GOLD Classifications, COPD Hospitalization, and All-Cause Mortality in Chronic Obstructive Pulmonary Disease: The HUNT Study

Figures & data

Table 1 Characteristics of COPD Participants Aged ≥40 Years in the HUNT Study (N=1300)

Characteristics	GOLD 2007 ^¶				GOLD 2011 ^¥				GOLD 2017 ^†
	Grade 1 (n=415)	Grade 2 (n=704)	Grade 3 (n=163)	Grade 4 (n=18)	Group A (n=771)	Group B (n=311)	Group C (n=98)	Group D (n=120)	Group A (n=847)	Group B (n=400)	Group C (n=22)	Group D (n=31)
Participants (%)	31.9	54.2	12.5	1.4	59.3	23.9	7.6	9.2	65.1	30.8	1.7	2.4
Women (%)	35.4	38.2	36.2	38.9	34.0	43.4	33.7	43.3	33.5	42.0	50.0	61.3
Age(years) (Mean±SD)	64.9±11.3	65.4±10.4	68.1±9.6	65.2±10.5	65.0±10.6	65.8±11.2	68.3±9.2	66.6±9.8	65.3±10.5	66.2±11.0	69.4±7.7	64.0±8.7
BMI (Mean±SD)	26.8±4.0	26.7±4.6	24.7±4.0	23.2±2.6	26.3±4.0	27.8±5.2	24.5±3.4	25.4±4.4	26.2±4.0	27.1±5.1	25.1±2.1	27.5±4.3
Smoking pack-years (Mean±SD)	22.9±14.7	25.0±15.2	27.3±16.4	29.5±25.3	24.4±14.8	24.3±16.1	25.9±14.9	27.1±18.6	24.7±14.8	25.4±17.2	22.1±14.5	20.4±11.3
Current smoker (%)	44.1	51.6	44.6	22.2	49.9	48.4	45.3	35.7	50.1	46.2	23.8	27.6
Physically inactive (%)	9.6	11.3	9.9	20.0	7.6	17.4	12.3	12.5	8.1	15.9	7.1	19.1
Education ≥10 years (%)	39.5	35.4	29.1	33.3	40.4	28.9	28.4	31.0	39.4	29.4	26.3	30.4
CVD (%)	19.8	22.2	20.4	23.5	18.5	29.0	20.6	19.3	18.6	27.9	22.7	6.5
Asthma ever (%)	52.3	60.5	77.9	94.4	54.2	60.8	77.6	86.7	55.7	65.8	100.0	96.8
Diabetes ever (%)	5.3	5.3	4.3	5.6	4.5	7.2	4.1	5.0	4.5	6.6	5.6	6.5
SBP (mean, SD)	147±22.6	147.2±21.8	149.8±24.7	136.7±20.3	147.1±22.1	147.2±22.1	150.5±25.2	145.9±22.9	147.4±22.3	147.1±22.1	151.9±27.2	143.4±25.0
Cholesterol (Mean±SD)	6.3±1.2	6.3±1.2	6.3±1.2	6.3±1.0	6.3±1.2	6.4±1.3	6.3±1.3	6.3±1.2	6.3±1.2	6.4±1.3	7.0±1.2	6.3±1.2
COPD hospitalization (at least one) (n)	104	293	109	16	248	128	64	82	296	191	16	19
COPD hospitalization rate (per 1000 person-years)	18.6 (15.4–22.6)	39.2 (35.0–44.0)	111.1 (92.1–134.0)	364.4 (223.2–594.8)	26.7 (23.6–30.3)	37.7 (31.7–44.8)	100.6 (78.7–128.5)	106.5 (85.8–132.3)	30.3 (27.1–34.0)	49.6 (43.0–57.1)	99.5 (61.0–162.5)	61.0 (38.9–95.6)
All-cause mortality (n)	234	499	146	17	503	208	86	99	571	289	18	18
All-cause mortality rate (per 1000 person-years)	38.5 (33.9–43.8)	56.0 (51.3–61.1)	101.5 (86.3–119.4)	97.5 (60.6–156.8)	48.0 (44.0–52.4)	52.2 (45.6–59.8)	93.3 (75.6–115.3)	81.3 (66.7–99.0)	51.3 (47.3–55.7)	60.7 (54.1–68.1)	68.0 (42.9–108.0)	41.1 (25.9–65.2)

Notes: ^¶Grade 1 – percent-predicted forced expiratory volume in first second (ppFEV₁) ≥80; grade 2 –80>ppFEV₁≥50; grade 3 –50>ppFEV₁≥30; grade 4 –ppFEV₁<30. ^¥Group A – ppFEV₁≥50 and exacerbation history <2 and modified Medical Research Council dyspnoea scale (mMRC) <2; group B – ppFEV₁≥50 and exacerbation history <2 and mMRC ≥2; group C – ppFEV₁<50 or exacerbation history ≥2 and mMRC <2; group D – ppFEV₁<50 or exacerbation history ≥2 and mMRC ≥2. ^†group A – mMRC <2 & exacerbation history <2; group B – mMRC ≥2 & exacerbation history <2; group C – mMRC <2 & exacerbation history ≥2; group D – mMRC ≥2 & exacerbation history ≥2.

Abbreviations: HUNT, Nord-Trøndelag Health Study 1995–1997; SD, standard deviation; BMI, body mass index; CVD, cardiovascular disease; SBP, systolic blood pressure; GOLD, global initiative for chronic obstructive lung disease.

Figure 1 Distribution of participants in different GOLD classifications.

Table 2 Hazard Ratios for GOLD 2007, GOLD 2011, and GOLD 2017 Among Participants with COPD Aged ≥40 Years in the HUNT2 Study (N=1300)

Outcomes	GOLD Categories ^¶, ¥, †	GOLD 2007 ^¶		GOLD 2011 ^¥		GOLD 2017 ^†
		HR (95% CI) *	HR (95% CI) ^#	HR (95% CI) *	HR (95% CI) ^#	HR (95% CI) *	HR (95% CI) ^#
COPD hospitalization	Grade 1/group A	Reference	Reference	Reference	Reference	Reference	Reference
	Grade 2/group B	2.15 (1.72–2.69)	2.05 (1.63–2.57)	1.41 (1.14–1.75)	1.42 (1.14–1.76)	1.64 (1.36–1.96)	1.64 (1.36–1.97)
	Grade 3/group C	6.40 (4.87–8.41)	5.11 (3.85–6.78)	3.89 (2.95–5.14)	3.21 (2.42–4.27)	3.27 (1.97–5.41)	3.17 (1.88–5.32)
	Grade 4/group D	22.56 (13.19–38.57)	17.08 (9.77–29.86)	4.09 (3.18–5.26)	3.75 (2.88–4.88)	2.01 (1.26–3.20)	2.15 (1.33–3.46)
All-cause mortality	Grade 1/group A	Reference	Reference	Reference	Reference	Reference	Reference
	Grade 2/group B	1.51 (1.29–1.76)	1.56 (1.33–1.82)	1.10 (0.93–1.29)	1.03 (0.87–1.21)	1.21 (1.05–1.39)	1.16 (1.01–1.34)
	Grade 3/group C	3.13 (2.54–3.86)	2.88 (2.32–3.58)	2.21 (1.75–2.78)	1.74 (1.38–2.20)	1.39 (0.87–2.22)	1.16 (0.72–1.86)
	Grade 4/group D	2.95 (1.80–4.84)	3.87 (2.34–6.39)	1.84 (1.48–2.28)	2.04 (1.63–2.55)	0.79 (0.49–1.26)	1.05 (0.65–1.69)

Notes: *Model 1 (crude). ^#Model 2 - adjusted for age, sex, smoking, body mass index, education. ^¶Grade 1 – percent-predicted forced expiratory volume in first second (ppFEV₁) ≥80; grade 2 –80>ppFEV₁≥50; grade 3 –50>ppFEV₁≥30; grade 4 –ppFEV₁<30. ^¥Group A – ppFEV₁≥50 and exacerbation history <2 and modified Medical Research Council dyspnea scale (mMRC) <2; group B – ppFEV₁≥50 and exacerbation history <2 and mMRC ≥2; group C – ppFEV₁<50 or exacerbation history ≥2 and mMRC <2; group D – ppFEV₁<50 or exacerbation history ≥2 and mMRC ≥2. ^†Group A – mMRC <2 & exacerbation history <2; group B – mMRC ≥2 & exacerbation history <2; group C – mMRC <2 & exacerbation history ≥2; group D – mMRC ≥2 & exacerbation history ≥2.

Abbreviations: HUNT2, Nord-Trøndelag Health Study 1995–1997; GOLD, global initiative for chronic obstructive lung disease; HR, Hazard ratio; CI, confidence interval.

Table 3 AUC for GOLD 2007, GOLD 2011, and GOLD 2017 at 20 Years of Follow-Up Among Participants with COPD Aged ≥40 Years in the HUNT2 Study (N=1300)

Outcomes	GOLD 2007 ^¶	GOLD >2011 ^¥	GOLD 2017 ^†
	AUC (95% CI) *	AUC (95% CI) *	AUC (95% CI) *
COPD hospitalization	63.1 (58.7–66.9)	60.9 (56.1–64.4)	56.1 (54.0–58.1)
All-cause mortality	57.0 (54.8–59.1)	54.1 (52.1–56.0)	52.6 (51.0–54.3)

Notes: *Model 1 (crude model) - the Cox model included GOLD 2007, GOLD 2011, or GOLD 2017. ^¶Grade 1 – percent-predicted forced expiratory volume in first second (ppFEV₁) ≥80; grade 2 –80>ppFEV₁≥50; grade 3 –50>ppFEV₁≥30; grade 4 –ppFEV₁<30. ^¥Group A – ppFEV₁≥50 and exacerbation history <2 and modified Medical Research Council dyspnea scale (mMRC) <2; group B – ppFEV₁≥50 and exacerbation history <2 and mMRC ≥2; group C – ppFEV₁<50 or exacerbation history ≥2 and mMRC <2; group D – ppFEV₁<50 or exacerbation history ≥2 and mMRC ≥2. ^†Group A – mMRC <2 & exacerbation history <2; group B – mMRC ≥2 & exacerbation history <2; group C – mMRC <2 & exacerbation history ≥2; group D – mMRC ≥2 & exacerbation history ≥2.

Abbreviation: HUNT2, Nord-Trøndelag Health Study 1995–1997; AUC, area under receiver operating characteristics curves.

Figure 2 AUC curves for the GOLD 2007, GOLD 2011, and GOLD 2017 classifications for (A) COPD hospitalization and (B) all-cause mortality over follow-up time (years) among participants with COPD aged ≥40 years in the HUNT2 study (N=1300).