Mapping the relationship between clinical and quality-of-life outcomes in patients with ankylosing spondylitis

Expert Rev Pharmacoecon Outcomes Res. 2017 Apr;17(2):203-211. doi: 10.1080/14737167.2016.1200468. Epub 2016 Jun 24.

Abstract

Aim: To map health-related quality of life (Qol) with clinical parameters BASFI and ASDAS-CRP measure, and other covariates.

Methods: Our prospective multicenter non-interventional observation study of ankylosing spondylitis (AS) collected data about QoL and clinical outcomes on the initial and four subsequent visits. We employed simple linear regression analysis of a cross-sectional dataset, and fixed effect, random effect and pooled linear regression of a longitudinal dataset.

Results: We showed that BASFI and ASDAS-CRP are very strong, robust predictors of EQ-5D utilities in all regression specifications together with sex (female), invalidity, and activity impairment. Additionally, the longitudinal regression analysis showed that a fixed effect model may be a viable alternative to the most commonly used random effect model or pooled linear regression due to the nature of our dataset.

Conclusion: This is one of the first studies using a fixed effect model in longitudinal patient-level data, although, this method has been widely used in economics.

Keywords: Ankylosing spondylitis; fixed effect regression; health-related quality of life; longitudinal analysis; mapping; outcomes research; regression analysis.

Publication types

  • Multicenter Study
  • Observational Study

MeSH terms

  • Adult
  • Female
  • Follow-Up Studies
  • Humans
  • Linear Models
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Models, Theoretical*
  • Prospective Studies
  • Quality of Life*
  • Severity of Illness Index
  • Sex Factors
  • Spondylitis, Ankylosing / physiopathology*