Homogeneity meta-analysis

Meta-analysis aims to increase the statistical power of the available evidence by combining the results of smaller trials together using specific statistical methods. The validity of the meta-analysis will depend on the quality of the evidence on which it is based and how homogeneous or comparable the samples are. Combining very heterogeneous study populations can lead to bias. 

Also of interest was the comparison of clomipramine with other standard non-SRI antidepressants. When clomipramine was considered in the meta-analysis, the effect sizes were essentially unchanged (i.e., 0.79 and 0.70 Z scores = 7.6 and 7.2 probabilities of 10 and 10 ). These results were highly homogeneous, with the effect sizes consistent over all studies (Table 13-12). 

The results of the seven studies were analyzed using the statistical method of meta-analysis. Homogeneity of the studies was checked with an appropriate statistical test, while combined Pearson correlation coefficients were estimated with four different methods. The main findings were ... 

Gu C, Province M, Todorov A, Rao DC. Meta-analysis methodology for combining non-parametric sibpair linkage results genetic homogeneity and identical markers. Genet Epidemiol 1998 15 609-626. 

Case series and reviews have suggested superior effectiveness of zuclopenthixol acetate in the acute management of disturbed behavior caused by serious mental illness. However, this seems not to have been supported by the evidence from an analysis of randomized controlled trials (88). A meta-analysis of five randomized comparisons of zuclopenthixol acetate with other neuroleptic drugs in patients with considerable behavioral disturbance showed that in all studies there was some improvement in mental state scores (BPRS CGI), but none showed statistically significant differences between zuclopenthixol acetate and standard treatment. In three studies there was more sedation in those who took zuclopenthixol acetate than in those allocated to haloperidol. With regard to adverse effects, the studies were not homogeneous one study showed that people who took zuclopenthixol acetate were more likely to need antiparkinsonian drugs (OR = 6.4 Cl = 1.5,17) other studies did not show any differences in this particular outcome. 

Johnson, D.W., Johnson, R.T. and Maruyama, G (1983) Independence and interpersonal attraction among heterogeneous and homogeneous individuals a theoretical formulation and a meta-analysis... 

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