Interpreting the Treatment Algorithm: Evidence Levels, Diagnostic Workup, and the Stepwise Framework

The updated international CSU guidelines updated its treatment algorithm to reflect newer treatment options, with a strong recommendation for omalizumab and conditional recommendations for dupilumab and remibrutinib. This difference does not imply that the newer agents are inferior in efficacy or unsuitable as first-choice step-up therapies — rather, it reflects the relative weight of evidence accumulated over time. Omalizumab has been studied for more than a decade in CSU, with well over 50 real-world studies complementing its pivotal trial data. Dupilumab and remibrutinib, as newer approvals, carry robust but comparatively smaller bodies of evidence. Clinicians should read the visual distinction as a commentary on the maturity of the data, not a directive about prescribing sequence. Patient-specific factors, including comorbidities, preferred route of administration, speed of desired onset, and payer access, appropriately influence agent selection at this step of the algorithm.

Laboratory testing in CSU plays a diagnostic-adjacent rather than treatment-directive role. The recommended baseline panel, which includes complete blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total IgE, and thyroid peroxidase (TPO) antibody, is designed primarily to surveil for comorbid autoimmune conditions, most notably autoimmune thyroiditis, which occurs at elevated rates in CSU patients. These values do not inform the choice among omalizumab, dupilumab, and remibrutinib in the vast majority of cases; remibrutinib and dupilumab both work independently of IgE levels, further diminishing the utility of IgE testing as a treatment-selection tool. Clinicians should be explicit with patients about what these tests do and do not tell us: the CSU diagnosis is clinical, based on history and physical examination, and escalation decisions are not gated on laboratory findings.

In this video segment, Jasons Hawkes, MD, draws a clear distinction between diagnosis and management when addressing the testing framework, and Nicole Chase, MD, notes that she typically defers an extensive laboratory workup in straightforward presentations, reserving it for patients who are refractory to initial therapy or who present with features suggesting systemic disease. Both experts reaffirm that the stepwise framework — standard-dose antihistamines, then up-dosing to fourfold the approved dose, then step-up to a targeted agent — remains the structural backbone of the guidelines. The meaningful new development is the expanded menu at that third step, along with the flexibility extended to clinicians to individualize that choice based on the full clinical picture rather than defaulting to a single agent by convention.