PURPOSE: The value of QFT-G as a promising alternative to the tuberculin skin test (TST) in the diagnosis of latent tuberculosis infection (LTBI) can be illuminated by reports on actual test completion and the subsequent evaluation and treatment for patients with positive test results.
METHODS: In May 2006, pilot testing of QFT-G in foreign born patients began in 3 TB clinics in SCC where over 2400 LTBI cases are treated annually. Criteria for testing were based on FDA recommendations. Those with positive QFT-G were asked to return for evaluation. Retrospective chart review was performed on patients with a positive QFT-G test.
RESULTS: From May 2006 to March 2007, a total of 1914 QFT-G were done; 402/1914 (21%) results were positive, 50/1914 (3%) indeterminate, 1462/1914 (76%) negative. To date, 246 LTBI patients (58% female) with positive QFT-G were reviewed for age, sex, country of birth, risk for TB, reason for TB screening and LTBI treatment. 8/246 (3%) patients did not return for evaluation. Most common reasons for TB screening were work (52%), immigration (14%) and school (12%). 94% patients were born in a country where BCG is routinely offered with highest frequency born in Mexico (37%), India (13%) and Philippines (11%). Sixteen people (7%) were contacts considered to be high risk patients. 224 (91%) patients were prescribed chemoprophylaxis with either isoniazid (INH) 175/224(78%) or rifampin (RIF) 35/224 (16%) or combination of the two 13/224 (6%). To date, treatment has been completed in 22 (9%) and has been discontinued in 81(33%) due to adverse effects or noncompliance. 38% treated with RIF completed treatment compared to 14% treated with INH.
CONCLUSION: In a large foreign born BCG vaccinated cohort, QFT-G was well accepted. Increased specificity of the test may have led to a 28% decrease in the number of LTBI cases in our clinic from 2005 to 2006. Further testing and analysis is required to determine the overall clinical utility of QFT-G.
CLINICAL IMPLICATIONS: Quantifuron-G may be useful in eliminating unnecessary LTBI treatment.
DISCLOSURE: Susan Marantz, No Financial Disclosure Information; No Product/Research Disclosure Information