Logistic regression model for persistent asthma (2018, N=249)
| Model—do you still have asthma (yes/no) | OR | 95% CI | P value |
| Age | 1.01 | 0.99 to 1.04 | 0.312 |
| Never smoked (reference) | 1.00 | ||
| Ever Smoked | 0.92 | 0.51 to 1.64 | 0.775 |
| Work-related cause* | 0.027† | ||
| Chemical (any mention of) | 5.88 | 0.74 to 46.7 | 0.094 |
| Dust, organic | 2.13 | 1.09 to 4.16 | 0.026 |
Participants who reported doctor diagnosed asthma at baseline and also reported doctor diagnosed asthma in the 2018 respiratory questionnaire were included in this model. Each variable was adjusted for the others in the model. Gender was omitted from the model because of collinearity. Age is a continuous variable in this model; to assist interpretation an OR of 0.98 suggests that a 1-year increase in age lowers the odds of having asthma by 2%.
*Reference category is ‘no work-related cause of asthma’. ‘Dust, unspecified’ and ‘other’ were omitted because of collinearity.
†Overall test of significance for the ‘work-related cause’ variable