Baseline characteristics
The characteristics of the participants were assessed by the tertiles of RC in Table 1. In the whole cohort of 8782 subjects (46.4% males), mean age was 53.2 ± 10.4 years. The mean BMI was 24.7 ± 3.6 kg/m2, 47.3% had HTN, 8.4% had diabetes.
Table 1. Baseline Characteristics by Tertiles of remnant cholesterol
|
Total
n=8782
|
Remnant cholesterol
|
p-value
|
Tertile I (n=2949)
|
Tertile II (n=2932)
|
Tertile III (n=2901)
|
Age(year)
|
53.2±10.4
|
52.2±10.6
|
52.7±10.4
|
54.7±10.0
|
<0.001
|
Male (%)
|
4075(46.4)
|
1432(48.6)
|
1343(45.8)
|
1300(44.8)
|
0.012
|
Ethnicity of Han (%)
|
8277(94.2)
|
2664(90.3)
|
2820(96.2)
|
2793(96.3)
|
<0.001
|
Current smoking (%)
|
3118(35.5)
|
1121(38.0)
|
1022(34.9)
|
975(33.6)
|
0.001
|
Current drinking alcohol (%)
|
1992(22.7)
|
755(25.6)
|
619(21.1)
|
618(21.3)
|
<0.001
|
Physical activity
|
Low
|
2964(33.8)
|
819(27.8)
|
1033(35.2)
|
1112(38.3)
|
<0.001
|
Medium
|
1652(18.8)
|
566(19.2)
|
581(19.8)
|
505(17.4)
|
High
|
4091(46.6)
|
1534(52.0)
|
1290(44.0)
|
1267(44.0)
|
BMI (kg/m2)
|
24.7±3.6
|
24.7±3.8
|
24.4±3.6
|
24.8±3.5
|
<0.001
|
HTN (%)
|
4154(47.3)
|
1141(38.7)
|
965(32.9)
|
911(31.4)
|
<0.001
|
DM (%)
|
738(8.4)
|
201(6.8)
|
212(7.2)
|
325(11.2)
|
<0.001
|
SBP (mmHg)
|
140.5±22.7
|
144.0±24.3
|
137.1±21.6
|
140.3±21.5
|
<0.001
|
DBP (mmHg)
|
81.6±11.5
|
81.1±11.8
|
81.1±11.5
|
82.6±11.3
|
<0.001
|
FBG (mmol/l)
|
5.8±1.5
|
5.6±1.4
|
5.8±1.7
|
5.8±1.3
|
<0.001
|
TC (mmol/l)
|
5.2±1.0
|
4.7±0.9
|
5.0±0.8
|
5.8±1.0
|
<0.001
|
TG (mmol/l)
|
1.4±0.8
|
1.1±0.5
|
1.3±0.7
|
1.8±0.8
|
<0.001
|
HDL-C(mmol/l)
|
1.4±0.3
|
1.6±0.4
|
1.3±0.3
|
1.3±0.3
|
<0.001
|
LDL-C (mmol/l)
|
2.9±0.8
|
2.8±0.8
|
2.8±0.7
|
3.1±0.8
|
<0.001
|
Estimated eGFR (ml/min/1.73m2)
|
94.1±15.1
|
101.6±13.2
|
92.3±14.3
|
88.2±14.4
|
<0.001
|
Serum uric acid (μmol/l)
|
285.6±81.5
|
260.7±73.8
|
284.8±79.5
|
290.4±78.5
|
<0.001
|
RC (mmol/l)
|
0.83±0.44
|
0.36±0.16
|
0.84±0.10
|
1.32±0.30
|
<0.001
|
BMI: body mass index; DBP: diastolic blood pressure; DM: diabetes mellitus; FPG: fasting plasma glucose; GFR: glomerular; filtration rate; HDL-C: high-density lipoprotein cholesterol; HTN, hypertension; LDL-C: low-density lipoprotein cholesterol; RC: remnant cholesterol; SBP: systolic blood pressure; SD: standard deviation; TC: total cholesterol; TG: triglyceride.
Data are expressed as mean±SD or as n (%).
The mean concentration of RC was 0.8 ± 0.4 mmol/l. According to RC level, all participants were divided into three groups: tertile I (RC < 0.65 mmol/l), tertile II (RC 0.65-1.00mmol/l), and tertile III (RC ≥ 1.00mmol/l). Across tertiles of RC, age, serum level of lipids (TC and TG), uric acid, and proportion of DM increased gradually (all P < 0.001), whereas the level of eGFR, proportions of male, HTN, and current smoking significantly declined (all P < 0.05). HDL-C concentration and the proportion of current alcohol was significantly higher (both P < 0.001) in tertile I than those of other two groups (P < 0.001). LDL-C concentration was significantly higher in tertile III.
Survival analyses for different level of RC
After the median follow-up time of 4.66 years, a total of 431 CVD events occurred in the studied population (293 stroke cases, 150 CHD cases, and 71 myocardial infarction cases), including 148 fatal CVD cases. The Kaplan-Meier curves for each endpoint in participants with different levels of RC are shown in Figure 1. Participants in high level of RC (tertile III) had significantly higher cumulative incidences of combined CVD (P = 0.0019), CHD (P = 0.0101), stroke (P = 0.0448), and fatal CVD (P = 0.0465) compared to those in tertile II.
Table 2 shows the multivariable adjusted HRs for combined CVD, fatal CVD, stroke, and CHD incidence by RC concentration. In the categorial analysis of RC, risks for combined CVD (HR: 1.37; 95% CI: 1.07-1.74) and CHD (HR: 1.63; 95% CI: 1.06-2.53) were significantly higher among participants in tertile III, compared with those in tertile II after full adjustment. Whether adjustment or not, categorial concentration of RC had no significant influence on stroke or fatal CVD. In the continuous analysis, high level of RC significantly related with a 28% increased risk of combined CVD (HR: 1.28; 95% CI: 1.02-1.62) and a 51% increased risk of fatal CVD (HR: 1.51; 95% CI: 1.05-2.17) after full adjustment. Significantly higher stroke risk was found for participants in tertile III after adjustment for model 1(HR: 1.31; 95% CI: 1.03-1.67) and model 2 (HR: 1.30; 95% CI: 1.02-1.67). No significant association was found between continuous RC and CHD. The results were similar when intensity of physical activity was additionally adjusted (data not shown).
Table 2. Multivariate-adjusted hazard ratios and 95% confidence intervals for cardiovascular outcomes associated with baseline remnant cholesterol
|
RC Q1
|
RC Q2
|
RC Q3
|
RC continuous(1-SD†)
|
Combined CVD
|
|
|
|
|
n/N
|
139/2191
|
117/2932
|
175/2901
|
431/8782
|
Model 1
|
1.23(0.96-1.57)
|
1.00 (ref)
|
1.49(1.18-1.89)**
|
1.33 (1.09-1.63)**
|
Model 2
|
1.22(0.95-1.57)
|
1.00 (ref)
|
1.49(1.18-1.89)**
|
1.32 (1.08-1.62)**
|
Model 3
|
1.16 (0.90-1.50)
|
1.00 (ref)
|
1.37(1.07-1.74)*
|
1.28(1.02-1.62)*
|
CHD
|
|
|
|
|
n/N
|
55/2191
|
34/2932
|
61/2901
|
150/8782
|
Model 1
|
1.77(1.15-2.74)*
|
1.00 (ref)
|
1.71(1.12-2.61)*
|
1.17(0.82-1.67)
|
Model 2
|
1.74(1.12-2.70)*
|
1.00 (ref)
|
1.71(1.12-2.61)*
|
1.16(0.81-1.66)
|
Model 3
|
1.68(1.08-2.62)*
|
1.00 (ref)
|
1.63(1.06-2.53)*
|
1.15(0.76-1.74)
|
Stroke
|
|
|
|
|
n/N
|
88/2191
|
87/2932
|
118/2901
|
293/8782
|
Model 1
|
1.04(0.77-1.40)
|
1.00 (ref)
|
1.30(0.98-1.72)
|
1.31(1.03-1.67)*
|
Model 2
|
1.04(0.77-1.41)
|
1.00 (ref)
|
1.31(0.98-1.73)
|
1.30(1.02-1.67)*
|
Model 3
|
0.99(0.73-1.35)
|
1.00 (ref)
|
1.19(0.89-1.59)
|
1.25(0.94-1.66)
|
Fatal CVD
|
|
|
|
|
n/N
|
41/2191
|
44/2932
|
63/2901
|
148/8782
|
Model 1
|
0.97(0.64-1.49)
|
1.00 (ref)
|
1.394(0.95-2.05)
|
1.44(1.05-1.97)*
|
Model 2
|
0.95(0.62-1.46)
|
1.00 (ref)
|
1.421(0.97-2.09)
|
1.47(1.07-2.01)*
|
Model 3
|
0.90(0.58-1.39)
|
1.00 (ref)
|
1.37(0.92-2.05)
|
1.51(1.05-2.17)*
|
CHD: coronary heart disease; CVD: cardiovascular disease; RC remnant cholesterol
Model 1: adjusted for age (<65 years vs. ≥ 65 years), sex and ethnicity (Han or not). Model 2: adjusted for factors in model 1 and smoking status, drinking status, body mass index (normal, overweight, obesity). Model 3: adjusted for factors in model 2 and estimated glomerular filtration rate (< 60ml/min/1.73m2 vs. ≥ 60 ml/min/1.73m2), diabetes mellites (yes or no), hypertension (yes or no), triglyceride (continuous), hyperuricemia (yes or no).
†HR for continuous 1-SD increment. *P < 0.05; **P < 0.01
Stratification analyses
The relationships between RC and outcomes were assured between RC categorical groups (tertile II as reference), stratified with sex, age (<65 years vs. ≥ 65 years), smoking status (current smoker or no), drinking status (current drinker or no), BMI subgroups (normal, overweight, obesity), DM (yes or no), HTN (yes or no), renal dysfunction (eGFR < 60 ml/min/1.73m2 vs. eGFR ≥ 60 ml/min/1.73m2), hyperuricemia (yes or no). Due to small number of nationality other than Han, there was no subgroup comparisons for nationality. After full adjustment of other factors, CVD were more likely to be happened in the following subgroups of tertile III (Figure 2): females (HR:1.515, 95%CI:1.043-2.201), participants with age < 65years (HR:1.547, 95%CI:1.127-2.123), non-current smokers (HR:1.482, 95%CI:1.064-2.062), non-current drinkers (HR:1.431, 95%CI:1.079-1.898), normal BMI subgroup (HR:1.486, 95%CI:1.046-2.110), renal dysfunction subgroup (HR:1.357, 95%CI:1.050-1.752), and no hyperuricemia subgroup (HR:1.439, 95%CI:1.101-1.880). Same trends for CHD were found among subgroups in tertile III: participants with age <65 years, overweight subgroup, renal dysfunction subgroup, and normal uric acid subgroup (Supplementary Figure 2). For participants in tertile III, males had significantly higher risk for CHD (HR:2.170, 95%CI:1.038-4.537), and females had more probability of stroke (HR:1.643, 95%CI:1.010-2.686) compared to those in tertile II (Supplementary Figure 3). Compared with the reference, low level of RC (tertile I) also increased the risk for CHD in subgroups under 65 years, no current smoking, no current drinking, BMI 25-30kg/m2, renal dysfunction, normal uric acid (Supplementary Figure 4). No significant differences were found for fatal CVD between tertile II and tertile III, and combined CVD, stroke, and fatal CVD between tertile I and tertile II (data not shown).
Dose-response analyses of RC with cardiovascular outcomes
Dose-response analyses were implemented with RCS to investigate optimal level of RC for each outcome (Figure 3). Multivariable adjusted RCS analyses showed significant overall associations between RC and combined CVD (Poverall = 0.0324), or RC and CHD (Poverall = 0.0398). Significantly linear relationship (Plinear = 0.0225) between RC and combined CVD, and non-linear relationship (Pnon-linear = 0.0221) between RC and CHD are found for all participants. The risk of combined CVD was relatively flat until around 0.84mmol/l (32.76mg/dl) of RC and then started to increase rapidly afterwards. For participants with higher level of RC than 0.84mmol/l, the HR of combined CVD and CHD per standard deviation was 1.308 (1.102 to 1.553) and 1.411 (1.061 to 1.876), respectively.
Non-linear associations between RC and lnHRs for outcomes stratified by subgroups (age < 65 years or ≥ 65 years, DM or not) are shown in Figure 4. Significant nonlinearity association and “J” shape curves were shown for combined CVD (Pnon-linear = 0.0059) and CHD (Pnon-linear = 0.0002) in participants with age < 65 years (Figure 4. A). Meanwhile, linear association was found between RC and lnHR for fatal CVD (Plinear = 0.0104). A 50.7% increase risk for combined CVD, a 57.0% increase risk for CHD, and a 2.0% increase risk for fatal CVD were found for participants under 65 years with serum level of RC > 0.83mmol/l. The same trend was found for participants with DM and serum level of RC > 0.95mmol/l (Figure 4. B).