A study of baseline prevalence and cumulative incidence of comorbidity and extra-articular manifestations in RA and their impact on outcome

Objectives. To study the prevalence at diagnosis and cumulative incidence of comorbidity in RA, associations with clinical features and impact on outcome. Methods. Standard clinical, laboratory and radiological measures of RA, and details of comorbidity and extra-articular features were recorded at baseline and yearly in an inception cohort of 1460 patients with recently diagnosed RA from nine regions in the UK. The General Practice Research Database was used to compare the incidence of common comorbid conditions (International Classification for Disease-10 codes). Results. Baseline prevalence was 31.6% and 8.6% for all comorbidities and extra-articular features, respectively, and 15-year cumulative incidence was 81% and 53%, respectively. Rates of hypertension [standardized incidence ratio (SIR) = 1.61; 95% CI 1.43, 1.79] and ischaemic heart disease (SIR = 1.60; 95% CI 1.35, 1.84) were raised compared with figures for the general population, as was stroke in females (SIR = 1.34; 95% CI 1.02, 1.77) and chronic obstructive pulmonary disorder in males (SIR = 1.63; 95% CI 1.17, 2.26). Comorbidity was associated with risk of both all-cause and cardiovascular mortality (hazard ratio = 1.09; 95% CI 1.02, 1.17) and increased rates of functional decline over 10 years (b = 0.011; 95% CI 0.004, 0.019). Comorbidity was not related to disease activity or structural damage. Conclusion. Significant comorbidity was present at the outset of RA, increasing with follow-up, mainly in cardiovascular, non-cardiac vascular and respiratory systems. Specific conditions (e.g. hypertension) occurred more frequently than in the general population. Comorbidity was related to mortality and functional decline, and more intensive therapies may need consideration in these patients. As many co-existent conditions are amenable to preventative/therapeutic measures, comorbidity needs earlier detection and management in order to reduce its impact on outcome in RA.