Outcome Measures in Large Vessel Vasculitis: Relationship Between Patient-, Physician-, Imaging-, and Laboratory-Based Assessments

Objective To assess the relationship between measures of disease assessment in patients with large vessel vasculitis. Methods Patients with giant cell arteritis (GCA) or Takayasu arteritis (TAK) were recruited into a prospective, observational cohort. Assessments within the following outcomes were independently recorded: 1) patient-reported outcomes (Multidimensional Fatigue Inventory, patient global assessment of disease activity [PtGA], Short Form 36 health survey [SF-36], Brief Illness Perception Questionnaire), 2) physician global assessment of disease activity (PhGA), 3) laboratory outcomes (C-reactive protein [CRP] level, erythrocyte sedimentation rate [ESR]), and 4) imaging outcomes (PETVAS, a qualitative score of vascular(18)F-fluorodeoxyglucose-positron emission tomography activity). Results Analyses were performed on 112 patients (GCA= 56,TAK= 56), over 296 visits, with a median follow-up of 6 months. Correlation network analysis revealed assessment measures clustered independently by type of outcome. PhGAwas centrally linked to all other outcome types, but correlations were modest (rho = 0.12-0.32;P< 0.05).PETVAS,CRPlevel, and PtGAwere independently associated with clinically active disease. All 4patient-reported outcomesstrongly correlated with each other (rho = 0.35-0.60;P< 0.0001).Patient-reported outcomeswere not correlated withPETVAS, and only PtGAcorrelated withCRPlevel (rho = 0.16;P <0.01). Patients whose clinical assessment changed from active disease to remission (n = 29) had a corresponding significant decrease inESR,CRPlevel, andPETVASat the remission visit. Patients whose clinical assessment changed from remission to active disease (n = 11) had a corresponding significant increase inCRPlevel and PtGAat the active visit. Conclusion Measures of disease assessment in large vessel vasculitis consist of independent, yet complementary, outcomes, supporting the need to develop composite outcome measures or a standard set of measures covering multiple types of outcomes.