Life Expectancy a Swiss Cohort of Patients with Ankylosing Spondylitis: A 35-Year Follow-up Study

Zhixiu Li¹, Mohammad Khan², Sjef van der Linden³, Peter Villiger⁴, Heinz Baumberger⁵, Hermine Zandwijk⁶, Matthew Brown⁷ and Muhammad Khan⁸, ¹Queensland University of Technology (QUT), Translational Genomics Group, School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Translational Research Institute, Princess Alexandra Hospital, Brisbane, Qld, Australia, Brisbane, Queensland, Australia, ²Kent State University, Kent, OH, ³Department of Rheumatology, Immunology and Allergology, University of Bern, Inselspital, Bern, Switzerland, Mortroux, Belgium, ⁴Department of Rheumatology, Immunology and Allergology, University of Bern, Inselspital, Switzerland, Bern, Switzerland, ⁵Retired, Flims, Tajikistan, ⁶Retired, Mortroux, Belgium, ⁷Guy's and St Thomas, NHS Foundation Trust and King's College London NIHR Biomedical Research Centre, King's College London, London, United Kingdom, London, United Kingdom, ⁸Case Western Reserve University, Cleveland OH, Westlake, OH

Meeting: ACR Convergence 2020

Keywords: Ankylosing spondylitis (AS), genetics, Mortality, Outcome measures, spondyloarthritis

Session Information

Date: Monday, November 9, 2020

Session Title: Spondyloarthritis Including Psoriatic Arthritis – Diagnosis, Manifestations, & Outcomes Poster III: Axial SpA

Session Type: Poster Session D

Session Time: 9:00AM-11:00AM

Background/Purpose: To investigate life expectancy of a Swiss cohort of patients with ankylosing spondylitis (AS) versus general population during 35 years of longitudinal follow up, and to study the association of HLA-B27 with mortality in the general population.

Methods: In 1985 AS-affected members of the Swiss Ankylosing Spondylitis Patient Society were contacted to participate in this study, together with their first-degree relatives (FDRs). After ethical approvals and informed written consent, 1178 subjects completed questionnaires on disease manifestations, underwent rheumatological examination of axial and peripheral joins, and provided blood samples for genetic studies. Pelvic radiographs of 363 probands and 713 relatives were assessed blindly for presence of sacroiliitis according to the modified New York (mNY) radiographic criteria. Patients previously clinically diagnosed with AS irrespective of the findings of their pelvic radiographic studies were deemed to have axial spondyloarthritis (axSpA), those meeting the mNY criteria mNYAS, and those with axSpA but not meeting the mNY criteria, non-radiographic axial spondyloarthritis (nr-axSpA).

Approval of a follow-up study was obtained in 2019 from the ethical committee of the Swiss Kanton of Bern. City and village administrations provided current addresses of former participants, and also the deceased persons’ year of death, but not its cause. Among the 411 AS patients from the 1985 study, 182 were alive and 123 had died by December 31, 2019. For the remaining 106 patients who were lost to follow up, the year they moved away was taken as their year of last follow-up. Life expectancy was analysed in comparison with age- and gender-matched Swiss general population data, using Cesaro averaging methods and Kaplan-Meier analyses.

Survival in relation to HLA-B27 individuals in the general population was studied in the UK Biobank cohort (n=485,545, with 13,782 deaths).

Results: Patients meeting the mNYAS criteria have an increased standardized mortality rate (SMR) compared with the general population (1.21, 95% confidence interval 0.97-1.51, P=0.049). This was restricted to HLA-B27(+) mNYAS (SMR HLA-B27(+)=1.241, P=0.034, Figure 1; HLA-B27(-)=1.038, P=0.92). Mortality was increased amongst HLA-B27(+)mNYAS(+) women (SMR=1.89, P=0.004, Figure 2) but not men (SMR=1.14, p=0.26). No difference in survival was noted amongst HLA-B27(-)mNYAS(+) patients (SMR=1.04, p=0.92). Patients with nr-axSpA had reduced SMR compared with the general population (SMR=0.372, P=0.001). In the UK Biobank general population cohort, HLA-B27 carriage was not associated with mortality (hazard ratio (HR)=0.97, P=0.28), in either males (HR=1, P=0.96) or females (HR0.91, P=0.09).

Conclusion: We report in this 35 year longitudinal study that mNYAS patients, but not nr-axSpA patients, have a significantly shortened life expectancy. Increased mortality was particularly significant amongst women with HLA-B27(+) mNYAS, perhaps a reflection of their more severe disease. It also provides additional clinical evidence indicating heterogeneity of AS. HLA-B27 carriage in the general population does not influence survival.

Figure 1: Kaplan-Meier survival probability plot for HLA-B27(+) AS patients.

Figure 2: Kaplan-Meier survival probability plot for female HLA-B27(+) AS patients.

Disclosure: Z. Li, None; M. Khan, None; S. van der Linden, None; P. Villiger, None; H. Baumberger, None; H. Zandwijk, None; M. Brown, None; M. Khan, None.

To cite this abstract in AMA style:

Li Z, Khan M, van der Linden S, Villiger P, Baumberger H, Zandwijk H, Brown M, Khan M. Life Expectancy a Swiss Cohort of Patients with Ankylosing Spondylitis: A 35-Year Follow-up Study [abstract]. Arthritis Rheumatol. 2020; 72 (suppl 10). https://acrabstracts.org/abstract/life-expectancy-a-swiss-cohort-of-patients-with-ankylosing-spondylitis-a-35-year-follow-up-study/. Accessed January 20, 2021.

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