Incidence of tuberculosis infection among healthcare workers: Risk factors and 20-year evolution

Objective: To determine the incidence of latent tuberculosis infection (LTBI), and risk factors for tuberculosis skin test (TST) conversion among Healthcare workers (HCWs) during a 20-year follow-up period. Design: Prospective cohort analysis. Surveillance was conducted from January 1, 1988, to December 31, 2007. SETTING: 600-bed tertiary referral hospital in Barcelona, Spain. Participants: HCWs in risk for occupational tuberculosis (TB) exposure, with negative baseline TST, direct contact with patients and/or biological samples and at least one follow-up visit with TST. Methods: TST is performed in HCWs with no previous history of TB or no previous positive TST. When TST is negative this test is performed once a year in high-risk workers, or at least every 2 years according to the hospital's guidelines. In all cases an interview questionnaire to gather information on possible risk factors was performed. Results: The study included 614 HCWs, 27% worked in areas of risk for TB exposure. Annual incidence rate had decreased from 46.8 per 100 person-years in 1990 to 1.08 per 100 person-years in 2007. Cumulative incidence was higher in HCWs who work in high-risk areas (p = 0.004) and in time periods from 1990 to 1995, and from 1996 to 2001 (p < 0.0001). Cox regression model showed a hazard ratio of 1.55 (CI 95%; 1.05-2.27) in high-risk workers, adjusted by gender, age and professional status. Conclusions: Incidence of LTBI among HCWs is high, although it decreased throughout the follow-up period. It is crucial to maintain surveillance programs in HCWs.© 2012 Elsevier Ltd. All rights reserved.