Marijuana Use May Increase the Risk for Hypertension Mortality
Marijuana may be linked to cardiovascular disease, but evidence is scarce. Using data from the 2005 US National Health and Nutrition Examination Survey (NHANES) and 2011 mortality files of the National Center for Health Statistics, researchers estimated mortality rates and hazard ratios (HR) for hypertension, heart disease, and cerebrovascular deaths among people who use marijuana compared with those who do not.
- There were 1213 participants (aged ≥20) with 19,569 person-years of follow-up. Average age at entry was 38 years. Overall, 34% had neither marijuana nor cigarette use; 21% used marijuana only; 20% used marijuana and cigarettes; 16% used marijuana and were past smokers. Average duration of marijuana use was 12 years.
- In models adjusted for socio-demographic and medical characteristics (including smoking, alcohol use, and presence of hypertension and cardiovascular disease diagnoses), people with marijuana use had an increased risk of hypertension mortality (HR, 3.42), compared with those who did not. The HR for each year of marijuana use was 1.04.
- Hazard ratios for heart disease and cerebrovascular deaths were not significant.
Comments: This study suggests that marijuana use may increase the risk for hypertension mortality. These results should be replicated in a study assessing marijuana use over time, but raise concerns about the potential impact of recreational marijuana use on mortality from cardiovascular causes in an era of widespread legalization throughout the US.
Nicolas Bertholet, MD, MSc
Reference: Yankey BA, Rothenberg R, Strasser S, et al. Effect of marijuana use on cardiovascular and cerebrovascular mortality: A study using the National Health and Nutrition Examination Survey linked mortality file. Eur J Prev Cardiol. 2017;24(17):1833–1840.
2 comments
Association does not imply causality, particularly when there are other plausible explanations based on current understandings. I also think it reflects possible prejudice to use the word suggest rather than “associated with”. Note, given where CB1 receptors are in high concentration in the brain, it is very important to control for PTSD in people who use cannabis regularly. For if they have PTSD like issues they are more likely to respond to cannabis with less pain and anxiety. Point is: Regular cannabis Use/Abuse may well be associated with PTSD. Is PTSD associated with hypertension mortality? If so we might have a better explanation for the association found. Other confounding variables? Likely I would suggest. How about the legal, cultural status and stresses inherent with same? Might tobacco use be greater among those who use cannabis. Was the amount of tobacco smoked controlled for?
We agree that association does not necessarily imply causation, and authors did not imply causation in their paper. Similarly, we have not drawn any conclusions about causation in our comment. It nevertheless raises concerns and therefore the observed association should be further studied, including with studies that adjust for additional confounders (e.g. Mental health conditions including PTSD). Regarding the possible confounding by tobacco use, authors did indeed control for it (as it is reported in our summary).