Table 5.

Multivariate associations with bicarbonate (hemoglobin SS: the Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil Therapy Trial)

Variable	HbSS
	Coefficient [95% CI]	P Value
Age, yr	0.03 [−0.01 to 0.06]	0.16
Men	−0.24 [−0.96 to 0.49]	0.52
Erythroid reserve/hemolytic markers
Hb, g/dl	0.34 [0.11 to 0.57]	0.004
Erythropoietin,a U/L	−0.43 [−0.76 to −0.11]	<0.01
LDH,a IU/L
Total bilirubin,a mg/dl	−0.71 [−1.12 to −0.30]	<0.001
Absolute reticulocyte count, ×106/ml	<0.01 [0.00 to 0.01]	0.07
Physiologic reserve and renal function
TRV, m/s	0.81 [−0.12 to 1.74]	0.09
6-MWD, m	0.01 [0.01 to 0.01]	<0.001
Systolic BP, mmHg	0.03 [0.00 to 0.05]	0.04
Potassium, mM/L	−0.87 [−1.56 to −0.18]	0.01
Miscellaneous
Hydroxyurea use	0.96 [0.24 to 1.67]	<0.01
eGFR, ml/min per 1.73 m2	0.01 [0.01 to 0.02]	<0.001

HbSS, hemoglobin SS; 95% CI, 95% confidence interval; LDH, lactate dehydrogenase; TRV, tricuspid regurgitant jet velocity; 6-MWD, 6-minute walk distance.

^aPer 50% higher.