Monday, February 21, 2011

In POPADAD study, it was found that Aspirin is ineffective in Diabetics with Asymptomatic Peripheral Vascular Disease for primary prophylaxis! (BMJ 2008)

Peripheral arterial disease patients have an increased risk of subsequent myocardial infarction and stroke and are six times more likely to die from cardiovascular disease within10 years than patients without peripheral arterial disease. Patients with peripheral arterial disease have a 15 year accrued survival rate of about 22% compared with a survival rate of 78% in patients without such disease. So, there is always a question about beneficial effect and safety in giving Aspirin in the asymptomatic PAD patients to prevent the CV complications!

After this POPADAD study a question was asked as to whether these diabetic patients were at sufficient risk, in terms of peripheral arterial disease, as the cut-off point of an ankle brachial pressure index of 0.99 or less is higher than that used to define peripheral arterial disease in the population (<0.9). A subgroup analysis did not, however, find evidence of a difference in effect of aspirin between those with an index of 0.91-0.99 and those below this level.
Furthermore, one of the current major interventions in the specialty of diabetes mellitus is statin therapy. Calculations by two of the centres (DM and CK) in over 10 000 people with diabetes showed a mean total cholesterol level of 6.0 mmol/l in 1996 decreasing to 4.3 mmol/l in 2007. As aspirin was the first drug to have an evidence base for secondary prevention of cardiovascular disease it is always given to patients in subsequent trials and it might be asked if aspirin does indeed provide additional benefit when statins are used to good effect. The importance of the neutral effect of aspirin on cardiovascular events is that this drug is not without side effects. Aspirin is the most commonly prescribed drug in Scotland, with about 544 438 person years exposure per year in 2002. The number of prescriptions is increasing. The overwhelming majority of this, in the region of Tayside at least, is prescription based, with only about 7% being from over the counter use. Aspirin is one of the top 10 causes of adverse drug events reported to the Commission on Human Medicines. Gastrointestinal bleeding is associated ith general use of non-steroidal anti-inflammatory drugs in over 80%of reported cases, and 87%of that use is associated with aspirin, either alone or with other non-steroidal anti-inflammatory drugs. The risk of a bleeding event increases with age and also continuous exposure.
Although the calculated risk of major bleeding is relatively small, the number of people taking aspirin is relatively large and therefore in population terms aspirin induced bleeding is a major problem. In a meta-analysis the number needed to treat to cause an adverse event has been calculated as 248, and this is relevant to the large and increasing population with diabetes.
In addition, of concern was the fact that there was a tendency to harm in the antioxidant group. Anecdotally, many people with diabetes supplement with antioxidants after major publicity in the lay press of a deficiency in antioxidants in such people. It was also found there was no evidence for this perceived benefit in the studies.

Conclusion: Both Aspirin and Antioxidants are not useful in Diabetics with asymptomatic peripheral vascular disease in preventing the cardiovascular events!

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