Validity of the CAGE questionnaire in schizophrenic patients with alcohol abuse and dependence.

The objective of the study was to assess the sensitivity and the specificity of the CAGE questionnaire in 114 schizophrenic patients. The Composite International Diagnostic Interview was used to assess the DSM-III-R diagnosis of abuse of or dependence on alcohol. The CAGE questionnaire can be reliably used to assess alcohol use disorders in schizophrenic patients: with a cutoff score of 1 or more, the sensitivity of the CAGE questionnaire was 0.91 and the specificity was 0.83. With a cutoff score of 2 or more, the sensitivity of the CAGE questionnaire was 0.82 and the specificity was 0.94. The post test probabilities (PPV) were high (PPV1=0.74; PPV2=0.85) compared to the primary probability of alcoholism (29.8%).