Informativeness* of spirometric Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades and ABCD groups related to all-cause mortality among participants with chronic obstructive pulmonary disease (COPD) in the HUNT2 Lung Study
| Women (n=468)† | Men (n=736)† | |||||
|---|---|---|---|---|---|---|
| COPD classification | χ2 | (%) | p Value | χ2 | (%) | p Value |
| GOLD grades‡ | 62.53 | (100) | <0.001 | 32.47 | (100) | <0.001 |
| ABCD groups§ | 26.28 | (42) | <0.001 | 13.03 | (40) | 0.046 |
*The Cox null model included age (as the time scale), smoking (never, former, current, unknown) and education (<10, ≥10 years, unknown). The Cox alternative models included spirometric GOLD grades or ABCD groups in addition to all in the null model. The χ2 shows the difference in twice the log-likelihood between the null model and the alternative model. The most informative model has the highest value of χ2 and has been set to 100%.
†People with missing data on dyspnoea were excluded so that the results from the spirometric GOLD grades and the ABCD groups could be compared.
‡COPD defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.70 and graded as follows; GOLD 1=per cent predicted FEV1 (ppFEV1) ≥80; GOLD 2=50≤ ppFEV1 <80; GOLD 3=30≤ ppFEV1 <50; GOLD 4=ppFEV1 <30.
§ABCD groups defined as follows; A=dyspnoea ≤grade 1, GOLD 1 or 2, and ≤1 exacerbation last 12 months; B=dyspnoea ≥grade 2, GOLD 1 or 2, and ≤1 exacerbation last 12 months; C=dyspnoea ≤grade 1, and GOLD 3 or 4 or ≥2 exacerbations last 12 months; D=dyspnoea ≥grade 2, and GOLD 3 or 4 or ≥2 exacerbations last 12 months.