Impact of medical and recreational cannabis laws on inpatient visits for asthma

Objective: To examine the impact of medical and recreational cannabis laws on inpatient visits for asthma and by payer-type.

Study setting and design: Quasi-experimental difference-in-differences regression analysis was conducted while accounting for variations in cannabis laws implementation timing by states. Inpatient visits for asthma in states with a given type of cannabis law were compared with those in states that did not implement the specific law. Four different cannabis laws were examined in the study-initial passage of medical cannabis law, opening of a medical cannabis dispensary, home cultivation of medical cannabis, and recreational cannabis legalization.

Data sources and analytic sample: State-level quarterly inpatient visit data for asthma patients were utilized from the Healthcare Cost and Utilization Project Fast Stats database. The primary analysis included inpatient visits for asthma by all payer adult patients aged 19 and above in 38 states from 2005 to 2017, and the secondary analysis included inpatient visits for asthma by payer-type (i.e., private, Medicare, Medicaid, uninsured).

Principal findings: States with medical cannabis dispensaries and legalized recreational cannabis experienced 14.12% (2.14; 95% CI, 0.74-3.53; p < 0.01) and 20.45% (3.08; 95% CI, 1.47-4.69; p < 0.001) increases in inpatient visits for asthma compared with states without these policies, respectively. These increases in inpatient visits for asthma were primarily driven by populations covered by Medicare and private insurance, with Medicare population showing larger effects of both recreational cannabis laws and medical cannabis dispensaries.

Conclusions: States with medical cannabis dispensaries and legalized recreational cannabis experienced higher rate of inpatient visits for asthma compared with states without these policies. Clinicians and policymakers should consider strategies to curb adverse health outcomes of cannabis, that is likely to result in increased costs of healthcare.