N. B. Hoa

National survey of tuberculosis prevalence in Viet Nam.

OBJECTIVE To estimate the prevalence of tuberculosis in Viet Nam with data from a population-based survey, compare it with the prevalence estimated by the World Health Organization, and identify major demographic determinants of tuberculosis prevalence. METHODS A cross-sectional survey with multistage cluster sampling, stratified by urban, rural and remote areas, was done in 2006-2007 in 70 communes. All inhabitants aged > or = 15 years were invited for cough and chest X-ray examination. Participants with findings suggestive of tuberculosis provided sputum specimens for smear examination and culture. Point prevalence estimates, 95% confidence intervals and design effects were calculated. Confidence intervals and P-values were adjusted for the cluster design. FINDINGS Of 114,389 adult inhabitants, 94 179 (82.3%) were screened. Of 87,314 (92.7%) screened by both questionnaire and chest X-ray, 3522 (4.0%) had productive cough, 518 (0.6%) had a recent history of tuberculosis and 2972 (3.4%) had chest X-ray abnormalities suggestive of tuberculosis. Sputum tests were done for 7648 participants. Sputum test, bacterial culture or both confirmed 269 tuberculosis cases, 174 of which were smear-positive. The prevalence rate of smear-positive tuberculosis was 145 per 100,000 (95% confidence interval: 110-180) assuming no tuberculosis in persons aged < 15 years. Prevalence was 5.1 times as high in men as in women, increased with age, was higher in rural than in urban or remote areas and showed a north-to-south gradient. CONCLUSION In Viet Nam, the tuberculosis prevalence rate based on positive sputum smear tests was 1.6 times as high as previously estimated. Age and sex patterns were consistent with notification data. Tuberculosis control should remain a high priority in Viet Nam.

Changes in body weight and tuberculosis treatment outcome in Viet Nam.

SETTING National Tuberculosis Programme, Viet Nam, 2008. OBJECTIVE To assess the relationship between changes in body weight and tuberculosis (TB) treatment outcome. METHODS All treatment cards of patients from a sample of 30 randomly selected treatment units in the country were analysed. RESULTS Of 2609 patients, 2506 (96.1%) had a successful treatment outcome. The median body weight of all patients at diagnosis was 46.0 kg (25th and 75th percentiles 41-51). New sputum smear-positive TB patients with a successful treatment outcome gained an average of 2.6 kg during treatment. Patients with weight loss during the first 2 months of treatment were more likely to have an unsuccessful outcome than patients without (OR 4.9, 95%CI 3.0-7.9). Patients weighing <40 kg at treatment start who gained more than 5% of their body weight after 2 months of treatment had a significantly smaller risk of an unsuccessful treatment outcome than patients who did not (OR 0.2, 95%CI 0.05-0.96). CONCLUSIONS Patients failing to gain weight or losing weight, particularly during the first 2 months of treatment, require particular attention, as they appear to be at an increased risk of unsuccessful treatment outcome.

Characteristics of tuberculosis patients at intake in Cambodia, two provinces in China, and Viet Nam

BackgroundThe tuberculosis register is a critical data source for the information system of national tuberculosis control programs. From the information in the tuberculosis case register, it is possible to extend the standard analysis of age and sex characteristics among sputum smear-positive cases to all tuberculosis case categories. National tuberculosis programs might utilize such information to identify problems related to referral and access to diagnosis and treatment.ObjectivesBased on the electronic database we created, our objectives were to provide a detailed description of age and sex characteristics of tuberculosis patients at registration and to provide a comparison of age-specific sex characteristics among incident and prevalent sputum smear-positive cases.MethodsA representative sample of tuberculosis case registers from 1 January 2003 to 31 December 2005 was selected in Cambodia, two provinces in China and Viet Nam. Age and sex characteristics of cases in the three separate prevalence surveys in the three jurisdictions (Cambodia: year 2002; China: year 2000; and Viet Nam: year 2006-2007) were obtained for comparison.ResultsA total 37,635 patients had been registered during the period in the selected units in the three countries. Cases were more frequently male in all three countries with 53%, 71%, and 69% in Cambodia, China, and Viet Nam, respectively.The ratios of the female-to-male odds in the notification system to that in the prevalence survey in smear-positive cases in Cambodia, China and Viet Nam were 2.1, 0.9, and 1.8, respectively. Because of the small proportion of extrapulmonary tuberculosis registered in China, we limited the analysis on age and sex distribution for extrapulmonary cases to Cambodia and Viet Nam. The proportion with extrapulmonary tuberculosis among all cases was 18.5% in Cambodia and 15.7% in Viet Nam, decreasing in frequency with increasing age.ConclusionsCharacteristics of patients greatly differed between countries and between patient categories. In Cambodia and Viet Nam, efforts should be made for improved case-finding of sputum smear-positive tuberculosis among males.

Measuring socio-economic data in tuberculosis prevalence surveys.

Addressing social determinants in the field of tuberculosis (TB) has received great attention in the past years, mainly due to the fact that worldwide TB incidence has not declined as much as expected, despite highly curative control strategies. One of the objectives of the World Health Organization Global Task Force on TB Impact Measurement is to assess the prevalence of TB disease in 22 high-burden countries by active screening of a random sample of the general population. These surveys provide a unique opportunity to assess socio-economic determinants in relation to prevalent TB and its risk factors. This article describes methods of measuring the socio-economic position in the context of a TB prevalence survey. An indirect measurement using an assets score is the most feasible way of doing this. Several examples are given from recently conducted prevalence surveys of the use of an assets score, its construction, and the analyses of the obtained data.

Household-Contact Investigation for Detection of Tuberculosis in Vietnam

BACKGROUND Active case finding is a top priority for the global control of tuberculosis, but robust evidence for its effectiveness in high‐prevalence settings is lacking. We sought to evaluate the effectiveness of household‐contact investigation, as compared with standard, passive measures alone, in Vietnam. METHODS We performed a cluster‐randomized, controlled trial at clinics in 70 districts (local government areas with an average population of approximately 500,000 in urban areas and 100,000 in rural areas) in eight provinces of Vietnam. Health workers at each district clinic or hospital were assigned to perform either household‐contact intervention plus standard passive case finding (intervention group) or passive case finding alone (control group). In the intervention districts, household contacts of patients with positive results for tuberculosis on sputum smear microscopy (smear‐positive tuberculosis) were invited for clinical assessment and chest radiography at baseline and at 6, 12, and 24 months. The primary outcome was the cumulative incidence of registered cases of tuberculosis among household contacts of patients with tuberculosis during a 2‐year period. RESULTS In 70 selected districts, we enrolled 25,707 household contacts of 10,964 patients who had smear‐positive pulmonary tuberculosis. In the 36 districts that were included in the intervention group, 180 of 10,069 contacts were registered as having tuberculosis (1788 cases per 100,000 population), as compared with 110 of 15,638 contacts (703 per 100,000) in the control group (relative risk of the primary outcome in the intervention group, 2.5; 95% confidence interval [CI], 2.0 to 3.2; P<0.001); the relative risk of smear‐positive disease among household contacts in the intervention group was 6.4 (95% CI, 4.5 to 9.0; P<0.001). CONCLUSIONS Household‐contact investigation plus standard passive case finding was more effective than standard passive case finding alone for the detection of tuberculosis in a high‐prevalence setting at 2 years. (Funded by the Australian National Health and Medical Research Council; ACT2 Australian New Zealand Clinical Trials Registry number, ACTRN12610000600044.)

Yield of interview screening and chest X-ray abnormalities in a tuberculosis prevalence survey.

BACKGROUND Tuberculosis (TB) prevalence surveys generally rely on a combination of screening methods to identify suspects eligible for sputum culture. OBJECTIVE To assess the yield of screening methods applied in a recent prevalence survey in Viet Nam and estimate the proportion of TB cases missed due to incomplete participation. METHODS TB suspects were identified based on self-reported TB history or productive cough by interview and chest X-ray (CXR). We calculated the case yield of these two screening methods by dividing the number of cases detected per method by the total number of cases detected. As not all participants underwent the full screening procedure, we recalculated the maximum yield of the screening methods using multiple imputation methods. RESULTS The yield from screening by interview and CXR were respectively 38% and 91%. Adjusting for missing data by multiple imputation, we estimated that we missed 9.9% (95%CI 6.8-14.2) of expected TB cases. CONCLUSION In prevalence surveys, screening by pre-structured interview is insufficient, and should be supplemented with CXR to achieve sufficient identification of TB cases. The effect of incomplete participation in the full screening procedure may be substantial and should be adjusted for in the analysis.

Health-seeking behaviour among adults with prolonged cough in Vietnam

Objective  To assess health‐seeking behaviour among adults with prolonged cough in a population‐based, nationally representative sample in Vietnam.

First national tuberculin survey in Viet Nam: characteristics and association with tuberculosis prevalence.

OBJECTIVES To estimate the prevalence of infection with Mycobacterium tuberculosis and the annual risk of tuberculous infection (ARTI) and to compare this with the prevalence of tuberculosis (TB) over study clusters and households. METHODS A nationwide, stratified cluster sample survey was carried out in 2006-2007 in Viet Nam to assess the prevalence of infection with M. tuberculosis. A representative sample of children aged 6-14 years underwent a tuberculin skin test (TST) using the Mantoux method. RESULTS Of 23,160 children registered, 21,487 (92.8%) were tested and read and available for analysis. Using a cut-off point of 10 mm, the estimated prevalence of TST positivity was 16.7%, and the ARTI was 1.7% (95%CI 1.5-1.8). Higher infection rates were found in urban than in rural and remote areas, and infection rates increased with age. There was significant association between the prevalence of TB disease and infection at the cluster level (regression coefficient 0.54, 95%CI 0.06-1.01, P = 0.027, correlation coefficient R(2) 0.120). Children with a (recent) case of TB in the household were 1.6 times more likely to be TST-positive than children in households with no recent cases (P < 0.05). CONCLUSION The estimated nationwide ARTI was 1.7%. TST positivity was associated with the presence of a TB case in the household.

Diagnosis and Treatment of Tuberculosis in the Private Sector, Vietnam

To the Editor: In many countries, the private sector (practitioners not employed by government and nongovernment institutions, e.g., hospitals, pharmacies) is a major source of care, even for poor persons, and the area where services for the public are widely available (1,2). However, little information is available from high-incidence countries about the role of the private sector in tuberculosis (TB) detection and treatment (3). In Vietnam, ≤40% of all TB cases in Ho Chi Minh City (the largest city in Vietnam and with the highest rate of economic growth in the country) were estimated to be treated in the private sector (4), and half of all patients with a diagnosis of TB in the public sector (National Tuberculosis Program [NTP]) in Ho Chi Minh City initially sought help in the private sector (5). However, this estimate does not reflect private care in the entire country

The fourth national anti-tuberculosis drug resistance survey in Viet Nam.

SETTING Viet Nams Fourth National Anti-Tuberculosis Drug Resistance Survey was conducted in 2011. OBJECTIVE To determine the prevalence of resistance to the four main first-line anti-tuberculosis drugs in Viet Nam. METHODS Eighty clusters were selected using a probability proportion to size approach. Drug susceptibility testing (DST) against the four main first-line anti-tuberculosis drugs was performed. RESULTS A total of 1629 smear-positive tuberculosis (TB) patients were eligible for culture. Of these, DST results were available for 1312 patients, including 1105 new TB cases, 195 previously treated TB cases and 12 cases with an unknown treatment history. The proportion of cases with resistance to any drug was 32.7% (95%CI 29.1-36.5) among new cases and 54.2% (95%CI 44.3-63.7) among previously treated cases. The proportion of multidrug-resistant TB (MDR-TB) cases was 4.0% (95%CI 2.5-5.4) in new cases and 23.3 (95%CI 16.7-29.9) in previously treated cases. CONCLUSIONS The fourth drug resistance survey in Viet Nam found that the proportion of MDR-TB among new and previously treated cases was not significantly different from that in the 2005 survey. The National TB Programme should prioritise the detection and treatment of MDR-TB to reduce transmission of MDR-TB in the community.