Abstract:

Objective: To analyze the risk and influencing factors among household close contacts of pulmonary tuberculosis (PTB) patients in a high tuberculosis burden setting. Methods: From January 1, 2018 to December 31, 2021, patients diagnosed with PTB in 12 counties in Kashgar Prefecture of Xinjiang Uygur Autonomous Region were selected from the subsystem “Tuberculosis Management Information System” of the China Information System for Disease Control and Prevention as indicator cases. A family close contact cohort was established through contact screening, and the incidence was followed up and observed. Poisson regression model was used to analyze the etiological characteristics, treatment status, exposure, and previous history of PTB in close family contacts of the indicator cases. Results: As of December 31, 2021, a total of 40182 indicated cases of PTB and 57142 close contacts within the household had been investigated. During the 4-year follow-up period, the median (quartile) duration of follow-up was 3.2 (2.7, 3.3) years, 3585 close family contacts with secondary cases were identified, the secondary attack rate was 6.27%, total 180543 person-years of observation, with an average incidence density of 1985.68/100000 person-years. Among them, the highest incidence of PTB among close contacts within household was about 3317.62/100000 person-years in the first year after the diagnosis of the indicated case. Poisson regression analysis showed that smear-negative pathogenetic testing in the indicated cases, primary treatment, close contacts in the household being male, ≥55 years of age, previous exposure to PTB and history of PTB were all risk factors for the development of PTB in close contacts in the household (RR (95%CI) were 2.491 (2.347-2.562), 1.221 (1.102-1.354), 1.449 (1.306-1.607), 8.451 (6.388-11.179), 2.680 (2.314-3.104), 4.479 (3.852-5.207)). Conclusion: Close contacts within household are the high-risk group for the transmission of indicated cases of PTB, and screening and education of close contacts should be strengthened, especially the elderly, males, previous PTB patients or contacts of PTB patients; there is also a need to systematically scale up and strengthen household contact tracing and preventive treatment strategies for close contacts in high tuberculosis burden areas. It is also recommended to include all PTB patients for screening based on the current strategy, especially smear-negative and only positive molecular biological test patients.

Key words: Tuberculosis, pulmonary, Family health, Contact tracing, Cohort study, Factor analysis, statistical, Communicable disease control