Incidence of latent tuberculosis infection(LTBI) among high risk healthcare workers at a tertiary referral hospital in South Korea

Aims: The aim of the study is to estimate incidence of LTBI among high risk health care workers at a tertiary referral hospital in South Korea Methods: Records of annual LTBI screening of high risk healthcare workers with frequent exposure to active tuberculosis patients from 2014 to 2016 were retrospectively reviewed. Interferon-γ release assay (IGRA) was used for LTBI screening. Only staffs with initial negative IGRA results were included in the cohort. Results: Total 170 staffs were included and total follow-up was 245 person-years. 11 cases of new LTBI infection defined as whose IGRA result converted to positive were identified. Incidence rate was 4.49% (/person-year). Departments were classified according to quality of tuberculosis exposure (inpatient/outpatient, usual/during invasive procedure) – 1) Inpatient, usual exposure (pulmonology ward), 2) Outpatient, usual exposure (pulmonology outpatient clinic), 3) Inpatient, exposure during endotracheal intubation (intensive care unit, emergency room), 4) Outpatient, exposure during bronchoscopy (bronchoscopy room), and 5) Exposure to specimens with tuberculosis (laboratory facilities). Contacts with active tuberculosis of co-worker or families living together were surveyed as a confounding factor. In a generalized estimating equation model, working in the laboratory facilities was a significant risk factor for LTBI, when compared with intensive care unit or emergency room (adjusted OR=4.86, p=0.033). Age was also a risk factor for LTBI (adjusted OR= 1.08, p= 0.013). Conclusions: Annual incidence of LTBI was 4.49%. Working in the laboratory facilities, old age were significant risk factors for LTBI.