Table 1. Characteristics of participants by quartiles of C-reactive Protein
|
Overall
|
C-reactive Proteina
|
P
|
Q1
|
Q2
|
Q3
|
Q4
|
0.27
(0.17, 0.36)
|
0.75
(0.61, 0.93)
|
1.76
(1.40, 2.21)
|
6.59
(4.07, 14.74)
|
No. of participants
|
2206
|
564
|
547
|
544
|
551
|
|
Age, median (IQR), years
|
93 (86, 100)
|
93 (87, 100)
|
92 (85, 100)
|
92 (86, 100)
|
94 (88, 100)
|
0.389
|
Female, n (%)
|
1417 (64.23)
|
405 (71.81)
|
344 (62.89)
|
336 (61.76)
|
332 (60.25)
|
0.000
|
Residence, n (%)
|
|
|
|
|
|
0.102
|
Urban
|
280 (12.81)
|
64 (11.43)
|
58 (10.70)
|
78 (14.42)
|
80 (14.76)
|
|
Rural
|
1905 (87.19)
|
496 (88.57)
|
484 (89.30)
|
463 (85.58)
|
462 (85.24)
|
|
Education time, years
|
|
|
|
|
|
0.706
|
0
|
1714 (78.41)
|
444 (79.86)
|
417 (76.94)
|
424 (78.23)
|
429 (78.57)
|
|
≥1
|
472 (21.59)
|
112 (20.14)
|
125 (23.06)
|
118 (21.77)
|
117 (21.43)
|
|
Smoking status, n (%)
|
|
|
|
|
|
0.986
|
Current
|
220 (10.22)
|
56 (10.13)
|
53 (9.98)
|
54 (10.13)
|
57 (10.63)
|
|
Not current
|
1933 (89.78)
|
497 (89.87)
|
478 (90.02)
|
479 (89.87)
|
479 (89.37)
|
|
Alcohol drinking status, n (%)
|
|
|
|
|
|
0.780
|
Current
|
254 (11.81)
|
68 (12.34)
|
67 (12.64)
|
61 (11.47)
|
58 (10.80)
|
|
Not current
|
1896 (88.19)
|
483 (87.66)
|
463 (87.36)
|
471 (88.53)
|
479 (89.20)
|
|
Frequent vegetable intake, n (%)b
|
1240 (57.57)
|
309 (55.98)
|
325 (61.21)
|
315 (59.10)
|
291 (54.09)
|
0.085
|
Frequent fruit intake, n (%)b
|
795 (36.75)
|
223 (40.11)
|
205 (38.46)
|
203 (37.94)
|
164 (30.43)
|
0.005
|
Frequent meat intake, n(%)b
|
1024 (48.51)
|
251 (45.72)
|
271 (52.62)
|
277 (53.47)
|
225 (42.53)
|
0.000
|
Habitual exercise, n (%)c
|
263 (12.51)
|
82 (15.27)
|
63 (12.14)
|
61 (11.66)
|
57 (10.90)
|
0.146
|
Medical history
|
|
|
|
|
|
|
Hypertension, n (%)
|
841 (38.12)
|
254 (45.04)
|
201 (36.75)
|
191 (35.11)
|
195 (35.39)
|
0.000
|
Diabetes, n (%)
|
189 (8.57)
|
34 (6.03)
|
38 (6.95)
|
58 (10.66)
|
36 (6.53)
|
0.005
|
CVD, n (%)
|
311 (14.10)
|
71 (12.59)
|
69 (12.61)
|
83 (15.26)
|
88 (15.97)
|
0.405
|
Frailty
|
|
|
|
|
|
0.002
|
Frail, n (%)
|
740 (33.54)
|
194 (34.40)
|
159 (29.07)
|
168 (30.88)
|
219 (39.75)
|
|
Prefrail, n (%)
|
753 (34.13)
|
193 (34.22)
|
189 (34.55)
|
186 (34.19)
|
185 (33.58)
|
|
Robust, n (%)
|
713 (32.32)
|
177 (31.38)
|
199 (36.38)
|
190 (34.93)
|
147 (26.68)
|
|
MMSE, median (IQR)
|
25 (18, 28)
|
25 (17, 28)
|
26 (19, 28)
|
26 (19, 28)
|
24 (16, 28)
|
0.321
|
BMI, median (IQR), kg/m2
|
20.00
(17.78, 22.81)
|
19.48
(17.58, 22.03)
|
20.41
(18.29, 23.45)
|
20.34
(18.03, 22.96)
|
19.93
(17.78, 22.75)
|
0.461
|
Systolic pressure, median (IQR), mmHg
|
140 (126, 160)
|
143 (130, 160)
|
140 (128, 160)
|
141.5 (127.5, 160)
|
140 (121, 155.5)
|
0.000
|
Total cholesterol, median (IQR), mmol/L
|
4.31 (3.67, 5.02)
|
4.38 (3.68, 5.02)
|
4.33 (3.75, 5.02)
|
4.43 (3.78, 5.17)
|
4.07 (3.5, 4.83)
|
0.014
|
Triglycerides, median (IQR), mmol/L
|
0.86 (0.64, 1.19)
|
0.83 (0.61, 1.12)
|
0.88 (0.66, 1.23)
|
0.92 (0.67, 1.28)
|
0.84 (0.63, 1.17)
|
0.132
|
Glucose, median (IQR), mmol/L
|
4.68 (4.00, 5.45)
|
4.48 (3.89, 5.17)
|
4.71 (4.07, 5.45)
|
4.80 (4.10, 5.54)
|
4.69 (3.96, 5.67)
|
0.001
|
a Quartiles of C-reactive Protein: median (IQR), mg/L
b “Frequent intake” was defined by the frequencies of “almost every day” or “often”.
c “Habitual exercise” was defined as “exercise at present”.
Table 2. Association between CRP and all-cause mortality
|
HR [95% CI]a for all-cause mortality
|
Model 1
|
Model 2
|
Model 3
|
Risk by quartiles
|
|
|
|
Q1
|
1.00 (reference)
|
1.00 (reference)
|
1.00 (reference)
|
Q2
|
1.15 (0.94, 1.40)
|
1.10 (0.89, 1.36)
|
1.17 (0.94, 1.46)
|
Q3
|
1.27 (1.03, 1.55)
|
1.24 (1.00, 1.53)
|
1.28 (1.01, 1.61)
|
Q4
|
1.54 (1.27, 1.86)
|
1.50 (1.23, 1.84)
|
1.50 (1.20, 1.87)
|
P-trend
|
0.000
|
0.000
|
0.000
|
Risk by levels
|
|
|
|
<1.0
|
1.000 (reference)
|
1.000 (reference)
|
1.000 (reference)
|
1-3.0
|
1.171 (0.98, 1.39)
|
1.18 (0.98, 1.41)
|
1.17 (0.96, 1.42)
|
>3.0 mg/L
|
1.45 (1.22. 1.71)
|
1.44 (1.21, 1.73)
|
1.39 (1.15, 1.70)
|
P-trend
|
0.000
|
0.000
|
0.001
|
a HR: hazard ratio; CI: confidence interval;
Model 1: adjusted for age, sex.
Model 2: adjusted for age, sex, education, residence, smoking, drinking, exercise, fruit intake, meat intake, vegetable intake.
Model 3: adjusted for age, sex, education, residence, smoking, drinking, exercise, fruit intake, meat intake, vegetable intake, BMI, MMSE, frailty, hypertension, diabetes, CVD, cholesterol, triglycerides.
Table 3. Subgroup analyses for the hazard ratio of all-cause mortality for each 10 mg/L increase in CRP
Subgroup
|
HR [95%CI]a
|
P-interaction
|
Age
|
|
0.214
|
80+ years
|
1.02 (0.85, 1.23)
|
|
90+ years
|
1.04 (0.93, 1.16)
|
|
100+ years
|
1.23 (1.05, 1.45)
|
|
Sex
|
|
0.135
|
Woman
|
1.16 (1.04, 1.29)
|
|
Man
|
0.98 (0.87, 1.10)
|
|
Education time
|
|
0.226
|
0 year
|
1.11 (1.02, 1.20)
|
|
≥1 year
|
0.92 (0.68, 1.24)
|
|
Residence
|
|
0.418
|
Urban
|
0.95 (0.76, 1.18)
|
|
Rural
|
1.10 (1.01, 1.19)
|
|
Smoking status
|
|
0.011
|
Current
|
0.83 (0.66, 1.03)
|
|
Not current
|
1.17 (1.07, 1.28)
|
|
Drinking status
|
|
0.446
|
Current
|
0.98 (0.68, 1.40)
|
|
Not current
|
1.08 (0.10, 1.17)
|
|
Habitual exercise
|
|
0.820
|
Yes
|
1.02 (0.63 1.67)
|
|
No
|
1.08 (1.00, 1.17)
|
|
Vegetable intake
|
|
0.289
|
Often
|
1.16 (1.00, 1.34)
|
|
Not often
|
1.05 (0.95, 1.16)
|
|
Fruit intake
|
|
0.125
|
Often
|
1.18 (0.98, 1.43)
|
|
Not often
|
1.03 (0.94, 1.13)
|
|
Meat intake
|
|
0.646
|
Often
|
1.07 (0.89, 1.29)
|
|
Not often
|
1.09 (1.00, 1.18)
|
|
BMI
|
|
0.798
|
<18.5
|
1.14 (0.98, 1.32)
|
|
≥18.5 and <24
|
1.04 (0.94, 1.16)
|
|
≥24
|
0.99 (0.73, 1.35)
|
|
MMSE scores
|
|
0.556
|
<24
|
1.10 (1.00, 1.21)
|
|
≥24
|
1.05 (0.91, 1.21)
|
|
Frailty
|
|
0.784
|
Frail
|
1.08 (0.95, 1.22)
|
|
Prefrail
|
1.10 (0.97, 1.25)
|
|
Robust
|
1.00 (0.81, 1.23)
|
|
a HR: hazard ratio; CI: confidence interval.
HRs were adjusted for age, sex, education, residence, smoking, drinking, exercise, fruit intake, meat intake, vegetable intake, BMI, MMSE, frailty, hypertension, diabetes, CVD, cholesterol, triglycerides.