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Table 3 Intraclass correlation coefficients (ICC) and required measuring days based on baseline measurements

From: Feasibility of home-based sampling of salivary cortisol and cortisone in healthy adults

  Mean CV% ICC Days to obtain Days to obtain Days to obtain
ICC = 0.60 ICC = 0.70 ICC = 0.80
Cortisol      
 S1 31.9 0.41 2 3 6
 CAR      
  CAR30 (30 min—S1) 75.3 0.17 3 4 7
  CARpeak (Peak cortisol—S1) 52.3 0.17 2 3 5
 CARauc 20.1 0.56 1 2 4
 DCS      
  Wake-to-bed slope 59.7 0.35 3 4 7
  Peak-to-bed slope 31.9 0.51 1 1 3
Cortisone      
 S1 17.1 0.28 4 6 10
 CAR      
  CAR30 (30 min—S1) 49.0 0.29 4 6 10
  CARpeak (Peak cortisol—S1) 44.8 0.60 1 2 3
  CARauc 14.7 0.57 1 2 4
 DCS      
  Wake-to-bed slope 37.5 0.18 7 11 18
  Peak-to-bed slope 24.1 0.68 1 2 3
  1. The table present the coefficient of variation (%) and intraclass correlation coefficient (ICC) for concentrations of cortisol and cortisone within the same participant at baseline and the required number of measuring days to obtain ICC values of 0.60, 0.70 and 0.80
  2. S1 The salivary sample collected immediately upon awakening, CAR Cortisol (or cortisone) awakening response, CAR30 Difference between S1 and the salivary sample 30 min later, CARpeak Difference between S1 and the value of the second or third morning salivary sample, whichever was the largest; CARauc The area under the curve for the morning salivary samples, DCS Diurnal cortisol (or cortisone) slope