When the dioxin level was included as quartiles in the model, AORs were 1.8 (95% CI 1.1–2.9), 2.9 (95% CI 1.7–4.8), and 3.4 (95% CI 2.0–5.8) for the second, third, and fourth quartiles with a positive trend ( P < 0.001) (Table 2 ).
When the misclassification was not related to the exposure status (random misclassification), it would lead to an underestimation of the relative risk (biased towards the null), which is compatible with our case: the OR was higher than the null value (larger than 1) but did not reach statistical significance.