Use of interferon-gamma release assay and tuberculin skin test in diagnosing tuberculosis in Lithuanian adults: A comparative analysis.

BACKGROUND AND OBJECTIVE: Lithuania belongs to the group of countries with a high-incidence of tuberculosis (TB). Some scientific studies show that the interferon-gamma release assay is more accurate and correlates more highly with TB exposure as compared to the tuberculin skin test (TST). This study aimed at comparing the efficacy between the T SPOT TB and TST for diagnosing TB among Lithuanian adults.

MATERIALS AND METHODS: Individuals with diagnosed TB, healthcare workers with known risk for TB and individuals without any known risk for TB underwent clinical examinations, interviews about their history of TB exposure and chest radiography. Then the TST and the T SPOT TB were performed on patients.

RESULTS: A positive T SPOT TB was more common in the group with diagnosed TB compared to healthcare workers and the low risk for TB groups (97.5%, 36.4%, and 0%, respectively, P<0.01). Positive TST results did not differ between the groups with diagnosed TB and the healthcare workers (92.5% vs. 95.5%, P>0.05). Agreement between TST and T SPOT TB was poor (kappa 0.14, P>0.05). T SPOT TB had higher specificity and sensitivity compared to TST (area under the ROC 0.9±0.04, P<0.01, vs. 0.5±0.06, P>0.05).

CONCLUSIONS: The T SPOT TB showed greater accuracy in diagnosing TB than TST did. Positive T SPOT TB result but not the TST was more common in patients with diagnosed TB.