Prevalence and prognostic ability of the GOLD 2017 classification compared to the GOLD 2011 classification in a Norwegian COPD cohort

Figures & data

Table 1 Characteristics of participants in the GenKOLS study 2003–2005 by GOLD 2011 and GOLD 2017 ABCD classifications

	GOLD A	GOLD B	GOLD C	GOLD D	p-value
GOLD 2011 classification
N total	193	267	57	395
mMRC dyspnea score	1 (0)	2.6 (0.8)	1 (0)	3.3 (1.1)	<0.01
N exacerbations last year	0.1 (0.3)	0.2 (0.4)	0.9 (1.2)	1.1 (1.6)	<0.01
% FEV1^a	66 (8)	63 (8)	42 (15)	37 (13)	<0.01
Male gender, %	66	60	56	60	0.36
Age, yrs	61 (9)	66 (10)	63 (10)	67 (10)	<0.01
Current smoker, %	60	47	61	40	<0.01
Pack-years	31 (16)	31 (18)	29 (15)	32 (19)	0.72
BMI, kg/m^2	25.5 (4)	26.6 (5)	23.8 (5)	24.7 (5)	<0.01
Heart attack/angina, %	9	22	19	21	<0.01
Chronic cough, %	53	74	57	76	<0.01
Phlegm, %	49	64	56	73	<0.01
Wheeze, %	59	77	68	85	<0.01
GOLD 2017 classification
N total	225	476	25	186
mMRC dyspnea score	1 (0)	2.9 (1,0)	1 (0)	3.3 (1.1)	<0.01
N exacerbations last year	0.1 (0.3)	0.2 (0.4)	1.8 (1.2)	2.1 (1.7)	<0.01
% FEV1^a	62 (14)	50 (17)	53 (17)	42 (17)	<0.01
Male gender, %	66	61	48	57	0.16
Age, yr	62 (9)	66 (10)	62 (11)	67 (10)	<0.01
Current smoker, %	59	46	72	35	<0.01
Pack-years	31 (16)	32 (17)	27 (11)	32 (21)	0.71
BMI, kg/m^2	25.2 (4)	25.6 (5)	24.3 (6)	25.3 (5)	0.17
Heart attack/angina, %	12	19	12	30	<0.01
Chronic cough, %	54	75	50	78	<0.01
Phlegm, %	49	66	60	78	<0.01
Wheeze, %	61	80	64	84	<0.01

Notes: ^aPost-bronchodilator FEV1 in % of predicted.

Table 2 GOLD 2011 and GOLD 2017 ABCD classifications by GOLD airflow limitation severity stages 2–4

	GOLD airflow limitation severity
	Stage 2	Stage 3	Stage 4	Total
GOLD 2011
Group A, N (%)	193 (37.8)	0	0	193 (21.2)
Group B, N (%)	267 (52.4)	0	0	267 (29.3)
Group C, N (%)	10 (2.0)	33 (12.1)	14 (10.8)	57 (6.3)
Group D, N (%)	40 (7.8)	239 (87.9)	116 (89.2)	395 (43.3)
Total, N (%)	510 (55.9)	272 (29.8)	130 (14.3)	912 (100)
GOLD 2017
Group A, N (%)	188 (36.9)	26 (9.6)	11 (8.5)	225 (24.7)
Group B, N (%)	244 (47.8)	163 (59.9)	69 (53.1)	476 (52.2)
Group C, N (%)	15 (2.9)	7 (2.6)	3 (2.3)	25 (2.7)
Group D, N (%)	63 (12.4)	76 (27.9)	47 (36.2)	186 (20.4)
Total, N (%)	510 (55.9	272 (29.8)	130 (14.3)	912 (100)

Table 3 GOLD 2017 ABCD classification by GOLD 2011

	GOLD 2011
	Group A	Group B	Group C	Group D	Total
GOLD 2017
Group A, N (%)	188 (97.4)	0	37 (64.9)	0	225 (24.7)
Group B, N (%)	0	244 (91.4)	0	232 (58.7)	476 (52.2)
Group C, N (%)	5 (2.6)	0	20 (35.1)	0	25 (2.7)
Group D, N (%)	0	23 (8.6)	0	163 (41.3)	186 (20.4)
Total, N (%)	193 (21.2)	267 (29.3)	57 (6.3)	395 (43.3)	912 (100)

Figure 1 Distribution of subjects in GOLD groups. (A) GOLD 2011 classification. (B) GOLD 2017 classification. (C) GOLD 2017 classification, separated by sampling source (250 subjects from general population and 662 from a patient population).

Figure 2 Kaplan–Meier graphs for respiratory mortality for GOLD 2011 and GOLD 2017 ABCD.

Figure 3 Kaplan–Meier graph for respiratory mortality for GOLD 2017 2A–4D.

Note: Group 2C, 3C, and 4C are excluded because of the very low number of outcome.

Table 4 Mortality outcomes by GOLD 2011, GOLD 2017 ABCD and GOLD 2017 2A–4D classifications. Univariate and multivariate logistic regression analyses with post hoc receiver operating curve estimations (8-year follow-up of the GenKOLS study)

		All-cause mortality			Respiratory mortality
GOLD	N total	N dead	Unadjusted OR (95% CI)	Adjusted OR** (95% CI)	N dead	Unadjusted OR (95% CI)	Adjusted OR** (95% CI)
2011 Group A	193	27	1 (ref)	1 (ref)	4	1 (ref)	1 (ref)
2011 Group B	267	64	1.9 (1.2–3.2)	1.3 (0.7–2.3)	13	2.4 (0.8–7.5)	1.9 (0.6–6.0)
2011 Group C	57	9	1.2 (0.5–2.6)	0.8 (0.3–2.1)	2	1.7 (0.3–9.6)	1.2 (0.2–6.8)
2011 Group D	395	187	5.5 (3.5–8.7)	4.0 (2.4–6.7)	90	13.9 (5.0–38.6)	9.6 (3.4–27.1)
AUC (95% CI)			0.68 (0.64–0.71)	0.81 (0.77–0.84)		0.73 (0.69–0.76)	0.82 (0.78–0.86)
2017 Group A	225	34	1 (ref)	1 (ref)	6	1 (ref)	1 (ref)
2017 Group B	476	159	2.8 (1.9–4.3)	2.1 (1.3–3.4)	62	5.5 (2.3–12.8)	4.3 (1.8–10.3)
2017 Group C	25	2	0.5 (0.1–2.2)	0.4 (0.1–2.0)	0	*	*
2017 Group D	186	92	5.5 (3.4–8.7)	4.6 (2.7–7.8)	41	10.3 (4.3–24.9)	7.9 (3.2–19.7)
AUC (95% CI)			0.65 (0.62–0.68)^a	0.80 (0.77–0.83)		0.66 (0.62–0.70)^b	0.79 (0.74–0.83)^a
2017 Group 2A	188	26	1 (ref)	1 (ref)	4	1 (ref)	1 (ref)
2017 Group 2B	244	53	1.7 (1.0–2.9)	1.2 (0.7–2.1)	10	2.0 (0.6–6.4)	1.5 (0.4–4.9)
2017 Group 2C	15	1	*	*	0	*	*
2017 Group 2D	63	25	4.1 (2.1–7.9)	2.6 (1.2–5.6)	9	7.7 (2.3–25.9)	4.7 (1.3–17.1)
2017 Group 3A	26	5	1.5 (0.5–4.3)	0.8 (0.3–2.6)	0	*	*
2017 Group 3B	163	64	4.0 (2.4–6.8)	2.5 (1.4–4.4)	26	8.7 (3.0–25.6)	5.4 (1.8–16.3)
2017 Group 3C	7	0	*	*	0	*	*
2017 Group 3D	76	35	5.3 (2.9–9.8)	3.8 (1.9–7.6)	14	10.4 (3.3–32.7)	7.3 (2.2–24.2)
2017 Group 4A	11	3	2.3 (0.6–9.4)	2.1 (0.5–9.7)	2	*	*
2017 Group 4B	69	42	9.7 (5.1–18.3)	8.1 (4.0–16.6)	26	27.8 (9.2–83.9)	19.8 (6.3–61.8)
2017 Group 4C	3	1	*	*	0	*	*
2017 Group 4D	47	32	13.3 (6.3–27.9)	14.0 (6.0–32.6)	18	28.6 (9.0–90.4)	21.5 (6.4–71.9)
AUC (95% CI)			0.71 (0.67–0.74)^b,c	0.83 (0.79–0.85)^a,c		0.77 (0.73–0.82)^b,c	0.84 (0.80–0.87)^a,c

Notes: *Odds ratio not reported for groups with three or fewer outcomes due to uncertain estimates. **Adjusted for gender, age, smoking, body mass index, comorbidities (diabetes, angina/heart attack, high blood pressure). ^ap<0.05 and ^bp<0.001 as compared with GOLD 2011 ABCD. ^cp<0.001 as compared with GOLD 2017 ABCD.

Abbreviations: AUC, area under the curve; CI, confidence interval; OR, odds ratio.

Figure 4 Comparison of univariate area-under-the curve analyses for GOLD 2011, GOLD 2017 ABCD, and GOLD 2017 2A–4D. Separate analyses for all-cause mortality and respiratory mortality.

Table 5 All-cause and Respiratory hospitalizations (0 OR≥1) by GOLD 2011 and GOLD 2017 classifications and Univariate and Multivariate logistic regression analyses with post hoc receiver operating curve estimations

		All-cause hospitalizations			Respiratory hospitalizations
GOLD	N Total	N Outcome	Unadjusted OR (95% CI)	Adjusted OR** (95% CI)	N Outcome	Unadjusted OR (95% CI)	Adjusted OR** (95% CI)
2011 Group A	193	119	1 (ref)	1 (ref)	10	1 (ref)	1 (ref)
2011 Group B	267	223	3.2 (2.0–4.9)	2.3 (1.5–3.7)	45	3.7 (1.8–7.6)	3.5 (1.6–7.5)
2011 Group C	57	47	2.9 (1.4–6.1)	3.0 (1.3–6.6)	11	4.4 (1.8–10.9)	3.9 (1.5–10.3)
2011 Group D	395	351	5.0 (3.2–7.6)	3.7 (2.3–5.8)	179	15.2 (7.8–29.5)	14.8 (7.2–30.1)
AUC (95% CI)			0.66 (0.62–0.71)	0.77 (0.74–0.81)		0.73 (0.70–0.76)	0.78 (0.74–0.81)
2017 Group A	225	143	1 (ref)	1 (ref)	16	1 (ref)	1 (ref)
2017 Group B	476	401	3.1 (2.1–4.4)	2.4 (1.6–3.5)	132	5.0 (2.9–8.7)	4.9 (2.8–8.7)
2017 Group C	25	23	6.6 (1.5–28.7)	8.5 (1.9–38.9)	5	3.3 (1.1–9.8)	2.9 (0.9–9.1)
2017 Group D	186	173	7.6 (4.0–14.3)	5.4 (2.8–10.3)	92	12.8 (7.1–22.9)	12.3 (6.6–22.8)
AUC (95% CI)			0.68 (0.64–0.72)	0.78 (0.75–0.82)		0.69 (0.66–0.72)^a	0.75 (0.71–0.78)^a
2017 Group 2A	188	114	1 (ref)	1 (ref)	10	1 (ref)	1 (ref)
2017 Group 2B	244	201	3.0 (2.0–4.7)	2.4 (1.5–3.8)	33	2.8 (1.3–5.8)	2.7 (1.2–5.9)
2017 Group 2C	15	13	4.2 (0.9–19.2)	5.3 (1.1–25.3)	3	4.5 (1.1–18.3)	4.4 (1.0–19.1)
2017 Group 2D	63	60	13.0 (3.9–42.9)	6.6 (1.9–22.6)	25	11.7 (5.2–26.4)	9.7 (4.0–23.4)
2017 Group 3A	26	20	2.2 (0.8–5.6)	1.5 (0.5–4.2)	4	3.2 (0.9–11.2)	2.9 (0.8–10.2)
2017 Group 3B	163	138	3.6 (2.1–6.0)	2.5 (1.5–4.4)	56	9.3 (4.6–19.0)	8.8 (4.1–18.8)
2017 Group 3C	7	7	*	*	1	*	*
2017 Group 3D	76	68	5.5 (2.5–12.1)	3.8 (1.7–8.8)	40	19.8 (9.1–43.1)	19.5 (8.5–44.9)
2017 Group 4A	11	9	2.9 (0.6–13.9)	3.9 (0.8–20.0)	2	*	*
2017 Group 4B	69	62	5.8 (2.5–13.2)	4.8 (2.0–11.4)	43	29.4 (13.2–65.6)	32.2 (13.7–75.6)
2017 Group 4C	3	3	*	*	1	*	*
2017 Group 4D	47	45	14.6 (3.4–62.0)	13.9 (3.2–60.7)	27	24.0 (10.2–56.8)	27.8 (11.1–69.7)
AUC (95% CI)			0.69 (0.65–0.73)^a	0.79 (0.75–0.82)^a		0.77 (0.74–0.80)^b,c	0.80 (0.77–0.84)^b,c

Notes: *Odds ratio not reported for groups with three or fewer outcomes due to uncertain estimates. **Adjusted for gender, age, smoking, body mass index, comorbidities (diabetes, angina/heart attack, high blood pressure). ^ap<0.05 and ^bp<0.001 as compared with GOLD 2011 ABCD. ^cp<0.001 as compared with GOLD 2017 ABCD.

Abbreviations: AUC, area under the curve; CI, confidence interval; OR, odds ratio.

Table S1 Characteristics of female participants in the GenKOLS study 2003–2005, by GOLD 2017 classification

	A n=77	B n=185	C n=13	D n=80	p*
mMRC dyspnea score, mean (SD)	1 (0)	3.0 (1.1)	1 (0)	3.3 (1.2)	<0.001
Exacerbations last year, mean (SD)	0.1 (0.4)	0.2 (0.4)	2.1 (1.6)	2.5 (2.1)	<0.001
% pred.post-bd FEV1, mean (SD)	60 (12)	49 (17)	54 (18)	45 (17)	<0.001
Age (yrs), mean (SD)	61 (8.4)	65 (9.9)	66 (9.6)	65 (10.1)	0.02
Current smokers (%)	69	49	54	43	0.01
Pack years, mean (SD)	26 (14)	28 (14)	23 (12)	24 (14)	0.21
BMI (kg/m^2), mean (SD)	25 (5)	25 (6)	24 (6)	25 (6)	0.61
Diabetes (%)	3	5	8	4	0.91
Heart attack/angina (%)	3	14	15	23	0.02
High blood pressure (%)	25	26	15	26	0.85
Chronic cough (%)	52	77	67	75	0.08
Phlegm (%)	48	62	38	80	0.001
Wheeze (%)	60	81	54	86	<0.001
All-cause admission days per year	2.1 (3)	4.4 (4)	3.9 (3)	6.3 (6)	<0.001
Respiratory admission days per year	0.1 (0)	1.1 (3)	0.5 (1)	2.0 (4)	<0.001
All-cause mortality (%)	10	31	0	45	<0.001
Respiratory mortality (%)	4	14	0	25	0.001
Cardiovascular mortality (%)	3	4	0	4	0.81

Note: Overall test for equality of populations: Chi-square test for categorical variables with >5 observations in each cell, Fisher’s exact test for categorical variables with <5 observations in a cell (diabetes, heart attack, all-cause, respiratory, and cardiovascular mortality), and Kruskal–Wallis test for continuous variables. N=355.

Abbreviations: mMRC, modified Medical Research Council dyspnea score; post-bd FEV1, post-bronchodilator forced expiratory volume in 1 s; BMI, body mass index.

Table S2 Characteristics of male participants in the GenKOLS study 2003–2005, by GOLD 2017 classification

	A n=148	B n=291	C n=12	D n=106	p*
mMRC dyspnea score, mean (SD)	1 (0)	2.8 (1.0)	1 (0)	3.3 (1.0)	<0.001
Exacerbations last year, mean (SD)	0.1 (0.3)	0.1 (0.3)	1.6 (0.8)	1.9 (1.3)	<0.001
% pred.post-bd FEV1, mean (SD)	62 (14)	50 (17)	51 (18)	40 (16)	<0.001
Age (yrs), mean (SD)	62 (9.5)	67 (10.2)	58 (10.9)	68 (9.6)	<0.001
Current smokers (%)	54	43	92	29	<0.001
Pack years, mean (SD)	34 (17)	35 (19)	31 (10)	39 (23)	0.47
BMI (kg/m^2), mean (SD)	26 (4)	26 (4)	25 (6)	25 (5)	0.22
Diabetes (%)	5	7	0	11	0.30
Heart attack/angina (%)	16	22	8	35	0.003
High blood pressure (%)	32	31	8	30	0.39
Chronic cough (%)	55	73	38	80	0.004
Phlegm (%)	50	69	83	76	<0.001
Wheeze (%)	61	80	75	82	0.001
All-cause hosptalizations per year	2.1 (3)	4.2 (4)	3.8 (6)	7.1 (6)	<0.001
Respiratory hospitalizations days per year	0.1 (1)	0.7 (2)	1.3 (5)	1,9 (4)	<0.001
All-cause mortality (%)	18	35	17	53	<0.001
Respiratory mortality (%)	2	13	0	20	<0.001
Cardiovascular mortality (%)	1	5	8	6	0.21

Notes: N=557. *Overall test for equality of populations: Chi-square test for categorical variables with >5 observations in each cell, Fisher’s exact test for categorical variables with <5 observations in a cell (diabetes, heart attack, all-cause, respiratory and cardiovascular mortality), and Kruskal–Wallis test for continuous variables.

Abbreviations: mMRC, modified Medical Research Council dyspnea score; post-bd FEV1, post-bronchodilator forced expiratory volume in 1 s; BMI, body mass index.

Table S3 Mortality outcomes by GOLD 2011 and GOLD 2017 classifications, unadjusted and adjusted cox regression statistics

	All-cause mortality		Respiratory mortality
GOLD group	Unadjusted hazard ratio (95% CI)	Adjusted hazard ratio (95% CI)	Unadjusted hazard ratio (95% CI)	Adjusted hazard ratio (95% CI)
2011 group A	1	1	1	1
2011 group B	1.8 (1.2–2.9)	1.4 (0.9–2.3)	2.5 (0.8–7.7)	2.0 (0.6–6.3)
2011 group C	1.2 (0.5–2.5)	0.9 (0.4–2.0)	1.7 (0.3–9.4)	1.1 (0.2–6.3)
2011 group D	4.3 (2.8–6.4)	2.9 (1.9–4.5)	13.7 (5.0–37.4)	9.2 (3.3–25.3)
Harrell’s C***	0.65	0.75	0.73	0.82
2017 group A	1	1	1	1
2017 group B	2.5 (1.7–3.6)	1.9 (1.2–2.8)	5.4 (2.3–12.6)	4.3 (1.8–10.1)
2017 group C	0.5 (0.1–2.1)	0.4 (0.1–1.8)	Omitted	Omitted
2017 group D	4.1 (2.7–6.0)	2.9 (1.9–4.4)	10.1 (4.3–23.9)	6.9 (2.9–16.6)
Harrell’s C***	0.62	0.75	0.67	0.80
2017 group 2A	1	1	1	1
2017 group 2B	1.7 (1.0–2.6)	1.2 (0.7–2.0)	2.0 (0.6–6.5)	1.5 (0.4–5.1)
2017 group 2D	3.3 (1.9–5.7)	2.1 (1.2–3.8)	7.7 (2.3–25.1)	4.8 (1.4–16.1)
2017 group 3B	3.3 (2.1–5.2)	2.2 (1.4–3.5)	8.6 (3.0–24.8)	5.5 (1.9–16.2)
2017 group 3D	4.0 (2.4–6.7)	2.8 (1.6–4.8)	10.6 (3.5–32.3)	7.1 (2.3–22.2)
2017 group 4B	6.5 (4.0–10.7)	4.7 (2.8–7.9)	26.6 (9.3–76.5)	18.5 (6.4–53.8)
2017 group 4D Harrell’s C***	7.7 (4.5–12.9) 0.67	5.5 (3.1–9.5) 0.80	27.8(9.3–82.8) 0.77	16.8 (5.5–51.4) 0.84

Notes: Multivariate models adjusted for gender, age, smoking, body mass index, comorbidities (diabetes, angina/heart attack, high blood pressure). ***Posthoc estimation of Harrel's C concordance statistic following Cox regression.

Table S4 All-cause and respiratory hospitalization by GOLD 2011 and GOLD 2017 classifications, univariate and multivariate* Cox proportional hazards regression analyses

	All-cause hospitalizations		Respiratory hospitalizations
GOLD group	Hazard ratio (95% CI)	Adjusted hazard ratio (95% CI)	Hazard ratio (95% CI)	Adjusted hazard ratio (95% CI)
2011 group A	1	1	1	1
2011 group B	1.8 (1.3–2.3)	1.6 (1.2–2.1)	1.9 (0.8–4.5)	2.0 (0.8–5.2)
2011 group C	1.7 (1.1–2.6)	1.6 (1.0–2.4)	2.7 (0.9–8.5)	2.6 (0.8–8.4)
2011 group D	2.4 (1.8–3.1)	2.0 (1.5–2.6)	9.1 (4.2–19.6)	9.6 (4.1–22.1)
Harrell’s C**	0.60	0.66	0.72	0.77
2017 group A	1	1	1	1
2017 group B	1.9 (1.5–2.4)	1.6 (1.3–2.1)	5.8 (2.9–11.6)	5.6 (2.7–11.6)
2017 group C	2.7 (1.5–4.7)	3.5 (2.0–6.3)	5.7 (1.5–21.0)	8.1 (2.1–30.8)
2017 group D	3.0 (2.2–4.0)	2.6 (1.9–3.5)	12.1 (5.7–25.4)	11.9 (5.4–26.2)
Harrell’s C**	0.61	0.67	0.69	0.78
2017 group 2A	1	1	1	1
2017 group 2B	1.7 (1.3–2.3)	1.5 (1.2–2.0)	2.1 (0.8–5.3)	2.2 (0.8–5.8)
2017 group 2D	3.2 (2.0–4.9)	2.3 (1.5–3.7)	9.4 (3.3–26.7)	7.7 (2.6–23.3)
2017 group 3B	2.0 (1.5–2.8)	1.7 (1.2–2.3)	9.9 (4.4–22.3)	8.3 (3.4–20.0)
2017 group 3D	2.4 (1.6–3.6)	2.1 (1.3–3.2)	12.4 (5.0–30.7)	13.2 (5.0–34.8)
2017 group 4B	2.7 (1.8–4.0)	2.2 (1.5–3.3	19.7 (8.5–45.7)	20.3 (8.1–50.7)
2017 group 4D	5.1 (3.1–8.3)	5.5 (3.3–9.1	26.6 (10.1–70.3)	36.5 (12.7–104.5)
Harrell’s C**	0.62	0.68	0.77	0.83

Notes: *Multivariate models adjusted for gender, age, smoking, body mass index, comorbidities (diabetes, angina/heart attack, high blood pressure). **Posthoc estimation of Harrel's C concordance statistic following Cox regression.

Figure S1 Distribution (%) of female and male by GOLD 2011 classification and by GOLD 2017 classification.

Figure S2 Kaplan–Meier graphs for all-cause mortality according to GOLD 2011, GOLD 2017 ABCD and GOLD 2017 2A–4D.