Marijuana correlates with use of other illicit drugs in a pain patient population.

BACKGROUND: A significant number of chronic pain patients may use marijuana. Physicians treating those patients can benefit by knowing whether their patients using marijuana are at higher risk for using other illicit drugs such as cocaine and/or methamphetamine.

OBJECTIVE: Our objective was to determine whether marijuana-using chronic pain patients have a higher incidence of cocaine and/or methamphetamine use.

STUDY DESIGN: A retrospective study of the incidence of pain patients using marijuana and/or other illicit drugs such as methamphetamine and cocaine versus the incidence of pain patients not using marijuana but using methamphetamine and/or cocaine.

METHODS: Urine specimens from chronic pain patients were analyzed by LC-MS/MS to determine the co-occurrence of these abused substances.

RESULTS: In this study 21,746 urine specimens were obtained from chronic pain patients. We found a 13.0% incidence of patients positive for the acid form of Tetrahydrocannabinol (THCA). The percentage of those positive for cocaine was 4.6%, those positive for methamphetamine totaled 1.07%. Using both chi-square and a Logistic Regression analysis, we determined that there was a correlation between marijuana use and the use of other illicit drugs. The odds ratio was > 3.7 for other illicit drug use.

LIMITATIONS: The study is limited in that we obtained no data as to the causal relationships of this type of drug use.

CONCLUSIONS: Pain physicians should be aware that this relationship exists and marijuana-using patients are at greater risk for use of other illicit drugs although no causal relationship is implied. Increased monitoring of these patients may help minimize potential morbidity due to drug interactions as well as identify patients who may be diverting prescriptions in order to pay for illicit drugs.