Results from logistic regression where self-reported diagnosis of a thyroid condition was regressed on urinary fluoride (Cycles 2 and 3) and fluoride concentration of tap water (Cycle 3)
| Predictor variable | Cycle 2 of CHMS | Cycle 3 of CHMS | ||||
| Unadjusted† estimates for fluoride urine subsample (OR, 95% CI) | Adjusted‡ estimates for fluoride urine subsample (OR, 95% CI) (n=1466) | Unadjusted† estimates for fluoride urine subsample (OR, 95% CI) | Adjusted‡ estimates for fluoride urine subsample (OR, 95% CI) (n=1570) | Unadjusted† estimates for fluoride tap water subsample (OR, 95% CI) | Adjusted‡ estimates for fluoride tap water subsample (OR, 95% CI) (n=1564) | |
| Urinary fluoride (μmol/L) (cont) | 0.98 (0.94 to 1.03) | 0.98 (0.95 to 1.02) | 1.00 (0.99 to 1.02) | 1.00 (0.99 to 1.01) | – | – |
| Fluoride concentration of tap water (mg/L) (cont) | – | – | – | – | 0.92 (0.22 to 3.94) | 0.98 (0.28 to 3.45) |
| Sex (ref: male) | 6.36* (1.52 to 26.68) | 6.31* (1.29 to 30.89) | 4.09* (1.27 to 19.52) | 4.20* (0.90 to 19.53) | 4.00* (1.02 to 15.72) | 4.13* (0.94 to 18.21) |
| Age (years) (cont) | 1.04** (1.02 to 1.07) | 1.05** (1.02 to 1.08) | 1.05** (1.03 to 1.08) | 1.06** (1.03 to 1.09) | 1.05** (1.03 to 1.08) | 1.06** (1.03 to 1.09) |
| Household income adequacy (ref: lower and middle income) | 0.95 (0.39 to 2.35) | 1.09 (0.29 to 4.07) | 0.78 (0.23 to 2.61) | 1.23 (0.30 to 5.03) | 0.77 (0.22 to 2.64) | 1.20 (0.30 to 4.83) |
| Highest attained education in the household (ref: less than bachelor’s degree) | 1.67 (0.84 to 3.28) | 2.03 (0.81 to 5.10) | 0.40*** (0.15 to 1.10) | 0.37*** (0.11 to 1.22) | 0.41*** (0.15 to 1.11) | 0.38 (0.12 to 1.26) |
†Column contains bivariate associations between predictor variable and the outcome (self-reported diagnosis of a thyroid condition).
‡Column contains associations from single model containing all predictor variables (age, sex, household income adequacy and highest attained education in the household).
*p<0.05, **p<0.01, ***p<0.1.
Note: these models were rerun using creatinine-adjusted urinary fluoride (μmol/mmol) and no significant observations were detected (data not shown).
CHMS, Canadian Health Measures Survey; RRR, relative risk ratio; TSH, thyroid-stimulating hormone.