The second national tuberculosis prevalence survey in Vietnam

Abstract

Introduction Tuberculosis (TB) remains a significant cause of morbidity and mortality in Vietnam. The current TB burden is unknown as not all individuals with TB are diagnosed, recorded and notified. The second national TB prevalence survey was conducted in 2017-2018 to assess the current burden of TB disease in the country. Method Eighty-two clusters were selected using a multistage cluster sampling design. Adult (�15 years of age) residents having lived for 2 weeks or more in the households of the selected clusters were invited to participate in the survey. The survey participants were screened for TB by a questionnaire and digital chest X-ray after providing written informed consent. Individuals with a positive symptom screen and/or chest X-ray suggestive of TB were asked to provide sputum samples to test for Mycobacterium tuberculosis by Ziehl-Neelsen direct light microscopy, Xpert MTB/RIF G4, BACTEC MGIT960 liquid culture and Lö wenstein-Jensen solid culture. Bacteriologically confirmed TB cases were defined by an expert panel following a standard decision tree. Result Of 87,207 eligible residents, 61,763 (70.8%) participated, and 4,738 (7.7%) screened positive for TB. Among these, 221 participants were defined as bacteriologically confirmed TB cases. The estimated prevalence of bacteriologically confirmed adult pulmonary TB was 322 (95% CI: 260-399) per 100,000, and the male-to-female ratio was 4.0 (2.8-5.8, p<0.001). In-depth interviews with the participants with TB disease showed that only 57.9% (95% CI: 51.3-64.3%) reported cough for 2 weeks or more and 32.1% (26.3-38.6%) did not

An Evaluation of Programmatic Community-Based Chest X-ray Screening for Tuberculosis in Ho Chi Minh City, Vietnam

“…This evaluation shows that programmatic community-based CXR screening followed by Xpert testing can result in high yields of TB among people who are likely to be missed by existing government health services. We recorded an Xpert-positive TB prevalence which is more than 2.5× the Xpert-positive TB prevalence in the Southern Region of Vietnam [ 2 ], indicating that our community sensitization efforts were effective at targeting and mobilizing higher risk individuals. In addition, half of the people diagnosed in this study had sub-clinical or low-grade TB and we estimate that only one quarter of our yield would have been detected if we had followed standard NTP screening and diagnostic guidelines.…”

“…Actual Xpert yields were converted into estimated culture yields using an 85% sensitivity rate for Xpert [ 23 ] and then AFB smear microscopy yields were estimated using a 43% sensitivity rate [ 24 ]. We did not attempt to estimate the yields of TB for participants with symptoms and normal CXR results, as the TB prevalence in this cohort was estimated to be <10 per 100,000 in Vietnam’s second TB prevalence survey [ 2 ]. The following six screening and diagnostic algorithms were investigated: (1) cough for ≥2 weeks followed by AFB smear microscopy testing, (2) cough for ≥2 weeks followed by Xpert testing, (3) any cough followed by AFB smear microscopy testing, (4) any cough followed by Xpert testing, (5) CXR abnormal followed by AFB smear microscopy testing and (6) CXR abnormal followed by Xpert testing.…”

“…Across Asia, modern TB prevalence surveys have shown that 40–79% of adults with culture-confirmed, pulmonary TB do not report a prolonged cough (≥2 weeks) [ 6 ], and a recent meta-analysis indicates that the proportion of people with sub-clinical and low-grade TB may be significantly higher in Asia compared to Africa [ 7 ]. Vietnam’s second TB prevalence survey results seem to affirm these findings; 42% of the people with TB detected by the survey did not report a prolonged cough [ 2 ]. These individuals were only indicated for diagnostic testing through the use of chest X-ray (CXR) screening.…”

“…An estimated 170,000 people developed tuberculosis (TB) in Vietnam in 2019, resulting in 11,400 TB-related deaths [ 1 ]. Vietnam recently completed its second national TB prevalence survey [ 2 ], which documented a 59.9% reduction in smear-positive TB prevalence in the 11 years since the country’s first TB prevalence survey was conducted [ 3 ]. However, the new prevalence survey results demonstrated that Vietnam’s total estimated TB burden was higher than previously thought, due to improved survey methods and the use of more sensitive TB diagnostic tests.…”

Enhanced Private Sector Engagement for Tuberculosis Diagnosis and Reporting through an Intermediary Agency in Ho Chi Minh City, Viet Nam

“…In 2014, Viet Nam committed to reduce TB prevalence to 20 per 100,000 by 2030 [4]. However, following the second national prevalence survey in 2018 [5], the country's estimated TB incidence rate was revised upward from 124 to 174 per 100,000, suggesting that just 57% of the estimated burden was captured by the NTP's official TB case notification statistics [6].…”