Association Between C-Reactive Protein and Albumin Ratios and Risk of Mortality in Patients with Chronic Obstructive Pulmonary Disease

Figures & data

Figure 1 Diagram flow of data screening and population selection.

Table 1 Characteristics of Study Participants

Variables	Total (n=1210)	5 Years of Survival		Statistics	P
		Alive (n=1100)	Dead (n=110)
Age, years, Mean (S.E)	54.84 (0.61)	54.48 (0.65)	59.29 (2.63)	t=−1.73	0.093
Age (years), n (%)				χ^2=0.200	0.655
<45	217 (21.00)	206 (21.24)	11 (17.98)
>=45	993 (79.00)	894 (78.76)	99 (82.02)
Gender, n (%)				χ^2=3.608	0.057
Male	774 (61.03)	698 (60.22)	76 (71.19)
Female	436 (38.97)	402 (39.78)	34 (28.81)
Race, n (%)				χ^2=7.960	0.093
Mexican American	104 (2.81)	97 (2.86)	7 (2.20)
Other Hispanic	81 (2.23)	78 (2.35)	3 (0.76)
Non-Hispanic White	784 (82.89)	706 (82.73)	78 (84.83)
Non-Hispanic Black	198 (7.52)	179 (7.28)	19 (10.47)
Other races-including multiracial	43 (4.56)	40 (4.78)	3 (1.74)
Education level, n (%)				χ^2=15.142	0.004
Less than 9th grade	135 (4.98)	120 (4.65)	15 (9.17)
9th-11th grade	231 (14.65)	204 (14.00)	27 (22.86)
High school grade	335 (28.29)	309 (28.61)	26 (24.17)
Some college or AA degree	282 (27.16)	258 (27.07)	24 (28.32)
College graduate or above	227 (24.92)	209 (25.67)	18 (15.48)
Marital status, n (%)				χ^2=18.468	0.002
Married	704 (62.99)	655 (64.27)	49 (46.90)
Widowed	113 (7.02)	92 (6.28)	21 (16.33)
Divorced	179 (12.41)	157 (11.78)	22 (20.30)
Separated	32 (1.88)	28 (1.78)	4 (3.21)
Never married	95 (8.07)	88 (8.28)	7 (5.44)
Living with partner	87 (7.62)	80 (7.60)	7 (7.82)
PIR, n (%)				χ^2=1.211	0.546
<1.3	341 (16.87)	303 (16.56)	38 (20.76)
>=1.3	780 (76.69)	717 (77.00)	63 (72.72)
Unknown	89 (6.44)	80 (6.43)	9 (6.52)
BMI, kg/m^2, n (%)				χ^2=8.075	0.018
<=24.99	434 (37.05)	392 (36.65)	42 (42.04)
>=25–29.9	425 (36.71)	397 (37.96)	28 (21.00)
>=30	351 (26.24)	311 (25.39)	40 (36.97)
Smoking status, n (%)				χ^2=4.950	0.084
Never	343 (30.76)	324 (31.77)	19 (18.10)
Current smoking	442 (35.04)	399 (34.50)	43 (41.92)
Quit smoking	425 (34.19)	377 (33.73)	48 (39.98)
Hypertension, n (%)				χ^2=2.647	0.104
No	398 (39.57)	377 (40.74)	21 (24.85)
Yes	812 (60.43)	723 (59.26)	89 (75.15)
Diabetes, n (%)				χ^2=6.972	0.008
No	968 (85.38)	892 (86.13)	76 (75.95)
Yes	242 (14.62)	208 (13.87)	34 (24.05)
Dyslipidemia, n (%)				χ^2=0.383	0.536
No	252 (20.71)	233 (20.95)	19 (17.78)
Yes	958 (79.29)	867 (79.05)	91 (82.22)
CVD, n (%)				χ^2=3.601	0.058
No	1031 (88.56)	947 (89.12)	84 (81.50)
Yes	179 (11.44)	153 (10.88)	26 (18.50)
Close relative had heart attack, n (%)				χ^2=0.028	0.868
No	1041 (87.50)	945 (87.55)	96 (86.88)
Yes	169 (12.50)	155 (12.45)	14 (13.12)
CKD, n (%)				χ^2=14.723	<0.001
No	1129 (95.12)	1034 (95.77)	95 (87.03)
Yes	81 (4.88)	66 (4.23)	15 (12.97)
Chronic bronchitis, n (%)				χ^2=0.493	0.483
No	1105 (92.53)	1006 (92.67)	99 (90.73)
Yes	105 (7.47)	94 (7.33)	11 (9.27)
Asthma, n (%)				χ^2=2.917	0.088
No	963 (78.77)	869 (78.13)	94 (86.80)
Yes	247 (21.23)	231 (21.87)	16 (13.20)
Intestines problem, n (%)				χ^2=4.666	0.097
No	1052 (87.40)	951 (86.89)	101 (93.75)
Chronic constipation	61 (5.37)	59 (5.67)	2 (1.59)
Chronic diarrhea	97 (7.23)	90 (7.43)	7 (4.66)
Cancer, n (%)				χ^2=0.142	0.706
No	1024 (83.80)	932 (83.94)	92 (82.03)
Yes	186 (16.20)	168 (16.06)	18 (17.97)
Segmented neutrophils num, 1000 cell/UL, Mean (S.E)	4.41 (0.06)	4.37 (0.05)	4.98 (0.19)	t=−3.30	0.002
Lymphocyte number, 1000 cells/UL, Mean (S.E)	2.07 (0.02)	2.07 (0.02)	2.10 (0.08)	t=−0.37	0.715
Eosinophils number, 1000 cells/UL, Mean (S.E)	0.22 (0.01)	0.22 (0.01)	0.22 (0.02)	t=0.13	0.898
ALT, U/L, Mean (S.E)	25.42 (0.53)	25.54 (0.57)	23.85 (1.49)	t=1.02	0.314
AST, U/L, Mean (S.E)	26.29 (0.31)	26.24 (0.30)	26.87 (1.18)	t=−0.54	0.595
Bronchodilator, n (%)				χ^2=0.001	0.971
No	1060 (88.57)	966 (88.56)	94 (88.71)
Yes	150 (11.43)	134 (11.44)	16 (11.29)
ICS, n (%)				χ^2=0.853	0.356
No	1142 (94.44)	1041 (94.65)	101 (91.87)
Yes	68 (5.56)	59 (5.35)	9 (8.13)
COPD severity, n (%)				χ^2=8.256	0.004
Mild	647 (56.75)	605 (57.88)	42 (42.63)
Moderate-severe	563 (43.25)	495 (42.12)	68 (57.37)
Baseline FEV1, mL, Mean (S.E)	2662.52 (34.06)	2678.60 (34.07)	2460.66 (156.98)	t=1.36	0.182
Baseline FVC, mL, Mean (S.E)	4153.23 (48.50)	4170.36 (48.85)	3938.07 (221.84)	t=1.03	0.311
ALB, g/L, Mean (S.E)	42.68 (0.10)	42.73 (0.11)	42.01 (0.44)	t=1.49	0.147
CRP, mg/dL, Mean (S.E)	0.40 (0.04)	0.38 (0.04)	0.63 (0.14)	t=−1.79	0.083
CAR*100, Mean (S.E)	0.99 (0.10)	0.94 (0.10)	1.61 (0.38)	t=−1.69	0.100
Log (CAR*100), Mean (S.E)	−0.91 (0.04)	−0.95 (0.04)	−0.46 (0.11)	t=−4.24	<0.001
Log (CAR*100), n (%)				χ^2=17.696	<0.001
<-1.80	282 (24.65)	268 (25.26)	14 (16.93)
−1.80 to −0.97	273 (25.12)	248 (25.32)	25 (22.61)
−0.97 to −0.11	297 (25.08)	277 (25.72)	20 (17.07)
≥-0.11	358 (25.15)	307 (23.70)	51 (43.39)
Follow-up, months, Mean (S.E)	57.76 (0.33)	60.00 (0.00)	29.69 (1.85)	t=16.38	<0.001

Abbreviations: AA, associate of arts; PIR, poverty income ratio; BMI, body mass index; CVD, cardiovascular disease; CKD, chronic kidney disease; ALT, Alanine aminotransferase; AST, Aspartate aminotransferase; ICS, inhaled corticosteroids; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; ALB, albumin; CRP, C-reactive protein; CAR, CRP to ALB ratio; χ2, Chi-square test; t, t test.

Figure 2 The KM curve of the survival in different CAR groups.

Table 2 Association Between CAR and Risk of 5-Year Mortality in Patients with COPD

Variables	Model 1		Model 2		Model 3
	HR (95% CI)	P	HR (95% CI)	P	HR (95% CI)	P
Log (CAR*100)	1.33 (1.16–1.51)	0.001	1.17 (1.01–1.36)	0.038	1.19 (1.02–1.38)	0.028
Log (CAR*100)
<-1.80	Ref		Ref		Ref
−1.80 to −0.97	1.32 (0.69–2.51)	0.394	1.29 (0.69–2.43)	0.416	1.23 (0.66–2.28)	0.510
−0.97 to −0.11	0.99 (0.46–2.13)	0.985	0.94 (0.40–2.22)	0.879	0.92 (0.38–2.18)	0.837
≥-0.11	2.64 (1.52–4.60)	0.001	1.96 (1.11–3.49)	0.023	1.94 (1.07–3.50)	0.029

Notes: Model 1 was an unadjusted model; model 2 adjusted for education level, marital status, BMI, smoking status, diabetes, CKD, and segmented neutrophils num; model 3 adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS.

Abbreviations: Ref, Reference; HR, hazard ratio; CI, confidence interval; COPD, chronic obstructive pulmonary disease; CAR, C-reactive protein (CRP) to albumin (ALB) ratio.

Table 3 Subgroup Analyses of the Association Between CAR and the Risk of Mortality in Patients with COPD

Subgroups	Variables	Model 1			Model 2			Model 3
		HR (95% CI)		P	HR (95% CI)		P	HR (95% CI)		P
COPD Severity
Mild	Log (CAR*100)	1.53 (1.19–1.96)		0.002	1.52 (1.13–2.06)		0.007	1.46 (1.05–2.02)		0.025
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.39 (0.42–4.65)		0.580	1.59 (0.44–5.69)		0.468	1.36 (0.31–6.06)		0.678
	3: −0.97–−0.11	1.26 (0.38–4.17)		0.692	1.25 (0.35–4.47)		0.724	1.01 (0.29–3.49)		0.991
	4: ≥−0.11	3.99 (1.36–11.73)		0.014	3.59 (1.12–11.55)		0.033	3.00 (0.89–10.15)		0.075
Moderate-Severe	Log (CAR*100)	1.15 (0.94–1.40)		0.164	1.01 (0.82–1.22)		0.998	1.01 (0.81–1.24)		0.980
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.15 (0.44–2.98)		0.768	0.94 (0.35–2.48)		0.891	0.90 (0.36–2.22)		0.809
	3: −0.97–−0.11	0.75 (0.32–1.76)		0.498	0.62 (0.25–1.54)		0.293	0.67 (0.28–1.62)		0.364
	4: ≥−0.11	1.60 (0.70–3.65)		0.257	1.14 (0.51–2.56)		0.736	1.16 (0.49–2.73)		0.728
BMI
<=24.99	Log (CAR*100)	1.44 (1.19–1.75)		<0.001	1.32 (1.05–1.66)		0.019	1.32 (1.02–1.72)		0.036
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	0.99 (0.36–2.77)		0.998	0.83 (0.30–2.25)		0.702	0.65 (0.29–1.44)		0.276
	3: −0.97–−0.11	1.71 (0.60–4.85)		0.304	1.46 (0.44–4.80)		0.521	1.04 (0.34–3.26)		0.938
	4: ≥−0.11	3.62 (1.63–8.03)		0.002	2.43 (1.16–5.13)		0.021	2.20 (1.06–4.55)		0.035
≥25–29.9	Log (CAR*100)	1.67 (1.21–2.30)		0.003	1.52 (1.06–2.19)		0.023	1.56 (1.11–2.19)		0.012
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	0.99 (0.17–5.79)		0.996	0.99 (0.16–6.02)		0.990	0.96 (0.13–6.93)		0.965
	3: −0.97–−0.11	0.78 (0.13–4.60)		0.775	0.67 (0.11–4.30)		0.666	0.67 (0.11–4.16)		0.662
	4: ≥-0.11	4.02 (0.85–19.04)		0.077	3.54 (0.75–16.76)		0.108	3.55 (0.73–17.25)		0.112
≥30	Log (CAR*100)	0.89 (0.62–1.27)		0.513	0.76 (0.53–1.07)		0.113	0.80 (0.55–1.16)		0.231
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	2.20 (0.39–12.39)		0.358	2.16 (0.54–8.70)		0.268	2.55 (0.63–10.33)		0.182
	3: −0.97–−0.11	0.54 (0.06–4.65)		0.563	0.41 (0.06–3.03)		0.371	0.47 (0.07–3.38)		0.443
	4: ≥−0.11	1.39 (0.28–6.81)		0.677	0.99 (0.25–3.98)		0.988	1.24 (0.29–5.30)		0.760
Gender
Male	Log (CAR*100)	1.36 (1.10–1.70)		0.007	1.23 (0.97–1.56)		0.081	1.24 (0.98–1.56)		0.070
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.51 (0.77–2.97)		0.220	1.39 (0.77–2.53)		0.267	1.41 (0.73–2.74)		0.294
	3: −0.97–−0.11	0.78 (0.29–2.10)		0.615	0.66 (0.25–1.77)		0.394	0.69 (0.24–2.01)		0.488
	4: ≥−0.11	2.78 (1.33–5.79)		0.008	1.91 (0.90–4.02)		0.087	1.97 (0.89–4.36)		0.093
Female	Log (CAR*100)	1.34 (1.03–1.74)		0.032	1.28 (0.93–1.76)		0.131	1.45 (1.02–2.05)		0.039
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	0.64 (0.12–3.37)		0.590	0.34 (0.04–2.63)		0.293	0.21 (0.02–2.43)		0.202
	3: −0.97–−0.11	1.60 (0.47–5.37)		0.439	1.23 (0.27–5.61)		0.780	1.45 (0.37–5.69)		0.587
	4: ≥−0.11	2.74 (0.77–9.68)		0.114	2.69 (0.86–8.47)		0.087	2.92 (1.08–7.91)		0.036
Smoking status
Never	Log (CAR*100)	1.15 (0.70–1.89)		0.559	1.12 (0.71–1.76)		0.625	0.97 (0.53–1.77)		0.923
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.66 (0.31–8.79)		0.541	2.13 (0.52–8.71)		0.284	2.71 (0.74–9.90)		0.127
	3: −0.97–−0.11	0.24 (0.03–1.77)		0.155	0.27 (0.04–2.03)		0.196	0.14 (0.02–1.23)		0.075
	4: ≥−0.11	1.81 (0.31–10.52)		0.496	1.84 (0.44–7.63)		0.391	1.34 (0.21–8.63)		0.751
Current smoking	Log (CAR*100)	1.68 (1.41–2.00)		<0.001	1.68 (1.31–2.16)		<0.001	1.73 (1.43–2.11)		<0.001
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	0.77 (0.14–4.17)		0.753	0.83 (0.14–4.87)		0.832	0.69 (0.17–2.83)		0.598
	3: −0.97–−0.11	1.75 (0.48–6.46)		0.385	2.13 (0.50–9.08)		0.296	1.73 (0.47–6.36)		0.394
	4: ≥−0.11	3.87 (1.64–9.13)		0.003	4.16 (1.54–11.25)		0.007	3.63 (1.61–8.23)		0.003
Quit smoking	Log (CAR*100)	1.05 (0.84–1.30)		0.673	0.79 (0.64–0.99)		0.039	0.83 (0.64–1.07)		0.149
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.43 (0.57–3.60)		0.434	1.35 (0.52–3.52)		0.526	1.34 (0.51–3.55)		0.543
	3: −0.97–−0.11	0.74 (0.22–2.52)		0.616	0.49 (0.12–2.00)		0.309	0.41 (0.11–1.47)		0.163
	4: ≥−0.11	1.80 (0.79–4.11)		0.157	0.80 (0.33–1.98)		0.626	0.98 (0.39–2.45)		0.958
CVD
No	Log (CAR*100)	1.32 (1.14–1.53)		<0.001	1.20 (1.04–1.38)		0.014	1.21 (1.03–1.42)		0.025
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.37 (0.61–3.09)		0.437	1.44 (0.66–3.12)		0.344	1.30 (0.60–2.82)		0.492
	3: −0.97–−0.11	1.13 (0.44–2.90)		0.788	1.14 (0.42–3.10)		0.794	1.09 (0.40–3.01)		0.863
	4: ≥−0.11	2.88 (1.36–6.12)		0.007	2.35 (1.12–4.93)		0.025	2.26 (1.06–4.82)		0.035
Yes	Log (CAR*100)	1.28 (0.87–1.89)		0.205	1.14 (0.67–1.93)		0.619	1.57 (0.87–2.83)		0.127
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.05 (0.19–5.87)		0.953	1.50 (0.16–13.76)		0.711	1.85 (0.29–11.90)		0.503
	3: −0.97–−0.11	0.48 (0.10–2.33)		0.353	0.69 (0.10–4.65)		0.697	0.63 (0.09–4.64)		0.640
	4: ≥−0.11	1.55 (0.50–4.83)		0.434	1.19 (0.27–5.25)		0.809	2.19 (0.51–9.32)		0.277
CKD
No	Log (CAR*100)	1.40 (1.20–1.63)		<0.001	1.30 (1.12–1.52)		0.001	1.30 (1.15–1.47)		<0.001
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.79 (0.80–4.02)		0.154	1.65 (0.75–3.64)		0.206	1.71 (0.81–3.63)		0.156
	3: −0.97–−0.11	1.11 (0.43–2.85)		0.831	0.97 (0.38–2.47)		0.942	1.05 (0.40–2.76)		0.927
	4: ≥−0.11	3.33 (1.58–7.01)		0.002	2.56 (1.22–5.36)		0.014	2.59 (1.28–5.22)		0.009
Yes	Log (CAR*100)	0.79 (0.50–1.24)		0.280	0.69 (0.39–1.24)		0.199	0.58 (0.28–1.21)		0.138
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	-		-	-		-	-		-
	3: −0.97–−0.11	0.59 (0.15–2.22)		0.409	0.72 (0.13–3.94)		0.688	0.19 (0.02–2.05)		0.160
	4: ≥−0.11	0.41 (0.09–1.87)		0.232	0.18 (0.03–1.02)		0.053	0.07 (0.01–0.66)		0.023
Diabetes
No	Log (CAR*100)	1.38 (1.18–1.61)		<0.001	1.30 (1.09–1.55)		0.005	1.29 (1.08–1.54)		0.006
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.30 (0.60–2.85)		0.495	1.21 (0.55–2.66)		0.628	1.25 (0.58–2.69)		0.560
	3: −0.97–−0.11	0.89 (0.38–2.08)		0.785	0.80 (0.35–1.85)		0.596	0.86 (0.35–2.17)		0.750
	4: ≥−0.11	2.69 (1.43–5.05)		0.003	2.14 (1.08–4.25)		0.031	2.17 (1.13–4.18)		0.022
Yes	Log (CAR*100)	1.08 (0.79–1.47)		0.639	0.87 (0.62–1.22)		0.405	0.97 (0.68–1.37)		0.858
	Log (CAR*100)
	1: <−1.80	Ref			Ref			Ref
	2: −1.80–−0.97	1.32 (0.38–4.64)		0.654	0.99 (0.27–3.63)		0.985	1.92 (0.67–5.53)		0.217
	3: −0.970.11	1.28 (0.30–5.53)		0.728	1.20 (0.25–5.88)		0.814	1.66 (0.23–11.76)		0.602
	4: ≥−0.11	1.98 (0.51–7.60)		0.309	1.18 (0.28–5.03)		0.819	1.92 (0.46–7.99)		0.357

Notes: Model 1 was un adjusted model; Model 2 of COPD severity subgroup analysis adjusted for education level, marital status, BMI, smoking status, diabetes, CKD, and segmented neutrophils num. Model 2 of BMI subgroup analysis adjusted for education level, marital status, smoking status, diabetes, CKD, and segmented neutrophils num. Model 2 of gender subgroup analysis adjusted for education level, marital status, BMI, smoking status, diabetes, CKD, and segmented neutrophils num. Model 2 of smoking status subgroup analysis adjusted for education level, marital status, BMI, diabetes, CKD, and segmented neutrophils num. Model 2 of CVD subgroup analysis adjusted for education level, marital status, BMI, smoking status, diabetes, CKD, and segmented neutrophils num. Model 2 of CKD subgroup analysis adjusted for education level, marital status, BMI, smoking status, diabetes, and segmented neutrophils num. Model 2 of diabetes adjusted for education level, marital status, BMI, smoking status, CKD, and segmented neutrophils num. Model 3 of COPD severity subgroup analysis adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS. Model 3 of BMI subgroup analysis adjusted for education level, marital status, smoking status, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS. Model 3 of gender subgroup analysis adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS. Model 3 of smoking status subgroup analysis adjusted for education level, marital status, BMI, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS. Model 3 of CVD subgroup analysis adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, diabetes, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, bronchodilator, and ICS. Model 3 of CKD subgroup analysis adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, diabetes, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS. Model 3 of diabetes adjusted for education level, marital status, BMI, smoking status, segmented neutrophils num, CKD, chronic bronchitis, asthma, intestines problem, cancer, ALT, AST, hypertension, dyslipidemia, CVD, bronchodilator, and ICS.

Abbreviations: Ref, Reference, HR, hazard ratio, CI, confidence interval, COPD, chronic obstructive pulmonary disease, CAR, C-reactive protein (CRP) to albumin (ALB) ratio, BMI, body mass index, CVD, cardiovascular disease, CKD, chronic kidney disease.

Figure 3 Predictive performance of CAR in predicting the mortality in COPD patients.