The clinical use of regularly monitoring potassium levels in young women taking spironolactone for acne has also been questioned. The drug has been linked to an increased risk for hyperkalemia, but the prevalence is unclear. “I got a lot of normal potassium levels in these patients [when] I was in training and I really questioned, ‘Why am I doing this? What is the rationale?’ ” Dr. Kirby said.
TB testing and biologics
Whether or not to test for TB in patients with psoriasis taking biologic therapies represents another conundrum, she continued. Patients taking biologics are at risk of reactivation of latent TB infection, but in her experience, package inserts contain language like “perform TB testing at baseline, then periodically,” or “use at baseline, then with active TB symptoms,” and “after treatment is discontinued.”
“What the inserts didn’t recommend was to perform TB testing every year, which is what my routine had been,” Dr. Kirby said. “In the United States, thankfully we don’t have a lot of TB.” In athat informed her own practice, researchers at a single academic medical center retrospectively reviewed the TB seroconversion rate among 316 patients treated with second-generation biologics (J Am Acad Dermatol. 2020 Oct 1;S0190-962232676-1. doi: 10.1016/j.jaad.2020.09.075). It found that only six patients (2%) converted and had a positive TB test later during treatment with the biologic. “Of these six people, all had grown up outside the U.S., had traveled outside of the U.S., or were in a group living situation,” said Dr. Kirby, who was not affiliated with the study.
“This informs our rationale for how we can do this testing. If insurance requires it every year, fine. But if they don’t, I ask patients about travel, about their living situation, and how they’re feeling. If everything’s going great, I don’t order TB testing. I do favor the interferon-gamma release assays because they’re a lot more effective than PPDs [purified protein derivative skin tests]. Also, PPDs are difficult for patients who have a low rate of returning to have that test read.”