Anticitrullinated protein antibodies and rheumatoid factor are associated with increased mortality but with different causes of death in patients with rheumatoid arthritis

OBJECTIVE: Patients with rheumatoid arthritis (RA)-related autoantibodies have an increased mortality rate. Different autoantibodies are frequently co-occurring and it is unclear which autoantibodies associate with increased mortality. In addition, association with different causes of death is thus far unexplored. Both questions were addressed in three early RA populations.

METHODS: 2331 patients with early RA included in Better Anti-Rheumatic Farmaco-Therapy cohort (BARFOT) (n=805), Norfolk Arthritis Register (NOAR) (n=678) and Leiden Early Arthritis Clinic cohort (EAC) (n=848) were studied. The presence of anticitrullinated protein antibodies (ACPA), rheumatoid factor (RF) and anticarbamylated protein (anti-CarP) antibodies was studied in relation to all-cause and cause-specific mortality, obtained from national death registers. Cox proportional hazards regression models (adjusted for age, sex, smoking and inclusion year) were constructed per cohort; data were combined in inverse-weighted meta-analyses.

RESULTS: During 26 300 person-years of observation, 29% of BARFOT patients, 30% of NOAR and 18% of EAC patients died, corresponding to mortality rates of 24.9, 21.0 and 20.8 per 1000 person-years. The HR for all-cause mortality (95% CI) was 1.48 (1.22 to 1.79) for ACPA, 1.47 (1.22 to 1.78) for RF and 1.33 (1.11 to 1.60) for anti-CarP. When including all three antibodies in one model, RF was associated with all-cause mortality independent of other autoantibodies, HR 1.30 (1.04 to 1.63). When subsequently stratifying for death cause, ACPA positivity associated with increased cardiovascular death, HR 1.52 (1.04 to 2.21), and RF with increased neoplasm-related death, HR 1.64 (1.02 to 2.62), and respiratory disease-related death, HR 1.71 (1.01 to 2.88).

CONCLUSIONS: The presence of RF in patients with RA associates with an increased overall mortality rate. Cause-specific mortality rates differed between autoantibodies: ACPA associates with increased cardiovascular death and RF with death related to neoplasm and respiratory disease.