A new prediction score was developed to identify remission at 24 weeks after the initialization of tocilizumab monotherapy in patients with rheumatoid arthritis (RA), according to study results published in ACR Open Rheumatology.

According to the study researchers, better prediction tools are needed in RA to help patients and clinicians make informed treatment decisions about drugs that may achieve remission. Many patients with RA receive biologic disease-modifying antirheumatic drugs (DMARDs) with methotrexate; however, tocilizumab has been shown to be effective with or without methotrexate in achieving remission.

The objective of this study was to develop and validate a prediction model and associated remission score to determine the patients with RA who were most likely to achieve remission with tocilizumab monotherapy.

Researchers identified 4 randomized controlled trials among patients with RA and included the tocilizumab monotherapy arm from each trial. Two studies were chosen for derivation, and 2 for internal validation. The primary outcome was disease remission, defined as a Clinical Disease Activity Index (CDAI) score of <2.8 at 24 weeks after randomization. Logistic regression was used to evaluate the association between remission and potential predictors, which included age, sex, race, geographic location, and body mass index. Researchers assessed model performance in the validation data set after choosing variables and assessing model performance in the derivation data set, then combined cohorts to calculate a remission prediction score.

A total of 1019 patients were enrolled in the tocilizumab monotherapy arm across the 4 trials; however, primary analysis included 853 patients (median age, 53 years; 80% women; 80% white) with complete data. At baseline, the median Health Assessment Questionnaire Disability Index score was 1.6, with median CDAI score of 40.1 and median disease duration of 21 months. In the derivation data set, increased odds of remission were associated with patient characteristics including location of Europe and South America, no history of DMARD or methotrexate use, shorter disease duration, higher hematocrit levels, no cardiovascular disease, and diabetes. 

After choosing predictors in the derivation data set, researchers ran the selected models in the validation data set. The area under the receiver operating characteristic curve was 0.739 in the derivation data set and 0.728 in the validation data set. Patients were then categorized into 3 distinct remission prediction categories based on the remission prediction score: 40% in the low (<10% probability of remission), 45% in the intermediate (10%-25% probability), and 15% in the moderate (>25% probability) remission prediction category.

Study limitations included potentially important predictors, including smoking history and rheumatoid factor that were not consistently collected across all 4 trials and were not included in the analysis, and the fact that only 1 trial included patients with early RA, and different predictors may be associated with these patients. 

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Study researchers concluded that remission prediction score may help predict remission of RA at 24 weeks after starting tocilizumab monotherapy. “These results may provide guidance to clinicians tailoring treatment options based on clinical characteristics,” they wrote.

Disclosure: This clinical trial was supported by Genentech. Please see the original reference for a full list of authors’ disclosures.

Reference

Collins JE, Johansson FD, Gale S, et al. Predicting remission among patients with rheumatoid arthritis starting tocilizumab monotherapy: model derivation and remission score development [published online January 1, 2020]. ACR Open Rheumatol. doi:10.1002/acr2.11101