Approximately every fourth schizophrenia patient in our sample of studies had a diagnosis of CUDs. CUDs were especially common in younger and first-episode patient samples as well as in samples with a high proportion of males.

Approximately every fifth patient with schizophrenia had lifetime AUD diagnosis. When contrasted with the most recent review, there might be a descending trend in AUD prevalence in patients with schizophrenia.

When choosing databases, the extent of coverage and topic should be taken into account, as there is no single database that covers all information needs. In the case of interdisciplinary topics, the Web of Science or PsycINFO should be considered; PsycINFO should be included especially on topics related to psychology. The use of several relevant bibliographic databases, including others than those used here, is recommended.