Correlation of the Dietary Protein Intake between Those Estimated from a Short Protein Food-Recall Questionnaire and from 24-Hour Urinary Urea-Nitrogen Excretion in Stages 3-4 Chronic Kidney Disease Patients

Table 2

T-test comparison of DPI estimation from the 2 methods in different stages of CKD.

Stage of CKD	Number of study participants	Estimated DPI		Difference: mean (95% CI)	value
		S-PFRQ	PNA
3A	21	21.22 ± 10.26	39.58 ± 13.62	−18.35 (−25.21 to −11.49)	0.0001
3B	28	33.43 ± 12.14	40.62 ± 18.70	−7.18 (−17.87 to 3.50)	0.175
4	11	25.14 ± 13.51	41.49 ± 18.10	−16.83 (−20.57 to 10.3)	0.357

CKD = chronic kidney disease, DPI = daily protein intake, PNA = protein-equivalent of total nitrogen appearance, S-PFRQ = short-protein Food Recall Questionnaire. Mean difference = DPI estimation from S-PFRQ minus DPI estimation from PNA.