To determine if substance abuse significantly increases the risk of relapse in first episode psychosis patients over a two year follow-up even after adherence to medication is improved.

Relapse was based on ratings on the Scale for Assessment of Positive Symptoms and weekly ratings on Life Chart Schedule (WHO). Predictor variables included gender, duration of untreated psychosis (DUP), duration of untreated illness from the time of first psychiatric symptoms (DUI), age of onset, pre-morbid adjustment, co-morbid diagnosis of substance abuse at one year, time to remission of psychotic symptoms and adherence to medication. Univariate analyses were followed by logistic regression for rate of relapse and survival analysis with Cox proportional hazard regression was used for time to relapse as the dependent variable.

Of the 207 patients, 162 achieved remission of positive symptoms and were treated and followed for two years. Relapse rates were relatively low (21.6% in the first and 13.8% in 2nd year, respectively) with 33 weeks as the mean time to relapse. Relapse rates were significantly higher for patients with a co-morbid diagnosis of substance abuse (OR= 2.59, CI 1.28-5.21), especially for the second year (OR=3.66, CI 1.30-10.27) and for those with shorter DUI (OR=0.437, CI 0.209-0.914) after controlling for other predictors. Likelihood of relapse during follow-up was associated only with a co-morbid diagnosis of substance abuse (HR= 2.49, p=.01, CI 1.21-5.10).

Specialized treatment of substance abuse may further reduce risk of relapse even after improving adherence to medication.