Digital Chest X-Ray with Computer-aided Detection for Tuberculosis Screening within Correctional Facilities

Rationale: Realizing the Global Plan to End Tuberculosis (TB) will require reaching at least 90% of people in key populations, such as inmates, through optimizing case-finding approaches. Objectives: To evaluate the value of adding digital chest X-ray (d-CXR) with computer-aided detection (CAD) to symptom-based screening on TB yield among inmates. Methods: Consecutive adult inmates from four correctional facilities in South Africa were screened for TB using symptoms and d-CXR. Any person with at least one symptom or CAD score of >= 50 provided two sputa for liquid culture and GeneXpert MTB/RIF Ultra (Xpert Ultra) testing. In a sample of 800 symptom-negative inmates with CAD score < 50, Xpert Ultra testing was also conducted. TB yield was defined as the proportion of new patients with bacteriologically confirmed TB who were identified. Results: We enrolled 3,576 participants: 99.6% male, median age of 34 years (interquartile range, 28-41), and 584 (16.3%) with positive test results for human immunodeficiency virus. Of those screened, 867 (24.2%) participants required investigation (394 [11.2%] symptomatic, 685 [19.1%] with abnormal CAD results, and 867 [24.2%] with either). Sputum was taken in 747 (86.2%) participants, with 28 (7.8 per 1,000 population) new TB cases diagnosed. On the basis of hypothesized screening modalities, yield would have been 3.6 per 1,000 population on the basis of symptoms alone and 7.0 per 1,000 population on the basis of d-CXR alone. Among an additional 800 inmates tested who initially screened symptom negative and had a CAD score,50, five TB cases were diagnosed. There was no difference in TB yield when comparing Xpert Ultra against culture (5.6 vs. 4.8 per 1,000 population; P = 0.21). Conclusions: The addition of d-CXR identified two times more patients with undiagnosed TB than did investigation of symptoms alone. Complementary use of d-CXR may potentially overcome the subjectivity inherent in symptom screening alone for identifying TB in this population.

Automated summary

This study evaluates the value of combining digital chest X-ray with symptom-based screening in improving the tuberculosis detection rate among inmates. The results show that adding digital chest X-ray can identify twice as many undiagnosed tuberculosis cases compared to symptom-based screening alone.