Alcohol use disorders in schizophrenia: a national cohort study of 12,653 patients.

Background: Comorbid alcohol use disorders (AUDs) in schizophrenia are associated with increased morbidity, more inpatient treatment, and violent offending. It is of clinical importance to identify those with schizophrenia who may go on to develop an alcohol use disorder; however, the risk factors are not well understood. The aim of this study was to identify risk factors for the development of an AUD in patients after they had been diagnosed with schizophrenia.

Method: We conducted a retrospective case-control study of 12,653 individuals diagnosed with ICD-defined schizophrenia in Sweden in 1973-2004, using data from national registers. We tested the associations between individual factors (marital status, immigrant status, and previous violent offending), sociodemographic factors (income and education), and parental risk factors (AUDs, psychosis, and violent offending) ICD-defined and AUD development using logistic regression modeling.

Results: Over a median follow-up of 17.3 years, 7.6% of patients had at least 1 hospital diagnosis of AUD. After adjustment for gender and age at diagnosis in a multivariate regression model, previous violent offending (OR = 2.1; 95% CI, 1.8-2.5), low education (OR = 1.3; 95% CI, 1.1-1.5), maternal AUD (OR = 1.9; 95% CI, 1.4-2.7), and paternal AUD (OR = 1.9; 95% CI, 1.5-2.3) remained independently associated with increased risk of patient AUD.

Conclusions: AUDs are a common sequela of schizophrenia. Risk factors that could be identified at the time of first presentation include low educational attainment, previous violent offending, and parental history of AUDs and may inform clinical treatment and follow-up of those most at risk.