Logistic regression analysis of factors associated with severe compared with mild-to-moderate asthma
| Odds ratio (95% CI)# | Significance | |
| Vitamin C µM | 0.934 (0.898–0.972) | p = 0.001 |
| Socioeconomic status | 0.282 (0.107–0.743) | p = 0.01 |
| Bilirubin µM | 0.691 (0.514–0.929) | p = 0.014 |
| Total cholesterol mM | 1.975 (1.045–3.732) | p = 0.036 |
CI: confidence interval. #: indicates change in risk per unit of antioxidant or category of socioeconomic status. The backward stepwise logistic regression analysis included the following covariates in the model: age, sex, body mass index, socioeconomic status (1 = low, 2 = middle and 3 = high, based on the patient's residential postcode), atopic and smoking status, vitamin supplement use and the plasma concentrations of all antioxidants and cholesterol.