Table 1 Sensitivity, specificity, PPV and NPV of questionnaire-based definitions of atopy compared to the gold standard of SPT and sample size calculations for a nested cohort study
Number of atopic conditions | Sensitivity | Specificity | Youden’s index | PPV | NPV | Sample size for nested cohort study |
|---|---|---|---|---|---|---|
1 | 54.3% | 65.8% | 20.1% | 72.6% | 46.3% | 344 |
2 | 24.4% | 98.7% | 23.1% | 96.9% | 44.8% | 2948 |
3 | 4.7% | 100.0% | 4.7% | 100.0% | 39.3% | 21034 |