The course of rheumatoid arthritis (RA) is variable, with outcomes dependent upon the degree of joint damage, the physical functional status of the patient, psychological health, and the presence of comorbid illness such as cardiovascular disease, infection, and B-cell lymphomas. Loss of functional capacity in RA occurs as a result of the summation of loss of function in individual joints. Individual joint function is affected by the severity of disease activity and the structural integrity of the joint.

In a study published in the Journal of Rheumatology, van den Hoek and colleagues describe that patients with RA and specific comorbid conditions have an increased risk of long-term low functional outcomes.   Their Dutch longitudinal study was conducted over 11 years and included 882 patients with diagnosed RA.  Baseline questionnaires included the Health Assessment Questionnaire (HAQ) on 20 chronic diseases, the generic Medical Outcomes Study Short Form-36 (SF-36), and the Center for Epidemiologic Depression Scale.

The researchers found that patients with RA and circulatory conditions or depression had higher HAQ scores and worse physical functioning than those without comorbid conditions.  Worse physical functioning was also noted in patients with RA and concomitant respiratory, musculoskeletal, or neoplastic disease.  Comorbid respiratory disease was also associated with worse mental functioning in patients with RA.

Limitations of the study included the single-population design and that osteoporosis, a common comorbid condition in patients with RA, was not specific in the National Health Interview Survey and not mentioned in the study.

Summary and Clinical Applicability

Patients with RA have an increased prevalence of other serious illness. Specific comorbid conditions are associated with worse long-term physical and mental performance in patients with RA.  By knowing which diseases appear to most negatively affect long-term loss of function, physicians can be better equipped to address them and thereby improve quality of life for their patients.

Reference

van den Hoek J, Roorda L, Boshuizen H, Tijhuis G, van den Bos G, Dekker J.  Physical and mental functioning in patients with established rheumatoid arthritis over an 11-year follow-up period: the role of specific comorbidities. J Rheumatol. 2016; Jan 15. pii: jrheum.150536. [Epub ahead of print]