NTCA - Implementation and Assessment of QuantiFERON®TB Gold (in-tube) for the Diagnosis of Latent TB Infection in New Jersey

Data indicates that QFT has significantly reduced the workload and improved the efficiency of testing and evaluation for LTBI over TST.
Patricia Woods, RN, MSN, Nurse Consultant, New Jersey Department of Health and Senior Services (NJDHSS); Alfred Lardizabal, MD, UMDNJ/NJMS Global TB Institute; Susan Mikowski, M.Ed., MT(ASCP)SM, Cynthia Bartlett, MS and Paul Seitz, BS, MT(ASCP)CPM, NJDHSS Public Health and Environmental Laboratories

Background: Since October 2010, the New Jersey Department of Health and Senior Services (NJDHSS) has offered QuantiFERON®TB Gold in-tube (QFT) testing at six clinical locations in collaboration with the NJ Public Health & Environmental Laboratories (PHEL). PHEL is vital to this initiative for quality assurance purposes, courier services, specimen analysis and reporting of test results. The purpose of initiating QFT testing was to reduce the number of false positives when compared to the tuberculin skin test (TST), maximizing clinical efficiency and minimizing unnecessary treatment for latent TB infection (LTBI).

Methods: State funding was identified to purchase incubators and test kits for the six sites. It was determined that incubation would occur at the clinic sites to maximize the time available to transport specimens to PHEL and minimize courier costs. PHEL developed procedures for the appropriate handling of specimens and requisition and reporting forms. Initial training was provided by PHEL at two locations. A practicum was provided at each clinical site by the TB Program‟s nurse consultants for all licensed personnel that would be performing the venous draw. Criteria were established to determine who would be offered QFT to maximize the benefit and minimize the costs associated with this improved diagnostic tool. Cost analysis was performed to determine any savings associated with the use of QFT over TST.

Results: Of the 349 QFT test results reported to date, 247 were negative (70.8%), 100 were positive (28.7%) and 2 were indeterminate (0.6%). Of 275 persons with a previous BCG vaccination, 189 were negative (68.7%), 84 were positive (30.5%) and 2 indeterminate (0.6%). Of 166 patients with a previously positive TST, 108 were negative (65.1%), 56 were positive (33.7) and 2 were indeterminate (1.2%). Of 145 patients with a previous positive TST and BCG vaccination, 98 were negative (67.6%), 45 positive (31.0%) and 2 indeterminate (1.4%). Of 21 patients with a previous positive TST, but no BCG vaccination, 10 were negative (47.6%) and 11 positive (52.4%) upon QFT testing. It was determined that a $10,300 cost savings was realized utilizing QFT rather than TST.

Conclusion(s): Data indicates that QFT has significantly reduced the workload and improved the efficiency of testing and evaluation for LTBI over TST.