A nomogram predicts cardiovascular events in patients with peritoneal dialysis-associated peritonitis

Figures & data

Figure 1. Enrollment and outcomes of the cohort.

Table 1. Baseline characteristics of the study populations.

Variable	Total (n = 150)	0 (n = 94)	1 (n = 56)	P
Female	89 (59.33)	53 (56.38)	36 (64.29)	0.341
Age, year	51.02 ± 10.92	47.77 ± 9.40	56.48 ± 11.19	<0.001
Age.cut				<0.001
<65 years, n%	133 (88.67)	92 (97.87)	41 (73.21)
≥65 years, n%	17 (11.33)	2 (2.13)	15 (26.79)
BMI.cut(kg/m*m)				0.632
<18.5	10 (6.67)	6 (6.38)	4 (7.14)
18.5–23.9	92 (61.33)	60 (63.83)	32 (57.14)
24–27.9	37 (24.67)	23 (24.47)	14 (25.00)
≥28	11 (7.33)	5 (5.32)	6 (10.71)
Smoking, n%	17 (11.33)	11 (11.70)	6 (10.71)	0.854
Diabetes mellitus, n%	25 (16.67)	13 (13.83)	12 (21.43)	0.227
SBP, mmHg, ± sd	139.47 ± 24.09	136.13 ± 24.00	145.07 ± 23.39	0.027
DBP, mmHg, ± sd	90.13 ± 15.16	91.44 ± 15.10	87.95 ± 15.13	0.173
HR, times/min, ± sd	90.13 ± 15.25	90.72 ± 15.99	89.14 ± 14.01	0.541
History of CVEs	29 (19.33)	6 (6.38)	23 (41.07)	<0.001
White blood cells,10^9/L, ± sd	9.49 ± 3.96	9.71 ± 3.92	9.14 ± 4.02	0.769
Neutrophil/lymphocyte ratio,%, ± sd	11.56 ± 10.51	11.39 ± 11.28	11.83 ± 9.18	0.420
Hemoglobin, g/L, ± sd	95.75 ± 20.31	98.04 ± 19.47	91.91 ± 21.26	0.074
Creatinine, umol/L, ± sd	882.45 ± 253.54	913.69 ± 261.08	830.00 ± 233.28	0.050
Serum uric acid, umol/L, ± sd	374.80 ± 89.35	381.16 ± 87.85	364.12 ± 91.61	0.260
CRP, mg/L, ± sd	59.02 ± 54.69	56.77 ± 55.43	62.83 ± 53.70	0.517
Calcium, mmol/L, ± sd	2.26 ± 0.21	2.29 ± 0.21	2.20 ± 0.20	0.006
Phosphorus, mmol/L, ± sd	1.53 ± 0.57	1.55 ± 0.62	1.48 ± 0.48	0.484
Serum albumin, g/L				<0.001
<30, n%	46 (30.67)	21 (22.34)	25 (44.64)
30 g–34.9, n%	47 (31.33)	25 (26.60)	22 (39.29)
≥35, n%	57 (38.00)	48 (51.06)	8 (14.29)
Alkaline phosphatase, u/L, ± sd	95.71 ± 100.50	82.33 ± 34.86	118.16 ± 156.49	0.034
Triglycerides, mmo/L, ± sd	1.57 ± 1.11	1.48 ± 0.93	1.71 ± 1.35	0.238
HDL-C, mmol/L, ± sd	1.15 ± 0.34	1.16 ± 0.32	1.15 ± 0.38	0.908
LDL-C, mmol/L, ± sd	2.74 ± 0.98	2.64 ± 0.94	2.91 ± 1.02	0.113
24hours urine output				0.913
<400, ml, n%	94 (62.67)	58 (61.70)	36 (64.29)
400–1000, ml, n%	35 (23.33)	23 (24.47)	12 (21.43)
>1000, ml, n%	21 (14.00)	13 (13.83)	8 (14.29)
iPTH, pg/ml, ± sd	275.11 ± 285.31	265.18 ± 295.36	291.78 ± 269.38	0.582
ACEI/ARB, n%	46 (30.67)	29 (30.85)	17 (30.36)	0.949
Number of peritonitis episodes				0.482
≥3, n%	25 (16.67)	13 (13.83)	12 (21.43)
1, n%	85 (56.67)	55 (58.51)	30 (53.57)
2, n%	40 (26.66)	26 (27.66)	14 (25.00)
Culture-positive, n%	108 (72.00)	60 (63.83)	48 (85.71)	0.004
The first modality for renal replacement therphy				0.478
PD, n%	143 (95.33)	91 (96.81)	52 (92.86)
HD, n%	7 (4.67)	3 (3.19)	4 (7.14)
Dialysis duration, month, ± sd	38.49 ± 32.33	38.29 ± 32.62	38.84 ± 32.11	0.920
Peritoneal function				0.097
Low transport, n%	14(9.59)	8(8.7)	6(11.11)
Low average transport, n%	52(35.62)	39(42.39)	13(24.07)
High average transport, n%	64(43.84)	38(41.3)	26(48.15)
High transport, n%	16(10.96)	7(7.61)	9(16.67)
Follow-up time, month, ± sd	28.60 ± 20.54	31.60 ± 21.06	23.57 ± 18.78	0.02

0: no cardiovascular events group; 1: cardiovascular events group.

BMI: body mass index; HR: heart rate; CVEs: cardiovascular events; SBP: systolic blood pressure; DBP: diastolic blood pressure; CRP: C-reactive protein; ACEI: angiotensin converting enzyme inhibitor; ARB: angiotensin receptor blockers; HDL-C, high density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; iPTH, intact parathyroid hormone; PD: peritoneal dialysis; HD: hemodialysis; sd: standard deviation.

Table 2. Results of univariate and multivariate Regression Analysis.

Variable	Univariate analysis		Multivariate analysis
	HR (95% CI)	P	HR (95% CI)	P
Age	1.071 (1.044, 1.100)	<0.001	——	——
Age (≥65 years)	4.298 (2.330, 7.928)	<0.001	2.453 (1.071, 5.619）	0.034
SBP	1.011 (1.001, 1.022)	0.036	——	——
History of CVEs	2.972 (1.738, 5.082)	<0.001	2.296 (1.220, 4.321)	0.010
Calcium	0.201 (0.068, 0.597)	0.004	——	——
Serum albumin
<30	ref
30–34.9	0.762 (0.427, 1.360)	0.357	——	——
≥35	0.239 (0.111, 0.514)	<0.001	0.396 (0.170, 0.924)	0.032
Alkaline phosphatase	1.003 (1.002, 1.005)	<0.001	1.004 (1.002, 1.005)	＜0.001
Culture-positive	2.770 (1.308, 5.866)	0.008	2.173 (1.009, 4.682)	0.047
High mean transport	2.396 (1.021, 5.621)	0.045	——	——

SBP: systolic blood pressure; CVEs: cardiovascular events; HR: hazard ratio; CI: credible interval.

Figure 2. A nomogram for predicting the risk of cardiovascular events in PD patients with peritonitis.

Table 3. Multivariate COX regression model for predicting cardiovascular events in patients with peritoneal dialysis-related peritonitis.

Variable HR (95% CI)	Final model	Model 1	Model 2	Model 3	Model 4
Age (≥65 years)	2.453 (1.071, 5.619)	4.442 (2.368, 8.332)	4.526 (2.321, 8.824)	4.103 (1.840, 9.151)	4.835 (2.561, 9.128)
Gender		0.876 (0.497, 1.544)	1.102 (0.586, 2.070)	0.915 (0.494, 1.695)	0.844 (0.477, 1.495)
History of CVEs	2.296 (1.220, 4.321)
Diabetes			1.687 (0.865, 3.291)	1.836 (0.877, 3.844)
Smoking			2.165 (0.828, 5.663)
SBP			1.009 (0.998, 1.021)
BMI (≥28)				1.500 (0.606, 3.711)
CRP				1.000 (0.994, 1.006)
Alkaline phosphatase	1.004 (1.002, 1.005)			1.003 (1.002, 1.005)	1.004 (1.002, 1.005)
Serum albumin	0.396 (0.170, 0.924)			0.461 (0.185, 1.151)
HDL-C			0.489 (0.198, 1.209)
Culture-positive	2.173 (1.009, 4.682)
C-index	0.732	0.605	0.668	0.723	0.639
C-index (Se)	0.033	0.040	0.045	0.036	0.046
AIC value	441.209	463.719	450.284	450.314	456.792
BIC value	453.361	467.770	462.328	472.395	462.868

HR: hazard ratio; CI: credible interval; CVEs: cardiovascular events; SBP: systolic blood pressure; CRP: C-reactive protein; HDL-C, high density lipoprotein cholesterol; AIC: Akaike Information Criterion; BIC: Bayesian information criterion; Se: standard error.

Table 4. The collinearity of the final multivariable model.

	GVIF	Df	GVIF (1/(2 × Df))
Age (≥65 years)	1.818	1	1.348
History of CVEs	1.373	1	1.172
Serum albumin (g/L)	1.452	2	1.098
Alkaline phosphatase(u/L)	1.123	1	1.060
Culture-positive	1.029	1	1.014

CVEs: cardiovascular events; GVIF: generalized variance inflation factor; Df: degree of freedom.

Figure 3. ROC curve for time-dependent cardiovascular events in PD patients with peritonitis.

Figure 4. Kaplan-Meier survival curves on the basis of the nomogram.

Figure 5. Time-dependent non-cardiovascular events for plots depict the calibration of the nomogram in terms of the agreement between predicted and observed.

Table 5. Nomogram score for each indicator.

Variable	Levels	Point
Age (year)	<65	0.00
	≥65	20.75
History of CVEs	No	0.00
	Yes	19.23
Serum_albumin (g/L)	<30	21.42
	30–34.9	28.67
	≥35	0.00
Alkaline_phosphatase (u/L)	100	8.33
	200	16.67
	300	25
	400	33.33
	500	41.67
	600	50
Culture	Negative	0.00
	Positive	17.96

Table 6. Sensitivity analysis and Bootstrap internal validation to test the robustness of the prediction model.

Variable HR (95% CI)	Nomogram model (n = 150)	Late-onset peritonitis (n = 135)	Complete case (n = 145)	Bootstrap
Age ≥ 65 years	2.453 (1.071, 5.619)	2.662 (1.193, 5.942)	2.398 (0.995, 5.775)	2.479 (1.007, 6.172)
History of CVEs	2.296 (1.220, 4.321)	2.282 (1.209, 4.310)	2.146 (1.096, 4.201)	2.377 (0.989, 4.563)
Serum albumin (g/L)
<30		ref
30–34.9	1.368 (0.683, 2.740)	1.378 (0.680, 2.795)	1.285 (0.636, 2.596)	1.370 (0.677, 2.962)
≥35	0.396 (0.170, 0.924)	0.381 (0.165, 0.882)	0.376 (0.161, 0.875)	0.363 (0.173, 1.078)
Alkaline phosphatase (u/L)	1.004 (1.002, 1.005)	1.003 (1.002, 1.005)	1.003 (1.002, 1.005)	1.004 (0.999, 1.007)
Culture-positive	2.173 (1.009, 4.682)	2.081 (0.959, 4.515)	2.209 (1.022, 4.775)	2.286 (0.892, 5.349)
C-index	0.732	0.736	0.726	0.747 (0.659, 0.778)
C-index (Se)	0.033	0.035	0.034	0.033 (0.028, 0.040)

HR: hazard ratio; CI: credible interval; CVEs: cardiovascular events; Se: standard error.

Data availability statement

The data presented in this study are available on request from the corresponding author.