This study aims to provide preliminary evidence of the validity of a sensor-based assessment of rheumatoid arthritis (RA) symptoms, and to collect structured qualitative feedback from RA Enbrel patients regarding the potential of a future biosensor/PRO mHealth application. The investigators' overarching hypothesis is that if patients have better and more timely information about whether Enbrel is working, then they will become more empowered and engaged in their treatment, more curious about how it may - or may not - be working, and potentially more compliant with therapy. However, this hypothesis remains largely untested.

Patients with rheumatoid arthritis (RA) often endure a remitting and flaring disease-course characterized by considerable pain, stiffness, and fatigue. The social and emotional well-being of RA patients can suffer as a result. Data demonstrate that adherence to Enbrel significantly improves both functional status and health related quality of life (HRQOL) in RA patients. Yet patients prescribed Enbrel often exhibit non-adherence through early discontinuation, dose-stretching, and reduced persistence following medication "holidays". The knowledge, attitudes, and beliefs held by patients with regard to RA and Enbrel influence their perceptions of the benefits of, and barriers to, treatment.

Decisions to adhere occur when combined levels of susceptibility and severity provide the motivation to act, and the perception of benefits (less barriers) indicates a path of action. A given patient's ability to follow this path of action hinges on their relative self-efficacy: the conviction that they can successfully execute a behavior required to produce an expected outcome. Landscape literature reviews conducted by CORE-UCLA suggest that interventions targeting self-efficacy offer the greatest chance of improving adherence to Enbrel. Self-efficacy plays an important mediating role in self-management activities, allowing for the adoption and maintenance of health behaviors. Many studies have identified measures of self-efficacy as significant predictors of adherence in RA patients. Additionally - though with the caveat that they are methodologically heterogeneous and of limited generalizability - a number of studies have found that interventions targeting self-efficacy can significantly improve adherence related outcomes. Seminal works in the field - including Bandura's Social Cognition Theory and Rosenstock's Health Beliefs Model - have converged on the following recommendations for behavioral interventions targeting self-efficacy:

1. Identify and reinforce the patient's past and present successes or accomplishments.
2. Direct patients to observe successful behaviors and coping mechanisms of similar others, even if this involves having them alter or expand their social network.
3. Provide positive feedback for the patient's efforts or encourage people in the patient's social network, such as family members or friends, to do this.
4. Facilitate the patient in adopting new health behaviors by ensuring that patients do not interpret incorrectly how they are feeling.

Enabled by recent advances in microelectronics, signal processing algorithms, and networking capabilities, wireless health technologies hold the potential to support numerous aspects of these recommendations. Namely, motion sensors might contribute to the formation of a complete feedback loop involving self- monitoring, data presentation, and tailored messaging. Consumer Health Informatics (CHI) applications that offer complete feedback loops hold the most promise for improving self-efficacy.

Inclusion Criteria:

• Enbrel users between week -2 and week 5 of therapy, inclusive.
• Current active prescription for Enbrel with intent to use.
• 21 years or older.
• English speaking
• Have an understanding, ability, and willingness to fully comply with study procedures and restrictions.

Exclusion Criteria:

• Allergic to latex or dry natural rubber
• Using a pacemaker, implantable cardiac defibrillator, neurostimulator, hearing aids, cochlear implants or other electronic medical equipment.

Patients with rheumatoid arthritis who are candidates to undergo treatment with the drug etanercept.