Temporal trends in mortality in patients with rheumatoid arthritis: a Danish population-based matched cohort study

Abstract

Objectives To investigate the 5-year all-cause mortality in patients with rheumatoid arthritis (RA) compared with the general population. Methods Nationwide population-based matched cohort study. RA patients diagnosed between 1996 and the end of 2015 were identified using administrative heath registries and followed until the end of 2020 allowing 5 years of follow-up. Patients with incident RA were matched 1:5 on year of birth and sex with non-RA individuals from the Danish general population. Time-to-event analyses were performed using the pseudo-observation approach. Results Compared with matched controls in 1996–2000, the risk difference for RA patients ranged from 3.5% (95%CI 2.7–4.4%) in 1996–2000 to -1.6% (95%CI -2.3 to -1.0%) in 2011–2015, and the relative risk from 1.3 (95%CI 1.2–1.4) in 1996–2000 to 0.9 (95%CI 0.8–0.9) in 2011–2015. The age-adjusted 5-year cumulative incidence proportion of death for a 60-year-old RA patient decreased from 8.1% (95%CI 7.3–8.9%) when diagnosed in 1996–2000 to 2.9% (95%CI 2.3–3.5%) in 2011–2015, and for matched controls from 4.6% (95%CI 4.2–4.9%) to 2.1% (95%CI 1.9–2.4%). Excess mortality persisted in women with RA throughout the study period, while the mortality risk for men with RA in 2011–2015 was similar to their matched controls. Conclusions Enhanced improvement in mortality was found in RA patients compared with matched controls, but for sex-specific differences excess mortality was only persistent in females with RA.

The Risk of Rheumatoid Arthritis: Incidence, Prevalence, and Mortality

“…Study III was designed as a nationwide population-based matched cohort study with patients with RA diagnosed between 1996 and 2015 in Denmark (94). A description of the used registers is available in Paper III (Appendix C).…”

“…Patients with RA ≥ 18 years of age, were identified using the previously described RA case definition A. Incident RA patients were matched 1:5 on year of birth and sex with non-RA individuals (Appendix C) (94). To reduce the risk of including prevalent RA cases in the study population individuals with an ICD-8 or ICD-10 code for RA before 1996, and those ≥ 18 years of age immigrating during the study period were excluded (Appendix C).…”