Trends of Cannabis Use Disorder in the Inpatient: 2002 to 2011

The nationwide prevalence of cannabis use/abuse has more than doubled from 2002 to 2011. Whether the outpatient trend is reflected in the inpatient setting is unknown. We examined the prevalence and incidence of cannabis abuse/dependence as determined by discharge coding in a 10-year (2002-2011) National Inpatient Sample, as well as various trends among demographics, comorbidities, and hospitalization outcomes.

Cannabis abuse/dependence was identified on the basis of International Classification of Diseases, 9th Revision, Clinical Modification codes 304.3* and 305.2* in adults aged 18 years or more. We excluded cases coded "in remission." National estimates of trends and matched-regression analyses were conducted.

Overall, 2,833,567 (0.91%) admissions with documented cannabis abuse/dependence were identified, patients had a mean age of 35.12 ± 0.06 years, 62% were male, and there was an increasing trend in prevalence from 0.52% to 1.34% (P <.001). The mean Charlson Comorbidity Index was 0.47 ± 0.006, and inpatient mortality was 0.41%. All of the above demonstrated an increasing trend (P <.001). Mean length of stay was 6.23 ± 0.06 days. The top primary discharge diagnoses were schizoaffective/mood disorders, followed by psychotic disorders and alcoholism. Asthma prevalence in nontobacco smokers had a steeper increase in the cannabis subgroup than in the noncannabis subgroup (P = .002). Among acute pancreatitis admissions, cannabis abusers had a shorter length of stay (-11%) and lower hospitalization costs (-7%) than nonabusers.

Cannabis abuse/dependence is on the rise in the inpatient population, with an increasing trend toward older and sicker patients with increasing rates of moderate to severe disability. Psychiatric disorders and alcoholism are the main associated primary conditions. Cannabis abuse is associated with increased asthma incidence in nontobacco smokers and decreased hospital resource use in acute pancreatitis admissions.