Screening for tuberculosis using an interferon-γ assay is indicated for this patient before initiation of a tumor necrosis factor (TNF)-α inhibitor. This patient with rheumatoid arthritis has active disease despite treatment with triple therapy using nonbiologic disease-modifying antirheumatic drugs. In addition, she has poor prognostic markers, including positive rheumatoid serology and high inflammatory markers. Appropriate therapy with a biologic agent is being planned. TNF-α inhibitors are the mainstay of initial biologic therapy for rheumatoid arthritis. Reactivation of tuberculosis is a significant risk for most biologic agents, and particularly with TNF-α inhibitors because they inhibit formation of granuloma. Prior to starting any biologic agent, appropriate testing for latent tuberculosis is needed by obtaining either a tuberculosis skin test or an interferon-γ release assay (IGRA). Either of these two tests can be used to screen for latent tuberculosis. IGRA is more costly but may be more sensitive in patients on immunosuppressive therapy.

Chest radiography will be needed if the patient is symptomatic with pulmonary symptoms or has positive testing for latent tuberculosis infection but is currently not necessary.

Common variable immunodeficiency (CVID) occurs in both adults and children. Serum IgG levels are markedly reduced, and serum IgA and/or IgM levels are frequently low. Patients with CVID frequently develop chronic lung diseases, autoimmune disorders such as rheumatoid arthritis, malabsorption, recurrent infections, and lymphoma. Recurrent sinopulmonary infections, ear infections, and conjunctivitis are common. Measuring immunoglobulin levels in this patient without evidence of recurrent infection is not indicated.

Radiographs of the hands and feet can confirm the presence of erosions in active rheumatoid disease but are not needed in this patient prior to starting a biologic because disease activity has already been established by physical examination and laboratory testing.