The role of TST in the diagnosis of latent tuberculosis infection among military personnel in South Korea.

BACKGROUND

The rapid and accurate diagnosis of latent tuberculosis infection (LTBI) is crucial in military settings because military personnel live in crowded circumstances and are of an age group with a high incidence of tuberculosis (TB). We tried to elucidate whether the tuberculin skin test (TST) accurately reflects the risk of TB infection among military personnel, in a setting of intermediate TB prevalence and where bacille Calmette-Guérin (BCG) vaccination is mandatory.

METHODS

A multi-stage cluster survey was conducted among military personnel in South Korea. Participants were grouped according to their risk of TB infection: Group 1, no identifiable risk of TB; Groups 2 and 3, recent casual (Group 2) or close (Group 3) contact with smear-positive TB patients.

RESULTS

Of 1045 participants, 857 (82.0%) had been BCG-vaccinated. The odds ratio (OR) of a positive TST (10 mm cut-off) for Group 2 (n = 184) and Group 3 (n = 83) compared with Group 1 (n = 778) were 0.95 (95%CI 0.67-1.38) and 1.7 (95%CI 1.06-2.70), respectively (P value for trend 0.16).

CONCLUSIONS

The TST does not accurately reflect the risk of LTBI among young military personnel in a setting where there is intermediate TB prevalence and extensive BCG coverage.