Table 3.
Association between urinary iodine concentration and place of residence, socio-demographic factors, anthropometry and salt iodine content.
| Unadjusted | Adjusted | ||||||||||
| UIC 1 < 100 µg/L | UIC 1 ≥ 300 µg/L | UIC 1 < 100 µg/L | UIC 1 ≥ 300 µg/L | ||||||||
| n | % 2 | RPR 3 | C.I. 5 | % 2 | RPR 4 | C.I. 5 | RPR3 | C.I. 5 | RPR 4 | C.I. 5 | |
| Gender | |||||||||||
| p 6 = 0.44 | p 7 < 0.001 | p 6 = 0.41 | p 7 < 0.001 | ||||||||
| Male | 780 | 9.9% | 1 | – | 30.1% | 1 | – | 1 | – | 1 | – |
| Female | 780 | 13.1% | 1.2 | 0.8–1.8 | 19.6% | 0.6 | 0.4–0.8 | 1.2 | 0.8–1.8 | 0.5 | 0.3–0.7 |
| Age | |||||||||||
| p 6 = 0.06 | p 7 = 0.54 | p 6 = 0.045 | p 7 = 0.41 | ||||||||
| 6–7 years | 441 | 13.4% | 1 | – | 26.9% | 1 | – | 1 | – | 1 | – |
| 8–9 years | 537 | 12.7% | 0.9 | 0.6–1.4 | 23.9% | 0.8 | 0.6–1.2 | 0.9 | 0.6–1.6 | 0.8 | 0.6–1.2 |
| 9–12 years | 582 | 8.7% | 0.6 | 0.4–0.9 | 24.8% | 0.8 | 0.6–1.2 | 0.6 | 0.4–0.9 | 0.8 | 0.6–1.1 |
| Milieu | |||||||||||
| p 6 = 0.92 | p 7 = 0.75 | p 6 = 0.89 | p 7 = 0.89 | ||||||||
| Urban | 858 | 11.4% | 1.0 | 0.5–2.0 | 25.7% | 1.1 | 0.6–2.2 | 1.0 | 0.5–1.8 | 1.0 | 0.6–1.5 |
| Rural | 702 | 11.4% | 1 | – | 23.8% | 1 | – | 1 | – | 1 | – |
| Region | |||||||||||
| p 6 < 0.001 | p 8 < 0.001 | p 6 = 0.008 | p 7 < 0.001 | ||||||||
| Greater Tunis | 240 | 11.2% | 1 | – | 28.1% | 1 | – | 1 | – | 1 | – |
| North East | 180 | 25.5% | 2.3 | 1.5–3.4 | 13.1% | 0.5 | 0.2–1.2 | 2.1 | 1.4–3.1 | 0.4 | 0.2–1.1 |
| North West | 360 | 8.4% | 0.7 | 0.4–1.2 | 22.1% | 0.7 | 0.2–2.0 | 0.6 | 0.3–1.2 | 0.6 | 0.2–1.8 |
| Central East | 240 | 8.9% | 0.6 | 0.3–1.4 | 15.2% | 0.4 | 0.1–1.4 | 0.6 | 0.3–1.3 | 0.4 | 0.1–1.4 |
| Central West | 180 | 9.7% | 0.8 | 0.3–2.2 | 22.8% | 0.7 | 0.2–2.4 | 0.8 | 0.3–1.9 | 0.6 | 0.2–1.9 |
| South East | 180 | 7.5% | 1.4 | 0.3–6.2 | 62.5% | 4.5 | 1.5–13.9 | 1.2 | 0.3–5.2 | 4.9 | 1.6–14.7 |
| South West | 180 | 4.3% | 0.4 | 0.2–0.9 | 34.2% | 1.2 | 0.4–3.4 | 0.4 | 0.1–1.0 | 1.1 | 0.4–3.0 |
| Education of the father | |||||||||||
| p 6 = 0.54 | p 7 = 0.16 | p 6 = 0.26 | p 7 = 0.032 | ||||||||
| No formal schooling | 92 | 9.8% | 0.9 | 0.4–1.7 | 32.7% | 1.5 | 1–2.3 | 0.9 | 0.4–1.9 | 1.8 | 1.2–2.7 |
| Primary schooling | 648 | 9.9% | 0.8 | 0.5–1.2 | 25.8% | 1.1 | 0.8–1.5 | 0.7 | 0.4–1.2 | 1.2 | 0.9–1.8 |
| Secondary and more | 820 | 12.7% | 1 | – | 23.8% | 1 | – | 1 | – | 1 | – |
| Education of the mother | |||||||||||
| p 6 = 0.17 | p 7 = 0.77 | p 6 = 0.41 | p 8 = 0.52 | ||||||||
| No formal schooling | 236 | 6.8% | 0.6 | 0.3–1.2 | 29.1% | 1.2 | 0.7–2.1 | 0.7 | 0.3–1.7 | 1.4 | 0.8–2.5 |
| Primary schooling | 648 | 12.6% | 1.1 | 0.6–2.0 | 24.6% | 1.0 | 0.7–1.4 | 1.2 | 0.7–2.1 | 1.1 | 0.8–1.6 |
| Secondary and more | 676 | 11.7% | 1 | – | 24.3% | 1 | – | 1 | – | 1 | – |
| Occupation of the father | |||||||||||
| p 6 = 0.24 | p 7 = 0.79 | p 6 = 0.033 | p 7 = 0.82 | ||||||||
| Not working | 93 | 13.3% | 1.5 | 0.8–2.9 | 22.9% | 1.0 | 0.4–2.3 | 1.9 | 1.0–3.5 | 1.0 | 0.4–1.8 |
| Worker/employee | 1104 | 12.1% | 1.4 | 0.9–2.2 | 25.3% | 1.1 | 0.8–1.4 | 1.7 | 1.1–2.5 | 0.8 | 0.4–1.7 |
| Middle/upper executive | 363 | 9.0% | 1 | – | 24.8% | 1 | – | 1 | – | 1 | – |
| Occupation of the mother | |||||||||||
| p 6 = 0.86 | p 7 = 0.88 | p 6 = 0.75 | p 7 = 0.45 | ||||||||
| Not working | 1234 | 11.6% | 0.9 | 0.5–1.6 | 24.8% | 0.9 | 0.5–1.5 | 0.7 | 0.3–1.9 | 0.9 | 0.4–2.0 |
| Worker/employee | 181 | 9.9% | 0.8 | 0.3–2.1 | 24.9% | 0.9 | 0.4–1.7 | 0.9 | 0.5–1.6 | 0.7 | 0.4–1.3 |
| Middle/upper executive | 145 | 12.1% | 1 | – | 26.9% | 1 | – | 1 | – | 1 | – |
| Body Mass Index forage (z–scores) | |||||||||||
| p 6 = 0.66 | p 8 = 0.29 | p 6 = 0.76 | p 8 = 0.15 | ||||||||
| Thinness(<–2) | 138 | 9.5% | 0.8 | 0.4–1.8 | 23.7% | 0.9 | 0.5–1.6 | 1.0 | 0.4–2.1 | 1.0 | 0.6–1.7 |
| Normal weight (–2 to <+1) | 1162 | 11.2% | 1 | – | 24.7% | 1 | – | 1 | – | 1 | – |
| Overweight (≥+1) | 260 | 13.7% | 1.4 | 0.6–3.0 | 27.2% | 1.2 | 0.9–1.7 | 1.4 | 0.6–3.3 | 1.4 | 0.9–2.1 |
| Iodine content of salt used in the household (mg/kg) | |||||||||||
| p 6 = 0.24 | p 7< 0.001 | p 6 = 0.22 | p 7 = 0.002 | ||||||||
| Non iodized (0) | 103 | 7.6% | 0.6 | 0.3–1.5 | 16.5% | 0.5 | 0.3–0.9 | 0.7 | 0.3–2.0 | 0.5 | 0.2–1.0 |
| Inadequately iodized (>0 to <15) | 207 | 17.0% | 1.5 | 1.0–2.5 | 15.6% | 0.5 | 0.4–0.8 | 1.5 | 1.0–2.3 | 0.7 | 0.4–1.1 |
| Adequately iodized(≥15 to <25) | 890 | 10.4% | 1 | – | 26.0% | 1 | – | 1 | – | 1 | – |
| Excessively iodized (≥25) | 360 | 10.8% | 1.1 | 0.7–1.9 | 29.8% | 1.0 | 0.8–1.4 | 1.0 | 0.6–1.7 | 1.1 | 0.8–1.5 |
1 UIC: Urinary iodine concentration; 2 Weighted % (accounting for sampling design, including unequal probabilities of selection); 3 RPR: For category of cofactor vs. reference category (for which RPR = 1), crude or adjusted Relative Prevalence Ratio of having UIC < 100 vs. having UIC in the 100 < UIC < 300 category (base response category); 4 RPR: For category of cofactor vs. reference category (for which RPR = 1), crude or adjusted Relative Prevalence Ratio of having high iodine (IUC ≥ 300) vs. having UIC in the 100 < UIC < 300 category (base response category); 5 C.I.: 0.95 sampling design based confidence interval for crude or adjusted RPR; 6 Crude or adjusted P-value for association of ID (iodine <100) with co-factor; 7 Crude or adjusted p-value for association of excess of iodine (≥300) with a co-factor.