Early Treatment Diabetic Retinopathy Study (ETDRS)
Summary
To evaluate the effectiveness of both argon laser photocoagulation and aspirin therapy in delaying or preventing progression of early diabetic retinopathy to more severe stages of visual loss and blindness.
To help determine the best time to initiate photocoagulation treatment in diabetic retinopathy.
To monitor closely the effects of diabetes mellitus and of photocoagulation on visual function.
To produce natural history data that can be used to identify risk factors and test etiologic hypotheses in diabetic retinopathy.
Description
ETDRS was a multicenter, randomized clinical trial designed to evaluate argon laser photocoagulation and aspirin treatment in the management of patients with nonproliferative or early proliferative diabetic retinopathy. A total of 3,711 patients were recruited to be followed for a minimum of 4 years to provide long-term information on the risks and benefits of the treatments under study.
The eligibility criteria for the ETDRS were designed to include a broad range of macular edema severity, from a few small hard exudates within a disc diameter of the fovea with normal visual acuity to extensive cystoid spaces with a visual acuity of 20/200. All study patients had one eye randomly assigned to immediate photocoagulation and the other eye to deferral of photocoagulation until high-risk proliferative retinopathy developed. During followup, additional photocoagulation was allowed for any degree of macular edema within the eligibility range, but additional photocoagulation was required only for edema involving or threatening the center of the macula. The term "clinically significant macular edema" was coined to designate this level of severity.
The trial use of aspirin therapy was based on clinical observation and on aspirin's possible mechanisms of action. Previous observations of diabetic patients who were taking large doses of aspirin for rheumatoid arthritis showed that the prevalence of retinopathy in this group was lower than the prevalence that would be expected in the diabetic population at large. Evidence suggested that diabetic patients have altered platelet aggregation and disaggregation, which may contribute to the capillary closure seen in retinopathy. This abnormality is reversed by aspirin in vitro . However, because of aspirin's other possible mechanisms of action and its well-known side effects, such as allergic, idiosyncratic, and intolerance reactions, the use of this therapy in the ETDRS was carefully controlled and monitored.
Study Design
Allocation: Randomized, Primary Purpose: Treatment
Conditions
Blindness
Intervention
Aspirin, Argon Laser Photocoagulation
Status
Completed
Source
National Eye Institute (NEI)
Results (where available)
Links
- Source: http://clinicaltrials.gov/show/NCT00000151
- Information obtained from ClinicalTrials.gov on July 15, 2010
Medical and Biotech [MESH] Definitions
Argon Plasma Coagulation
A method of tissue ablation and bleeding control that uses argon plasma (ionized argon gas) to deliver a current of thermocoagulating energy to the area of tissue to be coagulated.
Angioplasty, Laser
A technique utilizing a laser coupled to a catheter which is used in the dilatation of occluded blood vessels. This includes laser thermal angioplasty where the laser energy heats up a metal tip, and direct laser angioplasty where the laser energy directly ablates the occlusion. One form of the latter approach uses an EXCIMER LASER which creates microscopically precise cuts without thermal injury. When laser angioplasty is performed in combination with balloon angioplasty it is called laser-assisted balloon angioplasty (ANGIOPLASTY, BALLOON, LASER-ASSISTED).
Sodium Salicylate
A non-steroidal anti-inflammatory agent that is less effective than equal doses of ASPIRIN in relieving pain and reducing fever. However, individuals who are hypersensitive to ASPIRIN may tolerate sodium salicylate. In general, this salicylate produces the same adverse reactions as ASPIRIN, but there is less occult gastrointestinal bleeding. (From AMA Drug Evaluations Annual, 1992, p120)
Asthma, Aspirin-induced
Asthmatic adverse reaction (e.g., BRONCHOCONSTRICTION) to conventional NSAIDS including aspirin use.
Argon
Argon. A noble gas with the atomic symbol Ar, atomic number 18, and atomic weight 39.948. It is used in fluorescent tubes and wherever an inert atmosphere is desired and nitrogen cannot be used.
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