Table 3. Odds ratios (ORs) for Mycobacterium tuberculosis infection (MTI), by potential risk factors, among 1797 Greenlandic schoolchildren stratified by TB contact.
| Potential risk factor | Without known TB contact |
With known TB contact |
Test for effect modification of TB contact |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Children |
OR | 95% CI | P | Children |
OR | 95% CI | P | P | |||||
| No. | With MTI | No. | With MTI | ||||||||||
| Sex | 1617 | 104 | – | – | 0.76 | 180 | 48 | – | – | 0.55 | 0.50 | ||
| Female | 812 | 50 | 0.94 | 0.62–1.41 | – | 91 | 27 | 1.24 | 0.61–2.52 | – | – | ||
| Malea | 805 | 54 | 1 | – | – | 89 | 21 | 1 | – | – | – | ||
| Age (years) | 1617 | 104 | – | – | 0.002 | 180 | 48 | – | – | 0.29 | – | ||
| 5–7a | 249 | 9 | 1 | – | – | 33 | 10 | 1 | – | – | – | ||
| 8–10 | 449 | 21 | 1.43 | 0.71–2.89 | – | 51 | 9 | 0.86 | 0.26–2.80 | – | – | ||
| 11–13 | 534 | 29 | 1.55 | 0.76–3.14 | – | 62 | 20 | 1.85 | 0.56–6.07 | – | – | ||
| 14–15 | 272 | 28 | 3.14 | 1.55–6.36 | – | 24 | 8 | 2.10 | 0.55–7.95 | – | – | ||
| ≥ 16 | 113 | 17 | 3.30 | 1.43–7.61 | – | 10 | 1 | 0.33 | 0.03–3.94 | – | – | ||
| OR per each additional year of age | – | – | 1.14 | 1.06–1.23 | 0.0003 | – | – | 1.05 | 0.92–1.20 | 0.45 | 0.29c | ||
| Ethnicity | 1617 | 104 | – | – | 0.03 | 180 | 48 | – | – | 0.03 | 0.44 | ||
| Inuit | 1439 | 101 | 3.55 | 1.15–11.0 | – | 154 | 47 | 8.53 | 1.19–61.4 | – | – | ||
| Non-Inuita | 178 | 3 | 1 | – | – | 26 | 1 | 1 | – | – | – | ||
| Mother’s age (years) at birth of study child | 1617 | 104 | – | – | 0.24 | 180 | 48 | – | – | 0.12 | 0.32 | ||
| 15–19 | 205 | 20 | 1.39 | 0.80–2.40 | – | 23 | 9 | 2.70 | 0.78–9.28 | – | – | ||
| ≥ 20a | 1412 | 84 | 1 | – | – | 157 | 39 | 1 | – | – | – | ||
| Type of residence | 1488 | 88 | – | – | 0.44 | 174 | 48 | – | – | 0.68 | 0.89 | ||
| Family dwellinga | 1355 | 69 | 1 | – | – | 158 | 42 | 1 | – | – | – | ||
| Orphanage, dorm | 93 | 14 | 1.28 | 0.60–2.75 | – | 9 | 4 | 2.00 | 0.34–11.6 | – | – | ||
| Foster family | 40 | 5 | 1.84 | 0.69–4.90 | – | 7 | 2 | 1.60 | 0.17–15.0 | – | – | ||
| No. of adults in household (CF 1) | 1437 | 81 | – | – | 0.06 | 171 | 47 | – | – | 0.15 | 0.02 | ||
| 1–2a | 1133 | 71 | 1 | – | – | 140 | 33 | 1 | – | – | – | ||
| 2+ | 304 | 10 | 0.50 | 0.24–1.02 | 31 | 14 | 2.18 | 0.76–6.25 | – | – | |||
| Average no. of people per room (CF 2) | 1266 | 60 | – | – | 0.77 | 142 | 40 | – | – | 0.57 | – | ||
| < 1 | 244 | 10 | 0.85 | 0.39–1.83 | – | 24 | 4 | 0.98 | 0.21–4.57 | – | – | ||
| 1–1.49a | 556 | 27 | 1 | – | – | 54 | 12 | 1 | – | – | – | ||
| ≥ 1.50 | 466 | 23 | 1.15 | 0.59–2.26 | – | 64 | 24 | 1.62 | 0.62–4.18 | – | – | ||
| OR per each additional category | – | – | 1.17 | 0.7–1.77 | 0.47 | – | – | 1.37 | 0.68–2.79 | 0.38 | 0.71c | ||
| Study child in own room (CF 3) | 1482 | 89 | – | – | 0.64 | 171 | 48 | – | – | 0.26 | 0.48 | ||
| Yesa | 807 | 53 | 1 | – | – | 87 | 19 | 1 | – | – | – | ||
| No | 675 | 36 | 1.13 | 0.69–1.84 | – | 84 | 29 | 1.57 | 0.71–3.45 | – | – | ||
| Sum of CFsb | 1617 | 104 | – | – | 0.45 | 180 | 48 | – | – | 0.11 | – | ||
| 0 CFsa | 666 | 52 | 1 | – | – | 68 | 9 | 1 | – | – | – | ||
| 1 CF | 529 | 36 | 0.95 | 0.60–1.51 | – | 58 | 18 | 2.82 | 1.04–7.60 | – | – | ||
| 2 CFs | 350 | 15 | 0.72 | 0.38–1.37 | – | 41 | 14 | 2.52 | 0.89–7.16 | – | – | ||
| 3 CFs | 72 | 1 | 0.28 | 0.04–1.81 | – | 13 | 7 | 4.24 | 1.04–17.3 | – | – | ||
| OR per each additional CF | – | – | 0.82 | 0.64–1.06 | 0.13 | – | – | 1.54 | 1.00–2.30 | 0.03 | 0.009c | ||
| Age difference (years) with next older sibling | 1113 | 62 | – | – | 0.19 | 122 | 33 | – | – | 0.17 | 0.90 | ||
| < 1 (including twin) | 52 | 7 | 1.80 | 0.74–4.42 | – | 9 | 5 | 3.47 | 0.90–13.3 | – | – | ||
| 1a | 256 | 17 | 1 | – | – | 31 | 8 | 1 | – | – | – | ||
| 2 | 197 | 6 | 0.47 | 0.19–1.16 | – | 21 | 4 | 0.56 | 0.11–2.84 | – | – | ||
| ≥ 3 | 608 | 32 | 0.90 | 0.52–1.58 | – | 61 | 16 | 1.04 | 0.35–3.04 | – | – | ||
| Mother’s education | 977 | 45 | – | – | 0.57 | 127 | 30 | – | – | 0.01 | – | ||
| 1: 8th grade and no further schooling | 100 | 4 | 0.84 | 0.20–3.51 | – | 17 | 8 | 3.92 | 1.21–12.7 | – | – | ||
| 2: 8th grade and skilled labour | 215 | 11 | 0.96 | 0.39–2.32 | – | 28 | 7 | 0.87 | 0.21–3.59 | – | – | ||
| 3: 10th grade and skilled laboura | 427 | 22 | 1 | – | – | 65 | 13 | 1 | – | – | – | ||
| 4: 10th grade, 3 years vocational training & courses, and bachelor’s degree d | 5 | 1 | 3.25 | 0.39–27.4 | – | 1 | 0 | – | – | – | – | ||
| 5: High school and skilled labour | 142 | 3 | 0.37 | 0.11–1.27 | – | 12 | 2 | 0.41 | 0.09–1.96 | – | – | ||
| 6: High school and bachelor’s/master’s degree | 88 | 4 | 1.03 | 0.34–3.10 | – | 4 | 0 | – | – | – | – | ||
| OR per each additional education level | – | – | 0.93 | 0.71–1.20 | 0.56 | – | – | 0.55 | 0.34–0.88 | 0.01 | 0.05c | ||
| Region | 1617 | 104 | – | – | 0.0002 | 180 | 48 | – | – | 0.97 | 0.03 | ||
| Easta | 331 | 19 | 1 | – | – | 36 | 9 | 1 | – | – | – | ||
| South | 880 | 83 | 1.58 | 0.91–2.75 | – | 130 | 35 | 1.15 | 0.42–3.16 | – | – | ||
| West | 406 | 2 | 0.09 | 0.02–0.40 | – | 14 | 4 | 1.10 | 0.21–5.71 | – | – | ||
| BMIe | 1599 | 101 | – | – | 0.03 | 178 | 47 | – | – | 0.62 | – | ||
| Underweight | 14 | 1 | 3.11 | 0.43–22.7 | – | 2 | 0 | – | – | – | – | ||
| Normala | 1260 | 76 | 1 | – | – | 138 | 35 | 1 | – | – | – | ||
| Overweight | 262 | 14 | 0.74 | 0.42–1.31 | – | 14 | 4 | 0.61 | 0.08–4.45 | – | – | ||
| Obese | 63 | 10 | 2.52 | 1.07–5.91 | – | 5 | 1 | 1.10 | 0.38–3.17 | – | – | ||
| OR per increase in BMI class | – | – | 1.15 | 0.76–1.75 | 0.51 | – | – | 1.14 | 0.50–2.38 | 0.72 | 0.99c | ||
| Obese (measured by BMI)f | 1599 | 101 | – | – | 0.02 | 178 | 47 | – | – | 0.62 | 0.19 | ||
| Noa | 1536 | 91 | 1 | – | – | 173 | 46 | 1 | – | – | – | ||
| Yes | 63 | 10 | 2.51 | 1.09–5.78 | – | 5 | 1 | 0.63 | 0.10–4.01 | – | – | ||
BMI, body mass index; CF, crowding factor; CI, confidence interval.
The estimates were fully adjusted for the following variables: sex, age, ethnicity, mother’s age at birth of study child, region and age difference between study child and next older sibling.
a Reference category.
b The sum of the CFs was obtained by adding the three CFs given in the table, as follows: CF 1 was added when 3 or more adults lived in the household; CF 2, when the average number of people per room was at least 1.5; and CF 3, when the study child did not have their own room.
c Interaction test performed as test for homogeneity of trends.
d Instead of qualifying for entrance to a bachelor’s programme through three years of upper secondary school, a person in Denmark and Greenland can qualify for entrance by completing three years of certified vocationally oriented training and courses.
e BMI categories were defined according to age- and sex-specific percentiles evaluated by Centers for Disease Control and Prevention BMI-for-age growth charts for girls and boys. Definitions were as follows: underweight, < 5th percentile; normal weight, 5th percentile to < 85th percentile; overweight, 85th percentile to < 95th percentile; obese, ≥ 95th percentile.
f Obesity was defined as in previous footnote; underweight, normal weight and overweight were combined into a single category.