The incremental inpatient costs associated with marijuana comorbidity

In this paper we examine the incremental cost of marijuana comorbidity for alcohol, mood and thought diagnoses in hospital settings. We use data from the 1993-2000 National Hospital Discharge Survey to examine the effect on length of stay and the 1995-2000 Florida Hospital Discharge Data to examine charges. General linear modeling (GLM) and propensity score methods are employed to deal with concerns stemming from the distribution of the dependent variables and statistically significant differences in the baseline characteristics of marijuana users versus non-users. Marijuana comorbidity is associated with longer length of stays and higher charges for patients suffering from a primary diagnosis of an alcohol problem. We also find higher average charges for patients suffering from mood disorders, though the finding is not robust across all model specifications. We do not find any significant effects for thought disorders. Findings from this study suggest that a marijuana comorbidity increases the cost of treating patients with alcohol problems and mood disorder diagnoses, implying that there may be real health consequences associated with marijuana abuse and dependence and more work considering this possibility is warranted.