Table 2

New data elements (DEs) with their corresponding value set (ie, categorical drop-down options) applied to the registry to uniformly summarise patient encounters, with regards to relapse probability

DE keyDEValue set (categorical values)
DE1Change in ANCA level
  • DE1 was established using serial direct ELISA or indirect immunofluorescence (IF, if ELISA data missing) results:

  • The delta value (%) of the ANCA titre (anti-MPO or anti-PR3) was calculated between the encounter of interest and the preceding value, which was on average 3 months prior (maximal 12 months).

    • Delta=(encounter of interest value–preceding value)/preceding value×100 (400%=4 fold rise)

  • If ELISA results were missing, IF results were used to infer the delta value:

    • negative->positive=‘<4-fold rise’

    • negative->negative=‘no rise’

    • positive->positive=‘no rise’

    • positive->negative=‘no rise’

  • 4-fold rise

  • <4 fold rise

  • No rise

DE2Suggestive bloods/urine
  • A composite of at least one suggestive blood(s) and/or urine biomarker result(s) including the occurrence of at least one of the following:

    • 20% rise in creatinine level,

    • new haematuria (>10 red blood cells per high power field and/or >3+ blood on dipstick),

    • new proteinuria (>3+ protein on dipstick),

    • C reactive protein above upper limit of normal

    • or 20% rise in urine soluble CD163 (usCD163, normalised to urine creatinine) to a value >400 ng/mmol (Euroimmun assay).

  • Suggestive of relapse

  • Not suggestive

DE3Suggestive imaging
  • Suggestive imaging incorporated all modalities and was considered ‘suggestive of relapse’ if the radiologist reported a finding consistent with active vasculitis. Findings included, but were not limited to, new or worsening destructive nasal disease, pulmonary nodules or cavitating lesions.

  • ‘Not suggestive’ was selected if imaging was performed but it did not show signs of active vasculitis.

  • Suggestive of relapse

  • Not suggestive

  • No imaging performed

DE4Immunosuppression (IS) status
  • DE4 summarises the IS therapy at the time of the encounter.

  • ‘Currently on IS’ describes the ‘IS status’ of a patient on prednisolone >10 mg and/or an additional IS agent (eg, azathioprine) at the time of the encounter.

  • Currently on IS

  • Discontinued within 6 months

  • Discontinued >6 months

DE5IS medication in response to the encounter (IS response)
  • The change in IS by the physician, in response to their clinical assessment, was dichotomised into ‘IS increased’ or not in DE5.

  • An increase was defined as:

    • a clinically meaningful escalation in the dose of the same agent, as determined by the treating physician (as distinct from dose optimisation/titration when an agent is commenced). An increase in prednisolone dose to >20 mg was considered clinically significant.

    • a switch from a typical maintenance agent (or regimen) to a typical induction agent (eg, azathioprine switched to cyclophosphamide or an induction rituximab regimen).

  • Increased

  • Not increased