PRECISE is an open-label, single arm, single-center site study to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of dosing interval-optimized etanercept in obese patients with Rheumatoid Arthritis (RA) and Juvenile Idiopathic Arthritis (JIA). Approximately 30 patients with JIA or RA who are starting etanercept standard-of-care will take part in the study.~Eligible patients will have blood collections before and after starting the biologic of interest to assess PK and disease activity. Five (5) blood samples will be collected through a combination of clinic and home visits.
The purpose of this study is to learn more about how adult and children's bodies use etanercept and how bodyweight influences how well etanercept works. This study will help us understand the proper dose of etanercept in obese children and adults.