Drug-induced psychosis and drug abuse/dependence in schizophrenia are new clinical problems due to the increasing prevalence of drug consumption in this population. the objective is to know if the abuse/dependence of illegal drugs may influence the duration of acute hospitalization in schizophrenia.

It was conducted a retrospective cohort study on a sample of 256 acute hospitalizations of patients with schizophrenia and related disorders in Valladolid (Spain) between 2004 and 2006. at the moment of admission 82 patients had active drug abuse/dependence and 174 did not. A Cox proportional-hazards regression model was constructed considering drug abuse/dependence as predicting factor and length of stay as result variable.

The mean length of stay was 12.2 days (SD= 7.5) in the group without drug abuse/dependence and 7.7 days (SD= 29.0) in the drug group (means difference p=0.05). When abuse/dependence of drugs is present, the risk of discharge at any moment during the hospitalization increases in 34% (p=0.04). When Global Assessment of Functioning at the moment of admission is included in the regression model, the results remain significant (risk 35%, p=0.047). Clinical status at discharge was significantly better for the drug users group. Drug users were more frequently at his/her first hospitalization (58.2% versus 35.2%; p=0.001).

In schizophrenia, abuse/dependence of drugs is associated with a 34% lower duration of acute hospitalization. This fact might be due to a relevant proportion of drug-induced psychosis who recovers earlier than idiopathic schizophrenia episodes.