The difference in putamen volume between MSA and PD: Evidence from a meta-analysis

Background: The accurate and non-invasive tool for differential diagnosis between multiple system atrophy (MSA) and Parkinson's disease (PD) is needed at the early stage of disease for clinical trials of disease modifying therapy. PET is helpful, but the availability is limited. MRI is considered to be more available and potential method instead of PET. We aimed to investigate the effect of MSA and PD on putamen volume using a meta-analysis approach. Methods: A computer literature search yielded 6 eligible studies. Putamen volume was expressed as the standardized mean difference between MSA and PD patients. Moreover, subgroup analyses planed to be performed in order to identify factors which contributed to heterogeneity if included studies were not homogeneous. The proportion of variation due to heterogeneity was computed and expressed as 12. Results: Six studies, comprising a sample size of 84 MSA and 180 PD, were included in this meta-analysis. The overall effect indicated that putamen volume in MSA was significantly more reduced than that in PD with heterogeneous studies (P = 0.0004, 6 studies, n = 264, I-2 = 87%). A subgroup analysis revealed that the category of "Hoehn-Yahr stage of PD" showed a significant subgroup difference with a significant subgroup summary effect (subgroup difference: P = 0.003). Conclusions: Our findings based on group-level analysis suggested that volumetry of the putamen could be useful for differential diagnosis between MSA and PD at the early stage of disease, and also help to enroll more accurate disease group for disease modifying study in future. (C) 2014 Elsevier Ltd. All rights reserved.