Table 4.
Risk factors for chronic bronchitis and respiratory symptoms by using multiple logistic regression analysis
| Independent variables | Dependent variables | ||||
|---|---|---|---|---|---|
| Variables | Categories | Chronic bronchitis | Sputum production | Dyspnoea grade ≥2a | Recurrent wheeze |
| Age | ≤40 years >40 ≤60 years >60 years |
1 2.02 (1.06–3.83) 2.31 (1.17–4.54) |
1 2.02 (1.26–3.26) 3.41 (2.09–5.58) |
1 2.10 (0.79–5.58) 4.38 (1.68–11.44) |
1 1.95 (1.10–3.43) 2.14 (1.17–3.94) |
| Area of domicile | Västra Götaland Gothenburg |
1 1.85 (1.13–3.03) |
1 0.97 (0.70–1.36) |
1 2.38 (1.21–4.69) |
1 0.87 (0.57–1.33) |
| Level of education | University Lower than university |
1 1.89 (1.14–3.13) |
1 1.32 (0.93–1.88) |
1 2.36 (1.16–4.79) |
1 1.61 (1.03–2.53) |
| Current smoking status | Non-smoker Ex-smoker Smoker |
1 1.20 (0.69–2.07) 2.42 (1.33–4.38) |
1 1.36 (0.93–2.00) 2.93 (1.88–4.57) |
1 1.03 (0.51–2.11) 1.64 (0.71–3.79) |
1 1.05 (0.63–1.74) 3.48 (2.07–5.84) |
| Exposure to occupational dust, gas or fumes | No Yes |
1 1.38 (0.84–2.26) |
1 1.80 (1.26–2.56) |
1 1.50 (0.78–2.89) |
1 1.73 (1.11–2.68) |
Risks expressed as odds ratios (OR) with 95% confidence intervals (CI).
a
MRC-scale=Medical Research Council breathlessness scale: Grade 2=‘Walk slower than most people my age on the level’ and/or ‘have to stop for breath when walking at my own pace on the level’. Grade 3=‘stop for breath after walking 100 yards on level ground’. Grade 4=‘get out of breath when I wash myself or dress myself’. Significant risk factors are depicted in bold.