Table 4.
Multivariate, mixed-effect logistic regression of reported head lice (lice/no lice) in a prospective 5-month period (Period 3) in primary school children at 12 schools in Oslo, Norway
| Variable | P-value | Category | Prevalence (n) | OR (95% CI) |
|---|---|---|---|---|
| Siblings with lice | <0.001 | No | 5.1% (1695) | 1 |
| Yes | 55.2% (29) | 25.64 (10.30–63.81) | ||
| Sex | >0.999 | Female | 6.7% (875) | 1 |
| Male | 5.1% (849) | 0.98 (0.46–2.11) | ||
| Hair type | 0.237 | Straight | 5.7% (1304) | 1 |
| Wavy | 8.0% (299) | 1.47 (0.86–2.51) | ||
| Curly | 3.3% (121) | 0.66 (0.22–1.93) | ||
| Hair length | 0.058 | Short | 4.9% (839) | 1 |
| Medium | 8.4% (239) | 2.23 (1.10–4.49) | ||
| Long | 6.3% (646) | 1.61 (0.62–4.17) | ||
| Income | 0.242 | Low | 6.2% (469) | 1 |
| Medium | 6.9% (759) | 1.14 (0.68–1.93) | ||
| High | 4.2% (496) | 0.71 (0.38–1.34) |
Class affiliation was used as random variable. Total number of children was 1724 split into 197 classes. ORs are in relation to the first category of each variable. All variables added were significant at P < 0.15 in univariate analysis.
Random effect variance (CI): class = 0.88 (0.11–1.66), P < 0.001; school = 0.08 (−0.21 to 0.38), P = 0.506.