Sensitivity, specificity and correct classification rates (%) of measures of secondhand smoke exposure
| Own home | Relative's home | Friend's home | Automobile | 4-Item scale | 3-Item scale | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 24 h | 7 days | 24 h | 7 days | 24 h | 7 days | 24 h | 24 h | 7 days | Home smoking rules | |
| >0.05 ng/mL | ||||||||||
| Sensitivity | 32.4 | 38.2 | 5.9 | 9.1 | 11.8 | 21.2 | 14.7 | 35.3 | 41.2 | 44.1 |
| Specificity | 94.0 | 90.5 | 97.6 | 97.6 | 96.4 | 96.4 | 98.8 | 90.5 | 86.9 | 79.8 |
| Correct classification | 76.2 | 75.4 | 71.2 | 72.4 | 72.0 | 75.0 | 74.5 | 74.6 | 73.8 | 69.5 |
| >0.215 ng/mL | ||||||||||
| Sensitivity | 66.7 | 75.0 | 16.7 | 16.7 | 33.3 | 41.7 | 41.7 | 75.0 | 75.0 | 66.7 |
| Specificity | 92.5 | 88.7 | 98.1 | 97.1 | 97.2 | 95.2 | 99.1 | 89.6 | 84.9 | 77.4 |
| Correct classification | 89.9 | 87.3 | 89.8 | 88.8 | 90.7 | 89.8 | 93.2 | 88.1 | 83.9 | 76.3 |
| >0.80 ng/mL | ||||||||||
| Sensitivity | 71.4 | 85.7 | 28.6 | 28.6 | 28.6 | 57.1 | 42.9 | 71.4 | 85.7 | 71.4 |
| Specificity | 90.1 | 86.5 | 98.2 | 97.2 | 95.5 | 94.5 | 97.3 | 86.5 | 82.9 | 75.7 |
| Correct classification | 88.9 | 86.5 | 94.1 | 93.1 | 91.5 | 92.2 | 94.0 | 85.6 | 83.1 | 75.6 |
The 3-item scale combines past 7-day SHS exposure in the residence of one's own, of friends and of relatives; the 4-item scale combines past 24-h residential SHS exposure with automobile SHS exposure. For examination of correct classification, sum scores of 1 or greater on these scales were coded as exposed (1) versus not exposed (0).
Bold font shows classification rates for the item that outperformed the other measures.
SHS, secondhand smoke.