Association between comorbidities and disease activity in axial spondyloarthritis: results from the BSRBR-AS

Sizheng Steven Zhao, Gareth T Jones, Gary J Macfarlane, David M Hughes, Robert J Moots, Nicola J Goodson* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
3 Downloads (Pure)


OBJECTIVE: Whether comorbidities influence disease activity assessment in axial SpA (axSpA) is unclear. Comorbidities inflate DAS28 in rheumatoid arthritis through the patient global score. We examined whether axSpA disease activity measures are differentially affected, and whether comorbidities inflate the AS disease activity score (ASDAS) through the patient global component.

METHODS: We used baseline data from the British Society for Rheumatology Biologics Register for AS, including 14 physician diagnosed comorbidities. Linear models were used to compare disease activity (BASDAI, spinal pain, ASDAS) and ESR/CRP according to comorbidity count, adjusted for age, gender, BMI, smoking, socioeconomic status, and education. The same models were used to examine whether the patient global score was associated with comorbidities, additionally adjusting for other ASDAS components.

RESULTS: The number of participants eligible for analysis was 2043 (67% male, mean age 49 years); 44% had at least one comorbidity. Each additional comorbidity was associated with higher BASDAI by 0.40 units (95% CI: 0.27, 0.52) and spinal pain by 0.53 (95% CI: 0.37, 0.68). Effect size for ASDAS (0.09 units; 95% CI: 0.03, 0.15) was not clinically significant. ESR and CRP were not associated with comorbidity count. Depression, heart failure and peptic ulcer were consistently associated with higher disease activity measures, but not CRP/ESR. Patient global was associated with comorbidity count, but not independently of other ASDAS components (P = 0.75).

CONCLUSION: Comorbidities were associated with higher patient reported disease activity in axSpA. Clinicians should be mindful of the potential impact of comorbidities on patient reported outcome measures and consider additionally collecting ASDAS when comorbidities are present.

Original languageEnglish
Pages (from-to)3189–3198
Number of pages10
Issue number7
Early online date17 Dec 2020
Publication statusPublished - Jul 2021

Bibliographical note

Funding: The BSRBR-AS is funded by the British Society for Rheumatology (BSR) who have received funding for this from Pfizer, AbbVie and UCB. These companies receive advance copies of manuscripts for comments. They have no input in determining the topics for analysis or work involved in undertaking it.

We are grateful to the staff of the BSRBR-AS register and to the recruiting staff at the clinical centres, details of which are available at:

S.S.Z. analysed the data and wrote the manuscript, with significant input from all co-authors. G.J.M. and G.T.J. are Chief Investigator and Deputy Chief Investigator, respectively, on BSRBR-AS and designed the study and oversaw its conduct. In the current project they discussed results and provided input into drafts of the manuscript.

Disclosure statement: The authors have declared no conflicts of interest.

Data Availability Statement

Data from the British Society for Rheumatology
Biologics Register for AS are available to external investigators,
on reasonable request. For information on how
to access data, see:

Supplementary data are available at Rheumatology


  • axial spondylarthritis
  • AS
  • comorbidity
  • disease activity
  • patient global
  • spondylarthritis


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