Assessment of health-related quality of life as an outcome measure in granulomatosis with polyangiitis (Wegener's)

Abstract

Objective: To assess a generic measure of health-related quality of life (HRQOL) as an outcome measure in granulomatosis with polyangiitis (Wegener's) (GPA).

Methods: Subjects were participants in the Wegener's Granulomatosis Etanercept Trial (WGET) or the Vasculitis Clinical Research Consortium Longitudinal Study (VCRC-LS). HRQOL was assessed with the Short Form 36 (SF-36) health survey that includes physical and mental component summary scores (PCS and MCS, respectively). Disease activity was assessed with the Birmingham Vasculitis Activity Score for Wegener's Granulomatosis (BVAS/WG).

Results: The data from 180 subjects in the WGET (median followup 2.3 years, mean number of visits 10) and 237 subjects in the VCRC-LS (median followup 2.0 years, mean number of visits 8) were analyzed. A 1 unit increase in the BVAS/WG corresponded to a 1.15 unit (95% confidence interval [95% CI] 1.02, 1.29) decrease for the PCS and a 0.93 (95% CI 0.78, 1.07) decrease for the MCS in the WGET, and to a 1.16 unit decrease for the PCS (95% CI 0.94, 1.39) and a 0.79 unit decrease for the MCS (95% CI 0.51, 1.39) in the VCRC-LS. In both arms of the WGET study, SF-36 measures improved rapidly during the first 6 weeks of treatment followed by gradual improvement among patients achieving sustained remission (0.5 improvement in PCS per 3 months), but worsened slightly (0.03 decrease in PCS every 3 months) among patients not achieving sustained remission (P = 0.005).

Conclusion: HRQOL, as measured by the SF-36, is reduced among patients with GPA. SF-36 measures are modestly associated with other disease outcomes and discriminate between disease states of importance in GPA.

Trial registration: ClinicalTrials.gov NCT00315393.

Figure 1

Longitudinal changes in mean SF-36 summary scores in the Wegener’s Granulomatosis Etanercept Trial cohort according to whether or not subjects achieved sustained remission. Time in years is on the x-axes and mean scores on the y-axes. Broken lines represent 95% confidence limits. Panel A: data for the PCS score; Panel B: data for the MCS score (PCS=Physical component summary, MCS=Mental component summary).

Figure 2

A longitudinal change in the difference of true and artificial summary SF-measures according to whether sustained remission was achieved. Time in years is on the x-axes and the difference in scores between those who did and did not achieve sustained remission on the y-axes. The artificial scores are presented with 95% confidence limits. There is greater difference in the true SF-36 summary measures than is observed for the artificial scores. (Δscore=difference in scores between those who did and did not achieve sustained remission, PCS=Physical component summary, PCS_ART= Artificial PCS score, MCS= Mental component summary, MCS_ART= Artificial MCS score).