Annals of Emergency Medicine
Volume 32, Issue 3 , Pages 361-363, September 1998

Editorials:☆☆☆

Marijuana and Injury: Is There a Connection?

Department of Medical Education Methodist Hospital Department of Preventive Medicine University of Tennessee Medical School Memphis, TN

Article Outline

Abstract 

[Brookoff D: Marijuana and injury: Is there a connection?. Ann Emerg Med September 1998;32:361-363.]

 

See related article, p 353.

Marijuana has been used as an herbal remedy and as an intoxicant for thousands of years. After an upsurge in its use in the United States during the Great Depression, marijuana was outlawed in 1937—despite vigorous opposition to the ban by the American Medical Association. 1 Criminalization greatly reduced its consumption, but by the 1960s many Americans came to regard marijuana as a “soft” drug and its use again flourished. 2 Marijuana proved to be particularly attractive to budding adults. By the mid-1980s, more than a third of American high school seniors reported having used marijuana (half of them fitting the definition of “current users”), and two thirds of adults aged 18 to 25 years reported use. 3 Currently, marijuana is the most commonly used illicit substance in the United States, and forecasts call for continued growth.

In the past few years, a well-financed movement promoting the medicinal use of marijuana has taken root throughout the country. This movement has found a particularly fertile political environment in the western United States and has succeeded in lifting or loosening legal restrictions on marijuana in Alaska, California, and Arizona. In addition, court cases and referenda have sprouted up that could lead to legalization in many other states. 4

Much of the debate about the use of marijuana has centered on the issue of toxicity, with proponents maintaining that marijuana does not cause significant organ damage and opponents raising specters ranging from permanent cognitive impairment 5 to immune dysfunction. 6 Both sides agree that far more death and illness are caused by tobacco and alcohol than by marijuana, 7 but they argue over whether this is a result of the low toxicity of the drug or the effectiveness of the sanctions that limit its use.

With the consumption of marijuana on the rise, what health problems can we anticipate? In this issue of Annals , Braun and her colleagues take an important step in broadening our concept of drug effects by examining the relationship between the consumption of marijuana and medically attended injury. In a study that is sure to be widely referenced and even more widely misquoted, the authors analyzed self-reports of marijuana use by participants in an employer-sponsored health maintenance organization and records of their subsequent medical visits for injury. They found no association between self-reported marijuana use and injury. Interestingly, a previous study from the same institution found an association between self-reports of frequent marijuana use and an increased risk of injury. 8

Braun’s study is a departure from many previous studies on the role of marijuana in injury, which examined levels of cannabinol in individual trauma victims. These studies were limited because they could not address impairment caused by the drug and lacked a control group to help gauge the “ambient” level of marijuana in the population. 9, 10 As Braun et al point out, a major confounder to this approach to examining the role of marijuana in injury is that many injured patients who test positive for marijuana also test positive for alcohol. 11

How can a drug that is specifically used to cause cognitive impairment not be associated with injury? Marijuana certainly degrades driving skills, 12 and it does so in a manner that can be detected on roadside sobriety tests. 13, 14 Surveys show that most marijuana users believe that smoking marijuana impairs their ability to drive. These same surveys report that marijuana users often drive while intoxicated (these studies are reviewed by Gieringer 15). To add to the risk of injury, regular marijuana users are disproportionately young, male, and socially rebellious—groups that are prone to high rates of motor vehicle crashes. 16 Other surveys have found that there is an increased risk for motor vehicle crashes among marijuana users. 15, 17 Braun’s study reveals a higher rate of motor vehicle crashes among marijuana users than among nonusers, but few cases were included in the analysis.

Marijuana research is hard to do and, sometimes, even harder to evaluate. One example is a recent US Department of Transportation–sponsored study on the effect of low-to-moderate doses of marijuana on actual driving performance (carried out, for some reason, on an empty highway in Holland). The authors of the study concluded that marijuana impaired the ability to drive but that users (who had study monitors seated next to them) “retained insight into their impairments and tended to compensate for them by slowing down or increasing their efforts.” 18

In an attempt to prove that marijuana is safe, some authors have pointed out that the percentage of fatally injured drivers with marijuana metabolites in their blood is roughly equal to the proportion of marijuana users in the population. 15 This is hardly proof of safety, since the same relation holds for alcohol, which has been irrefutably linked to injury. 19 Two thirds of Americans report that they are current alcohol users, and approximately two thirds of drivers in accidents have ethanol in their blood. 20 Braun et al could have provided us with an important “reality check” by examining the relation between reported alcohol use and injury among their subjects, but they did not choose to do so. Hopefully, the fact that their data collection was funded in part by the Alcoholic Beverage Medical Research Council did not play a role in this decision.

The attempt of Braun et al to delineate the health costs of marijuana use is noteworthy but should not be considered the final word on the issue. As the authors themselves point out, they could not assess the effects of acute marijuana intoxication. They also acknowledge that their study is based on self-reports of drug use, which is a questionable approach to assessing drug consumption. Studies suggest that subjects greatly underreport their use of illicit drugs even when they can provide this information in a confidential or anonymous fashion. 21 In this case, the respondents were not anonymous, since their responses could be linked directly to their medical records.

Impaired driving due to substance abuse is one of this country’s most serious public health problems. Injury is the leading cause of death of Americans between the ages of 5 and 32. 22 As marijuana consumption rises, the question of whether marijuana (by itself or in combination with other drugs) contributes to motor vehicle accidents and other injuries will become increasingly important. Physicians and researchers who have an interest in injury prevention are bound to get drawn into the enlarging marijuana debate.

There is a pressing need for high-quality research on the potential connection between marijuana use and injury. Very few police departments are equipped to test impaired drivers for marijuana, 14 and the value of toxicologic testing for marijuana remains controversial. 15 More studies must be conducted using a variety of research methodologies before the term “high way driving” takes on a whole new meaning. 23

Back to Article Outline

References 

  1. American Medical Association . Federal regulation of the medicinal use of marijuana [editorial]. JAMA. 1937;108:1543
  2. Brecher EM. In: Licit and Illicit Drugs. Boston: Little, Brown; 1972;p. 267–306
  3. Nicholi AM. The nontherapeutic use of psychoactive drugs: A modern epidemic. N Engl J Med. 1983;308–311
  4. Voth EA, Schwartz RH. Medicinal applications of delta-9-tetrahydrocannabinol and marijuana. Ann Intern Med. 1997;126:791–798
  5. Murray JB. Marijuana’s effects on human cognitive functions, psychomotor functions and personality. J Gen Psychol. 1986;113:23–55
  6. Cabral GA, Vasquez R. Delta-9-tetrahydrocannabinol suppresses macrophage extrinsic anti-herpes activity. In:  Nahas GG,  Latour C editor. Cannabis: Physiopathology, Epidemiology, Detection. Boca Raton, FL: CRC Press; 1993;p. 137–153
  7. DuPont RL, Voth EA. Drug legalization, harm reduction and drug policy. Ann Intern Med. 1995;123:461–465
  8. Polen MR, Sidney S, Tekawa IS, et al.  Health care use by frequent marijuana smokers who do not smoke tobacco. West J Med. 1993;158:635–637
  9. Francis M, Eldemire D, Clifford R. The pilot study of alcohol and drug-related traffic accidents and death in two Jamaican parishes. West Indian Med J. 1995;44:99–101
  10. Soderstrom CA, Dischinger PC, Kerns TJ, et al.  Marijuana and other drug use among automobile and motorcycle drivers treated at a trauma center. Accid Anal Prev. 1995;27:131–135
  11. Chesher GB. The effects of alcohol and marijuana in combination: A review. Alcohol, Drugs and Driving: Abstracts and Reviews. 1986;2:105–120
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  13. Reeve VC, Robertson WB, Grant J, et al.  Hemolyzed blood and serum levels of delta-9-THC: Effects on the performance of roadside sobriety tests. J Forensic Sci. 1983;28:963–971
  14. Brookoff D, Cook CS, Williams C, et al.  Testing reckless drivers for cocaine and marijuana. N Engl J Med. 1994;331:518–522
  15. Gieringer DH. Marijuana, driving and accident safety. J Psychoactive Drugs. 1988;20:93–101
  16. Terhune KW, Fell JC. The Role of Alcohol, Marijuana and Other Drugs in Accidents of Injured Drivers. Springfield, Virginia: US Department of Transportation; 1982; US Department of Transportation Report No. DOT-HS-806-181
  17. Smart R, Fejer D. Drug use and driving risk among high school students. Accid Anal Prev. 1976;8:33–38
  18. Robbe HWJ, O’Hanlon JF. Marijuana and Actual Driving Performance. Springfield, VA: US Department of Transportation; 1993; US Department of Transportation Report No. DOT-HS-808-078
  19. Anda RF, Williamson DF, Remington PL. Alcohol and fatal injuries among US adults. JAMA. 1988;260:2529–2532
  20. Clark W, Midanik L. Alcohol use and alcohol problems among young adults: Results of a 1979 national survey. In: Alcohol Consumption and Related Problems. Rockville, MD: National Institute on Alcohol Abuse and Alcoholism; 1982;
  21. Mieczkowski T. The accuracy of self-reported drug use: An evaluation and analysis of new data. In:  Weisheit R editors. Drugs, Crime and the Criminal Justice System. Cincinnati, OH: Anderson Publishing; 1990;p. 275–302
  22. National Highway Traffic Safety Administration . Drunk Driving Facts. Washington DC: US Department of Transportation; 1991;
  23. Saylor KE, DuPont RL, Brown H. The high way: Driving under influences other than alcohol. JAMA. 1992;267:652–653

☆ Reprint no. 47/1/92116

☆☆ Address for reprints: Daniel Brookoff, MD. PhD Department of Medical Education Methodist Hospital 1265 Union Avenue Memphis, TN 38104 901-726-8255 Fax 901-726-8255 E-mail brookofd@mhsgate-mem.org

PII: S0196-0644(98)70014-9

Annals of Emergency Medicine
Volume 32, Issue 3 , Pages 361-363, September 1998

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