Opioid and cannabis co-use: The role of opioid use to cope with negative affect.

INTRODUCTION: The opioid epidemic is a significant public health concern, particularly among adults with chronic pain. There are high rates of cannabis co-use among these individuals and co-use is related to worse opioid-related outcomes. Yet, little work has examined mechanisms underlying this relationship. In line with affective processing models of substance use, it is possible that those who use multiple substances do so in a maladaptive attempt to cope with psychological distress. METHOD: We tested whether, among adults with chronic lower back pain (CLBP), the relation between co-use and more severe opioid-related problems would occur via the serial effects of negative affect (anxiety, depression) and more coping motivated opioid use. RESULTS: After controlling for pain severity and relevant demographics, co-use remained related to more anxiety, depression, and opioid-related problems (but not more opioid use). Further, co-use was indirectly related to more opioid-related problems via the serial effect of negative affect (anxiety, depression) and coping motives. Alternative model testing found co-use was not indirectly related to anxiety or depression via serial effects of opioid problems and coping. CONCLUSIONS: Results highlight the important role negative affect may play in opioid problems among individuals with CLBP who co-use opioid and cannabis.