The term uSAID means “undifferentiated autoinflammatory disease”. It is also called undiagnosed or unclassified or it simply means systemic autoinflammatory disorders of undefined etiology. These are usually patients with negative genetics results, and from the clinical symptoms, it’s not clear if they have FMF, CAPS, TRAPS, HIDS, etc. Also, they don’t really fulfil the clinical criteria for diagnosis into one of these conditions. However, being identified with some sort of systemic autoinflammatory disease or periodic fever syndrome, they should be able to receive treatment like any of the others. Some of these cases will respond to colchicine but if they don’t, they will eventually have to be put on biologics.
Doctors are also starting to realise that many of these patients, despite having negative genetic results, often suffer from overlapping conditions. Sometimes patients suffer from two autoinflammatory diseases (CAPS & TRAPS, TRAPS & Bechet’s, FMF & TRAPS, etc) or maybe even from autoinflammatory and autoimmune diseases, making the diagnosis even more challenging.
1) Anakinra as a diagnostic challenge and treatment option for systemic autoinflammatory disorders of undefined etiology. https://insight.jci.org/articles/view/86336
2) Preclinical characterization and clinical development of ILARIS® (canakinumab) for the treatment of autoinflammatory diseases
3) Current Therapeutic Options for the Main Monogenic Autoinflammatory Diseases and PFAPA Syndrome: Evidence-Based Approach and Proposal of a Practical Guide
4) Colchicine: an effective treatment option for unclassified autoinflammatory diseases in children https://ard.bmj.com/content/77/Suppl_2/509.1.abstract