The temporal mortality trend in seropositive and seronegative rheumatoid arthritis: a Danish population-based cohort study

<h2>ABSTRACT</h2><h3>Objectives</h3> This study investigated the 5-year all-cause mortality trend for women and men with seropositive versus seronegative rheumatoid arthritis (RA) compared with the background population (BP). <h3>Methods</h3> Using nationwide registers, a population-based cohort of incident patients with RA diagnosed in Denmark between 2000 and 2014 was identified. Based on immunoglobulin M-rheumatoid factor and/or anticitrullinated peptides, a prespecified algorithm was used to determine the serologic status. The pseudo-observation method was used to determine the cumulative incidence proportion, the age-adjusted risk difference, and the relative risk of mortality. <h3>Results</h3> During the study period, the cumulative incidence proportion decreased by at least 50% for both the BP and the RA cohort. The largest change in relative risk was seen for men with seropositive RA compared with seronegative RA, with a relative risk 2000-2004 of 1.1 (95% CI, 0.9-1.4) to a relative risk of 1.4 (95% CI, 1.2-1.7) in 2010-2014. No significant difference was observed for women stratified by serology. Patients with seropositive RA continued to have an excess mortality risk compared with the BP, whereas the relative risk for patients with seronegative RA became similar to the BP. <h3>Conclusions</h3> A higher 5-year all-cause mortality risk persisted for patients with seropositive RA compared with the BP. Men with seropositive RA had a higher mortality risk than men with seronegative RA, a difference not seen in women. Future studies are needed to explore the findings of higher mortality risk in seropositive patients and especially the influence of sex and confounders.