medwireNews: Baseline erythrocyte sedimentation rate (ESR) and DAS28 may be the strongest predictors of disease trajectory in patients with rheumatoid arthritis (RA) that does not respond to conventional DMARD therapy, suggest researchers from South Korea.
Using group-based trajectory modeling, Ji Seon Oh (Asan Medical Center, Seoul) and colleagues identified four distinct RA disease trajectories in their study of 688 patients from the Korean College of Rheumatology Biologics and Targeted Therapy registry who had received second-line treatment with a biologic or targeted synthetic DMARD.
During 4 years of follow-up, the researchers found that patients in group 1 (n=319) experienced a rapid decrease in disease activity, as measured by DAS28, during the first 2 years followed by stable disease at a below-moderate level, whereas those in group 2 (n=36) had a rapid decrease for the first 2 years followed by an increase back to baseline levels during the subsequent 2 years.
Participants in group 3 (n=290) showed a slow but continuous decrease in DAS28 throughout the study period while those in group 4 (n=43) had a sustained level of high disease activity.
Analysis of baseline characteristics showed that smoking status, hemoglobin levels, ESR, and initial DAS28 differed significantly between the groups. Groups 1 and 2 had a lower proportion of current smokers than groups 3 and 4 (3.4 and 2.8 vs 6.9 and 14.0%, respectively), while groups 1, 2, and 3 had higher mean hemoglobin levels than group 4 (12.2, 12.0, and 11.9 vs 11.6 g/dL, respectively).
Mean baseline ESR was lower in group 1 than in groups 2, 3, and 4 (43.0 vs 54.6, 54.5, and 55.6 mm/hour, respectively) and initial DAS28 was lower in groups 1 and 2, on average, than in groups 3 and 4 (5.4 and 5.5 vs 5.9 and 6.1 points, respectively).
There were also treatment differences among the groups, with numerically more patients in group 1 never switching from their initially prescribed biologic or targeted DMARD, at 86.5% versus 52.8%, 50.3%, and 25.6%, respectively.
In addition, the proportion of patients who were prescribed a non-tumor necrosis factor inhibitor as their first treatment was numerically higher in group 1 (44.2%) than in groups 2, 3, and 4 (30.5%, 23.4%, and 18.6%, respectively), while the mean number of biologics or targeted DMARDs prescribed was lower in groups 1, 2, and 3 than in group 4 (1.1, 1.7, and 1.6 versus 2.3, respectively).
Oh and team then used Shapley additive explanations analysis to show that ESR and DAS28 were the strongest contributing factors for each of the trajectories.
“In this study, baseline ESR and DAS28 were the most important features in common for predicting trajectory,” the authors remark in Arthritis Research & Therapy.
They conclude: “Our study suggests that the trajectory-based clustering approach for disease activity may be useful in predicting treatment responses from longitudinal data in real-world practice and making decisions about treatment plans in patients with RA.”
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