Revisiting annual screening for latent tuberculosis infection in healthcare workers: a cost-effectiveness analysis

Abstract

BackgroundIn North America, tuberculosis incidence is now very low and risk to healthcare workers has fallen. Indeed, recent cohort data question routine annual tuberculosis screening in this context. We compared the cost-effectiveness of three potential strategies for ongoing screening of North American healthcare workers at risk of exposure. The analysis did not evaluate the cost-effectiveness of screening at hiring, and considered only workers with negative baseline tests.MethodsA decision analysis model simulated a hypothetical cohort of 1000 workers following negative baseline tests, considering duties, tuberculosis exposure, testing and treatment. Two tests were modelled, the tuberculin skin test (TST) and QuantiFERON®-TB-Gold In-Tube (QFT). Three screening strategies were compared: (1) annual screening, where workers were tested yearly; (2) targeted screening, where workers with high-risk duties (e.g. respiratory therapy) were tested yearly and other workers only after recognised exposure; and (3) post exposure-only screening, where all workers were tested only after recognised exposure. Workers with high-risk duties had 1% annual risk of infection, while workers with standard patient care duties had 0.3%. In an alternate higher-risk scenario, the corresponding annual risks of infection were 3% and 1%, respectively. We projected costs, morbidity, quality-adjusted survival and mortality over 20 years after hiring. The analysis used the healthcare system perspective and a 3% annual discount rate.ResultsOver 20 years, annual screening with TST yielded an expected 2.68 active tuberculosis cases/1000 workers, versus 2.83 for targeted screening and 3.03 for post-exposure screening only. In all cases, annual screening was associated with poorer quality-adjusted survival, i.e. lost quality-adjusted life years, compared to targeted or post-exposure screening only. The annual TST screening strategy yielded an incremental cost estimate of $1,717,539 per additional case prevented versus targeted TST screening, which in turn cost an incremental $426,678 per additional case prevented versus post-exposure TST screening only. With the alternate “higher-risk” scenario, the annual TST strategy cost an estimated $426,678 per additional case prevented versus the targeted TST strategy, which cost an estimated $52,552 per additional case prevented versus post-exposure TST screening only. In all cases, QFT was more expensive than TST, with no or limited added benefit. Sensitivity analysis suggested that, even with limited exposure recognition, annual screening was poorly cost-effective.ConclusionsFor most North American healthcare workers, annual tuberculosis screening appears poorly cost-effective. Reconsideration of screening practices is warranted.

Cost-Effectiveness of Annual Screening for Tuberculosis among Italian Healthcare Workers: A Retrospective Study

“…HCWs have been historically considered to be at higher risk for tuberculosis infection, but it could be no longer the case [14][15][16]. Our study suggests that, in an Italian hospital setting, the conversion rate is low, and the routine annual screening for HCWs who work in typical healthcare facilities provides limited benefit at high cost as compared to a more targeted strategy.…”

“…Indeed, the resources used for the testing could be spent more effectively in the prevention of occupational contagion in intermediate/high risk groups. In a study conducted in Canada [15], the annual TST screening strategy was not cost-effective and yielded an additional cost estimate of $1717.539 Canadian dollars (over 1,511,000 euros) per additional case prevented versus targeted screening. Those evaluations were based on the conversion rate estimated in a low-risk scenario, as it is in our case.…”

“…In this population, the observed conversion rate was 0.3% per year, and a limited proportion of cases was attributable to occupational exposure [14], raising questions about the cost-effectiveness of routine screening for TB among HCWs. A recent analysis conducted in Canada found that the annual TST screening strategy was not cost effective when compared with more targeted TST screening [15]. The annual TST screening strategy yielded an extremely high incremental cost per additional case prevented versus targeted TST screening.…”

False-Positive Tuberculin Skin Test Results Among Low-Risk Healthcare Workers Following Implementation of Fifty-Dose Vials of Purified Protein Derivative

“…3 Annual screening for low-risk HCWs prevents active TB disease at an incremental cost of more than US$1.5 million per case prevented compared to testing only those with known TB exposure. 10 Here, we demonstrate that false-positive TST conversions can result in expenditures of hospital resources beyond the cost of a low-yield LTBI testing and treatment program. 3 An increase in false-positive results occuring over a short period of time in a population with a very low baseline rate of test conversions can give the appearance of institutional TB transmission, leading to unnecessary investigations by hospital epidemiology and infection control personnel.…”

“…When the prevalence of a disease in the population is low (e.g., <1%) and the performance characteristics of screening tests are poor, 4 most positive tests are falsely positive. 3,10 Annual TB screening programs should be modified to eliminate automatic annual LTBI testing for low-risk, previously negative HCWs and could instead be structured to carefully evaluate individual exposure risks and personal health history.…”