Background Most studies on cardiovascular mortality in patients with inflammatory rheumatic diseases (IRD) have been performed in clinical cohorts, defining patients with relatively severe disease. Working persons with IRD are thought to have a milder disease activity than persons in the general population with these diseases and consequently levels of cardiovascular co-morbidities could be lower. Along this line, it is unknown to what extent cardiovascular co-morbidities predispose for higher levels of mortality in those persons that remain at work.
Objectives To evaluate the risk to develop cardiovascular diseases in employed individuals with IRD (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis) or gout and to explore the contribution of this co-morbidity on mortality.
Methods Employees from 45 companies in the Netherlands (n=12,140) were followed in a large prospective cohort and completed questionnaires for 10 years (1998-2008). Self-reported rheumatic and cardiovascular diseases were verified in the hospital records for a subsample of patients (50%) to validate and specify the diagnosis. Information on the vital status was obtained through record linkage with the Dutch Municipal Population Registries and cause-specific mortality through the Central Bureau of Statistics. Cox proportional hazard models were used to determine the contribution of rheumatic morbidity and cardiovascular co-morbidity on the 10 year mortality risk, with adjustment for confounding factors. Standardized mortality ratios were calculated to compare the observed mortality with the expected mortality in the general Dutch population.
Results All-cause mortality during follow-up was lower for males (SMR 0.63, 95%>CI: 0.55 to 0.72) and females (SMR 0.22, 95%>CI: 0.16 to 0.30) in this cohort as compared to the general Dutch population. The risk of developing cardiovascular disease over 10 years tended to be higher in workers with prevalent IRD (RR 2.30, 95%>CI: 0.91 to 5.81), as compared to individuals without IRD, and was significantly increased in workers with prevalent gout (RR 3.64, 95%>CI: 1.64 to 8.09), as compared to those without gout. Self-reported rheumatic disease at baseline was not related to mortality (HR 0.77, 95%>CI: 0.41 to 1.46) while mortality was increased for self-reported cardiovascular disease at baseline (HR 1.58, 95%>CI: 1.08 to 2.31), as compared to cohort members without those diseases. No interactions were found between self-reported rheumatic and cardiovascular disease (p>0.05). In the sample verified by clinical review, an increased mortality risk was observed for gout (HR 4.19, 95%>CI: 1.33 to 13.25) and cardiovascular disease (HR 2.19, 95%>CI: 1.24 to 3.84), as compared to individuals without those diseases. There were no deaths observed in those with inflammatory rheumatic diseases.
Conclusions Inflammatory rheumatic disease, especially gout, is associated with cardiovascular co-morbidity in employed individuals. In this study, though, cardiovascular co-morbidity did not result in a higher 10-year mortality risk in persons with inflammatory rheumatic disease.
Gabriel SE, Michaud K. Epidemiological studies in incidence, prevalence, mortality, and comorbidity of the rheumatic diseases. Arthritis Res Ther. 2009;11(3):229.
Disclosure of Interest None Declared