Assessment of Protein Nitrogen Appearance in Chinese Peritoneal Dialysis Patients—Which Method to Use?

Figures & data

Table 1. Demographic and baseline clinical data

No. of patients	208
Sex (M:F)	104:104
Age (years)	57.0 ± 12.1
Body height (m)	1.60 ± 0.08
Body weight (kg)	58.0 ± 11.1
Renal diagnosis
Glomerulonephritis	71 (34.1%)
Diabetic nephropathy	63 (30.3%)
Polycystic kidney	9 (4.3%)
Hypertensive nephrosclerosis	8 (3.8%)
Obstructive uropathy	5 (2.4%)
Others/unknown	52 (25.0%)
Major comorbidity
Diabetes	71 (34.1%)
Cardiovascular disease	47 (22.6%)
HBsAg positive	16 (7.7%)

Table 2. Dialysis adequacy and nutritional status at 0 month and 6 months

	0 Month	6 Months	p Value
Protein nitrogen appearance
PNA-Berg (g/day)	61.8 ± 14.8	59.8 ± 14.3	p = 0.034
PNA-Rand (g/day)	58.1 ± 14.5	56.3 ± 14.0	p = 0.069
NPNA-IBW (g/kg/day)	1.13 ± 0.26	1.10 ± 0.25	p = 0.039
NPNA-Watson (g/kg/day)	1.14 ± 0.26	1.11 ± 0.25	p = 0.055
IBW (kg)	54.6 ± 5.7	54.6 ± 5.7	p = NS
SBW (kg)	54.8 ± 9.3	54.7 ± 9.3	p = 0.114
Protein loss
TPr (g/day)	7.3 ± 3.0	6.9 ± 2.8	p = 0.029
DPr (g/day)	6.5 ± 2.6	6.4 ± 2.5	p = 0.086
UPr (g/day)	0.8 ± 1.2	0.5 ± 0.9	p<0.001
Kt/V (total, weekly)	1.97 ± 0.52	1.91 ± 0.51	p = 0.09
Kt/V (peritoneal, weekly)	1.52 ± 0.38	1.54 ± 0.38	p = NS
CCr (L/week, total)	69.4 ± 31.0	62.2 ± 28.2	p<0.0001
Residual GFR (mL/min)
Mean ± SD	2.13 ± 2.22	1.67 ± 2.09	p<0.001
Median	1.67	0.88

Data were compared by paired Student's t test.

Figure 1. Scatter plot of PNA-Rand vs. PNA-Berg at 0 month. The line of equality is shown for reference.

Figure 2. Bland and Altman's plot of the difference between PNA-Rand and PNA-Berg vs. PNA-Berg at 0 month. Closed circles indicate cases with total protein loss (TPr) below 10 g/day; open circles, TPr 10–15 g/day; closed triangles, TPr above 15 g/day. Dotted lines indicate the overall limits of agreement.

Figure 3. Scatter plot of NPNA-Watson and NPNA-IBW at 0 month. The line of equality is shown for reference.

Figure 4. Bland and Altman's plot of the difference between NPNA-Watson and NPNA-IBW vs. NPNA-IBW at 0 month. Dotted lines indicate the overall limits of agreement.

Figure 5. Scatter plot of ΔPNA-Rand vs. ΔPNA-Berg after 6 months. The line of equality is shown for reference.

Figure 6. Bland and Altman's plot of the difference between ΔPNA-Rand and ΔPNA-Berg vs. ΔPNA-Berg after 6 months. Closed circles indicate cases with total protein loss (TPr) below 10 g/day; open circles, TPr 10–15 g/day; closed triangles, TPr above 15 g/day. Dotted lines indicate the overall limits of agreement.