Measuring quality of life of patients with axial spondyloarthritis for economic evaluation

Monica Hernández Alava, Allan Wailoo, Georgios Chrysanthou, Filipe Barcelos, Floris Alexander van Gaalen, Helena Santos, Karen Fagerli, Laura Gago, Maria Margarida Cunha, Marleen van de Sande, Maura Couto, Miguel Bernardes, Roberta Ramonda, Sofia Exarchou, Pedro Carvalho, van der Heijde Désirée, Pedro Machado

Research output: Contribution to journalArticlepeer-review

Abstract

Objectives

To estimate the relationship between EQ5D (3-level, UK version) and the Ankylosing Spondylitis Disease Activity Score (ASDAS) for use in the economic evaluation of health technologies for people with axial spondyloarthritis (axSpA). To compare against the relationship with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI).

Methods

An electronic, prospective, Portuguese, nationwide, rheumatic disease register (Reuma.pt) provided data on 1140 patients (5483 observations) with a confirmed diagnosis of axSpA. We estimated models of EQ5D as a function of ASDAS, alone or in combination with measures of functional impairment, using bespoke mixture models which reflect the complex distributional features of EQ5D. The SPondyloArthritis Caught Early (SPACE) cohort provided data from 344 patients (1405 observations) in four European countries and was used for validation. A previously published model of BASDAI/BASFI was also used to generate predicted EQ5D scores and model performance compared.

Results

A non-linear relationship exists between EQ5D from ASDAS. The final model included ASDAS, ASDAS-squared, age and age-squared and demonstrated close fit in both datasets except where data was sparse for patients with very high levels of disease activity (ASDAS >4). This finding held in the validation dataset. Models that included BASFI improved model fit. The ASDAS based models fit the data marginally less well than models using BASDAI.

Conclusions

Mapping models linking ASDAS to EQ5D allow results from clinical studies to be used in economic evaluation of health technologies with confidence. There is some loss of information compared to BASDAI but this has only a marginal impact.
Original languageEnglish
Article numbere001955
JournalRMD Open
Volume8
Issue number1
Early online date17 Feb 2022
DOIs
Publication statusPublished - 17 Feb 2022

Keywords

  • ankylosing
  • economics
  • patient reported outcome measures
  • spondylitis

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology

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