[Comorbidity in rheumatoid arthritis of early onset. Effects on outcome parameters]

Three-year follow-up data of 1,032 patients with recent onset rheumatoid arthritis (RA) were analyzed regarding the frequency of 21 common comorbid chronic conditions and their impact on health outcome (i.e., pain, functional capacity, disease activity, and radiographic joint damage). Multivariate logistic regression analyses were used to calculate age- and gender-adjusted odds ratios for each chronic condition on severe functional capacity (<60% of full function). Comorbidity was already common at the onset of RA, with 72% of the patients having at least one comorbid condition and almost 50% having at least two. Common comorbidities were associated with significantly worse baseline measures in at least three of seven investigated outcome parameters. The more of these conditions patients had, the worse their 3-year outcome. Functional capacity was most sensitive to comorbid conditions. In logistic regression, obesity, hypercholesterolemia, type II diabetes, and osteoporosis resulted in a twofold risk of severe functional limitation (<60% of full function), independent of each other and of age and gender. The impact of comorbidity on measures of disease severity should be considered when used to compare outcome parameters of different RA samples.