A risk/cost analysis of alternative screening intervals for occupational tuberculosis infection.
Am Ind Hyg Assoc J 1998 Feb; 59(2):104-112
The Center for Disease Control and Prevention (CDC) recommends that new health care employees receive a baseline skin test for Mycobacterium tuberculosis(M.tb) infection and that testing be repeated periodically. However, CDC does not explain the quantitive basis for its suggested screening intervals. This article examines the efficacy of alternative screening intervals for workers subject to different annual rates of M.tb infection and estimates the costs. An equation is developed for the cumulative risk of tuberculosis(TB) at 12 years given a specified annual rate of infection (ARI), screening interval, and a combined proportion (p) of successful skin testing and antibiotic prophylaxis. Equations for total cost of screening and cost per disease case prevented are provided. Results assume: (a) costs of $10 per skin test and $10,000 per TB disease case;(b) p=0.88; and (c) an acceptable cumulative risk of 1 per 1000. For ARI's that might be deemed low(0.2% to 0.5%) and medium (1%), CDC screening intervals of 12 months and 6-12 months, respectively, minimize the cost per disease case prevented but permit residual disease risks greater than 1 per 1000. Recommended screening intervals are (i) 6 months for low-risk employee groups and(ii) 3 months for medium and high risks (e.g., ARIs of > or equal to 5%) groups. Interval (i) limits risk to 1 per 1000 and is approximately 50% shorter than the CDC interval for a low-risk group. Interval (ii), which is 67% shorter than the CDC interval for medium-risk groups but equal to that recommended for high-risk groups, permits a risk above 1 per 1000, but is likely the most feasible interval.
Health-care-workers; Pulmonary-system-disorders; Respiratory-system-disorders; Quantitative-analysis; Risk-factors; Infection-control
Center for Occupational and Environmental Health, School of Public Health, University of California-Berkley, Berkley, CA 94720
Research Tools and Approaches: Risk Assessment Methods
American Industrial Hygiene Association Journal
University of California, School of Public Health, Center for Occupational and Environmental Health, Berkeley, California