Abstract
Background: Several meta-analyses have been conducted to determine the magnitude of cognitive deficits in patients with schizophrenia. The effect of several key variables—such as age, gender, education, duration of illness, symptomatology, patient status, psychiatric comorbidity, publication year and sample size—has also been evaluated with moderator analysis to understand the nature of the deficit. One overlooked methodological aspect to consider is the potential influence of methodological quality of the meta-analysis in order to draw valid inferences. The main objective of this systematic review of meta-analysis was to evaluate the methodological quality of the meta-analyses evaluating cognition in schizophrenia. Methods: Meta-analysis published between 1970 and October 2015 were identified according to the following criteria: (1) Group of patients with a diagnosis of schizophrenia and schizophrenia spectrum; (2) Comparative group (patients with schizophrenia or healthy control group); (3) Cognitive outcomes derived from neuropsychological tests; (4) Moderators analysis computed on cognition. Methodological quality assessment of included meta-analyses was carried out using R-AMSTAR (Revised Assessment of Multiple Systematic Reviews), which provides a rating ranging from 11 to 44 points. Results: A total of 34 meta-analyses were included in this systematic review: 16 meta-analyses comprised a healthy control group and 18 meta-analyses comprised a group of patients with schizophrenia. R-AMSTAR mean scores were 23.31 points (SD = 2.85; range = 18–28) and 25.44 points (SD = 4.69; range = 19–38) respectively, which indicates moderate quality. Conclusion: Few meta-analyses used guidelines such as PRISMA and MOOSE. A methodological guideline pointing out variables that could influence cognition in schizophrenia is highlighted while considering methodological quality of meta-analysis. Limits and recommendations on the methodological quality assessment of meta-analysis are also discussed.