Why Some Are Saying Marijuana May Increase Stroke And Heart Failure

Study finds increased risks, but more research is needed.

heart failure
Photo by stevanovicigor/Getty Images

A study from a private healthcare network in Pennsylvania sent shockwaves and questions through the cannabis community. Led by Dr. Aditi Kalla, it used the National Inpatient Sample (NIS) database to scrutinize the medical records of patients from more than 1,000 hospitals in the U.S.


The study focused on patients ages 18-55 years who were released from hospitals in 2009 and 2010. Marijuana use was “diagnosed” in roughly 1.5 percent of the study sample. Researchers concluded that the marijuana users had a 26 percent increase in the risk of stroke and a 10 percent increase the likelihood of later heart failure. 

It’s what the study does not emphasize which may be of greatest importance to question further. Ironically, the medical records used were from a time when no states had regulated recreational marijuana and most states were not allowing medical marijuana. So, at best, most respondents probably were using illegal market marijuana. Additionally, researchers did not know how patients ingested it, when they last used it or even how much they used.   

Only 1.5 percent of the sample identified as cannabis users, while National Institute on Drug Abuse found that at least 5.8 percent of Americans used marijuana in 2007, a number that continued to grow even before the study’s data set was created. 


Just because two data points line up, it doesn’t infer causality. To do so incorrectly is officially known as questionable cause logical fallacy. A well known case involving women and hormone replacement therapy, HRT, inferred from correlation of facts that women on HRT had lower incidence of heart disease. However, upon closer inspection and further research showed that the women who could afford the HRT were also from a higher socioeconomic standing, allowing for better diet and exercise.

We had the opportunity to speak to Dr. Kalla about these findings:

“This is not an ‘anti-cannabis’ study and none of the researchers involved in this study, including myself, have a political agenda.  All drugs typically undergo studies to determine if there are any side effects. If any are found, then researchers try to first narrow down which organs are affected and subsequently look for a dose-dependent curve. “

Although some may assume otherwise, Dr. Kalla pointed out that she is not against medical marijuana:

“Cannabis use has benefits. I would like patients consuming cannabis for medicinal and/or recreational purposes to be aware that cannabis use may have cardiovascular side effects. Informing your physician about any cannabis use will allow your physician to appropriately monitor you for potential cardiovascular complications.‘

Like all research, these early findings and assumed correlations must be tested further and in a way that is specifically targeted at examining relationships between stroke, cardiovascular disease, heart attacks and cannabis use. Until then, as Dr. Kalla noted, informing your physician about cannabis use affords you a professional opinion on the matter.


 

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