(042) Laboratory screening tests before and during the use of systemic immunomodulatory agents in patients with chronic inflammatory skin diseases

Publication Number: 1038

Background: Laboratory testing for the presence of tuberculosis, hepatitis, cytopenia, liver function, and other parameters before starting systemic immunomodulatory agents is recommended in patients with chronic inflammatory skin diseases (CISD) but current testing patterns in the US are unclear.

Objectives: In this study, we aimed to investigate the current practice of laboratory screening tests in the United States before and after the initiation of a range of systemic immunomodulatory agents in dermatology.

Methods: The time-trend analysis of US commercial insurance claims database (MarketScan) from 2003-2020 included adult patients with a CISD (psoriasis, hidradenitis suppurativa, or atopic dermatitis) who started an immunomodulatory agent, including methotrexate, tumor necrosis factor-alpha inhibitors (TNFi), ustekinumab, interleukin (IL)-17Ai, IL-23i, dupilumab, or apremilast. Dupilumab and apremilast are unique in that they have no lab testing requirements, and were used as controls. We computed the proportion of patients undergoing screening tests as suggested by professional societies, including for tuberculosis, hepatitis, complete blood counts (CBCs), liver function tests (LFT), and lipid panels. The frequency of tests was conducted in each 2-month interval starting 6 months before starting treatment and during 2 years after treatment started. Follow-up lasted until the first of the following events occurred: death, disenrollment, discontinuation of medication, end of data stream, or 2 years of follow-up.

Results: We identified patients with CISDs who started methotrexate (28,709), TNFi (40,996), ustekinumab (12,852), IL-17Ai (9,805), IL-23i (6,126), dupilumab (7,802), or apremilast (16,134). Across agents, the most common pre-treatment tests were CBCs with 41% to 69% across treatments. Less than 60% of patients were screened for tuberculosis before treatment and 2%-14% had renewed tests 1 year later. 13%-41% had pre-treatment hepatitis panels done. The testing levels of apremilast remained low before (15%-45%) and a year into the treatment (3%-15%), similar to dupilumab (11%-41% and 9%-11%).

Conclusions: Among patients with CISDs starting systemic immunomodulatory treatment in the US, fewer than 60% received recommended pre-treatment testing, while others received tests that were not required. Testing to fulfill professional society recommendations and insurance coverage approval criteria may be seen as replaceable in patients who are low-risk and well-known to prescribers. There are several differences among published guidelines for laboratory monitoring, which contributes to uncertainty around recommendations and possible over-testing in some patients.