Rheumatic diseases are frequently associated with the presence of one or more additional diseases or disorders, called comorbidities. These medical conditions or diseases may represent an active, past, or transient illness that coexist with rheumatic disease. Comorbidities may be either linked to the rheumatic disease process itself, or the consequence of its treatment. Comorbidity is usually defined as co-occurrence of one or more pathogenically related diseases in one patient.
Patients with inflammatory rheumatic disease are at a high risk for developing several comorbid disorders. These conditions may have atypical features and poorer outcomes in comparison to the same diseases in general population. Most important comorbid conditions associated with rheumatic diseases are cardiovascular events (myocardial infarction, stroke), infections, pulmonary diseases, depression and malignant diseases. Data from well-designed cohort studies and long-time follow up registries allowed us to collect important data about comorbidities in Rheumatoid Arthritis (RA), Gout, Systemic Lupus Erythematosus (SLE), ANCA-associated vasculitides and other rheumatic diseases.
Inflammatory rheumatic diseases are associated with increased risk of a cardiovascular disease. Myocardial infarction is usually more silent in patients with RA, having worse outcome compared to patients without such comorbidity. Patients with RA, as well as patients with SLE are at increased risk of nonfatal ischemic heart disease. They have higher mortality due to cardiovascular diseases, compared to age- and sex-matched subjects from the general population. Patients with RA have high prevalence of comorbidities and their risk factors. In COMORA Study the most frequently detected abnormality in patients with RA was elevated blood pressure, while the most frequently identified conditions producing laboratory test abnormalities were hyperglycaemia and hyperlipidaemia. Most frequently associated past or current comorbid conditions in 3920 analyzed patients with Rheumatoid Arthritis were: depression, 15%; asthma, 6.6%; cardiovascular events (myocardial infarction, stroke), 6%; solid malignancies (excluding basal cell carcinoma), 4.5%; and chronic obstructive pulmonary disease, 3.5%. Osteoporotic fractures, significantly associated with functional incapacity, are more common in patients with Rheumatoid Arthritis than in general population. Shortened life expectancy in patients with Rheumatoid Arthritis is usually a consequence of cardiovascular diseases, infections and/or malignant diseases. The burden of cardiovascular comorbidity is also important in gout. Moreover, additional important comorbidities that affect the management of patients with gout are obstructive sleep apnea and metabolic syndrome. Metabolic syndrome, the risk factor for cardiovascular disease, is associated with a pro-inflammatory state and represents an important comorbidity condition in other rheumatic diseases. The prevalence of metabolic syndrome is increased to almost double in ANCA-associated vasculitis versus controls.
Different drugs can influence comorbidity in patients with rheumatic diseases. Treatment with tumor necrosis factor (TNF)-inhibitors leads to about a 50% reduction in the first cardiovascular event in patient with RA. However, treatment with glucocorticoids is associated with an increased risk of cardiovascular events in RA. In randomized controlled trials (RCT) TNF-inhibitors did not increase the risk of solid malignancies, except for non-melanoma skin cancer (risk doubled compared to control treatment). Meta-analysis of registries and long-term extension studies showed no increased risk for total malignancies as well as for non-melanoma skin cancer when comparing TNF-inhibitors and the classical disease modifying anti-rheumatic drugs (DMARDs) treatment.
Comorbidities could influence the effectiveness of treatment of rheumatic diseases, make patient care more complex, increase medical costs, decrease patient's quality of life, contribute to work disability, and be associated with patient's shorter life expectancy. Cardiovascular diseases, pulmonary diseases and malignancies are usually associated with increased mortality, while depression is more commonly associated with work disability in our patients. Therefore, prevention, monitoring and management of comorbidities are of crucial importance for the proper treatment of our patients with rheumatic diseases.
Disclosure of Interest None declared