Table 1.

Hydroxyurea treatment increases EPO levels in SCD. Using a linear model, log(EPO) was regressed on age (year), gender, square root of haemoglobin concentration (g/dl), hydroxyurea treatment and clinical sites. Exponent of βs and P values are shown

	Walk-PHaSST (n = 586)		PUSH (n = 387)
	eβ (IU/l)	P	eβ (IU/l)	P
age	1.01	0.0018	1.00	1
female gender	0.79	2.7 × 10−5	0.93	0.2
haemoglobin	0.44	<2.0 × 10−16	0.16	<2.0 × 10−16
hydroxyurea	1.62	2.5 × 10−15	1.41	2.5 × 10−7