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Table 2 Comparison of sample sizes required for hypothetical trials with mean IMT or TPV as primary endpoints

From: A comparison of ultrasound measurements to assess carotid atherosclerosis development in subjects with and without type 2 diabetes

Endpoint Significance Level Power Ndiabetic Nnon-diabetic N total
IMT (inverse): 6 μ m difference
  0.05 0.70 601 601 1202
  0.05 0.80 764 764 1528
  0.05 0.90 1022 1022 2044
TPV (square root): 45.9 mm3 difference
  0.05 0.70 68 68 136
  0.05 0.80 86 86 172
  0.05 0.90 115 115 230
  1. Abbreviations: IMT, intima-media thickness; TPV, total plaque volume