Increasing Stroke Incidence Among Marijuana Users

Marlene Busko

October 23, 2018

A small but increasing number of hospitalized Americans are recreational marijuana users, and of these, the number of patients who are admitted for a stroke is increasing.

Using a representative sample of hospitals, researchers found that overall admissions for stroke increased slightly but not significantly during the period 2010 to 2014. However, among recreational marijuana users, there was a small but significant increase in hospital admissions for stroke.

Krupa Patel, MD, from Avalon University School of Medicine in Willemstad, Curacao, presented these findings from a 5-year observational study here at the 11th World Stroke Congress (WSC) 2018 — coincidentally on the day after recreational use of marijuana became legal in Canada.

The recreational marijuana users were identified from a specific International Classification of Disease, 9th Edition code, Patel explained to Medscape Medical News.

Patients whose treatment carried this code were likely to have undergone a urine drug toxicology screening test that detected the psychoactive compound tetrahydrocannabinol (THC), which is found in recreational marijuana, but the researchers lack any data about this.

This observational study cannot show that use of recreational marijuana is causing more strokes, Patel conceded.

More research is needed to explore how stroke risk in marijuana users is affected by the amount and frequency of marijuana use, the THC content, the presence of other stroke risk factors, and their use of tobacco, cocaine, or amphetamines, she said.

In the meantime, she added, "physicians should thoroughly screen for recreational marijuana use (duration, frequency, dose and co-usage of tobacco, alcohol, and illicit drugs) and preexisting conditions.

"Additionally, they should provide patients with up-to-date education on the health effects of recreational marijuana use."

Session co-chair Kent Simmonds, a fifth-year (2017-2018) DO-PhD student in epidemiology at Michigan State University, in East Lansing, said that the study was "speculative" but also "provocative."

"It remains a myth" that cannabis is a completely safe drug with limited side effects and that its use is not associated with risk for addiction, said Simmonds. He said it is important to continue studying it to better understand its risks and benefits.

Invited to comment, session co-chair Junfeng Liu, MD, from the Department of Neurology, West China Hospital, Sichuan University, in Chengdu, said that in China, some young people use nitrous oxide (laughing gas), which has also been associated with stroke.

Prevalence of Pot Use Among Hospitalized Stroke Patients

Previous research, Patel said, has suggested biologically plausible explanations for an association between marijuana use and stroke risk.

In rats, THC exposure induces cerebral mitochondrial dysfunction in a dose-dependent manner. Histologic studies in deceased marijuana users have reported stenosis in cerebral arteries. Marijuana use is also associated with increased serum apolipoprotein C-III levels

To examine the prevalence of recreational marijuana use in American stroke patients, the researchers analyzed deidentified patient data from 2010 to 2014 from the National Inpatient Sample database, a nationally representative sample from 20% of US hospitals.

They found that 2.3 million of these hospitalized patients were recreational marijuana users. Of these patients, 32,231 (1.4%) had had a stroke, and of these patients, 19,452 had had an ischemic stroke.

Over the 5 years, among all marijuana users and nonusers, the percentage who had been admitted for stroke increased from 2% to 2.2%, but this was not a significant trend (P trend = .07) because the increase was only in the past 2 years.

However, in the hospitalized marijuana users, the percentage who had been admitted for stroke increased steadily from 1.3% to 1.5%, which was a significant trend (P trend = .016), as was the increase in those who had been admitted for ischemic stroke, from 0.7% to 0.9% (P trend = .016), because the increase for both was seen in all 5 years.

This increase in stroke over time was seen in marijuana users in all studied age ranges: 18 to 44 years, 45 to 64 years, and 65 to 84 years.

Dr Patel has disclosed no relevant financial relationships.

11th World Stroke Congress (WSC) 2018. Presented October 19, 2018.

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