Table 4.

Changes in potential renal acid load during followup

	Usual Care Group	NaCl Group	${\text{HCO}}_3^{-}$ Group	P Value
Year 0	65.7 (17.3)	64.2 (11.7)	63.4 (12.0)	0.78*
Year 5	64.1 (15.3)	62.9 (11.3)	66.4 (8.3)	0.67*
Year 10	61.8 (11.8)	63.4 (12.3)	64.8 (8.3)	0.59*
Difference: year 5 vs. year 0	−1.6 (13.4)	−1.3 (16.7)	3.0 (14.1)	0.67
P value†	0.79	0.64	0.66
Difference: year 10 vs. year 0	−3.9 (13.2)	−0.8 (15.7)	1.4 (13.0)	0.43
P value†	0.26	0.81	0.85
Difference: year 10 vs. year 5	−2.3 (12.5)	0.5 (15.8)	−1.6 (14.1)	0.74
P value†	0.45	0.83	0.75

Values are means (SD) of potential renal acid load (in mmol/day); 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 determined as follows: mean difference = average (SD) of the year 10 value minus baseline, year 5 value minus baseline, and year 10 value minus year 5 value, respectively, for each patient.

^*Kruskal-Wallis test for comparing three groups. All other P values are 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.