Table 2

Estimated effects of marijuana use (OR and 95% CI) on the risk of head and neck cancer, by covariates selected for adjustmenta

No. of casesNo. of controlsCovariates
No covariates (crude)Pack-years of smokingPack-years of smoking plusb
Marijuana use
 Never1491591.01.01.0
 Ever24171.5 (0.8–2.9)1.7 (0.8–3.6)2.6 (1.1–6.6)
Times/day
 Continuous1.3 (0.9–1.9)1.4 (0.9–2.1)1.5 (0.9–2.4)
 01491591.01.01.0
 1861.4 (0.5–4.2)1.7 (0.5–5.7)4.0 (0.9–17.2)
 >1824.3 (0.9–20.4)5.1 (0.99–26)5.4 (0.9–33)
P for trend0.05490.03400.0214
Times/dayb
 Continuous1.3 (0.9–1.8)1.3 (0.9–1.9)1.4 (0.9–2.2)
 01491591.01.01.0
 116151.1 (0.5–2.4)1.3 (0.5–2.9)2.1 (0.8–6.0)
 >1824.3 (0.9–20.4)5.0 (0.97–26)4.9 (0.8–29)
P for trend0.09720.06360.0358
Years of use
 Continuous1.1 (0.98–1.1)1.1 (0.99–1.21)1.1 (1.01–1.27)
 01491591.01.01.0
 1–5861.4 (0.5–4.2)1.8 (0.6–5.8)3.9 (0.99–15.0)
 >51162.0 (0.7–5.4)3.3 (0.95–11.4)4.9 (1.07–22.3)
P for trend0.15740.03600.0134
Years of useb
 Continuous1.1 (0.98–1.1)1.1 (0.99–1.18)1.1 (1.002–1.2)
 01491591.01.01.0
 1–513111.3 (0.5–2.9)1.2 (0.5–3.0)1.9 (0.6–5.9)
 >51162.0 (0.7–5.4)3.2 (0.94–11)4.3 (0.99–19)
P for trend0.17260.07510.0325
  • a Also adjusted for age (continuous variable), gender (male = 0, female = 1); race (white = 0, non-white = 1); education (≤high school = 0; college = 1, >college = 2); heavy alcohol use (<100/month = 0, ≥100/month = 1); and passive smoking (no = 0, yes = 1).

  • b Missing data were replaced by median.