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.
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