Table 6.

Changes in plasma total CO₂ during followup

	Usual Care Group	NaCl Group	${\text{HCO}}_3^{-}$ Group	P Value
Year 0	26.1 (0.8)	25.8 (0.5)	25.9 (0.6)	0.42*
Year 5	26.0 (0.7)	25.7 (0.5)	26.2 (0.7)	<0.01
Year 10	25.2 (0.4)	25.1 (0.5)	26.1 (0.7)	<0.01
Difference: year 5 vs.  year 0	−0.1 (0.2)	−0.1 (0.1)	0.3 (0.4)	<0.01
P value†	<0.01	<0.01	<0.01
Difference: year 10 vs.  year 0	−0.9 (0.7)	−0.7 (0.3)	0.2 (0.4)	<0.01
P value†	<0.01	<0.01	<0.01
Difference: year 10 vs.  year 5	−0.8 (0.7)	−0.6 (0.2)	−0.1 (0.2)	<0.01
P value†	<0.01	<0.01	0.20

Values are means (SD) of plasma total CO₂ (in mM); n = 40 participants/group. Patients with chronic kidney disease stage 2 were divided into the following three groups: usual care or treatment with oral NaCl or NaHCO₃ (${\text{HCO}}_3^{-}$). Mean differences were calculated as follows = average (SD) of the year 10 value minus baseline, year 5 value minus baseline, and year 10 value minus year 5 value for each patient.

^*Kruskal-Wallis test for comparing three groups. All other P values were from one-way ANOVA.

^†Signed-rank test for assessing the within-group difference between baseline and year 5, baseline and year 10, and year 5 and year 10.