Does Smoking Cause Aspirin Resistance? A 2019 Pakistani Study Reveals smoking and aspirin resistance

smoking and aspirin resistance

Last Updated: July 31, 2025

For the millions who rely on a daily low-dose aspirin to prevent heart attacks and strokes, its effectiveness is a matter of life and death. Aspirin works by making blood platelets less sticky, reducing the risk of dangerous clots. But what if a common habit like smoking could render this life-saving therapy useless? A detailed doctoral thesis out of Pakistan provides compelling evidence that this might be the case. This post dives deep into the research to explore the critical link between smoking and aspirin resistance, and what it means for patient health.

Groundbreaking Research on Aspirin Resistance in Pakistan

This analysis is based on a 2019 Ph.D. thesis by Dr. Mudassar Noor from the National University of Medical Sciences in Rawalpindi, Pakistan. The study aimed to investigate the prevalence of aspirin resistance and its potential correlation with genetic and demographic factors in the Pakistani population. While the research explored many variables, one of the most statistically significant findings was the profound impact of smoking on the antiplatelet effects of aspirin.

The study involved 384 ischemic heart disease patients who were taking daily aspirin. Researchers used light transmission aggregometry—a gold standard method—to measure how well aspirin was preventing platelet clumping. Patients whose platelets showed more than 20% aggregation were classified as “aspirin resistant.”

The study’s results showed a clear and significant difference in aspirin response between smokers and non-smokers. While many factors like age, gender, and hypertension were evaluated, smoking was found to be a key predictor of poor aspirin response. This suggests that the cardioprotective benefits of aspirin could be severely blunted in individuals who smoke.

From the thesis abstract:

“Statistical analysis did not demonstrate significant association of any of the allele of the two evaluated SNPs with aspirin resistance, p > 0.05. We found a positive association between aspirin resistance and smoking, p < 0.001.“

This finding is crucial, as a p-value of less than 0.001 indicates a very high degree of statistical significance, meaning the result is extremely unlikely to be due to chance.

By the Numbers: How Smokers Responded to Aspirin

The data from Dr. Noor’s research paints a stark picture of how smoking and aspirin resistance are related.

  • The study population included 198 smokers (51.6%) and 186 non-smokers (48.4%).
  • Among non-smokers, aspirin was highly effective, with 93% responding well to the therapy. Only 7% (13 individuals) were found to be aspirin resistant.
  • In contrast, among smokers, only 79.8% responded to aspirin. A significantly higher portion, 20.2% (40 individuals), were aspirin non-responders.

This means smokers in the study were nearly three times more likely to be resistant to aspirin’s antiplatelet effects than their non-smoking counterparts.

Why Does Smoking Affect Aspirin’s Performance?

The discussion section of the thesis delves into the potential biological reasons behind this dangerous interaction. While some previous studies had conflicting results, Dr. Noor’s findings align with research suggesting that smoking fundamentally alters platelet behavior, making them more prone to clotting.

From the discussion:

“On the basis of these results we concluded that smoking has negative impact on aspirin efficacy as an antiplatelet agent… Our conclusion was strongly supported by Mirkhel et al, who investigated the aspirin effectiveness in 123 subjects… They multivariate analyzed their outcomes and concluded the solid association between tobacco smoking and antiplatelet treatment non-responsiveness.”

The Science Behind Platelet Hyperactivity in Smokers

The study highlights several ways smoking sabotages aspirin’s effectiveness:

  • Increased Platelet Reactivity: Smoking is known to cause endothelial damage (damage to the lining of blood vessels) and platelet hyper-reactivity. This creates an environment where platelets are already “primed” to form clots.
  • Pro-atherogenic Cholesterol: It induces the oxidation of cholesterol, which accelerates the buildup of plaques in arteries.
  • Heightened Thrombus Formation: Research shows that smoke inhalation directly enhances the formation of platelet thrombus (clots) through pathways that aspirin may not sufficiently block.

Essentially, smoking creates a pro-thrombotic state that can overpower the protective effects of a standard aspirin dose. This helps explain why aspirin effectiveness in smokers is a major clinical concern.

What This Means for Patients on Aspirin Therapy

The conclusion from this research is clear and has significant implications for public health, particularly for the vast number of cardiovascular patients who smoke.

From the conclusion:

“There can be many associated factors which may reduce the antiplatelet action of aspirin including age, gender, smoking, obesity, hypertension, diabetes mellitus and polymorphism of enzymes… But in our study only smoking was found to be associated with inadequate antiplatelet actions of aspirin.“

For patients, especially those with a history of heart disease, understanding the link between smoking and aspirin resistance is vital. It reinforces the urgent need for smoking cessation as a primary component of cardiovascular disease management. If you are taking aspirin for your heart health and you smoke, it is critical to have a conversation with your healthcare provider. This research suggests that your smoking habit may be undermining a key part of your treatment.

Author Bio: This analysis is based on the doctoral research of Dr. Mudassar Noor, conducted at the Department of Pharmacology & Therapeutics, Army Medical College, a constituent college of the National University of Medical Sciences (NUMS) in Rawalpindi, Pakistan.

Source & Citations

Disclaimer: Some sentences have been lightly edited for SEO and readability. For the full, original research, please refer to the complete thesis PDF.

What are your thoughts on this connection between smoking and aspirin’s effectiveness? Share your questions or experiences in the comments below!

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