Examining the Utility, Cost-Effectiveness of Repeat Tuberculosis Testing for Patients With Psoriasis Receiving TNFIs

These findings support the belief that serial LTBI testing in low-risk populations may be associated with higher likelihood of false-positive test results, unnecessary costs/treatment, and increased adverse events.

Conversion to latent tuberculosis infection (LTBI) was extremely uncommon among patients with psoriasis receiving tumor necrosis factor-α inhibitors (TNFIs), according to study data published in a research letter in the British Journal of Dermatology. As such, investigators suggested that serial repeat LTBI testing in patients with psoriasis receiving TNFIs may be of little clinical value in low-risk tuberculosis countries.

Investigators abstracted data between 2007 and 2015 from electronic medical records at the Cleveland Clinic. Patients with psoriasis who were treated with TNFIs and had results for ≥2 LTBI tests were eligible for inclusion. The specific LTBI test of interest was the QuantiFERON-TB Gold test (QFT). Demographic and clinical information were extracted for each patient, including type of TNFI therapy, length of TNFI use, and QFT results. In patients who received positive QFT results while on stable TNFI treatment, a 1-year retrospective review was performed of their medical record to identify potential risk factors for tuberculosis.

The study cohort comprised 570 patients with psoriasis (52.3% women; mean age, 48 years) who had a total of 1547 QFT tests. The most commonly used TNFI was adalimumab (n=227; 39.8%), followed by etanercept (n=203; 35.6%), infliximab (n=69; 12.1%), certolizumab (n=4; 0.70%), and golimumab (n=4; 0.70%). Patients received TNFI treatment for a median period of 4.8 years. The majority of QFT tests were negative (n=1455; 94.0%), with a minority of indeterminate (n=61; 3.9%) and positive (n=21; 1.4%) results. Just three patients (0.53%) had conversion from a negative QFT result at baseline to positive QFT status after initiating TNFI therapy. All three patients who underwent conversion had known tuberculosis risk factors at baseline, and only one of the three patients (0.18%) was considered a “true converter” and received latent tuberculosis treatment. Eleven patients had baseline positive QFT results prior to TNFI initiation; in six of these patients (54.5%) the QFT result reverted to negative with repeat testing, including several tests following repeat treatment for LTBI.

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The study is limited by its retrospective nature and search criteria that could only detect QFT results drawn from internal Cleveland Clinic laboratories.

“Routine serial repeat QFT testing” in patients receiving TNFIs for psoriasis revealed an extremely low conversion rate. As such, investigators suggested that routine LTBI testing may not be cost-effective in countries with low risk for tuberculosis. Instead, the authors endorsed serial LTBI screening in a smaller subset of patients with certain tuberculosis risk factors, including close contact with a patient with tuberculosis or from a tuberculosis-endemic area, work in a healthcare setting, or immunosuppressed status. Further research into the clinical utility and cost-effectiveness of repeat LTBI testing in patients receiving TNFIs is necessary, particularly at other institutions worldwide.  

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Ya J, Khanna U, Havele S, Fernandez AP. Utility of repeat latent tuberculosis testing with QuantiFERON-TB Gold test in psoriasis patients treated with TNF-α inhibitors at a single U.S. institution [published online August 27, 2019]. Br J Dermatol. doi:10.1111/bjd.18461