Risk factors for exacerbations (meta-analysis)
| Overall Adjusted OR* (95% CI) | Overall I2 (%) | p Value for overall I2 | |
| Female | 1.45 (1.00 to 2.09) | 0.0 | 0.8 |
| Age | 0.97 (0.95 to 0.99) | 42.1 | 0.03 |
| Education level | 0.95 (0.78 to 1.15) | 18.6 | 0.2 |
| Pack years smoked–per 10 increase | 0.90 (0.73 to 1.12) | 24.7 | 0.2 |
| Ex-smoker | 1.19 (0.81 to 1.74) | 0.0 | 0.8 |
| Current-smoker | 1.37 (0.85 to 2.21) | 0.0 | 0.5 |
| COPD—mild and moderate | 2.55 (1.70 to 3.82) | 44.0 | 0.03 |
| COPD—severe and very severe | 3.62 (2.11 to 6.18) | 0.0 | 0.6 |
| Doctor Diagnosed Asthma | 4.92 (3.77 to 6.42) | 0.0 | 0.9 |
| MMRC Dyspnoea—increased severity | 2.14 (1.86 to 2.46) | 31.7 | 0.1 |
| Chronic bronchitis | 3.03 (1.97 to 4.66) | 14.4 | 0.3 |
| Post BD FVC | 0.90 (0.68 to 1.19) | 40.4 | 0.04 |
| Current biomass exposure | 2.67 (1.25 to 5.68) | 57.0 | 0.01 |
| Current dusty job | 1.60 (1.16 to 2.22) | 15.5 | 0.3 |
| CVD | 1.28 (0.98 to 1.68) | 0.0 | 0.9 |
| Diabetes | 1.52 (0.94 to 2.48) | 35.3 | 0.08 |
| Tuberculosis | 2.76 (1.10 to 6.91) | 65.2 | 0.001 |
| Childhood respiratory disease | 1.52 (0.92 to 2.51) | 0.0 | 0.6 |
| Family history of COPD or asthma | 1.35 (1.00 to 1.83) | 11.4 | 0.3 |
↵* Mutual adjustment for all the risk factors in the table and height and weight, weighted for survey design.