Criteria used to classify cases of CSS according to clinical presentation including corticosteroid use
| Group A: CSS before initiation of LTRA | Group B: Potential unmasking of CSS by reduction in or stopping of continuous corticosteroids† within 6 months of development of CSS | Group C: Possible prodromal phase of CSS before initiation of LTRA | Group D: Unstable asthma at time of initiation of LTRA† | Group E: Stable asthma at initiation of LTRA |
| A1: Physician diagnosis of CSS before starting LTRA therapy | B1: Reduction in dose or stopping, of continuous OCS regardless of ICS dose | C: Documentation of ACR criteria of 3 before starting LTRA therapy | D1: Required a short course of OCS within 1 month before starting LTRA | E1: Taking continuous ICS within the 6 months before starting LTRA and no continuous OCS |
| A2: ACR criteria of ≥4 before starting LTRA therapy | B2: Reduction in dose or stopping continuous ICS and not on continuous OCS | D2: Started continuous OCS or was required to increase the dose of continuous OCS within 1 month before starting LTRA | E2: Not on any continuous ICS or OCS within 6 months of starting LTRA | |
| A3: Presence of a characteristic biopsy* in the presence of asthma and eosinophilia before LTRA therapy | B3: Reduction in dose or stopping of continuous corticosteroids (unspecified if oral or inhaled) | D3: Taking continuous OCS at stable dose in the 6 months before starting LTRA | Subset: E2-1: Corticosteroid-naïve, specifically documented never to have taken OCS or ICS | |
| D4: Hospital admission for asthma within 1 month of starting LTRA |
Cases were sequentially designated in categories from Groups A to E in descending order for each group.
↵* A positive biopsy refers to the presence of extravascular eosinophils and/or granulomas and/or vasculitis and/or a pathologist’s report that the histology is consistent with CSS. This excludes extravascular eosinophils on nasal polyp, sinus or bone marrow biopsy.
↵† “Continuous” corticosteroid use is defined as corticosteroid use for >1 month for at least 1 month before starting LTRA. It does not include continuous corticosteroid use if commenced within 1 month before, on the same day or after LTRA started. Short course OCS use is defined as a course of oral corticosteroids of <1 month duration. Initiation of corticosteroids or hospital admission within 1 month includes the day that LTRA was commenced.
CSS, Churg-Strauss syndrome; ICS, inhaled corticosteroid; LTRA, leukotriene receptor antagonist; OCS, oral corticosteroid.