Table 3.
Association between the healthy Plant-based Diet Index (hPDI) and the incidence of asthma symptoms, mediated by BMI.
| hPDI | No. | Total Effect | Direct Effect | Indirect Effect | Proportion Mediated |
|---|---|---|---|---|---|
| OR (95%CI) | OR (95%CI) | OR (95%CI) | |||
| Continuous | 551/5149 | 0.85 (0.73–1.01) | 0.90 (0.76–1.06) | 0.94 (0.89–1.00) | 33% |
| Quintile 1 | 107/969 | 1.00 (ref) | 1.00 (ref) | 1.00 (ref) | 40% |
| Quintile 2 | 108/1008 | 0.85 (0.63–1.11) | 0.87 (0.65–1.14) | 0.98 (0.95–0.99) | |
| Quintile 3 | 127/1119 | 0.87 (0.66–1.14) | 0.91 (0.69–1.20) | 0.96 (0.91–0.98) | |
| Quintile 4 | 110/1055 | 0.84 (0.62–1.09) | 0.89 (0.66–1.16) | 0.94 (0.89–0.98) | |
| Quintile 5 | 99/998 | 0.85 (0.62–1.11) | 0.91 (0.66–1.22) | 0.93 (0.87–0.97) |
Ref = referent values. Odds ratio (OR) and 95% confidence interval (CI) were estimated from marginal structural models for an increase of one quintile in the hPDI or per 10 increments of hPDI; 95% CI was obtained from 500 bootstrapped samples. The total effect represents the overall effect of the exposure (diet) on the disease (asthma); the indirect effect represents the effect passing through the mediator (body mass index); the direct effect represents the effect unexplained by the mediator. Models were adjusted for age, physical activity, smoking, educational level, marital status, and having farmer parents.