Odds of having COPD in wave 9 in never-smokers with 95% confidence interval, multivariable model
| Predictor variable | OR (95% CI) | p-value |
| BMI | 1.01 (0.97–1.05) | 0.736 |
| Education level | 0.042 | |
| Less than high school | Reference | |
| High school/trade/diploma | 0.63 (0.40–0.98) | |
| University/postgraduate | 0.58 (0.30–1.03) | |
| SEIFA (per 100 units) | 0.95 (0.76–1.21) | 0.692 |
| Breathing difficulties | <0.001 | |
| Never | Reference | |
| Rarely | 2.31 (1.34–3.86) | |
| Sometimes/often | 1.68 (0.89–3.08) | |
| Presence of asthma | 0.083 | |
| No | Reference | |
| Yes | 1.65 (0.92–2.89) | |
| SF-36 PCS (per 10 units) | 0.84 (0.67–1.05) | 0.115 |
| SF-36 MCS (per 10 units) | 0.78 (0.66–0.94) | 0.008 |
BMI: body mass index; SEIFA: Socioeconomic Indexes for Areas; SF-36 PCS: physical component summary; SF-36 MCS: mental component summary.