. In this spirit, it quickly grew.

There are now 342 community-based ophthalmologists and 207 academic-based ophthalmologists in the network. The day-to-day operations are coordinated by the Jaeb Center for Health Research in Tampa, Florida, an organization founded by Roy Beck in 1993 for the coordination of clinical trials and epidemiologic research in ophthalmic disorders and, more recently, diabetes. National Institutes of Health (NIH) and private funding for the DRCR Network have steadily grown. In 2011, NIH funding was $5.5 million.

Medscape: What are some of the things the DRCR Network has done?

Dr. Browning: In its first 10 years, 36 publications in top-tier journals have been written, 89 posters and presentations have been given at ophthalmic meetings, and an annual course has been instituted at the Academy. All 36 publications have had significant impact on the profession. Hundreds of investigators have been trained in clinical research over this time, through 2 meetings of the network each year and through a dense schedule of protocol development committee, writing committee, and operational committee meetings, mostly held as teleconferences. The network has developed an Internet-based model for gathering trial data in real time that has changed the way ophthalmic clinical research is done.

Medscape: Why is the DRCR Network important?

Dr. Browning: The DRCR Network is the only organization that does studies with a nonprofit perspective. Its focus is advancing the clinical care of diabetic retinopathy. It is NIH-funded for the most part. It does have support from industry and other private sources, but the goal is different from pharma, which exists to discover drugs that can be sold to make a profit for the company — a good but different goal.

Medscape: Which studies are making news now?

Dr. Browning: Protocol M is a clinical trial to determine whether the ophthalmologist's interaction with the patient can favorably influence systemic risk factors. In this study, diabetic patients with or without retinopathy are prospectively enrolled in 1 of 2 arms — a standard therapy arm, in which the patient receives his typical visit with the ophthalmologist, and a test arm, in which the patient has an in-office hemoglobin A1c test and blood pressure measurement with immediate feedback and personalized education about the risks implied by their data on progression of retinopathy. The outcome of this study is a mean change in A1c at 12 months.

Medscape: What is special about DRCR Network studies?

Dr. Browning: The DRCR Network studies provide high-level evidence (generally level 1) that can guide clinical care of diabetic retinopathy. This is rare. The majority of studies published are level 2 or 3 studies — good for hypothesis generation, but not for drawing conclusions about care.

Medscape: How will the DRCR Network affect the care of patients with diabetic retinopathy, diabetic macular edema, or associated conditions?

Dr. Browning: Protocol I indicated that intravitreal ranibizumab with prompt or deferred focal grid laser is superior to focal grid laser for the treatment of center-involved diabetic macular edema. There are 36 papers; this is just 1 of them. The full list is available on the DRCR Web site.

Medscape: Why are some of the studies large (1 has 1171 subjects), whereas others are much smaller (2 have 68 subjects)?

Dr. Browning: Study size is determined by whether the study is a pilot trial or a phase 3 trial, and by the estimated effect size of the intervention. Statistics and economics enter in to it. Big trials cost the NIH a lot of money.

Medscape: Which of these study areas are you most excited about?

Dr. Browning: Protocol S (Prompt Panretinal Photocoagulation [PRP] vs Intravitreal Ranibizumab With Deferred Panretinal Photocoagulation for Proliferative Diabetic Retinopathy). It is important because it may provide a nondestructive treatment for proliferative diabetic retinopathy

Medscape: What studies are upcoming?

Dr. Browning: Many more, such as a study to compare ranibizumab and bevacizumab given as intravitreal injections for diabetic macular edema. Also, a randomized trial is about to begin that will test whether serial ranibizumab injections with deferred PRP produces noninferior outcomes to standard prompt PRP in patients with proliferative diabetic retinopathy. The primary outcome is the mean change in visual acuity at 2 years.

Dr. Browning has disclosed no relevant financial relationships.