Table 6

Univariate predictors of incident TB
Determinant Persons Pyrs Cases Incidence (per 100,000 pyrs) P-value (chi-square test)
Total 5000 5527 13 235 -
Follow up TST outcome *
Negative < 10 mm 2912 3323 1 30
Positive ≥ 10 mm 582 679 11 1620 <0.001
Not done/not read** 1506 1525 1 66
Baseline TST outcome
Negative < 10 mm 4179 4574 12 262 <0.001
Positive ≥ 10 mm 802 890 1 112
Prior diagnosis TB
No 4990 5517 13 236 -
Yes 10 11 0 0
Schooling status
In school 4678 5193 13 250 -
Out of school 322 335 0 0
Age group (years)
12-14 2339 2778 4 144
15-16 1482 1583 4 253 0.093
17-18 1179 1167 5 429
Sex
Male 2589 2898 10 345
Female 2411 2630 3 114 0.028
Education level
> 7 years 696 733 2 273
None 40 37 0 0 0.752
≤ 7 years 4264 4757 11 231
TB Contact during follow-up
No 4732 5196 11 212 0.019
Yes 268 331 2 604
Cough during follow-up
<14 days 2250 2602 5 192
None 2102 2307 6 260 0.917
≥14 days 500 581 2 344

Abbreviation: Key: Pyrs Person years, TST Tuberculin Skin Test.

Note:

* One individual with TB during follow up had a positive TST of ≥10 mm at baseline;

**Those with a positive TST at baseline were not given TST again at 1 year and 2 years of follow up.

Waako et al.

Waako et al. BMC Infectious Diseases 2013 13:349   doi:10.1186/1471-2334-13-349

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