Prevalence of Pretreatment Testing Recommended for Patients With Chronic Inflammatory Skin Diseases.

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

Objective: To determine the prevalence of pretreatment testing that is recommended for patients with CISD (psoriasis, hidradenitis suppurativa, or atopic dermatitis).

Design, Setting, And Participants: This descriptive analysis of US commercial insurance claims databases from December 31, 2002, to December 31, 2020, included adult patients with CISD (psoriasis, hidradenitis suppurativa, or atopic dermatitis) who started an immunomodulatory agent, including methotrexate, tumor necrosis factor α inhibitors, interleukin (IL)-17Ai, ustekinumab, IL-23i, dupilumab, or apremilast.

Main Outcomes And Measures: The proportion of patients who underwent the screening tests as suggested by professional societies-including for tuberculosis, hepatitis, and liver function; complete blood cell counts; and lipid panels-were determined within 6 months before and during 2 years after treatment start.

Results: A total of 122 308 patients with CISDs (median [IQR] age, 49 [38-58] years; 63 663 [52.1%] male) starting systemic immunomodulatory treatment in the US were included. Treatment for patients with CISDs comprised methotrexate (28 684), tumor necrosis factor α inhibitors (40 965), ustekinumab (12 841), IL-23i (6116), IL-17Ai (9799), dupilumab (7787), or apremilast (16 116). Complete blood cell count was the most common test, performed in 41% (3161/7787) to 69% (19 659/28 684) of individuals before initiation across treatments. Between 11% (889/7787) and 59% (3613/6116) of patients had tuberculosis screening within 6 months before treatment, and 3% (149/4577) to 26% (1559/6097) had updated tests 1 year later. Between 13% (1006/7787) and 41% (16 728/40 965) had hepatitis panels before treatment. Low pretreatment testing levels before apremilast (15% [2331/16 116] to 45% [7253/16 116]) persisted a year into treatment (9% [816/8496] to 36% [2999/8496]) and were similar to dupilumab (11% [850/7787] to 41% [3161/7787] vs 3% [149/4577] to 25% [1160/4577]).

Conclusions And Relevance: In this descriptive analysis of patients with CISDs starting systemic immunomodulatory treatment in the US, less than 60% received the recommended pretreatment testing. Additional research is required to understand whether variations in testing affect patient outcomes.