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Editor's Correspondence
Feb 27, 2012

Limitations of Subgroup Analyses in Meta-analysis of Cardiac Resynchronization Therapy by QRS Duration—Reply

Author Affiliations

Author Affiliation: Harrington-McLaughlin Heart & Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio.

Arch Intern Med. 2012;172(4):375-376. doi:10.1001/archinternmed.2011.1685

In reply

I disagree with the comments of Magee et al. There was no multiple testing in our meta-analysis. The approach used in this meta-analysis was different from the exploratory subgroup analyses of a single clinical trial. The predefined hypothesis of this meta-analysis was that patients with moderately prolonged QRS interval (ie, 120-150 milliseconds [ms]) do not benefit from cardiac resynchronization therapy (CRT), which was suggested by many investigators even before the major clinical trials of CRT were performed and is biologically plausible.13 Therefore, the only subgroups examined in this analysis were moderately prolonged QRS interval vs severely prolonged QRS interval (ie, >150 ms). Because of this, making corrections for multiple testing does not pertain to this analysis. Moreover, even for a hypothetical situation where multiple testing would be relevant, the significant P value of <.001 for the difference in the response of the 2 QRS subgroups is so robust that the results would not change with any type of correction.

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