Epidemiologic Trend of Smear-Positive, Smear-Negative, Extra Pulmonary and Relapse of Tuberculosis in Iran (2001-2015); A Repeated Cross-Sectional Study.

Background: Trend analysis is an important tool to monitor epidemiological changes of disease over time to guide resource allocation. This study aimed to study incidence trends and change-points of smear positive, smear negative, extra-pulmonary and relapse of tuberculosis (TB) in Iran from 2001 to 2015.
Study Design: Repeated cross-sectional study METHODS: Nonlinear segmented regression was used to describe TB incidence trends; annual percent change (APC), average annual percent changes (AAPC) and change points for each disease separately.
Results: Of 154930 TB cases, 49.8% were smear positive, 19.7% smear negative, 27.32% extra-pulmonary and 3.18% relapse. For all TB types, the peak of incidence was in 2001. Two change point were estimated for all TB types (P<0.05). The APC of all TB types were -6.51 (95% CI: -7.4, -5.4) for first and 2.4 (95% CI: 0. 7, 4.1) for second segment. Although the trends were significantly decreasing from 2001 to 2015 for smear positive (AAPC=2.06%), smear negative (AAPC=3.57%), extra pulmonary (AAPC=3.2%) and relapse (AAPC=3.3%), the AAPCs of trends were not significant from 2006 to 2015. Except for Extra pulmonary TB (APC=4-.9%, 95%CI:-10, 1.2), the APCs of the last segments were significant.
Conclusions: Even though the TB incidence rates were decreasing, the amount of reductions seem inadequate, to reach the goals of TB control in Iran. Especially, the increase in the extra-pulmonary TB rates is a point of concern that highlights more attention is required for these cases. It is essential to improve economic supports toward TB control, illegal immigrants, data registry systems and physician's sensitivity in TB detection.