Trend of Smear‑positive Pulmonary Tuberculosis in Iran during 1995–2012: A Segmented Regression Model

Abstract

Background: Describing trend in tuberculosis (TB) over time can play an important role to assess the disease control strategies and predict the future morbidity and mortality. This study aimed to determine the incidence trend of smear‑positive pulmonary tuberculosis (SPPT) in sub‑age and sex groups during the years of 1995–2012.

Methods: This retrospective cohort study was performed in 2015 by using the dataset regarding National Statistics of SPPT reported by World Health Organization during 1995–2012. Annual percent changes (APCs) and average annual percent changes (AAPCs) were estimated to determine the summery statistics of trend using segmented regression model.

Results: During 1995–2012, there were 96,579 SPPT case notifications in Iran (male to female ratio: 0.99). There was only one change point in 1997 for SPPT incidence in subgroups of age
and sex during 1995–2012. The AAPCs for both genders and also all three age groups had a significant descending trend during the time period (P < 0.05).

Conclusions: Our results showed a downward trend in the SPPT incidence. It seems that to achieve the set goals and high successful in TB control program especially reduction in SPPT,
pay more attention to old age and males should be considered. In addition, improvement of clinical
and medical care services and notification processes would be imperative.

Keywords: Annual percent change, Iran, segmented regression, tuberculosis