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Demographic characteristics of subjects and controls.
| Variable | Subjects n (%) | Controls n (%) | χ 2 | P value |
|---|---|---|---|---|
| Age group (years) | ||||
| 4–8 | 54 (50.0) | 54 (50.0) | ||
| 9–13 | 82 (50.0) | 82 (50.0) | 0.001 | 1.000 |
| 14–17 | 64 (50.0) | 64 (50.0) | ||
| Gender | ||||
| Male | 109 (54.5) | 105 (52.5) | 0.16 | 0.688 |
| Female | 91 (45.5) | 95 (47.5) | ||
| Social class | ||||
| 1 | 18 (9.0) | 25 (12.5) | ||
| 2 | 27 (13.5) | 46 (23.0) | ||
| 3 | 42 (21.0) | 49 (24.5) | 12.296 | 0.015 |
| 4 | 95 (47.5) | 68 (34.0) | ||
| 5 | 18 (9.0) | 12 (6.0) |
