Sensitivity, Specificity, and Safety of a Novel ESAT6-CFP10 Skin Test for Tuberculosis Infection in China: 2 Randomized, Self-Controlled, Parallel-Group Phase 2b Trials

Current diagnostics for tuberculosis infection are limited. We evaluated the ESAT6-CFP10 skin test and found a good safety profile and high diagnostic accuracy. It may be a viable option, especially in low-income countries with universal bacillus Calmette Guerin vaccination. Background Diagnostics to identify tuberculosis infection are limited. We aimed to assess the diagnostic accuracy and safety of ESAT6-CFP10 (EC) skin test for tuberculosis infection in Chinese adults. Methods We conducted 2 randomized, parallel-group clinical trials in healthy participants and tuberculosis patients. All participants were tested with the T-SPOT.TB test, then received an EC skin test and tuberculin skin test (TST). The diameter of skin indurations and/or redness at injection sites were measured at different time periods. A bacillus Calmette Guerin (BCG) model was established to assess the diagnosis of tuberculosis infection using an EC skin test. Results In total, 777 healthy participants and 96 tuberculosis patients were allocated to receive EC skin test at 1.0 mu g/0.1 mL or 0.5 mu g/0.1 mL. The area under the curve was 0.95 (95% confidence interval [CI], .91-.97) for the EC skin test at 1.0 mu g/0.1 mL at 24-72 hours. Compared with the T-SPOT.TB test, the EC skin test demonstrated similar sensitivity (87.5, 95% CI, 77.8-97.2 vs 86.5, 95% CI, 79.5-93.4) and specificity (98.9, 95% CI, 96.0-99.9 vs 96.1, 95% CI, 93.5-97.8). Among BCG vaccinated participants, the EC skin test had high consistency with the T-SPOT.TB test (96.3, 95% CI, 92.0-100.0). No serious adverse events related to the EC skin test were observed. Conclusions The EC skin test demonstrated both high specificity and sensitivity at a dose of 1.0 mu g/0.1 mL, comparable to the T-SPOT.TB test. The diagnostic accuracy of the EC skin test was not impacted by BCG vaccination.

Automated summary

The EC skin test showed high specificity and sensitivity in diagnosing tuberculosis infection, comparable to the T-SPOT.TB test, and was not affected by BCG vaccination.