GOLD Classification of COPD: Discordance in Criteria for Symptoms and Exacerbation Risk Assessment

Figures & data

Table 1. Characteristics of the study population.

Characteristics	Males (n = 330)	Females (n = 70)
Age (years)	61.37 ± 9.06 (60.38–62.35)	61.36 ± 9.36 (59.12–63.59)
Post-bronchodilator FEV^1/FVC	0.47 ± 0.11 (0.46–0.49)	0.51 ± 0.10 (0.49–0.54)
Post-bronchodilator FEV^1 (% predicted)	57.26 ± 21.39 (54.94–59.42)	66.88 ± 23.93 (61.08–72.35)
GOLD stages
I	25 (7.6%)	8 (11.4%)
II	127 (38.5%)	30 (42.9%)
III	143 (43.3%)	26 (37.1%)
IV	35 (10.6%)	6 (8.6%)
mMRC grades
0–1	34 (10.3%)	11 (15.7%)
≥2	296 (89.7%)	59 (84.3%)
CAT scores
<10	47 (14.2%)	6 (8.6%)
≥10	283 (85/8%)	64 (91.4%)

Data in mean ± SD with 95% confidence intervals or as frequency with column percentage in parenthesis.

FEV¹, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mMRC, modified Medical Research Council; CAT, COPD Assessment Test.

Figure 1. Scatter of CAT scores with mean ± SD in patients with different mMRC grades of dyspnoea (Kruskal–Wallis analysis of variance, p < 0.0001). For post hoc paired comparisons, see text.

Figure 2. Proportion of patients with low (<10) and high (≥10) CAT scores among groups by mMRC grades (chi square test, p < 0.0001).

Table 2. Distribution of patients using mMRC or CAT scores.

	GOLD 2011 mMRC
	A	B	C	D
GOLD 2011 CAT	28 (7%)	123 (30.8%)	16 (4.0%)	233 (58.2%)
A 36 (9.0%)	3	33	0	0
B 116 (29%)	25	90	0	1
C 17 (4.2%)	0	0	2	15
D 231 (57.8%)	0	0	14	217

GOLD 2011 CAT: Global Initiative for Chronic Obstructive Lung Disease 2011 classification based on COPD Assessment Test (CAT) scores; GOLD 2011 mMRC: Global Initiative for Chronic Obstructive Lung Disease 2011 classification based on modified Medical Research Council (mMRC) grades; risk assessment was done using the higher of the assignment by GOLD stage or frequency of exacerbations; data shown as frequency with percentages in parenthesis; chi square p-value <0.0001; kappa coefficient: 0.61.

Table 3. Receiver operator characteristic analysis results.

CAT Score	Sensitivity (%)	95% CI	Specificity (%)	95% CI	Likelihood ratio
>2.00	99.44	97.98–99.93%	0.0	0.0–7.871%	0.99
>4.50	99.44	97.98–99.93%	2.22	0.06–11.77%	1.02
>5.50	98.87	97.14–99.69%	4.444	0.54–15.15%	1.04
>6.50	98.31	96.36–99.38%	6.667	1.40–18.27%	1.05
>7.50	96.34	93.82–98.04%	6.667	1.40–18.27%	1.03
>8.50	92.11	88.80–94.70%	11.11	3.71–24.05%	1.04
>9.50	85.92	81.86–89.36%	11.11	3.71–24.05%	0.97
>10.50	82.25	77.87–86.09%	24.44	12.88–39.54%	1.09
>11.50	76.06	71.27–80.40%	37.78	23.77–53.46%	1.22
>12.50	73.24	68.31–77.77%	55.56	40.00–70.36%	1.65
>13.50	70.70	65.67–75.39%	80.00	65.40–90.42%	3.54
>14.50	65.35	60.15–70.30%	88.89	75.95–96.29%	5.88
>15.50	60.00	54.70–65.13%	93.33	81.73–98.60%	9.00
>16.50	54.93	49.59–60.19%	97.78	88.23–99.94%	24.72
>17.50	52.11	46.78–57.41%	97.78	88.23–99.94%	23.45
>18.50	47.32	42.03–52.66%	100.0	92.13–100.0%

CAT, COPD Assessment Test; CI, confidence interval.

Figure 3. Receiver operator characteristic curve of different cut-offs of CAT score to identify patients with mMRC ≥ 2. The optimal combination of sensitivity and specificity was obtained with a CAT score of 17 and is shown by an arrow.

Table 4. Distribution of patients using mMRC or modified CAT score cut-off of 17.

	GOLD 2011 mMRC
	A	B	C	D
GOLD 2011 CAT 17	28 (7%)	123 (30.8%)	16 (4.0%)	233 (58.2%)
A 106 (26.5%)	28	77	0	1
B 42 (10.5%)	0	37	0	5
C 96 (24.0%)	0	1	16	79
D 156 (39.0%)	0	8	0	148

CAT 17: COPD Assessment Test scores with cut-off 17 to define more symptoms; GOLD 2011 mMRC: Global Initiative for Chronic Obstructive Lung Disease 2011 classification based on modified Medical Research Council (mMRC) grades; risk assessment was done using the higher of the assignment by GOLD stage or frequency of exacerbations; data shown as frequency with percentages in parenthesis; chi square p-value <0.0001; kappa coefficient: 0.40.

Figure 4. Frequency of exacerbations (Exac.) and hospitalisations (hosp.) across the old GOLD stages (ANOVA: F 9.718, p < 0.0001 and F 9.017, p < 0.0001, respectively). For post-hoc paired comparisons, see text.

Table 5. Distribution of patients using GOLD stage and frequency of exacerbations.

	GOLD 2011 stage
GOLD 2011	A	B	C	D
exacerbations	4 (1%)	276 (69%)	1 (0.25%)	119 (29.7%)
A 4 (1.0%)	3	0	1	0
B 195 (48.8%)	0	146	0	49
C 1 (0.25%)	1	0	0	0
D 200 (50%)	0	130	0	70

GOLD 2011 stage: Global Initiative for Chronic Obstructive Lung Disease 2011 classification based on spirometry stages; GOLD 2011 exacerbations: Global Initiative for Chronic Obstructive Lung Disease 2011 classification based on frequency of exacerbations; symptom assessment was done using higher of the assignment by mMRC or CAT scores; data shown as frequency with percentages in parenthesis; chi square p-value <0.0001; kappa coefficient: 0.12.