Rheumatoid factor positivity increases all-cause and cancer mortality: a cohort study

The aim of this study was to determine whether rheumatoid factor (RF) is associated with mortality from all-cause, cardiovascular disease (CVD), and cancer in the healthy adults. We recruited South Korean health check-up examinees without rheumatoid arthritis (RA). A cohort study was performed in 295,837 participants presumably free of osteoarthritis or RA, and who had undergone health screening between 2002 and 2012 and been followed up to determine the risk of all-cause, CVD, and cancer-specific mortality with respect to the presence or titer of RF. To determine whether the participants were deceased, we used National Death Index death certificates. The prevalence of RF positivity (≥20 IU/mL) was 4.4%. During 1,447,403 person-years of follow-up, 1402 participants died. Comparing subjects negative for RF with those positive for RF, the multivariable adjusted hazard ratio (HR; 95% CI) for all-cause and cancer mortality in subjects with RF-positivity was 1.50 (1.19–1.90) and 1.56 (1.12–2.16), respectively. Also, all-cause and cancer mortality risk was significantly greater in subjects with an RF titer greater than 100 IU/mL than in those with RF-negativity (HR = 2.68, 95% CI = 1.72–4.19; HR = 2.89, 95% CI = 1.58–5.28, respectively) after adjusting for multiple confounders. However, the HR for cardiovascular mortality was not higher in subjects with RF positivity than in those with RF negativity (HR = 0.98, 95% CI = 0.45–2.11). In Korean healthy adults, presumably without RA, RF was associated with a greater risk of all-cause and cancer mortality.