Pulmonary Tuberculosis Incidence and Risk Factors in Rural Areas of China: A Cohort Study

Wei Chen,Shiming Cheng,Yihua Xu,Yongchun Hou,Yinyin Xia,Weiguo Xu,Wen Shu,Shaofa Nie,Liqiong Bai,Min Wang,Monica Da Silva Nunes

doi:10.1371/journal.pone.0058171

Abstract

The incidence of tuberculosis (TB) and its risk factors in China remains unclear. This study examined TB incidence and relative risk factors in rural areas of China. Participants (n = 177,529) were recruited in Xiangtan County (in the central area of China) and in Danyang County (in the eastern area of China) in 2009 and a followed-up study was conducted for one year. The incidence density of pulmonary TB and smear-positive TB were 91.6 (95% CI: 78.7, 106.0) per 100,000 person-year and 36.7 (95% CI: 33.1, 52.4) per 100,000 person-year respectively in Xiangtan, and 47.3 (95% CI: 38.2, 57.5) per 100,000 person-year and 22.7 (95% CI: 16.5, 30.8) per 100,000 person-year in Danyang. The medical history of TB was associated with TB, with the relative risk (RR) of 7.00 (95% CI: 2.76, 17.18) in Xiangtan and that of 31.08 (95% CI: 13.22, 73.10) in Danyang. The association between TB and per capita living space over median was found in Xiangtan, with the RR of 1.86 (95% CI: 1.15, 3.01). No association was found between TB and the insurance status, the contact history with TB, the history of diabetes, smoking, or per capita annual income. The host genetic susceptibility, and social factors such as education and income could be considered in future studies.

Highlights

In 2010 an estimated 8.8 million (95% Confidence interval: 8.5, 9.2 million) new tuberculosis (TB) cases occurred in the world, equivalent to 128 cases per 100,000 population [1]
The Poisson model (Table 4) showed that people who had TB previously were more likely to develop TB again; the relative risk was 7.0 in Xiangtan and 31.1 in Danyang; the significance of contact history as a risk factor disappeared
In Xiangtan County, subjects in the group of per capita living space over median might be 1.8 times more likely (RR = 1.86, 95% confidence interval (95% CI): 1.15, 3.01) to develop TB

Summary

Introduction

In 2010 an estimated 8.8 million (95% Confidence interval: 8.5, 9.2 million) new tuberculosis (TB) cases occurred in the world, equivalent to 128 cases per 100,000 population [1]. In China’s 2010 National TB Prevalence Survey, the prevalence of active pulmonary TB in rural areas was about 1.8 times that of urban areas; that of sputum smear-positive TB was about 1.6 times that of urban areas. This large population of TB patients has a high prevalence of anti-TB drug resistance, which increases the rate of treatment failure and costs of control, and is a major challenge to public health for China [3]. The course of the disease is uncertain and not easy to follow, making it very difficult to estimate TB incidence based on TB prevalence

Methods

Results

Conclusion