Evolution of tuberculosis control and prospects for reducing tuberculosis incidence, prevalence, and deaths globally

Abstract

Context: The United Nations Millennium Development Goals (MDGs) are stimulating more rigorous evaluations of the impact of DOTS (the WHO-recommended approach to tuberculosis control based on 5 essential elements) and other possible strategies for tuberculosis (TB) control.

Objective: To evaluate the prospects for detecting 70% of new sputum smear-positive cases and successfully treating 85% of these by the end of 2005, for reducing TB incidence, and for halving TB prevalence and deaths globally between 1990 and 2015, as specified by the MDGs.

Data sources: TB case notifications (1980-2003) from DOTS and non-DOTS programs and cohort treatment outcomes (1994-2002) reported annually to the World Health Organization (WHO) by up to 200 countries, TB death registrations, and prevalence surveys of infection and disease.

Study selection: Case notification series that reflect trends in incidence, treatment outcomes from DOTS cohorts, death statistics from countries with WHO-validated vital registration systems, and national prevalence surveys of infection and disease.

Data extraction: Case reports, treatment outcomes, prevalence surveys, and death registrations from WHO's global TB database covering 1990-2003 to estimate TB incidence, prevalence, and death rates through 2015 for 9 epidemiologically different world regions.

Data synthesis: TB incidence increased globally in 2003, but incidence, prevalence, and death rates were approximately stable or decreased in 7 of 9 regions. The exceptions were regions of Africa with low (<4% in adults 15-49 years) and high rates (> or =4%) of HIV infection. The global detection rate of new smear-positive cases by DOTS programs increased from 11% in 1995 to 45% in 2003 (with the lowest case-detection rates in Eastern Europe and the highest rates in the Western Pacific) and could reach 60% by 2005. More than 17 million patients were treated in DOTS programs between 1994 and 2003, with overall treatment success rates more than 80% since 1998. In 2003, overall reported treatment success was 82%, with much variation among regions. The highest rates were reported in the Western Pacific region (89%) and lowest rates in African countries with high and low HIV infection rates (71% and 74%, respectively), in established market economies (77%), and in Eastern Europe (75%). To halve the prevalence rate by 2015, TB control programs must reach global targets for detection (70%) and treatment success (85%) and also reduce the incidence rate by at least 2% annually. To halve the death rate, incidence must decrease more steeply, by at least 5% to 6% annually.

Conclusion: Reduction of TB incidence, prevalence, and deaths by 2015 could be achieved in most of the world, but the challenge will be greatest in Africa and Eastern Europe.