Table 4.

Parameter estimates of effect modification covariates in hemoglobin change models

Covariate	Model
	TSAT		Ferritin		TSAT + Ferritin
	Estimate	P	Estimate	P	Estimate	P
ΔESA	−0.03	0.84	0.36	<0.001	−0.11	0.48
ΔESA*TSAT	0.04	<0.001	–	–	0.04	<0.01
ΔESA*TSAT2	−9.2E–04	<0.01	–	–	−9.0E–04	<0.01
ΔESA*TSAT3	5.9E–06	<0.01	–	–	5.8E–06	<0.01
ΔESA*Ferr	–	–	5.0E–04	0.07	3.8E–04	0.15
ΔESA*Ferr2	–	–	−2.6E–07	0.34	−2.3E–07	0.39
ΔESA*Ferr3	–	–	4.2E–11	0.54	4.25E–11	0.54

ΔESA = weight-adjusted dose change of Epoetin alfa from interval k to k + 1; ΔESA^*Ferr = interaction between adjusted Epoetin alfa dose change and ferritin; ΔESA^*Ferr² = interaction between adjusted Epoetin alfa dose change and ferritin²; ΔESA^*Ferr³ = interaction between adjusted Epoetin alfa dose change and ferritin³; ΔESA^*TSAT = interaction between adjusted Epoetin alfa dose change and TSAT; ΔESA^*TSAT² = interaction between adjusted Epoetin alfa dose change and TSAT²; ΔESA^*TSAT³ = interaction between adjusted Epoetin alfa dose change and TSAT³.