Predictors of functional status in patients with early rheumatoid arthritis

Abstract

Objective: To find disease parameters that can predict the functional capacity of patients with early rheumatoid arthritis (RA) at the first visit to the rheumatologist and one year after entry.

Methods: Patients referred to the outpatients clinic between 1995 and 1996, with a symptom duration of less than three years and fulfilling the American Rheumatism Association 1987 revised criteria for RA within one year after entry were included. Assessments of the duration of morning stiffness, the Disease Activity Score (DAS: a composite score based on erythrocyte sedimentation rate (ESR), number of painful and swollen joints and patient global assessment), pain (Visual Analogue Scale), the Arthritis Impact Measurement Scale (AIMS) and the Health Assessment Questionnaire (HAQ) were performed every three months. Possible predictors of the HAQ at entry and after one year were analysed by logistic regression.

Results: 133 patients were included in the study. The median duration of complaints was three months (range 0-35) and the median HAQ score at entry was 1.12 (range 0-3). There was no correlation between duration of complaints and the HAQ at entry (r = 0.01). An HAQ score under the 50th percentile at entry could be predicted correctly for 74% of the patients by entry DAS and C reactive protein concentration, and at one year could be predicted correctly for 73% of the patients by entry HAQ and pain score.

Conclusion: Disease activity is strongly correlated with a lower functional capacity at entry, whereas disease duration is not. The functional status at entry is a good predictor for functional status at one year. Severity rather than duration of arthritis prompts referral in this cohort.

Figure 1

Change of mean HAQ and DAS scores between entry and one year: comparison of the less disabled versus more disabled group partitioned by HAQ 50th percentile at one year.