Albertine Donker

Chapter 7 246 Table 6. Results of linear regression models for TSAT/hepcidin ratio (%/nmol/L) adjusted for age and time of blood sampling and stratified by sex Males 95% CI Variable Beta a Lower limit Upper limit R 2 , % b p Hb, g/dL -0.002 -0.112 0.108 22.9 0.971 Reticulocytes, x10^9/L -0.004 -0.010 0.002 21.7 0.184 MCV, fL 0.012 -0.014 0.039 21.2 0.354 Ferritin, µg/L d -1.325 -1.716 -0.934 39.0 0.000 Iron, µmol/L 0.024 0.007 0.040 24.9 0.005 TIBC, µmol/L 0.004 -0.006 0.014 21.1 0.420 sTfR, mg/L -0.050 -0.398 0.297 20.8 0.775 ALT, IU/L d -0.726 -1.295 -0.158 24.0 0.013 CRP, mg/L d,e -0.338 -0.462 -0.213 33.5 0.000 BMI f Normal weight ref ref ref Underweight -0.674 -1.266 -0.082 25.1 0.026 Overweight -0.280 -0.535 -0.025 0.031 Adipose -0.305 -0.768 0.158 0.195 Adjustment for age was done with age as a continuous variable; adjustment for sampling time was done with sampling time as a categorical variable (7.30 AM-12 PM, 12-3 PM, 3-6 PM). a Beta expresses the change in the dependent variable – log transformed TSAT/hepcidin ratio- that is associated with a 1-unit change in the independent variable. Independent variables marked with d were log-transformed; the interpretation of the regression coefficients for these variables is as follows: a 1% change in the independent variable corresponds to a beta % change in the TSAT/hepcidin ratio b For males multivariate linear regression model with log transformed TSAT/hepcidin as dependent variable and age (continuous variable) and sampling time as independent variables showed: R 2 21.3 %, with ß: 0.059, CI 0.040– 0.077 ( p 0.000), ß: -0.168, CI -0.350– 0.015 ( p 0.071), ß: -0.484, CI -0.738–