Time series analysis of pulmonary tuberculosis incidence in earthquake-affected and non-affected areas of Kermanshah Province

Earthquakes increase disease incidence and mortality due to overcrowding, poor housing and nutrition, stress, treatment discontinuation, and poor patient management. This study examined the impact of an earthquake on pulmonary tuberculosis (TB) incidence in three earthquake-stricken areas and 11 other districts of Kermanshah Province to better inform disease control planning. Monthly pulmonary TB case counts and population data for 14 districts of Kermanshah Province were obtained from the TB Registration Office and the Kermanshah Deputy of Medical Sciences Statistics Center, covering 2009–2018. The total cohort comprised 2,622 TB cases: 207 from three earthquake-affected districts (Sar-e-Pul-e-Zahab, Qasr-e Shirin, Salas-e Babajani) and 2,415 from eleven non-affected districts (e.g., Kermanshah, Islamabad, Paveh). The study period included 8 years pre-earthquake (2009–2016) and 2 years post-earthquake (2017–2018). The earthquake’s impact on monthly TB incidence trends was assessed using segmented regression, single-group Interrupted Time Series (ITS) analysis, and multiple-group ITS models comparing affected and control regions. The impact of the earthquake on TB incidence varied across districts. While earthquake-affected areas showed a significant increase in TB cases (ß2= 0.059, P < 0.011) following the event, the TB incidence trend showed a pronounced decline (ß3= -0.0042, P < 0.001) with 207 observations (184 before, 23 after). Similar patterns were observed in other districts, with some experiencing significant increases (e.g., Islamabad, ß2= 0.00028, P < 0.001) and others decreases (e.g., Paveh, ß2=-0.00049, P < 0.001) in TB levels following the earthquake. The earthquake did not result in a sustained increase in TB incidence in affected regions. The findings may reflect effective TB control efforts, post-disaster public health interventions, or underreporting. Strengthening TB surveillance and long-term monitoring in disaster zones is essential for informed response planning.