The Hidden Costs of Routine TB Testing Before IL-17 and IL-23 Inhibitors

Routine tuberculosis (TB) testing before starting interleukin (IL)-17 and IL-23 inhibitors does more than delay treatment. It causes a range of downstream harms for patients and practices. In the final segment of this HCPLive Special Report, 2 co-authors of the joint position statement from the National Psoriasis Foundation (NPF) and the International Psoriasis Council (IPC) outlined those harms and reflected on the statement’s impact.

They were Andrew Blauvelt, MD, MBA, adjunct professor in the Department of Dermatology at the University of Maryland School of Medicine, and Joseph F. Merola, MD, MMSc, chair of the Department of Dermatology at UT Southwestern Medical Center.

What Problems Can Routine TB Testing Create?

Merola described a recent patient, an older woman with no meaningful exposure risk who had rarely left her home in decades. She was tested only because her payer required it, and she received 2 indeterminate results in a row. Each round meant another hour-long drive to the clinic, which he suggested likely posed a greater risk to her than TB reactivation. It also added cost to the health system and further delayed the start of therapy.

He listed further problems: false-positive results, uncertainty about how to interpret indeterminate results, and repeated retesting. Patients are also commonly lost to follow-up. When they are tested at outside facilities, the results may never reach the prescribing office, and patients can return months later still untreated. Merola called the statement practice-changing rather than a minor adjustment.

Can TB Testing Lead to Unnecessary Treatment?

Blauvelt added that testing can also lead to unnecessary treatment for latent TB infection (LTBI). Merola agreed. He noted that as patients age, the risks of LTBI therapy, including liver toxicity, begin to outweigh its benefits. Testing an older, low-risk population can therefore trigger therapy that carries its own harms and may offer little benefit.

How Long Has This Issue Been Debated?

Blauvelt said the issue has long been a priority for him. While the phase 3 risankizumab program was being designed, he argued that TB testing was unnecessary. One of the 4 trials left testing out, but the other 3 kept it, and the requirement ended up in the label. He said the evidence is now clear and the statement, though arguably overdue, is better late than never.

Merola closed by encouraging clinicians to hold firm and push back when payers require TB testing for these agents. He noted that he has had to do so himself and hopes to see change.