Comorbidity burden and clinical characteristics of patients with difficult-to-control rheumatoid arthritis.

RA patients suffer from a variety of comorbidities. Cardiovascular and respiratory system diseases occur twice as often in difficult-to-control patients. RDCI may provide a valuable tool in evaluating a risk for difficult-to-control RA. Key Points • Hypertension, coronary artery disease and diabetes are the most prevalent comorbidities in rheumatoid arthritis. • Cardiovascular and respiratory tract diseases as well as gastroduodenal ulcers are more common among difficult-to-control patients, when compared with subjects with adequately controlled RA. • Rheumatic Diseases Comorbidity Index is an independent predictor for difficult-to-control RA.