Insufficient evidence to determine if marijuana use can affect cardiovascular risk

1. Evidence for effect of marijuana use on cardiovascular risk is insufficient.

2. A few studies suggests potential metabolic benefits from marijuana use, but require further in-depth studies to draw accurate conclusion.

Evidence Rating Level: 1 (Excellent)

Study Rundown: The importance of studying the effects of marijuana use has become increasingly important as marijuana is legalized and sold in an increasing number of States. There are several potential ways in which marijuana may affect the cardiovascular system, which include ischemia, increasing vascular risk factors, and increasing blood carboxyhemoglobin levels. As a result of these potential interactions, the authors of this study conducted a systematic review to determine the harms and benefits of marijuana with respect to cardiovascular risk factors and patient clinical outcomes. Generally, it was observed that there is currently insufficient evidence to draw conclusions regarding the impact of marijuana on cardiovascular risk. This study has several limitations. First, the quality of data was rated as poor or moderate, making it challenging to interpret the relationship between marijuana exposure and cardiovascular risk factors. Additionally, studies were limited to English only. Expanding the search to studies in other languages may have increased the number of studies included and made it easier to draw accurate conclusions. Finally, study design also varied greatly, which impacted the authors’ ability to accurately compare studies across multiple variables. Overall, the results of this study suggest that further research regarding the effects of marijuana on cardiovascular risk factors is required in order to draw conclusions.

Click to read the study in Annals of Internal Medicine

Relevant Reading: Cardiovascular Effects of Marijuana

In-Depth [systematic review]: The authors conducted a systematic literature review, searching a variety of databases for observational studies that included adults using any form of marijuana and had data regarding vascular risk factors and/or clinical outcomes. In total, 4 reviewers independently assessed studies for quality and characteristics, extracting data across a wide range of variables. A total of 3006 abstracts were initially collected, of which 147 were selected for full-text review and a total of 24 met the inclusion criteria. The authors assessed a variety of cardiovascular risk factors, such as obesity and stroke. Regarding stroke, two prospective studies assessed the risk of marijuana exposure on stroke and transient ischemic attack. Both studies did not determine an association between marijuana and stroke, but had multiple limitations that made it difficult to draw accurate conclusions from these findings. As well, 6 studies indicated that there might be a metabolic benefit from marijuana use; however, they were not supported by prospective studies and also had several limitations.

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