Low dose Aspirin ineffective in CVD Prevention in high body-size patients : Lancet

It is now established that low dose Aspirin has preventive role in primary as well as secondary prevention of cardiovascular diseases an about one billion people worldwide take regular aspirin for the same. In a study the researchers have found out that Low-dose aspirin may not be effective in preventing cardiovascular events in people weighing 70 kg (154 pounds) or more. The findings has appeared in a Lancet study .

The study was conducted on the premise that one-dose-fits-all approach to use of aspirin may not be providing adequate and desirable effect in long-term prevention of cardiovascular events. Aspirin inhibits just one of several pathways of platelet activation, so it is not surprising that many patients still experience cardiovascular events. The researchers hypothesised that usual standard low-dose aspirin (i.e. 75-100mg daily), which is commonly used may be insufficient at high body-size, whereas higher doses (325mg daily is widely used in the USA) would be excessive at lower body-size.

Professor Peter Rothwell of Oxford's Nuffield Department of Clinical Neurosciences and colleagues studied detailed data from their own previous trials (with over 130,000 participants) .They analyzed 10 trials that evaluated aspirin versus controls for primary prevention of cardiovascular events in subjects.

The researchers found that daily, low-dose aspirin (75–100 mg) was associated with reduced risk for cardiovascular events among those weighing less than 70 kg (odds ratio, 0.77), but there was no significant effect for heavier patients. In the heavier group, low-dose aspirin may be even less effective in smokers and in those who take enteric-coated aspirin.

In addition high-dose aspirin (300–325 or 500 mg) appeared to be effective in reducing primary cardiovascular events only patients weighing 70 kg or more (OR, 0.79).It was inferred that people with more body mass may have more esterases, which clear aspirin and may reduce the bioavailability of the drug.

Lead researcher, Rothwell, explained that 'The several hundred trials of aspirin in prevention of vascular events have all tested a ‘one-dose-fits-all’ approach, but it appears that this is not a very effective strategy, and might sometimes do more harm than good. Future trials should test strategies in which the dose of aspirin is tailored to the characteristics of the individual patient.'

The authors conclude: "A one-dose-fits-all approach to aspirin is unlikely to be optimal, and a more tailored strategy is required."Body weight may be among factors that potentially contribute to treatment failures, sometimes named as aspirin resistance.However further research is warranted to establish whether weight-adjusted dosing of aspirin should be incorporated into clinical care.

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DOI: https://doi.org/10.1016/S0140-6736(18)31133-4