Systematic TB screening using WHO radiograph categorisation and care outcomes.

BACKGROUND

An appropriate screening approach and quality care are crucial for TB programmes in prisons. This study assessed crude TB prevalence, accuracy of the screening methods and treatment outcomes in a Thai prison.METHOD: This was a retrospective analysis of findings from a mass CXR screening conducted among incarcerated people in July 2017. Digital radiographs were forwarded to a chest physician to read and classify in six categories using WHO categorisation. CXR with significant Categories 3 (no active TB), 4 (not TB), 5 (TB) and 6 (unclassified) abnormalities were eligible for sputum microscopy and Xpert testing. A screening questionnaire locally known as TB-P1 was used for case management. Patients with TB received care in the prison.

RESULTS

Of 2,382 prisoners screened, 6.3% had CXR Categories 3-6. Crude prevalence of bacteriologically confirmed TB was 1,133/100,000 (95% CI 748.3-1644.9). The screening´s sensitivity was 96.3% based on CXR Category 5 and 22.2% using TB-P1. Treatment success rates in drug-susceptible and drug-resistant TB patients were respectively 66.7% and 33.3%.

CONCLUSION

The WHO radiograph categorisation could be used to screen for TB in the field and may be applied in artificial intelligence for interpreting CXR; screening questionnaires are not effective in prison environments. Nonetheless, low treatment success rates remained a challenge.