Objective: To investigate the impact of patient age at symptom onset on radiographic joint damage at study entry, and on subsequent progression of damage in a cohort of patients with early seropositive rheumatoid arthritis (RA).
Methods: We studied 186 patients with RA of <15 months' duration. All patients had active disease and had not received disease-modifying antirheumatic drugs. At study entry and during followup, total Sharp scores (TSS), RA-associated joint space narrowing (RA-JSN), and erosions were determined on hand and foot radiographs. Baseline radiographs were also scored for osteoarthritis (OA)-related JSN (OA-JSN) and osteophytes. Older patients (>55 years) and younger patients (</=55 years) were compared by t-test, Mann-Whitney U test, chi-square, or Fisher's exact test. Multiple linear regression models were also constructed.
Results: The older group (n = 74) had a higher baseline total Sharp score (median 6.21) compared with the younger group (n = 112) (median 2.33) (P = 0.0002). This was mainly due to a higher baseline JSN score in the older group (median 3.96 versus 1.08) and not to differences in erosion score (median 0.91 versus 0.70). Disease activity and duration of RA symptoms were similar in the 2 groups, as were progression rates of the TSS, JSN score, and erosion score. At baseline, 26% of patients had osteophytes, with a prevalence of 13% in the younger age group and 50% in the older group. The presence of OA-JSN was highly correlated with the presence of osteophytes (r = 0.72). Also, increased age and RA-JSN were associated with increased severity of osteophytes and OA-JSN at baseline. Multiple linear regression analysis showed that both age and hand osteophytes contributed to the increase in baseline RA-JSN score and TSS, but not to erosion score.
Conclusion: In a cohort of patients with early RA, an increase in the baseline RA-JSN score and TSS can be accounted for in part by the presence of hand OA.