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Characterization of patients who report use of opioids and/or cannabis in a tertiary referral pain management center

Background. Chronic pain is a disease that affects more than 100 million Americans, bearing $635 billion on US economy annually. There are limited treatment options and even more limited evidence to guide their use. Opioids have long been a common treatment for patients with chronic pain, but these drugs are associated with significant morbidity and mortality. Some scientists advocated use of cannabis as an alternative for opioids; however, a growing number of patients are now using a combination of opioid and cannabis. There is a need to characterize the impact of the combination of opioids and cannabis which served as the motivation for this investigation. We first studied characteristics (measures about physical, psychological and social distress) of patients with chronic pain who report or deny use of opioids and/or cannabis. We then compared utilization of healthcare resources among these groups of patients. Methods. Stanford Pain Management Center has been using a learning healthcare system – Collaborative Health Outcomes Information Registry (CHOIR) – since 2012. CHOIR leverages NIH Patient Reported Outcomes Measure Information System (PROMIS) with legacy pain and treatment questions. We used the initial surveys of patients in this registry to compare patients in four groups: patient who report use of (1) neither opioid nor cannabis (reference group); (2) opioid only; (3) cannabis only; and (4) combination of opioid and cannabis. We used analysis of variance and chi-square to compare PROMIS measures and pain intensity between these groups. We then used logistic (emergency room visit and overnight hospital stay) and linear (number of physician visits) regression to compare healthcare utilization among these groups after adjustment for age, sex and variables found significantly different in previous analysis. Results. Patients who report use of opioid and/or cannabis experience higher levels of physical, psychological and social distress across multiple domains. Specifically, these patients experienced higher levels of pain intensity and pain catastrophizing; their pain interferes more with their life and causes more pain related behavior. These patients are more depressed, anxious and angry; they have poorer sleep and are not as satisfied with their social roles and activities. Moreover, they utilize higher level of healthcare resources. After adjustment for other variables, the patients who report use of opioid and cannabis have 1.29 (95% confidence interval of 1.04-1.60) times higher odds of visiting emergency room within 90 days leading to their visit at our clinic; they also have 1.6 (95% confidence interval of 1.26-2.04) times higher odds of staying overnight at the hospital within the same time period. These patients also report on average 1.51 (95% confidence interval of 0.68-2.43) more physician visits within the same period; this number is 0.93 (95% confidence interval of 0.47-1.39) for patients who report use of opioid only and 0.92 (95% confidence interval of 0.27-1.57) for patients who report use of cannabis only. Conclusion. Our findings suggest that use of opioid and/or cannabis is associated with worse outcome and higher healthcare utilization. As such, it will be important to characterize the trajectory of these patients in a prospective longitudinal study.