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 patientsusing marijuana are at higher risk for using other illicit drugs such as cocaine and/ormethamphetamine.Objective: Our objective was to determine whether marijuana-using chronic painpatients have a higher incidence of cocaine and/or methamphetamine use.Study Design: A retrospective study of the incidence of pain patients using marijuanaand/or other illicit drugs such as methamphetamine and cocaine versus the incidence ofpain patients not using marijuana but using methamphetamine and/or cocaine.Methods: Urine specimens from chronic pain patients were analyzed by LC-MS/MS todetermine the co-occurrence of these abused substances.Results: In this study 21,746 urine specimens were obtained from chronic painpatients. We found a 13.0% incidence of patients positive for the acid form ofTetrahydrocannabinol (THCA). The percentage of those positive for cocaine was 4.6%,those positive for methamphetamine totaled 1.07%. Using both chi-square and a LogisticRegression analysis, we determined that there was a correlation between marijuana useand 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 causalrelationships of this type of drug use.Conclusions: Pain physicians should be aware that this relationship exists andmarijuana-using patients are at greater risk for use of other illicit drugs although nocausal relationship is implied. Increased monitoring of these patients may help minimizepotential morbidity due to drug interactions as well as identify patients who may bediverting prescriptions in order to pay for illicit drugs.Key words: Marijuana, Tetrahydrocannabinol (THCA), Cocaine, Methamphetamine,Pain patients, correlation study