Markers of inflammation have recently been shown to be predictive of cardiovascular disease (CVD). Furthermore, the excess mortality in rheumatoid arthritis (RA), a disease characterized by chronic polyarthritis, is chiefly due to death from CVD. With this background, we studied the effect of inflammation, as reflected by the number of joints with soft tissue swelling, and rheumatoid factor (RF) seropositivity on CVD-related mortality.
Mortality rates and rate ratios for all-cause and CVD-related deaths were computed in a longitudinal, population-based cohort of Pima Indians in Arizona from 1965 through 1994. Repeated health examinations were performed, involving systematic assessment of the features of RA, cardiovascular risk factors, serum titers of RF, as well as mortality. The cohort comprised 4,120 subjects (1,861 men, 2,259 women) who were examined an average of 3.5 times during a mean followup of 14 years.
During the followup period, 182 CVD-related deaths ocurred. The age- and sex-adjusted CVD-related mortality rates increased significantly with the presence of a higher number of joints with soft tissue swelling (Ptrend = 0.04), and were 2.07 (95% confidence interval [95% CI] 1.30-3.31) times as high in those subjects who had 2 or more swollen joints as in those who had none. There were no significant additional effects on CVD-related mortality when seropositivity for RF or a previous diagnosis of RA were considered. In age- and sex-adjusted proportional hazards analyses, which were controlled for possible confounders, the effect of swollen joints remained significant (mortality rate ratio 1.33, 95% CI 1.04-1.71 per category increase [no swollen joints, 1 swollen joint, at least 2 swollen joints]).
Joint swelling is a significant risk factor for CVD-related death, independent of other known risk factors including a diagnosis of RA. This finding supports the hypothesis that inflammatory mechanisms are important for the development of CVD.