A recent study released last week has some pulses elevated. The European Journal of Preventive Cardiology published its findings from a retrospective study concluding an association between cannabis and a threefold risk of death from hypertension. But both the findings and the very structure of the study have come under fire.
The study of crafting results
The study contains enough holes to drive a truck through, but that won’t stop canna-critics from spouting it as scripture. So it’s necessary for consumers to know the truth behind the so called facts. Here’s a breakdown of how the study authors crafted their results.
In 2005-2006, the National Health and Nutrition Examination Survey polled 5,000 people. Of those, 1,213 participants admitted using marijuana at some point in life. These participants gave their first dates of use as well.
The study took these dates of first use and assumed that consumption by smoking remained steady from first use throughout the time period to 2011. Then the study pulled 2011 mortality data from the National Center for Health Statistics on these same individuals. Based on the number of deaths from cardiovascular problems in the group between the 2005 survey and 2011, the study published its results.
Shooting holes in the theory
The assumption of continuous use stands as the first hole in the findings. Saying that a user tried cannabis twenty years ago does not mean they continued to smoke it on a regular basis every day since then.
The second hole gapes just as wide. The “study” also fails to account for other potential factors that affect heart health, such as diet or exercise.
Those two assumptions invalidate the findings completely, as far as serious studies and controls for variables are concerned. Further, the study also assumed smoking as the primary form of ingestion, rather than vaping, oils, or edibles, which have surpassed smoking as the most popular forms of ingestion in the last decade.
Barbara A. Yankey, a PhD student from the School of Public Health at Georgia State University acted as lead author on the study. In a press statement about the findings, she said:
Our results suggest a possible risk of hypertension mortality from marijuana use. This is not surprising since marijuana is known to have a number of effects on the cardiovascular system.
Marijuana stimulates the sympathetic nervous system, leading to increases in heart rate, blood pressure, and oxygen demand. Emergency rooms have reported cases of angina and heart attacks after marijuana use.
Other activity that shows the same “effects” include diet, exercise, chocolate, sex, and many more. While the study took into account tobacco use, age, sex, and ethnicity, the actual cannabis use remained based on estimates created by study authors.
Steps are being taken towards legalisation and decriminalisation of marijuana in the United States, and rates of recreational marijuana use may increase substantially as a result. However, there is little research on the impact of marijuana use on cardiovascular and cerebrovascular mortality.
Why such a feeble scare tactic?
By now, any reader realizes that such a “study” sounds like the level of work a high school student puts into a book report they find particularly boring. Copy, paste, assume, print. Her statements relating to cannabis compared to tobacco also show a disparaging lean.
We found higher estimated cardiovascular risks associated with marijuana use than cigarette smoking. This indicates that marijuana use may carry even heavier consequences on the cardiovascular system than that already established for cigarette smoking.
However, the number of smokers in our study was small and this needs to be examined in a larger study. Needless to say, the detrimental effects of marijuana on brain function far exceed that of cigarette smoking.
Yankey cited her reason for the study as a lack of longitudinal studies on cannabis and potential heart problems. Her position reveals itself as one of trying to pull marijuana use away from public control.
If marijuana use is implicated in cardiovascular diseases and deaths, then it rests on the health community and policy makers to protect the public.
Premise as false as findings
Lack of long term use studies? Wait a minute. Researchers published a study just earlier this year on long term users. That study followed more than 5,000 people for 25 years. The authors of that study wrote,
Compared with no marijuana use, cumulative lifetime and recent marijuana use showed no association with incident CVD [cardiovascular disease], stroke, or transient ischemic attacks, coronary heart disease, or CVD mortality.
A study last year, tracking 38 years of use also came to the same conclusion. A leading expert on study design and results, Dr. Vinay Prasad, associate professor of medicine at Oregon Health & Science University commented on Yankey’s work. In an email reply to The Oregonian, he stated,
It does not prove that if you choose to use marijuana you are more likely to die of cardiovascular disease. I think the major limit of the study is that there may be unobserved differences between the people who used and admitted to using marijuana during the years of this study, and cardiovascular outcomes that the researchers did not adjust for. In fact, that is likely.
In reality, when looking at studies that try to disparage cannabis as a positive medicine, take their findings with a dash of salt. Oh, wait, that’s something else they forgot to take into account. True, cannabis increases heart rate, for a short time, and like exercise should be consulted about with a doctor if you have heart issues.
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