Global Epidemic Trend of Tuberculosis during 1990-2010: Using Segmented Regression Model

Anoushiravan Kazemnejad, Shahram Arsang Jang, Firouz Amani, Alireza Omidi


Background: Tuberculosis (TB) is a pandemic disease. It is the second leading cause of death from infectious diseases after human immunodeficiency virus (HIV) in the world.The main objective of this paper was to determine and compare the epidemiology of TB incidence rate and its trend changes during 1990-2010 in six WHO regions regarding age, gender and income levels.

Methods: The Average Annual Percent Change (AAPC) and Annual Percent Change (APC) of TB incidence, mortality, treatment-successes, case detection rates, as well as change points of trend was estimated using segmented regression model. The number of change points was selected by the permutation procedure based on likelihood ratio test.

Results: Two change points for global TB incidence rate trend with AAPC5years equaling -1.4 % was estimated, the maximum AAPC5years of six regions was attributed to the American region (-3.5%). AACP of TB treatment-successes rate for Eastern Mediterranean (+2.2), the Americas (+1.6), south East Asia (+.8) and Global (+1.1) were significant (P<0.05). Moreover AACP5years of TB case detection rate for South East Asia (+7.5), Eastern Mediterranean (+4.9), Africa (+2.8) and the Americas (+1.7) were significant (P<0.05). Globally, all of income categories had descending trend of TB incidence and mortality rate, except the upper-middle income level that had ascending incidence trend (AAPC=+0.7%).

Conclusions: Globally, TB incidence and mortality rates have downturn trend and TB treatment successes and detection rates have upward trend, but their changes rate are insufficient to reach the goal of TB stop strategy. The economic levels have effect on trend, with no clear pattern, so it seems necessary that evaluation TB control programs based on characteristics of countries for reach TB control goals.


Tuberculosis; Segmented regression; Change points; Annual Percent Change

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