Mortality in Ankylosing Spondylitis According to Treatment: A Nationwide Retrospective Cohort Study of 5,900 Patients From Israel

Abstract

Objective: In this large population-based study we aimed: 1) to assess mortality in patients with ankylosing spondylitis (AS) compared to the general population, considering demographics, comorbidities, and treatment, and 2) to assess factors associated with mortality within patients with AS.

Methods: This study was designed as a retrospective cohort study using the electronic database of the largest health maintenance organization in Israel. All patients with AS diagnosed between 2002 and 2018 were included. Controls were matched by age, sex, clinic, and enrollment time. Follow-up continued until death or the end of the study.

Results: The study comprised 5,930 AS patients and 29,018 matched controls who were followed up for a median period of 7.5 years. There were 667 deaths within the AS cohort and 2,919 deaths within controls; the mean age at death was 76.9 years and 77.1 years, respectively (P = 0.74). A total of 3,249 AS patients (54.8%) were treated only with nonsteroidal antiinflammatory drugs, 1,760 (29.7%) were treated with tumor necrosis factor inhibitors (TNFi), and 1,687 (28.4%) with disease-modifying antirheumatic drugs (DMARDs). Mortality rates were increased among AS patients compared to controls, with an age- and sex-adjusted hazard ratio (HR) of 1.19 (95% confidence interval [95% CI] 1.10-1.30). The association was significant for men (HR 1.15 [95% CI 1.04-1.27]) and women (HR 1.32 [95% CI 1.13-1.54]), and after adjusting for background comorbidities (HR 1.14 [95% CI 1.05-1.24]). AS patients treated with TNFi or with a combination of TNFi and DMARDs did not have significant difference in mortality rates compared to controls (HR 0.67 [95% CI 0.38-1.18] and HR 0.93 [95% CI 0.69-1.25], respectively). Age, male sex, mean C-reactive protein (CRP) levels and general comorbidities were predictors of mortality within the AS cohort.

Conclusion: AS patients had an increased mortality risk compared to the general population after adjusting for age, sex, and baseline comorbidities. AS patients treated with TNFi did not demonstrate excess mortality compared to matched controls. Within the AS cohort, age, male sex, background comorbidities, and higher CRP levels were identified as risk factors for mortality.