Prognostic modeling in early rheumatoid arthritis: reconsidering the predictive role of disease activity scores

Abstract

Objective: In this prospective cohort study, we provide several prognostic models to predict functional status as measured by the modified Health Assessment Questionnaire (mHAQ). The early adoption of the treat-to-target strategy in this cohort offered a unique opportunity to identify predictive factors using longitudinal data across 20 years.

Methods: A cohort of 397 patients with early RA was used to develop statistical models to predict mHAQ score measured at baseline, 12 months, and 18 months post diagnosis, as well as serially measured mHAQ. Demographic data, clinical measures, autoantibodies, medication use, comorbid conditions, and baseline mHAQ were considered as predictors.

Results: The discriminative performance of models was comparable to previous work, with an area under the receiver operator curve ranging from 0.64 to 0.88. The most consistent predictive variable was baseline mHAQ. Patient-reported outcomes including early morning stiffness, tender joint count (TJC), fatigue, pain, and patient global assessment were positively predictive of a higher mHAQ at baseline and longitudinally, as was the physician global assessment and C-reactive protein. When considering future function, a higher TJC predicted persistent disability while a higher swollen joint count predicted functional improvements with treatment.

Conclusion: In our study of mHAQ prediction in RA patients receiving treat-to-target therapy, patient-reported outcomes were most consistently predictive of function. Patients with high disease activity due predominantly to tenderness scores rather than swelling may benefit from less aggressive treatment escalation and an emphasis on non-pharmacological therapies, allowing for a more personalized approach to treatment. Key Points • Long-term use of the treat-to-target strategy in this patient cohort offers a unique opportunity to develop prognostic models for functional outcomes using extensive longitudinal data. • Patient reported outcomes were more consistent predictors of function than traditional prognostic markers. • Tender joint count and swollen joint count had discordant relationships with future function, adding weight to the possibility that disease activity may better guide treatment when the components are considered separately.

Keywords: Linear regression; Outcome assessment; Patient reported outcome; Precision medicine; Prognosis; Rheumatoid arthritis.

Fig. 1

Median mHAQ per year since initial diagnosis

Fig. 2

Heatmap demonstrating the p value of the correlations between each variable

Fig. 3

Receiver operator characteristic curve for each model including the AUROC, R², and RMSE and their 95% confidence interval. a) GLM to predict baseline mHAQ, b) GLM predicting mHAQ at one year from baseline variables, c) GLM predicting 18-months mHAQ from variables collected at 6-months, d) a LME longitudinal model to predict serially measured mHAQ from variables collected contemporaneously