Male gender is associated with deficit schizophrenia: a meta-analysis.

An association between deficit schizophrenia and male gender could be expected, since male schizophrenic subjects have been repeatedly found more severe than females on several dimensions of severity. Surprisingly, very few studies have confirmed such an association. We performed a more definitive test of this association using a meta-analysis. A pooled odds ratio was computed based on the 23 studies that reported the gender ratio in deficit vs. non-deficit schizophrenia. We tested for the heterogeneity of the association and examined the potential impact of the sampling method, the method used to assess the deficit syndrome, the breadth of diagnoses included and the mean duration of illness. A highly significant association between male gender and deficit schizophrenia was observed (pooled odds ratio=1.75). There was no definitive evidence that differences across studies in sampling methods, breadth of diagnoses included, mean duration of illness and methods to assess the deficit syndrome affected the strength of the association. However, the studies using the "Proxy Deficit Syndrome" method to assess the deficit syndrome yielded qualitatively weaker evidence. This significant association between male gender and deficit schizophrenia may reflect the influence of a gender related factor (e.g. sexual hormones) or gender differences in the liability to different etiologies of schizophrenia. The role of gender as a potential confounder must be closely examined in studies comparing deficit and non-deficit SZ.