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Cycle 5 (2016 Deadline)

An assessment of smoking and access to care as risk factors for gender-differences in TB rates – a substudy of the Vietnam NTP TB prevalence survey 2016-2018

PI: Nguyen Van Hung (, Vietnam National Tuberculosis Program
U.S. Partner: Payam Nahid, University of California, San Francisco
Project Dates: March 2017 - February 2020

Project Overview:
The global burden of 9.4 million annual cases of tuberculosis (TB) overwhelmingly falls on low-income countries, with 80% of cases occurring in just 22 high-burden countries. Between 1998 and 2008, the average male to female ratio of new smear-positive cases for high-burden countries was 1.85 (range = 0.47–3.16). The male to female ratio of notified new sputum smear positive TB cases for various World Health Organization’s (WHO) regions range from 1.4:1 in Africa; 1.5:1 in Americas, and 2: 1 in South-East Asia to 2.2: 1 in Europe. Although every country is unique, there are now reports that show that the gender differences observed in case notifications are often mirrored by gender differences in prevalent TB cases. These studies indicate that there are genuine gender differences in the biology and epidemiology of TB. Vietnam falls among the countries having the highest TB burden in the world, with an estimated incidence of around 140 new TB cases per 100,000 population annually. Additionally, the Annual Report of the Vietnam National Tuberculosis Program (NTP) notes that the program detects nearly three times more male than female TB patients in the notification rate of pulmonary TB.

Repeat TB prevalence surveys provide useful data on trends in the burden of disease caused by TB. Repeat surveys conducted with an interval of five years or more allow for direct measurement of whether the burden of TB is stable, increasing, or decreasing. They can also be used to assess the impact of efforts to control TB. In addition to the prevalence survey, the embedded sub-study assessing smoking and access to care as risk factors for TB plays an important part in determining the role smoking might play in creating gender differences among TB cases. The importance of a gender perspective on current policies regarding disease prevention and treatment is slowly being recognized, but so far this aspect on smoking and gender differences has not been fully acknowledged within programs to combat TB. The collaboration between the Vietnam NTP and the Vietnam Steering Committee on Smoking and Health is reportedly very limited. While the DOTS  (directly observed treatment, short-course) strategy has become the standard treatment protocol for TB control in most countries, most current TB control strategies fail to account for the increased risk of recurrence due to smoking. To reduce the risk of recurrence, it is thus imperative to incorporate effective smoking cessation measures into TB control program, as recommended by the WHO Stop TB Strategy. A better understanding of the incidence of, and factors associated with, TB infection and recurrence may help in identifying the most vulnerable populations and developing effective control measures that lower the rate of TB infection. The results from this study should help to inform policy and program managers and support advice to identify gender-sensitive recommendations on smoking policy and prevention to improve current TB control policies and programs to reach the Vietnam’s ambitious targets in 2020 and 2030.

Summary of Recent Activities:
As of February 2019, the 10 national research team members finished data collection in 120 selected clusters. The TB Prevalence Survey (TBPS) team organized a workshop to discuss data cleaning, validation, and analyses plans. The workshop also allowed researchers to practice data cleaning and analyses. Validation of data collected from the clusters was done by cross checking between digital and paper based data. Preliminary data analyses of the TBPS data included multiple imputation and sensitivity analysis. During the next year, the research team plans to continue data analyses and drafting of a technical report. They will continue to work closely with stakeholders including WHO and CDC. 

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