Conference Coverage

Repeat LTBI testing best in patients taking biologics with new risk factors



– Patients taking biologics who received latent tuberculosis testing on an annual basis were unlikely to convert from a negative QuantiFERON test to a positive result, which suggests that the test may be unnecessary for patients without new tuberculosis risk factors, according to research presented at the annual meeting of the American College of Rheumatology.

In addition, nearly all of the cost of repeat testing for latent tuberculosis infection (LTBI) went to patients who were not diagnosed with or treated for LTBI, noted Urmi Khanna, MD, a dermatologist with the Cleveland Clinic.

“All in all, about $1.4 million U.S. dollars was spent just on additional QuantiFERON testing, and only 1% of this additional cost was actually spent on testing patients who were diagnosed with and treated for latent tuberculosis,” Dr. Khanna said in her presentation at the meeting.

“Based on this study, we would like to propose that, in low incidence TB regions such as the United States, repeat LTBI testing in patients on biologic therapies should be focused on patients who have new risk factors for TB infection since their last screening,” she said.

The National Psoriasis Foundation has recommended patients be screened annually for LTBI, and the Centers for Disease Control and Prevention and the ACR have recommended patients taking biologics be screened annually for LTBI if they have new risk factors for TB, such as coming into contact with immigrants, a person infected with TB, immunosuppressed individuals, or persons working in areas where TB might be present. Annual screening was also recently added to the Medicare Merit-Based Incentive Payment System (MIPS), which will affect physician reimbursement. “Based on [the addition of this quality outcome measure], we expect that more and more physicians will adopt this practice of annual LTBI screening in all patients on biologics,” Dr. Khanna said.

She and her colleagues examined QuantiFERON tuberculosis test (QFT) results of 10,914 patients from the Cleveland Clinic Foundation between August 2007 and March 2019 where patients were receiving systemic biologic therapy for inflammatory or autoimmune conditions, including nearly 32% with inflammatory bowel disease, 29% with rheumatoid arthritis, and 25% with psoriatic disease. Overall, 5,212 patients were included in the final analysis, and patients had a median of three QFT results. Patients had a median age of 41 years, had taken an average of 1.80 biologics during follow-up, and had a median biologic therapy duration of about 49 months. The most common biologics used were adalimumab (33%), etanercept (17%), and infliximab (17%).

Of these patients, 4,561 patients had negative QFTs (88%), 172 patients had one or more positive QFTs (3%), and 479 patients had one or more indeterminate QFTs (9%). For patients who converted from a negative QFT to a positive QFT, the most common risk factors were exposure to someone with TB (26%), immigrating or traveling to an endemic area (26%), and occupational exposure (16%).

Within the group with one or more positive QFTs, there were 108 patients with baseline positive QFTs prior to starting biologic therapy (2.1%), 61 patients who converted from a baseline negative QFT to a positive QFT (1.2%), and 3 patients where a positive result overlapped with a negative result (0.1%). The majority of patients who converted to a positive QFT result had borderline positive results (70.5%), defined as 0.35 to 1 IU/mL, compared with 29.5% of converters who had a positive QFT result of more than 1.0 IU/mL.

Among the 61 patients who converted to a positive QFT result, 28 patients with LTBI (46%) and 1 patient with an active case of TB (2%) were diagnosed and treated. The active TB case was a 29-year-old patient with inflammatory bowel disease and ankylosing spondylitis receiving adalimumab who had recently traveled to India.

The researchers also examined the cost of additional QFTs in each group. Among negative QFTs, the cost of an additional 9,611 tests was $1,201,375. The cost of additional tests for indeterminate QFTs was $136,200, but Dr. Khanna noted that 99.99% of additional tests in this group were for patients never diagnosed with or treated for LTBI. Additional tests for positive QFTs cost another $47,700, and 26.1% of patients in this group were diagnosed and received treatment for LTBI, compared with 73.9% who did not receive an LTBI diagnosis or treatment.

In the discussion session following the presentation, Dr. Khanna emphasized that discontinuing annual screening in low-risk patients was not standard of care at the Cleveland Clinic, and this study was conducted to raise awareness of focusing testing on patients with new TB risk factors.

Dr. Khanna reported no relevant financial disclosures. A few of her coauthors reported financial relationships with pharmaceutical companies.

SOURCE: Khanna U et al. Arthritis Rheumatol. 2019;71(suppl 10), Abstract 1802.

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