Table 1

Urine cotinine levels by self-reported smoking status in November 2017, N=202

Self-reported smoking status*Age, mean (SD) (years)N (%)Cotinine levels (ng/mL)†
Median (IQR)P value‡Cotinine >50 ng/mL, N (%)Cotinine ≤50 ng/mL, N (%)P value‡
All participants29 (8)202 (100%)<LOD (<LOD, 106.75)68 (34)134 (66)
Current smoker30 (8)24 (12%)310.03 (76.23, 650.58)<0.0119 (79)5 (21)<0.01
Former smoker32 (9)28 (14%)7.84 (<LOD, 92.98)10 (36)18 (64)
Never smoked28 (8)150 (74%)<LOD (<LOD, 63.34)39 (26)111 (74)
  • Sensitivity: 19 true positive smokers/(19+10+39)×100=28%.

  • Specificity: 129 true negative former and never smokers/(5+18+111)×100=96%.

  • *November survey question: ‘do you smoke cigarettes?’.

  • †Values above 5000 ng/mL were put at 5000 ng/mL. LOD: 5 ng/mL.

  • ‡P value for overall difference between smoking groups.

  • LOD, limit of detection.