Plain language summary: gout remission with pegloticase

What is this summary about? Gout is a painful inflammatory form of arthritis that happens when urate levels build up in the blood for a long time. This causes urate crystals to form in the joints, tendons, and soft tissues, causing swelling and pain. Some patients have "uncontrolled gout" when conventional, oral medications do not work well or cause side effects. Pegloticase is an intravenously administered treatment for uncontrolled gout. It uses a modified enzyme to change urate into a substance called allantoin, which the body can easily remove via the kidneys. Patients take pegloticase with a medicine called methotrexate, which prevents their immune systems from making pegloticase ineffective. The MIRROR study investigated how well pegloticase worked with and without methotrexate in treating uncontrolled gout and how safe it was when used for a year. Afterward, the number of patients who went into remission, meaning their gout was well controlled, was investigated. There were two definitions of remission: one was more complex with six criteria and the other was simpler with three criteria. After 1 year of pegloticase treatment, 43% of patients met the complex definition and 70% met the simpler definition. These results show that pegloticase helped many people with long-term uncontrolled gout reach remission. The results also show that the simpler definition of uncontrolled gout is a practical way for doctors to see how well treatments work in managing uncontrolled gout. What were the results? Using the six-criteria remission definition (adapted from de Lautour 2016), 43% of included patients achieved gout remission after 52 weeks of pegloticase treatment. Using the three-criteria remission definition (adapted from G-CAN), 70% of included patients achieved gout remission after 52 weeks of pegloticase treatment. What do the results mean? All patients in the MIRROR RCT had uncontrolled gout, and patients had experienced gout for an average of approximately 14 years. These analyses showed that lowering serum urate levels with pegloticase for 12 months put gout into remission in a large proportion of these patients with hard-to-treat disease. Importantly, these findings indicate that the simplified criteria adapted from the G-CAN definition were practical to use in routine clinical care and could be used to see how well treatment is working in patients with uncontrolled gout.