RESEARCH - Impact of comorbidity on physical function in patients with RA

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Ann Rheum Dis doi:10.1136/ard.2009.118430

Clinical and epidemiological research

Extended report

Impact of comorbidity on physical function in patients with rheumatoid arthritis

Helga Radner, f S Smolen, Aletaha

Division of Rheumatology, Department of Internal Medicine 3, Medical

University of Vienna, Austria

Dr Helga Radner, Division of Rheumatology, Department of Internal

Medicine 3, Medical University Vienna, Waehringer Guertel 18-20, 1090

Vienna, Austria.

Abstract

Background

Physical disability is a main outcome in rheumatoid arthritis (RA)

which tends to increase with comorbidities. However, the extent to

which comorbidities contribute to the multifactorial process of

disability has not been investigated.

Objective

To quantify the contribution of comorbidity to physical disability in

patients with RA.

Methods

In a prospective cohort study, age-adjusted Charlson comorbidity index

(CCIA), serial measurements of disease activity and functional

disability (evaluated by the Health Assessment Questionnaire

Disability Index, HAQ) of 380 patients with established RA seen at an

outpatient clinic over 1 year (June 2007 to July 2008) were

ascertained. The association between comorbidity and physical

disability was assessed using analysis of variance (ANOVA) and

adjusted general linear regression models.

Results

Four patient groups with increasing levels of comorbidity (CCIA 0,

1–2, 3–4 and 5–9; potential range 0–38) were defined. Mean HAQ scores

were significantly different across these groups (0.67, 0.80, 1.24,

1.40, respectively; p<0.001) and also when adjusted for disease

activity, gender and disease duration in the regression model (0.84,

0.88, 1.14, 1.48, respectively; p<0.001). The effects of CCIA on

disability were similar within different strata of disease activity:

namely, remission (0.26, 0.31, 0.48 and 0.88, p<0.01); low disease

activity (0.83, 0.78, 0.98 and 1.36, p<0.01); and moderate to high

disease activity (1.22, 1.33, 1.70 and 1.91, p<0.01), and thus were

independent of disease activity. Several sensitivity analyses,

including the use of the Short Form Health Survey (SF-36), confirmed

these observations.

Conclusion

Physical disability becomes worse with increasing levels of

comorbidity, irrespective of disease activity.

http://ard.bmj.com/content/early/2010/02/03/ard.2009.118430.abstract?papetoc

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