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June 7, 1985

The Lipid Research Clinics Coronary Primary Prevention Trial

Author Affiliations

University of Toronto

JAMA. 1985;253(21):3091. doi:10.1001/jama.1985.03350450063008

To the Editor.—  We would like to point out a discrepancy between the final report of the Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT)1 and the report on the design and implementation of this trial.2 In the article on planning, the following statements appear in Appendix D under the heading, "Calculation of Sample Size": "Since the time, magnitude, and cost of this study make it unlikely that it could ever be repeated, it was essential to be sure that any observed beneficial effect of cholesterol lowering was a real one. Therefore, alpha was set at 0.01 rather than the usual 0.05." However, when the results appear for the primary end points and all-cause mortality, they are reported in relation to a level of significance of.05. We are concerned by this apparent post-hoc relaxation of the α-level used to judge the statistical significance of the LRC-CPPT results. Despite