Cannabis use disorder diagnoses nearly tripled in US hospitals from 2002 to 2011, with patients getting older and sicker | Research

The takeaway

Inpatient cannabis abuse/dependence diagnoses rose from 0.52% to 1.34% of all admissions between 2002 and 2011, with psychiatric disorders as the most common primary diagnoses and an unexpected finding of lower hospital costs for cannabis users with pancreatitis.

Read this if you want to understand how cannabis use disorder has changed in the hospital setting over time.

Cannabis-related inpatient diagnoses: 0.52% (2002) to 1.34% (2011)

What the researchers found

Among nearly 2.8 million hospital admissions with documented cannabis abuse/dependence (0.91% of all admissions), prevalence increased from 0.52% to 1.34% over the decade. The trend moved toward older and sicker patients with increasing rates of moderate to severe disability.

The most common primary diagnoses among cannabis-involved admissions were schizoaffective/mood disorders, followed by psychotic disorders and alcoholism. Inpatient mortality was 0.41%.

Two unexpected findings emerged: among non-tobacco smokers, cannabis users had a steeper increase in asthma prevalence than non-cannabis users. Among acute pancreatitis admissions, cannabis users actually had shorter hospital stays (-11%) and lower costs (-7%) than non-users.

Why it matters

The nearly tripling of cannabis-related inpatient diagnoses mirrors the outpatient trend but reveals that the inpatient population is shifting toward older, sicker patients. The psychiatric comorbidity pattern confirms that mental health, not physical health, drives most cannabis-related hospitalizations.

The numbers in context

Total admissions with cannabis diagnosis: 2,833,567 (0.91% of all). Prevalence: 0.52% (2002) to 1.34% (2011). Mean age: 35.1 years, 62% male. Inpatient mortality: 0.41%. Mean stay: 6.23 days. Cannabis pancreatitis patients: -11% length of stay, -7% costs. Top diagnoses: schizoaffective/mood disorders, psychotic disorders, alcoholism.

How the study worked

Analysis of the National Inpatient Sample (2002-2011), identifying cannabis abuse/dependence through ICD-9 codes 304.3* and 305.2*, excluding cases coded as "in remission." National trend estimates and matched regression analyses were conducted.

What this study cannot tell us

Administrative data (ICD-9 codes) may undercount cannabis diagnoses and cannot assess severity of use. Cannabis "involvement" does not mean cannabis caused the hospitalization. The study covers a period of changing social norms around cannabis, which may have affected diagnostic coding practices. Cannot distinguish between states with and without medical cannabis laws.

How to read the evidence

National inpatient database analysis covering 10 years. Large sample but limited by administrative coding practices and the inability to assess causation.

When this study was published

Published in 2017. Inpatient cannabis use disorder trends have continued to evolve with legalization and changing diagnostic practices.

The bigger picture

The trend toward older and sicker cannabis patients in hospitals suggests that cannabis use disorder is no longer predominantly a young person's diagnosis. As the population of lifetime cannabis users ages, healthcare systems will increasingly encounter cannabis-related issues in patients with multiple comorbidities, requiring more complex care.

Questions still open

Has the trend continued to accelerate after 2011 with widespread legalization? Why do cannabis users with pancreatitis have better outcomes? Is the asthma-cannabis association driven by cannabis smoke or by cannabinoid effects on airways?

Common questions

Why are cannabis patients in hospitals mostly there for psychiatric reasons?

The top primary diagnoses among cannabis-involved admissions were schizoaffective/mood disorders, psychotic disorders, and alcoholism. This likely reflects both the association between cannabis and mental health conditions and the fact that psychiatric crises are a common pathway to hospitalization for substance-involved patients.

Does cannabis cause asthma?

The study found that among non-tobacco smokers, cannabis users had a steeper rise in asthma prevalence over the study period. While cannabis smoke contains respiratory irritants, this observational finding cannot prove causation. Cannabis smoke and tobacco smoke share some harmful components.

Read the original research

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

The American journal of medicine, 130(6), 678-687.e7

View on PubMed ↗Publisher’s paper ↗

Citation

Charilaou, Paris; Agnihotri, Kanishk; Garcia, Pablo; Badheka, Apurva; Frenia, Douglas; Yegneswaran, Balaji. (2017). Trends of Cannabis Use Disorder in the Inpatient: 2002 to 2011.. The American journal of medicine, 130(6), 678-687.e7. https://doi.org/10.1016/j.amjmed.2016.12.035