The At-Home ULTRA Study will evaluate performance of the MINI system as indicated for the treatment of adults with active, moderate to severe rheumatoid arthritis who are inadequate responders or are intolerant to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), biologic DMARDs (bDMARDs), or targeted synthetic DMARDs (tsDMARDs). The non-invasive study device delivers ultrasound stimulation to the spleen to reduce inflammation. The study will enroll at least 60 participants at up to 8 sites. There will be three arms consisting of two active stimulation groups (treatment) and one non-active stimulation group (sham-control). After completing the double-blinded primary endpoint assessment period at Week 12, there will be a one-way crossover of control participants to active stimulation and an additional 12 week follow-up with all participants to evaluate long-term outcomes.

Inclusion Criteria:

1. Males and females ages 18 and above
2. Active moderate to severe seropositive RA
3. At least 6 total tender and/or swollen joints counted on a 28 joint assessment during screening and at Week 0 (a joint that is both tender and swollen will be counted as "2")
4. Demonstrated an inadequate response to, or loss of response to standard csDMARD treatment (e.g., methotrexate) or up to three total bDMARDs and tsDMARDs
5. Receiving stable background treatment with a csDMARD prior to start of the treatment period at Week 0. Methotrexate (if chosen as background treatment) must be maintained at a stable dose for at least 4 weeks prior to Week 0, while all other csDMARDs (if chosen as background treatment) must be maintained at a stable dose for at least 8 weeks prior to Week 0. Participants must be willing to maintain their background medication regimen throughout the 28-week study period.
6. For participants that have previously undergone treatment with bDMARDs or tsDMARDs therapy, those treatments must be discontinued at least 4 weeks prior to start of the treatment period at Week 0 and may not be resumed until after the Week 24 Closeout Visit
7. For participants that have previously undergone treatment with Golimumab or Infliximab, those treatments must be discontinued at least 8 weeks prior to start of the treatment period at Week 0 and may not be resumed until after the Week 24 Closeout Visit
8. Participants may receive up to 10 mg of daily prednisone as part of their background treatment but must have maintained a stable dose for a minimum of 6 weeks prior to start of the treatment period at Week 0, and must be willing to maintain the stable dose until after the Week 24 Closeout Visit
9. Torso circumference at the belly button and sternum level must both be in the range of 25 to 50 inches
10. Participants with an immunomodulation device must be willing and able to turn the device off at least 4 weeks prior to start of the treatment period at Week 0 and may not be resumed until after the Week 24 Closeout Visit
11. Participants must be willing not to initiate any new treatments with expected immune modulating effects during the study period, and any existing immune modulating treatments must be stabilized by Week 0
12. Participants must be willing and able to follow the medication rules described in the study's IRB-approved Medication Guide

Exclusion Criteria:

1. Active bacterial or viral infection
2. Pregnant women or those trying to become pregnant
3. Receiving active chemotherapy or immunotherapy to treat malignancy within 30 days prior to enrollment
4. Having received more than a total of three bDMARDs and tsDMARDs
5. Having received Rituximab monoclonal antibody medication
6. Presence of an implanted device or other solid object in the vicinity of the spleen that can interfere with or absorb the ultrasound beam
7. History of asplenia
8. History of splenomegaly
9. History of ascites
10. Recent abdominal surgery
11. Currently participating in an investigational drug or device study
12. Open wound/sores that would make performing study procedures too difficult
13. Inability to perform minimal daily self-cares associated with feeding or dressing, such as lifting a cup of water to the mouth or putting on clothing.
14. Refusal or inability to regularly attend the scheduled on-site visits and at-home visits, or perform the remote video observation sessions
15. Cannot speak English
16. Any other clinical reasons deemed by the investigators of the study in which the patient would not be an appropriate candidate for the study

All subjects, investigators, joint evaluators and outcome assessors will be blinded. Blinding of subjects will be assessed at Week 12.