Baseline characteristic of participants
Totally, 2,689 patients undergoing PD who were catheterized at our PD center were recruited. Of these, 354 patients who aged < 18 years, transferred from maintenance hemodialysis, underwent failed kidney transplantation, had malignant tumors, received PD for less than 3 months, or lacked baseline TyG-BMI data were excluded. The rest 2,335 participants were eligible for the final analysis (Fig. 1).
Participants’ mean age was 46.1 ± 14.8 years; 1,382 (59.2%) were male, and diabetic account for 24.2% (n = 564). The primary renal disease was chronic glomerulonephritis (61.3%), diabetic nephropathy (20.6%) and hypertension (7.7%). Baseline TyG-BMI ranged from 82.0 to 380.0 (median 183.7, interquartile range 165.5–209.2). The baseline characteristics of the participants by quartiles of TyG-BMI are presented in Table 1. Compared with patients in Q1, patients with higher TyG-BMI levels were older; had a higher incidence of diabetes, CVD, and hypertension; had a higher proportion of males; and had increased urine output and higher TC, LDL-C, uric acid, and hs-CRP levels but lower DBP and HDL-C levels (P < 0.05) (Table 1). There was no obvious distinction among the groups regarding SBP, hemoglobin, albumin, serum creatinine, urea nitrogen, and eGFR levels (P > 0.05) (Table 1).
Table 1
Baseline characteristics of different groups of TyG-BMI.
Characteristics | Total (n = 2,335) | Quartiles of TyG-BMI | P value |
Q1 (n = 584) < 165.5 | Q2 (n = 584) 165.5-<183.7 | Q3 (n = 584) 183.7-<209.2 | Q4 (n = 583) > 209.2 |
Age (years) | 46.1 ± 14.8 | 40.4 ± 15.1 | 45.2 ± 15.1 | 46.7 ± 13.8 | 50.2 ± 13.3 | < 0.001* |
Male sex (n, %) | 1382 (59.2) | 296 (50.7) | 357 (61.1) | 376 (64.4) | 353 (60.5) | < 0.001* |
Dialysis duration (months) | 46.6 (22.4–78.0) | 48.8 (21.8–89.0) | 46.0 (21.6–76.2) | 47.9 (24.4–75.3) | 43.5 (21.9–70.7) | 0.076 |
Primary renal diseases | | | | | | |
Glomerulonephritis (n, %) | 1432 (61.3) | 461 (78.9) | 395 (67.6) | 325 (55.7) | 251 (43.1) | < 0.001* |
Diabetic nephropathy (n, %) | 480 (20.6) | 33 (5.7) | 78 (13.4) | 143 (24.5) | 226 (38.8) | < 0.001* |
Renal vascular diseases (n, %) | 179 (7.7) | 23 (3.9) | 43 (7.4) | 51 (8.7) | 62 (10.6) | < 0.001* |
Others (n, %) | 244 (10.4) | 67 (11.5) | 68 (11.6) | 65 (11.1) | 44 (7.5) | 0.069 |
BMI (kg/m2) | 21.8 ± 3.2 | 18.4 ± 1.5 | 20.5 ± 1.3 | 22.5 ± 1.4 | 25.6 ± 2.6 | < 0.001* |
Systolic pressure (mmHg) | 136 ± 20 | 135 ± 19 | 137 ± 20 | 136 ± 20 | 136 ± 21 | 0.617 |
Diastolic pressure (mmHg) | 85 ± 14 | 87 ± 13 | 86 ± 14 | 84 ± 14 | 83 ± 13 | < 0.001* |
Urine output (ml) | 1000 (600–1500) | 900 (500–1400) | 1000 (600–1500) | 1000 (700–1600) | 1100 (600–1700) | < 0.001* |
Comorbidities | | | | | | |
Diabetes (n, %) | 564 (24.2) | 41 (7.0) | 96 (16.4) | 170 (29.1) | 257 (44.1) | < 0.001* |
CVD history (n, %) | 782 (33.5) | 136 (23.3) | 181 (31.0) | 213 (36.5) | 252 (43.2) | < 0.001* |
Hypertension (n, %) | 664 (28.4) | 79 (13.5) | 155 (26.5) | 188 (32.2) | 242 (41.5) | < 0.001* |
Laboratory parameters | | | | | | |
Hemoglobin (g/l) | 101 ± 22 | 101 ± 24 | 101 ± 22 | 101 ± 22 | 101 ± 20 | 0.900 |
Albumin (g/l) | 36.1 ± 5.1 | 36.9 ± 5.3 | 36.7 ± 4.9 | 36.5 ± 5.1 | 36.6 ± 5.1 | 0.593 |
Triglyceride (mg/dl) | 124 (89–178) | 91 (68–122) | 116 (89–156) | 130 (98–172) | 186 (134–274) | < 0.001* |
FBG (mg/dl) | 84.6 (75.6-100.8) | 79.2 (70.2–86.4) | 84.6 (75.6–95.4) | 88.2 (77.4-104.4) | 95.4 (82.8-138.6) | < 0.001* |
TyG index | 8.62 (8.23–9.08) | 8.17 (7.88–8.49) | 8.54 (8.23–8.85) | 8.69 (8.38–9.04) | 9.20 (8.78–9.65) | < 0.001* |
Total cholesterol (mg/dl) | 193 ± 52 | 185 ± 49 | 192 ± 50 | 196 ± 50 | 202 ± 55 | < 0.001* |
HDL-C (mg/dl) | 47.5 ± 16.3 | 54.4 ± 18.2 | 49.2 ± 16.5 | 45.7 ± 13.5 | 40.8 ± 13.2 | < 0.001* |
LDL-C (mg/dl) | 114 ± 39 | 108 ± 35 | 115 ± 37 | 119 ± 39 | 116 ± 42 | < 0.001* |
Serum creatinine (mg/dl) | 8.74 ± 3.10 | 8.82 ± 3.14 | 8.84 ± 3.20 | 8.64 ± 2.83 | 8.68 ± 3.23 | 0.661 |
Uric acid (mg/dl) | 7.15 ± 1.63 | 7.03 ± 1.60 | 7.17 ± 1.64 | 7.07 ± 1.62 | 7.32 ± 1.66 | 0.009* |
Urea nitrogen (mg/dl) | 49.8 ± 29.2 | 50.7 ± 21.0 | 49.2 ± 20.4 | 50.6 ± 20.2 | 48.9 ± 19.2 | 0.240 |
eGFR (ml/min/1.73 m2) | 6.73 ± 2.84 | 6.75 ± 2.71 | 6.73 ± 2.87 | 6.70 ± 2.65 | 6.73 ± 3.12 | 0.926 |
hs-CRP (mg/L) | 1.69 (0.66–5.31) | 0.86 (0.36–2.78) | 1.25 (0.24–3.95) | 1.58 (0.57–4.84) | 2.92 (1.03–7.43) | < 0.001* |
Medicine | | | | | | |
Antihypertension agents, n (%) | 2010 (86.1) | 483 (82.7) | 498 (85.3) | 509 (87.2) | 520(89.2) | 0.041* |
Antidiabetics agents, n (%) | 331 (14.2) | 23 (3.9) | 48 (8.2) | 96 (16.4) | 164(28.1) | < 0.001* |
Lipid-lowering agents, n (%) | 251 (10.7) | 29 (5.0) | 46 (7.9) | 70 (12.0) | 106(18.2) | < 0.001* |
BMI body mass index, CVD cardiovascular disease, FBG fasting blood glucose, TyG triglyceride glucose, HDL-C high density lipoprotein cholesterol, LDL-C low density lipoprotein cholesterol, eGFR estimated glomerular filtration rate, hs-CRP high-sensitivity C-reactive protein |
Factors Associated With Higher Tyg-bmi
Multivariate linear regression analysis showed that older age, male sex, history of CVD, higher albumin level, higher LDL-C level, and higher urine output were independently associated with higher TyG-BMI after adjusting for age, sex, history of CVD, urine output, SBP, DBP, hemoglobin, albumin, LDL-C, and use of lipid-lowering agents (P < 0.05) (Table 2).
Table 2
Association between TyG-BMI and reference parameters.
Variables | Unstandardized regression coefficient | Standardized regression coefficient | T | P value |
| B | Standard error | | | |
Age (years) | 0.497 | 0.053 | 0.214 | 9.288 | < 0.001* |
Sex (male vs. female) | -5.255 | 1.498 | -0.076 | -3.508 | < 0.001* |
History of CVD (yes vs. no) | 6.996 | 1.603 | 0.097 | 4.365 | < 0.001* |
Systolic pressure (mmHg) | -0.024 | 0.035 | -0.014 | -0.688 | 0.492 |
Hemoglobin (g/L) | -0.694 | 0.360 | -0.014 | -0.688 | 0.054 |
Albumin (g/L) | 4.841 | 1.534 | 0.073 | 3.157 | < 0.001* |
LDL-C (mg/dl) | 0.083 | 0.019 | 0.095 | 0.046 | < 0.001* |
Urine output (ml) | 0.007 | 0.001 | 0.132 | 6.172 | < 0.001* |
Lipid-lowering agents (yes vs. no) | 13.743 | 2.207 | 0.131 | 6.228 | < 0.001* |
CVD cardiovascular disease, LDL-C low density lipoprotein cholesterol |
Association Of Tyg-bmi With Cvd And All-cause Death
During the follow-up period of 46.6 (22.4–78.0) months, 615 (26.3%) deaths occurred. Furthermore, 426 (18.2%) patients were permanently transferred to hemodialysis, 595 (25.5%) received a kidney transplant, 86 (3.7%) were transferred to other centers, and 60 (2.6%) lost contact with our center. CVD (297; 48.3%) was the dominant cause of death. The remaining causes of death were infection (121; 19.7%), cachexia (36; 5.8%), malignancy (20; 3.3%), other reasons (72; 11.7%), and unknown reasons (69; 11.2%).
Kaplan-Meier estimates of CVD and all-cause mortality for patients among the quartiles of TyG-BMI are shown in Fig. 2. At the end of 1, 3, and 5 years, CVD mortality rates were 2.5, 5.1, and 9.7% in the Q1 group; 0.9, 6.1, and 11.0% in the Q2 group; 1.7, 6.2, and 12.1% in the Q3 group; and 1.7, 8.6, and 19.7% in the Q4 group, respectively. Patients with highest level of TyG-BMI (Q4 group) had a significantly raised CVD mortality rate compared to those in the Q1 group (P < 0.001) (Fig. 2a). The all-cause mortality rates were 4.0, 10.4, and 20.1% in the Q1 group; 2.7, 12.4, and 21.0% in the Q2 group; 4.1, 11.9, and 23.8% in the Q3 group; and 2.9, 14.8, and 31.2% in the Q4 group, respectively. Patients with highest level of TyG-BMI (Q4 group) had a higher rate of all-cause mortality compared with those in the Q1 group (P < 0.001) (Fig. 2b).
The results of the Cox regression analysis shown that TyG-BMI in Q4 was markedly associated with an increased risk of CVD mortality (HR 1.51, 95%CI 1.05–2.17; P = 0.027) and all-cause mortality (HR 1.36, 95%CI 1.05–1.75; P = 0.018) in comparison with Q1 in the final adjusted model. After full adjustment, a TyG-BMI increase of 1-standard deviation (SD) (34.2) was associated with a 28% higher risk (95%CI = 1.13–1.45; P < 0.001) and a 19% higher risk (95%CI = 1.09–1.31; P < 0.001) of CVD and all-cause death, respectively (Table 3).
Table 3
Association between TyG-BMI and CVD /all-cause mortality.
| Model 1 | Model 2 | Model 3 |
HR (95%CI) | P value | HR (95%CI) | P value | HR (95%CI) | P value |
| CVD mortality |
TyG-BMI (per SD increase ) | 1.38(1.24–1.53) | < 0.001* | 1.24(1.10–1.39) | < 0.001* | 1.28(1.13–1.45) | < 0.001* |
Quartile 2 | 1.47 (1.03–2.10) | 0.036* | 0.97 (0.68–1.40) | 0.883 | 0.93 (0.62–1.37) | 0.700 |
Quartile 3 | 1.40 (0.98-2.00) | 0.068 | 0.83 (0.58–1.20) | 0.323 | 0.80 (0.54–1.20) | 0.280 |
Quartile 4 | 2.46 (1.77–3.42) | < 0.001* | 1.50 (1.08–2.10) | 0.016* | 1.51 (1.05–2.17) | 0.027* |
All-cause mortality |
TyG-BMI (per SD increase ) | 1.28(1.19–1.38) | < 0.001* | 1.21(1.03–1.22) | 0.008* | 1.19(1.09–1.31) | < 0.001* |
Quartile 2 | 1.32 (1.04–1.69) | 0.023* | 0.92 (0.72–1.18) | 0.501 | 0.91 (0.69–1.19) | 0.487 |
Quartile 3 | 1.42 (1.12–1.80) | 0.004* | 0.85 (0.67–1.08) | 0.194 | 0.91 (0.70–1.19) | 0.503 |
Quartile 4 | 2.00 (1.59–2.51) | < 0.001* | 1.23 (0.98–1.55) | 0.080 | 1.36 (1.05–1.75) | 0.018* |
HR, hazard ratio |
CI, confidence interval |
SD, standard deviation |
Reference group was Quartile 1 |
Model 1: Unadjusted |
Model 2: Adjusted for age, sex, systolic pressure, and history of CVD |
Model 3: Adjusted for model 2 covariates and hemoglobin, serum albumin, LDL-C, urine output and use of lipid-lowering agents |
*P < 0.05 |
Subgroup analysis displayed higher TyG-BMI was associated with a higher CVD mortality risk in patients aged < 65 years (adjusted HR 1.36, 95%CI 1.17–1.58; P < 0.001), those with diabetes (adjusted HR 1.31, 95%CI 1.09–1.57; P = 0.004), and those with a history of CVD (adjusted HR 1.34, 95%CI 1.21–1.59; P = 0.001) (Fig. 3a). TyG-BMI was also associated analogously with all-cause death risk in patients aged < 65 years (adjusted HR 1.32, 95%CI 1.19–1.47; P < 0.001) as well as those with diabetes (adjusted HR 1.18, 95%CI 1.04–1.34; P = 0.013) (Fig. 3b).