Abstract:

Objective To obtain the prevalence,incidence of tuberculosis (TB) and influencing factors among elderly people aged 65 years and older, diabetic patients, people with TB history, close contacts of active TB patients, and HIV/AIDS patients(referred as “five key populations” hereafter) in China through continuous screening, and to provide basic evidence for developing screening strategies in key populations. Methods In 27 townships/communities of 10 counties selected from 10 provinces located in eastern, middle and western regions of China, face-to-face questionnaire surveys and chest X-ray examination were performed on all participants every year for 3 consecutive years. TB prevalence and incidence density of the five key populations were calculated, and univariate and multivariate analysis of different demographic characteristics were also conducted. Results From 2013 to 2015, 38193, 35305 and 30295 participants were screened respectively. After 3 years of continuous screening, the prevalence of bacteriologically confirmed TB in all key populations dropped by 28.9% ((246.1-174.9)/246.1×100%), and the annual decline rate was 15.7% ($\big(\sqrt \frac{246.1}{174.9}-1 \big)$×100%); the prevalence of active TB dropped by 32.3% ((746.2-505.0)/746.2×100%), and the annual decline rate was 17.7% ($\big(\sqrt \frac{746.2}{505.0}-1 \big)$×100%). Taking survey of 2013 as the baseline, the incidence density of bacteriologically confirmed TB and active TB with 1-year follow-up (2014) in all key populations were 132.3 per 100000 person years (36/27202.4) and 143.7 per 100000 person years (71/49393.8), while with 2-years follow-up (2015), they were 488.9 per 100000 person years (133/27202.4) and 475.8 per 100000 person years (235/49393.8). Multivariate analysis found: male, advanced age (group ‘aged 75-84’ and group ‘aged 85 and older’), living in rural areas, ethnic minorities, unmarried/divorced/widowed, low family income per capita (2300-9999 yuan) and malnutrition (body mass index BMI<18.5) were risk factors for TB (OR (95%CI) were 3.4 (2.6-4.5), 1.6 (1.2-2.2) and 2.2 (1.3-3.5), 2.0 (1.5-2.8), 2.2 (1.6-3.0), 1.4 (1.1-1.9), 1.8 (1.3-2.4) and 1.9 (1.4-2.6) respectively), and overweight (body mass index ≥24) was a protective factor for TB (OR (95%CI)=0.3 (0.2-0.5)). Male, ethnic minorities and family with low annual income per capita (2300-9999 yuan) were risk factors for the onset of TB (aHR (95%CI) were 2.5 (1.9-3.5), 6.8 (4.8-9.6), 1.4 (1.0-1.9)), and overweight (BMI≥24) was a protective factor for the onset of TB (aHR (95%CI) was 0.5(0.4-0.7)). Conclusion The five key populations are high-risk populations of TB in China. Continuous active screening should be carried out in those key populations to quickly reduce the tuberculosis epidemic. Through identify people with different combinations of risk factors, we can set high-risk populations to target at them, thereby to increase the screening benefits.

Key words: Tuberculosis,pulmonary, Multiphasic screening, Active case finding, Prevalence, Data interpretation,statistical