Fibrinogen, COPD and Mortality in a Nationally Representative U.S. Cohort

Figures & data

Table 1.  Demographic characteristics, fibrinogen levels, and mortality of subjects included in analysis

	N	Weighted Percent	Mean Fibrinogen Level in mg/dL (Standard Error)	Weighted Proportion with Fibrinogen > 403.0 mg/dL	Weighted Proportion Dead by December 2006
Age
40–49	2,303	36.1	285.6 (3.4)	5.7	7.5
50–59	1,673	24.2	300.0 (3.8)	9.7	15.4
60–69	2,017	21.0	316.5 (3.6)	13.0	36.4
70–79	1,496	13.6	326.1 (4.3)	14.5	66.1
80 and Older	1,018	5.1	333.9 (4.8)	17.7	93.2
Sex
Male	4,059	46.6	297.4 (3.2)	8.8	29.7
Female	4,448	53.4	309.0 (2.8)	11.1	26.3
Race-ethnicity
White	4,385	81.5	302.3 (3.2)	9.8	28.8
Black	1,925	8.7	317.5 (2.8)	13.7	30.2
Mexican-American	1,885	3.5	303.2 (4.2)	9.2	21.3
Other	312	6.3	301.4 (6.7)	8.2	16.7
Body Mass Index
< 18.5	136	1.7	288.7 (9.0)	10.3	45.9
18.5–24	2,690	35.3	294.8 (3.1)	8.7	27.3
25–29	3,259	36.6	300.9 (3.6)	9.0	27.8
> = 30	2,422	26.4	319.9 (2.9)	13.3	27.6
Smoking Status
Current Smoker	1,868	23.0	315.7 (3.5)	13.0	30.9
Former Smoker	2,824	35.1	301.4 (3.7)	9.8	30.4
Never Smoker	3,815	41.9	298.8 (3.1)	8.5	24.0
Modified GOLD Stage
Stage 3 or 4	245	2.9	351.2 (8.4)	24.4	70.2
Stage 2	826	9.1	327.5 (4.0)	16.9	52.4
Stage 1	1,081	11.7	303.6 (5.0)	11.2	38.8
Symptoms Only	1,823	22.1	306.8 (4.0)	10.3	25.8
Restrictive	1,233	10.2	324.3 (5.3)	14.1	40.0
None	3,299	44.0	289.0 (2.7)	6.3	15.3
Diabetes Mellitus
Yes	1,216	9.8	333.1 (4.9)	18.5	49.8
No	7,291	90.2	300.4 (2.8)	9.1	25.5
Cardiovascular Disease
Yes	1,178	10.1	334.0 (4.7)	17.9	63.8
No	7,329	89.9	300.2 (2.7)	9.1	23.8
Education Level
< 12	3,955	29.8	318.9 (4.1)	14.4	40.2
12 Years	2,197	29.0	303.5 (3.2)	9.5	29.1
> = 13 Years	2,355	41.2	292.5 (2.6)	7.2	18.1
Poverty Income Ratio
< 1	1,463	8.7	320.2 (5.3)	13.7	41.5
1 to 2	2,081	17.7	316.3 (3.7)	13.6	41.9
> = 2	4,125	66.6	297.2 (2.9)	8.3	21.4
unknown	838	7.1	311.6 (3.9)	12.6	36.9
Total	8,507	100.0	303.6 (2.8)	10.0	27.9

Table 2.  Correlates of fibrinogen levels from linear regression models

Covariate	Beta estimate	Standard Error	p-Value
Age (per 1 year)	1.15	0.15	< 0.0001
Sex
Male	-12.46	2.56	< 0.0001
Female	0	0
Race-ethnicity
White	0	0
Black	11.14	3.38	0.0018
Mexican-American	-1.17	4.74	0.8069
Other	0.86	6.04	0.8873
Body Mass Index
< 18.5	-22.5	7.73	0.0054
18.5 - 24	0	0
25 - 29	7.15	2.81	0.0143
> = 30	22.44	3.40	< 0.0001
Smoking Status
Current Smoker	21.54	4.60	< 0.0001
Former Smoker	2.90	2.75	0.2962
Never Smoker	0	0
GOLD Stage
Stage 3 or 4	43.71	9.70	< 0.0001
Stage 2	19.79	4.29	< 0.0001
Stage 1	3.04	4.20	0.4731
Symptoms Only	6.08	3.32	0.0730
Restrictive	17.19	4.95	0.0011
None	0	0
Diabetes Mellitus
Yes	16.78	4.54	0.0005
No	0	0
Cardiovascular Disease
Yes	11.96	4.33	0.0081
No	0	0
Education Level
< 12	5.95	4.21	0.1645
12 Years	-0.54	3.26	0.8683
> = 13 Years	0	0
Poverty Income Ratio
< 1	3.18	5.07	0.5325
1 to 2	2.38	3.20	0.4606
> = 2	0	0
unknown	-0.76	3.53	0.8304

Table 3.  Correlates of Fibrinogen levels > 403 mg/dL (top decile) from logistic regression models

Covariate	Odds Ratio	95% Confidence Interval
Age (per 1 year)	1.03	(1.01, 1.04)
Sex
Male	0.73	(0.59, 0.91)
Female	1	1
Race-ethnicity
White	1	1
Black	1.35	(1.08, 1.70)
Mexican-American	0.89	(0.64, 1.24)
Other	0.87	(0.52, 1.47)
Body Mass Index
< 18.5	0.76	(0.38, 1.49)
18.5–24	1	1
25–29	1.06	(0.79, 1.42)
> = 30	1.54	(1.19, 2.01)
Smoking Status
Current Smoker	1.76	(1.25, 2.48)
Former Smoker	1.15	(0.91, 1.45)
Never Smoker	1	1
GOLD Stage
Stage 3 or 4	3.10	(1.99, 4.81)
Stage 2	1.95	(1.41, 2.71)
Stage 1	1.43	(0.96, 2.14)
Symptoms Only	1.29	(0.95, 1.75)
Restrictive	1.57	(1.15, 2.15)
None	1	1
Diabetes Mellitus
Yes	1.65	(1.27, 2.15)
No	1	1
Cardiovascular Disease
Yes	1.29	(1.01, 1.65)
No	1	1
Education Level
< 12	1.37	(0.99, 1.90)
12 Years	1.03	(0.75, 1.40)
> = 13 Years	1	1
Poverty Income Ratio
< 1	1.02	(0.77, 1.35)
1 to 2	1.11	(0.84, 1.48)
> = 2	1	1
unknown	1.09	(0.77, 1.54)

Figure 1.  Interaction between elevated fibrinogen levels and modified GOLD stage, in Cox proportional hazard models predicting mortality and adjusted for age, sex, race-ethnicity, body mass index, smoking, diabetes, cardiovascular disease, education level, and poverty income ratio. The box represents the point estimate and the vertical line represents the 5% and 95% confidence interval.

Table 4.  Results of Cox Proportional Hazards Models for mortality at up to 18 years of follow-up.

Covariate	Model A Hazard Ratio	95% Confidence Interval	Model B Hazard Ratio	95% Confidence Interval
Age (per 1 year)	1.10	(1.09, 1.11)	1.10	(1.09, 1.11)
Sex
Male	1.45	(1.31, 1.61)	1.46	(1.32, 1.62)
Female	1
Race-ethnicity
White	1
Black	1.16	(1.03, 1.32)	1.15	(1.02, 1.30)
Mexican-American	0.85	(0.72, 1.00)	0.84	(0.72, 0.99)
Other	0.62	(0.46, 0.83)	0.62	(0.45, 0.84)
Body Mass Index
< 18.5	1.88	(1.29, 2.74)	1.93	(1.31, 2.84)
18.5 - 24	1
25 - 29	0.89	(0.77, 1.03)	0.88	(0.77, 1.02)
> = 30	0.95	(0.84, 1.07)	0.93	(0.82, 1.05)
Smoking Status
Current Smoker	1.82	(1.58, 2.09)	1.79	(1.55, 2.05)
Former Smoker	1.20	(1.04, 1.38)	1.20	(1.04, 1.38)
Never Smoker	1
GOLD Stage
Stage 3 or 4	3.34	(2.53, 4.41)	3.29	(2.50, 4.33)
Stage 2	1.82	(1.54, 2.15)	1.78	(1.51, 2.10)
Stage 1	1.15	(0.98, 1.36)	1.15	(0.98, 1.35)
Symptoms Only	1.32	(1.16, 1.51)	1.32	(1.16, 1.50)
Restrictive	1.81	(1.51, 2.18)	1.79	(1.48, 2.15)
None	1
Diabetes Mellitus
Yes	1.51	(1.33, 1.71)	1.49	(1.31, 1.70)
No	1
Cardiovascular Disease
Yes	1.55	(1.37, 1.75)	1.54	(1.37, 1.74)
No	1
Education Level
< 12	1.10	(0.93, 1.30)	1.09	(0.92, 1.29)
12 Years	1.22	(1.03, 1.44)	1.22	(1.03, 1.44)
> = 13 Years	1
Poverty Income Ratio
< 1	1.42	(1.19, 1.70)	1.42	(1.19, 1.70)
1 to 2	1.28	(1.13, 1.46)	1.29	(1.13, 1.46)
> = 2	1
unknown	1.08	(0.90, 1.31)	1.08	(0.89, 1.31)
Fibrinogen > 403.0 g/L
Yes	1.36	(1.13, 1.63)
No	1
Fibrinogen level (per 100 g/L)		1.17	(1.09, 1.26)

Model A includes fibrinogen as either elevated (> 403.0 mg/dL) or not elevated, whereas Model B includes fibrinogen as a continuous variable.

Table 5.  Results of Cox Proportional Hazards Models for mortality at up to 18 years of follow-up, stratified by GOLD Stage and adjusted for age, sex, race-ethnicity, body mass index, smoking status, diabetes mellitus, cardiovascular disease, education level, and poverty income ratio

	Model A Hazard Ratio	95% Confidence Interval	Model B Hazard Ratio	95% Confidence Interval
GOLD Stage 3 or 4	2.11	(1.27, 3.50)	1.30	(1.02, 1.66)
GOLD Stage 2	1.45	(1.08, 1.96)	1.23	(1.07, 1.42)
GOLD Stage 1	1.41	(0.99, 2.00)	1.13	(0.99, 1.30)
Symptoms Only	1.20	(0.91, 1.58)	1.11	(0.97, 1.26)
Restrictive	1.32	(0.90, 1.92)	1.21	(1.02, 1.44)
None	1.60	(1.17, 2.20)	1.15	(0.98, 1.34)

Model A includes fibrinogen as either elevated (> 403.0 mg/dL) or not elevated, Model B includes fibrinogen as a continuous variable (per 100 mg/dL increase in fibrinogen). Each result presents data from a separate model.