Crude and adjusted* risk (incidence rate ratio, IRR) of incident hospitalisations for chronic obstructive pulmonary disease
| Crude IRR (95% CI) | Adjusted* IRR (95% CI) | |
| Modified GOLD stage† | ||
| Normal | 1.0 | 1.0 |
| Restricted | 4.3 (3.3 to 5.5) | 4.7 (3.7 to 6.1) |
| GOLD 0 | 2.3 (1.8 to 2.9) | 2.1 (1.6 to 2.6) |
| GOLD 1 | 3.9 (3.1 to 4.9) | 3.2 (2.6 to 4.0) |
| GOLD 2 | 8.6 (6.9 to 10.7) | 8.0 (6.4 to 10.0) |
| GOLD 3 or 4 | 22.5 (17.3 to 29.4) | 25.5 (19.5 to 33.4) |
↵* Zero-inflated negative binomial regression adjusted for age, gender, education, smoking, physical activity, diabetes, heart disease and cohort (Atherosclerosis Risk in Communities Study/Cardiovascular Health Study).
↵† Modified Global Initiative on Obstructive Lung Disease (GOLD): normal (no lung disease), restricted (FEV1/FVC ≥0.70 and FVC <80% predicted), GOLD stage 0 (presence of respiratory symptoms in the absence of any lung function abnormality), GOLD stage 1 (FEV1/FVC <0.70 and FEV1 ≥80%), GOLD stage 2 (FEV1/FVC <0.70 and FEV1 ≥50% to <80% predicted) and GOLD stages 3 or 4 (FEV1/FVC <0.70 and FEV1 <50% predicted).