Agreement between (A) air nicotine concentrations and questionnaire reported smoking; and (B) between urinary cotinine and questionnaire reported smoking and air nicotine: sensitivity, specificity, positive and negative predictive value, and percentage misclassified
| Gold standard | Test method | Sensitivity | Specificity | PPV | NPV | % Misclassified | |
|---|---|---|---|---|---|---|---|
| *The limit of quantification (LOQ) was 0.24 μg/m3. | |||||||
| †The limit of detection (LOD) was 2 ng/ml. | |||||||
| Sensitivity, probability that someone who is truly exposed (gold standard) will be classified as exposed by the test method; specificity, probability that someone who is truly unexposed (gold standard) will be classified as unexposed by the test method; PPV, probability that someone who is classified as exposed by the test method is truly exposed; NPV, probability that someone who is classified as unexposed by the test method is truly unexposed; % misclassified, 100 × (number of subjects for which the two methods disagreed)/total number of subjects. | |||||||
| A | Germany | ||||||
| Air nicotine >LOQ* | Any questionnaire reported smoking during measurement period (yes/no) | 61.4% | 95.7% | 67.5% | 94.5% | 8.6% | |
| Air nicotine >LOQ* | Daily questionnaire reported smoking during measurement period (yes/no) | 55.3% | 98.0% | 77.8% | 94.5% | 6.9% | |
| Air nicotine >LOQ* | Any questionnaire reported smoking at the child’s age 4 years (yes/no) | 66.5% | 87.2% | 42.9% | 95.0% | 15.2% | |
| Netherlands | |||||||
| Air nicotine >LOQ* | Any questionnaire reported smoking during measurement period (yes/no) | 77.81% | 80.6% | 32.6% | 96.8% | 19.7% | |
| Air nicotine >LOQ* | Daily questionnaire reported smoking during measurement period (yes/no) | 73.3% | 95.6% | 66.7% | 96.8% | 6.7% | |
| Air nicotine >LOQ* | Any questionnaire reported smoking at the child’s age 4 years (yes/no) | 66.7% | 91.0% | 45.8% | 96.0% | 11.5% | |
| Sweden | |||||||
| Air nicotine >LOQ* | Any questionnaire reported Smoking during measurement period (yes/no) | 0% | 96.8% | 0% | 97.4% | 5.6% | |
| Air nicotine >LOQ* | Any questionnaire reported smoking at the child’s age 4 years (yes/no) | 55.6% | 81.2% | 7.2% | 98.6% | 19.4% | |
| B | Germany | ||||||
| Urinary cotinine >LOD† | Daily questionnaire reported smoking during measurement period (yes/no) | 46.2% | 97.6% | 75.0% | 92.2% | 9.2% | |
| Urinary cotinine >LOD† | Questionnaire reported smoking during 24 hours prior urine sampling (yes/no) | 42.3% | 93.0% | 47.8% | 91.4% | 13.7% | |
| Urinary cotinine >LOD† | Any questionnaire reported smoking at the child’s age 4 years (yes/no) | 52.2% | 89.5% | 49.0% | 90.7% | 16.5% | |
| Urinary cotinine >LOD† | Air nicotine > limit of quantification | 50.0% | 78.9% | 26.5% | 91.2% | 24.9% | |