RT Journal Article
SR Electronic
T1 Misclassification of disease activity when assessing individual patients with early rheumatoid arthritis using disease activity indices that do not include joints of feet
JF Annals of the Rheumatic Diseases
JO Ann Rheum Dis
FD BMJ Publishing Group Ltd and European League Against Rheumatism
SP 830
OP 835
DO 10.1136/annrheumdis-2011-146670
VO 71
IS 6
A1 Bakker, Marije F
A1 Jacobs, Johannes WG
A1 Kruize, Aike A
A1 van der Veen, Maaike J
A1 van Booma-Frankfort, Catharina
A1 Vreugdenhil, Simone A
A1 Bijlsma, Johannes WJ
A1 Lafeber, Floris PJG
A1 Welsing, Paco MJ
YR 2012
UL http://ard.bmj.com/content/71/6/830.abstract
AB Objective To study whether assessment of rheumatoid arthritis (RA) disease activity in individual patients using the disease activity score in 28 joints (DAS28) or other instruments excluding joints of feet may lead to misclassification of disease activity. Methods A cohort of RA patients was classified into three ‘regional radiographic damage progression’ groups: predominantly progression in feet, similar progression in hands and feet and predominantly progression in hands; both in early (0–2 years) and later (2–5 years) disease. Baseline and mean DAS28, individual DAS28 variables and tender joint counts (TJC) and swollen joint counts (SJC) of the feet were compared between groups. The longitudinal relation of DAS28 with radiographic damage was investigated using a mixed model analysis with rheumatoid factor status, baseline joint damage and TJC and SJC of the feet as covariates. Results Early (n=265) and later (n=200) in the disease course, by definition, the classification procedure resulted in 25% as predominantly foot, 25% as predominantly hand and 50% as similar progressors. In early RA predominantly foot progressors had higher TJC and SJC of the feet compared with predominantly hand progressors (p<0.001), but DAS28 was similar. This was not seen in later disease. The longitudinal relation between DAS28 and radiographic progression was influenced by the region of progression (predominantly foot progressors vs others, p<0.001), suggesting that DAS28 underestimates disease activity in predominantly foot progressors. In this group, joint counts for the feet were independently related to radiographic progression. Conclusions DAS28 underestimates actual disease activity and expected joint damage of individual early RA patients predominantly with disease in the feet.