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 f rom 2001 to 2015. study design: repeated cross-sectional study methods: nonlinear segmented regression w as 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% w ere smear positive, 19.7% smear negative, 27.32% extrapulmonary and 3.18% relapse. for all tb types, the peak of incidence w as in 2001. tw o change point w ere estimated for all tb types (p<0.05). the apc of all tb types w ere -6.51 (95% ci: -7.4, -5.4) for f irst and 2.4 (95% ci: 0. 7, 4.1) for second segment. although the trends w ere signif icantly decreasing f rom 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 w ere not signif icant f rom 2006 to 2015. except for extra pulmonary tb (apc=4-.9%, 95%ci:-10, 1.2), the apcs of the last segments w ere signif icant. conclusions: even though the tb incidence rates w ere 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 tow ard tb control, illegal immigrants, data registry systems and physician's sensitivity in tb detection.