Margaret A.WinkerMD, Deputy EditorPhil B.FontanarosaMD, Interim Coeditor
Copyright 1999 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.1999American Medical Association
To the Editor: Dr Fleischmann and colleagues1 provided a detailed summary of 2 commonly used noninvasive cardiac test modalities: exercise ECHO and exercise SPECT. We are concerned about the heterogeneity of the studies included in their meta-analysis.
Midgette et al2 state that when data from a number of reports are poorly correlated and heterogeneous, neither summary point estimates or summary receiver operating characteristic (SROC) curves are appropriate. Petitti3 has also reported that use of the fixed-effects model to create summary point estimates requires homogenous data. A test for homogeneity in the reports cited by Fleischmann et al reveals significant heterogeneity in both the exercise SPECT and exercise ECHO reports (χ2= 51.02 for SPECT, and 61.61 for ECHO, both P<.001). This leads us to question whether there might be significant underlying differences in the component reports, creating bias in the results.
Kymes S, Shaw L, Fletcher J. Exercise Echocardiography vs Exercise SPECT Testing. JAMA. 1999;282(17):1622. doi:10.1001/jama.282.17.1622-JLT1103-2-3