National tuberculosis prevalence surveys in Asia, 1990–2012: an overview of results and lessons learned

Abstract

Abstractobjective and methods In many countries, national tuberculosis (TB) prevalence surveys are the only way to reliably measure the burden of TB disease and monitor trends. They can also provide evidence about the current performance of TB care and control and how this could be improved. We developed an inventory of Asian surveys from 1953 to 2012 and then compiled and analysed a standard set of data for all national surveys implemented between 1990 (the baseline year for 2015 global TB targets) and 2012.results There were 21 surveys in 12 countries between 1990 and 2012; published results were available for 18. The participation rate was at least 80% and often much higher except for two surveys in Thailand. The prevalence of bacteriologically-positive TB disease among adults aged ≥15 years varied widely among countries (1.2 per 1000 population in China in 2010 to 15 per 1000 population in Cambodia in 2002), but age and sex distribution patterns were consistent with a progressive increase in rates of disease by age, and men accounting for 66-75% of prevalent cases. A high proportion of cases (40-79% across all surveys) did not report TB symptoms that met screening criteria (generally cough of 2-3 weeks or more, and blood in the sputum) and were only detected due to chest X-ray screening of all survey participants; this proportion increased over time in countries with repeat survey data. The ratio of prevalent cases to cases notified to national TB programmes was typically around two, but was as high as three in Lao PDR and Pakistan even after the internationally recommended TB control strategy had been implemented nationwide for several years. Four countries (China, Cambodia, the Republic of Korea and the Philippines demonstrated declines in smear or culture-positive pulmonary TB prevalence of approximately 50% over 10 years.conclusions National TB prevalence surveys in Asia show that large reductions in the prevalence of TB disease can be achieved within a decade, that men bear much more of the burden than women and that the epidemic is ageing. Comparisons among countries show that more can be achieved in TB control in some countries with existing strategies and technologies. However, with many prevalent cases not reporting classic TB symptoms, all countries face the challenge of defining and implementing strategies that will result in earlier detection and treatment of cases.

The Tuberculosis Cascade of Care in India’s Public Sector: A Systematic Review and Meta-analysis

“…This figure also represents an estimate of point prevalence and is possibly an underestimate of the 1-y period prevalence of TB. Also, prior TB prevalence studies conducted in India have usually screened individuals in the community for TB symptoms before collecting sputum specimens [33,35,36]; this approach may miss a considerable proportion of patients without symptoms, thereby underestimating TB prevalence [87]. In addition, a recent study estimating the number of TB patients treated in India’s private sector suggests that the overall burden of TB disease in India may be underestimated [88].…”

An evaluation of automated chest radiography reading software for tuberculosis screening among public- and private-sector patients

“…We did not test for HIV, but Bangladesh's TB–HIV co-infection rate is estimated to be less than 1% [30]. The entry point for our diagnostic algorithm was TB symptoms, meaning that CXR was not used to detect asymptomatic individuals with TB, who make up the majority of TB cases in recent prevalence surveys [31]. Our sample comprises only people willing to pay for CXR.…”

Sex Differences in Tuberculosis Burden and Notifications in Low- and Middle-Income Countries: A Systematic Review and Meta-analysis

“…Sex-specific P:N ratios were calculated as the ratio of smear-positive TB prevalence per 100,000 individuals to smear-positive TB case notifications per 100,000 individuals among adults [5,19]. WHO case notification data [20] and United Nations population estimates [21] were matched to each prevalence survey by country and year.…”