JNC VI guidelines

Abstract

MIDAS study investigator's replySir—Lionel Opie misunderstands the design, conduct, and analysis of MIDAS. First, the trial was designed so that both the isradipine and diuretic groups would have equal reductions in diastolic blood pressure (DBP), and as reported in the final results paper,1Borhani NO Mercuri M Borhani PA et al.Final outcome results of the multicenter isradipine diuretic artherosclerosis study (MIDAS): a randomised controlled trial.JAMA. 1996; 276: 785-791Crossref PubMed Google Scholar this equality was achieved; DBP had decreased by about 13 mm Hg in both treatment groups. With these equal DBP reductions, it is true that the diuretic group had a 3·5 mm Hg greater reduction in the systolic blood pressure (SBP) than did the isradipine group. However, this slight difference in SBP did not explain the 78% higher event rate in the isradipine group. As described in the final results paper, the mean SBPs in both treatment groups were reduced to within the normal ranges and, at the end of follow-up, there was no statistical difference in mean SBP between the two groups.With respect to the classification of events, the definitions were prospectively defined by the MIDAS investigators before they were unblinded to the results of the trial. It is true that after initially classifying the events and then being unblinded, the investigators did appoint an external review panel to blindly re-review the events. However, it is not true that the original classifications were not reported. The final results paper details the slight discrepancies between the two sets of classifications and clearly states that the conclusions were virtually identical: for the primary outcome measure of major vascular events, the external review panel found that there were 78% more events in the isradipine group (p=0·07), whereas the MIDAS investigators found 80% more events in that group (p=0·06). MIDAS study investigator's reply Sir—Lionel Opie misunderstands the design, conduct, and analysis of MIDAS. First, the trial was designed so that both the isradipine and diuretic groups would have equal reductions in diastolic blood pressure (DBP), and as reported in the final results paper,1Borhani NO Mercuri M Borhani PA et al.Final outcome results of the multicenter isradipine diuretic artherosclerosis study (MIDAS): a randomised controlled trial.JAMA. 1996; 276: 785-791Crossref PubMed Google Scholar this equality was achieved; DBP had decreased by about 13 mm Hg in both treatment groups. With these equal DBP reductions, it is true that the diuretic group had a 3·5 mm Hg greater reduction in the systolic blood pressure (SBP) than did the isradipine group. However, this slight difference in SBP did not explain the 78% higher event rate in the isradipine group. As described in the final results paper, the mean SBPs in both treatment groups were reduced to within the normal ranges and, at the end of follow-up, there was no statistical difference in mean SBP between the two groups. With respect to the classification of events, the definitions were prospectively defined by the MIDAS investigators before they were unblinded to the results of the trial. It is true that after initially classifying the events and then being unblinded, the investigators did appoint an external review panel to blindly re-review the events. However, it is not true that the original classifications were not reported. The final results paper details the slight discrepancies between the two sets of classifications and clearly states that the conclusions were virtually identical: for the primary outcome measure of major vascular events, the external review panel found that there were 78% more events in the isradipine group (p=0·07), whereas the MIDAS investigators found 80% more events in that group (p=0·06).