Randomized Trial of Aspirin and Cataracts in U.S. Physicians
Summary
To determine whether 325 mg of aspirin taken on -alternate days reduces the risk of developing cataract among male U.S. physicians who were aged 40 to 84 in 1982.
To identify potential risk factors for cataract development, such as age, blood pressure, blood cholesterol, height, diabetes, medication use, and history of previous eye trauma or surgery.
Description
Cataract is one of the most common causes of impaired vision as well as the third leading cause of blindness in the United States. Cataract surgery is one of the safest and most successful of all operations. The National Eye Institute has estimated that if the progression of cataract could be slowed enough to delay the need for surgery by even 10 years, the current annual number could be reduced by 45 percent.
Little is known about the relative importance of various potential risk factors in the development of cataract. Most current information on risk factors has come from anecdotal reports or from relatively small case-control studies. One major project, the Framingham Eye Study, has identified several factors that were significantly associated with subsequent cataract formation, including diabetes and dietary factors. Diabetes has long been thought to increase the risk of developing cataract.
Recently, aspirin has been proposed as a drug that can prevent cataract formation or slow its progression. Aspirin may affect tryptophan levels in patients with cataract, or it may inhibit aldose reductase, an enzyme associated with the development of diabetic cataract. Thus, data from this study sought to determine whether one 325-mg aspirin tablet, taken on alternate days, protects against cataract formation. The data also sought to reveal other additional cataract risk factors that emerge after simultaneous controlling for other variables.
The other primary objective of this trial was to assess the antioxidant effects of beta-carotene (50 mg on alternate days) on cataract development. In addition, factors that have been suggested to be cataractogenic were assessed in prospective cohort studies. These factors included age, blood pressure, blood cholesterol, height, diabetes, medication use, cigarette smoking, and history of previous eye trauma or surgery. In addition, the possible associations between history of vitamin E and selenium intake and cataract were explored.
This trial was part of the Physicians Health Study, an ongoing, randomized, placebo-controlled clinical trial of aspirin in the prevention of cardiovascular mortality and of beta-carotene in the prevention of cancer. Following randomization, each of the 22,071 physicians enrolled was assigned to one of four groups to take either aspirin or its placebo and beta-carotene or its placebo. Follow-up questionnaires were sent 6 and 12 months after randomization and every 12 months thereafter. The randomized aspirin component of the trial was terminated early (January 1988), after an average followup of approximately 5 years, because of a statistically extreme 44 percent reduced risk of a first myocardial infarction in the aspirin group.
Since this study is conducted by mail among physicians nationwide, examinations cannot be performed on all patients to determine when they have reached an end point. Reported diagnoses of cataract are confirmed by medical record review. The primary analysis will be of incidence of cataract in the aspirin and placebo groups. In addition, the Cox proportional hazards model will be used to determine whether there is a difference in time to cataract diagnosis between the two groups. It has been postulated that the potent antioxidant properties of beta-carotene might make it effective in preventing cataract development. The investigators will thus determine whether there is a difference in the numbers of cataracts between the beta-carotene/placebo groups and the aspirin/placebo groups.
Study Design
Allocation: Randomized, Control: Placebo Control, Primary Purpose: Prevention
Conditions
Cataract
Intervention
Aspirin
Status
Terminated
Source
National Eye Institute (NEI)
Results (where available)
Links
- Source: http://clinicaltrials.gov/show/NCT00000157
- Information obtained from ClinicalTrials.gov on July 15, 2010
Medical and Biotech [MESH] Definitions
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.
Aspirin
The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. (From Martindale, The Extra Pharmacopoeia, 30th ed, p5)
Cataract
Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)
Diflunisal
A salicylate derivative and anti-inflammatory analgesic with actions and side effects similar to those of ASPIRIN.
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