Medical conditions of primary care patients with documented cannabis use and cannabis use disorder in electronic health records: a case control study from an academic health system in a medical marijuana state

BACKGROUND: Approximately 3.8% of adults worldwide have used cannabis in the past year. Understanding how cannabis use is associated with other health conditions is crucial for healthcare providers seeking to understand the needs of their patients, and for health policymakers. This paper analyzes the relationship between documented cannabis use disorders (CUD), cannabis use (CU) and other health diagnoses among primary care patients during a time when medical use of marijuana was permitted by state law in California, United States of America. METHODS: The study utilized primary care electronic health record (EHR) data from an academic health system, using a case–control design to compare diagnoses among individuals with CUD/CU to those of matched controls, and those of individuals with CUD diagnoses with individuals who had CU otherwise documented. Associations of documented CU and CUD with general medical conditions and health conditions associated with cannabis use (both medical and behavioral) were analyzed using conditional logistic regression. RESULTS: Of 1,047,463 patients with ambulatory encounters from 2013–2017, 729 (0.06%) had CUD diagnoses and 3,731 (0.36%) had CU documented in their EHR. Patients with documented CUD and CU patients had significantly (p < 0.01) higher odds of most medical and behavioral diagnoses analyzed. Compared to matched controls, CUD-documented patients had highest odds of other substance use disorders (OR = 21.44: 95% CI 9.43–48.73), any mental health disorder (OR = 6.99; 95% CI 5.03–9.70) social anxiety disorder (OR = 13.03; 95% CI 2.18–77.94), HIV/AIDS (OR = 7.88: 95% CI 2.58–24.08), post-traumatic stress disorder (OR = 7.74: 95% CI 2.66–22.51); depression (OR = 7.01: 95% CI 4,79–10.27), and bipolar disorder (OR = 6.49: 95% CI 2.90–14.52). Compared to matched controls, CU-documented patients had highest odds of other substance use disorders (OR = 3.64; 95% CI 2.53–5.25) and post-traumatic stress disorder (OR = 3.41; 95% CI 2.53–5.25). CUD-documented patients were significantly more likely than CU-documented patients to have HIV/AIDS (OR = 6.70; 95% CI 2.10–21.39), other substance use disorder (OR = 5.88; 95% CI 2.42–14.22), depression (OR = 2.85; 95% CI 1.90–4.26), and anxiety (OR = 2.19: 95% CI 1.57–3.05) diagnoses. CONCLUSION: The prevalence of CUD and CU notation in EHR data from an academic health system was low, highlighting the need for improved screening in primary care. CUD and CU documentation were associated with increased risk for many health conditions, with the most elevated risk for behavioral health disorders and HIV/AIDS (among CUD-documented, but not CU-documented patients). Given the strong associations of CUD and CU documentation with health problems, it is important for healthcare providers to be prepared to identify CU and CUD, discuss the pros and cons of cannabis use with patients thoughtfully and empathically, and address cannabis-related comorbidities among these patients.