Dear Joaquim,

Thanks for your replay and I am still confused about the methods used in two of your published articles. Both articles are related to compare patient subgroups to the same control group in VBM study.

The first article is "Common and distinct patterns of grey-matter volume alteration in major depression and bipolar disorder: evidence from voxel-based meta-analysis"(Wise et al. 2017). For Major Depression, authors identified 41 studies that included 50 comparison (1736 patients, 2365 health controls). In supplementary tables 1, study "Arnone 2012" compare depressed MDD vs HC and remitted MDD vs HC (the same control group). In the meta-analysis, did authors include both comparison and "double-count" the control group? The other 9 studies also included multiple subgroups. Did each control group were included by multiple times in the meta-analysis, therefore, the total number of controls was 2365 ?

The second published article is "Comparative Multimodal Meta-analysis of Structural and Functional Brain Abnormalities in Autism Spectrum Disorder and Obsessive-Compulsive Disorder"(Carlisi et al. 2017). In the second paragraph of statistical methods, "some studies included different fMRI tasks in identical or largely overlapping samples, or compared patient subgroups to the same control subjects. To address this, SDM was modified to allow calculation of a single, combined map with reduced variance for such studies to avoid dependent data in analyses (see the Supplement Methods)."
Two of the included VBM studies had multiple patient subgroups (Subira et al. 2013, Hashimoto et al. 2014).

• How to deal with patient subgroups in this article? Combine multiple comparisons as fMRI multiple tasks? and the sample number of patients was sum of subgroups, and the sample number of control group was "single-count" ? (neither double-count nor split) (table 2)
• In the supplementary methods, "this new simple approach will be included in the next version of the SDM software to allow other researchers to conduct repeated-measures meta-analyses." Does the "combine images" function in the new version SDM-PSI use this new approach? Is it only suitable for multiple tasks in fMRI study, or also suitable for VBM subgroup study?

I really appreciated your help.

Best wishes,
Fei-Fei


Reference:

• Wise, T., J. Radua, E. Via, N. Cardoner, O. Abe, T. M. Adams, F. Amico, Y. Cheng, J. H. Cole, C. de Azevedo Marques Perico, D. P. Dickstein, T. F. D. Farrow, T. Frodl, G. Wagner, I. H. Gotlib, O. Gruber, B. J. Ham, D. E. Job, M. J. Kempton, M. J. Kim, P. Koolschijn, G. S. Malhi, D. Mataix-Cols, A. M. McIntosh, A. C. Nugent, J. T. O'Brien, S. Pezzoli, M. L. Phillips, P. S. Sachdev, G. Salvadore, S. Selvaraj, A. C. Stanfield, A. J. Thomas, M. J. van Tol, N. J. A. van der Wee, D. J. Veltman, A. H. Young, C. H. Fu, A. J. Cleare and D. Arnone (2017). "Common and distinct patterns of grey-matter volume alteration in major depression and bipolar disorder: evidence from voxel-based meta-analysis." Mol Psychiatry 22(10): 1455-1463.
• Carlisi, C. O., L. J. Norman, S. S. Lukito, J. Radua, D. Mataix-Cols and K. Rubia (2017). "Comparative Multimodal Meta-analysis of Structural and Functional Brain Abnormalities in Autism Spectrum Disorder and Obsessive-Compulsive Disorder." Biol Psychiatry 82(2): 83-102.
• Hashimoto, N., S. Nakaaki, A. Kawaguchi, J. Sato, H. Kasai, T. Nakamae, J. Narumoto, J. Miyata, T. A. Furukawa and M. Mimura (2014). "Brain structural abnormalities in behavior therapy-resistant obsessive-compulsive disorder revealed by voxel-based morphometry." Neuropsychiatr Dis Treat 10: 1987-1996.
• Subira, M., P. Alonso, C. Segalas, E. Real, C. Lopez-Sola, J. Pujol, I. Martinez-Zalacain, B. J. Harrison, J. M. Menchon, N. Cardoner and C. Soriano-Mas (2013). "Brain structural alterations in obsessive-compulsive disorder patients with autogenous and reactive obsessions." PLoS One 8(9): e75273.