Abstract
OBJECTIVE: To determine if the interaction of opiate misuse and marijuana use frequency is associated with behavioral health outcomes. SETTING: Community. PARTICIPANTS: Three thousand seven hundred fifty participants enrolled in the Traumatic Brain Injury Model Systems who completed the Pain Survey and had complete opioid use and marijuana use information. DESIGN: Cross-sectional, secondary analysis from a multisite observational cohort. MAIN OUTCOME MEASURES: Clinically significant behavioral health symptoms for posttraumatic stress disorder (PTSD), depression, anxiety, and sleep quality. RESULTS: Three thousand five hundred thirty-five (94.3%) participants did not misuse opiates, 215 (5.7%) did misuse opiates (taking more opioid pain medication than prescribed and/or using nonprescription opioid pain medication); 2683 (70.5%) participants did not use marijuana, 353 (9.3%) occasionally used marijuana (less than once a week), and 714 (18.8%) regularly used marijuana (once a week or more frequently). There was a statistically significant relationship (P < .05) between the interaction of opiate misuse and marijuana use frequency and all behavioral health outcomes and several covariates (age, sex, cause of injury, severity of injury, and pain group category). Pairwise comparisons confirm that statistically significant associations on behavioral health outcomes are driven by endorsing opiate misuse and/or regular marijuana use, but occasional marijuana use was not associated. CONCLUSIONS: Higher odds of clinically significant PTSD, depression, anxiety, and poor sleep quality are present in people with traumatic brain injury (TBI) who misuse opiates and/or who use marijuana regularly. In the absence of opiate misuse, regular marijuana use had higher odds of worse behavioral health outcomes than occasional and no use. The interaction of opiate misuse and regular marijuana use yielded the highest odds. Individuals with TBI should be informed of the relationship of substance use and behavioral health outcomes and that current chronic pain may mediate the association.