A case study published in Cureus reported on the efficacy of pegloticase (PEG) treatment in a 62-year-old male diagnosed with refractory polyarticular gout. The patient presented to the rheumatology office for chronic joint pain evaluation, mainly in the hands, knees, ankles, and feet. The severity of foot and ankle pain resulted in difficulty walking most days, and the patient described the pain as “constant, sharp, severe at times, and worse in the morning.” Laboratory testing and magnetic resonance imaging scans of the feet showed periarticular osteopenia and periarticular erosions of the metatarsophalangeal and interphalangeal joints, being described as consistent with seronegative rheumatoid arthritis, according to the attending radiologist. However, a dual-energy CT (DECT) scan was performed after the patient presented with markedly elevated uric acid levels. Scans showed extensive monosodium urate (MSU) crystal deposition in the feet and ankles, consistent with advanced polyarticular gout.
Due to the severity of the patient’s gout, PEG treatment was touted as the primary course of treatment. However, due to an inability to obtain insurance approval in a timely manner, the patient was started on allopurinol (titrated up to 700 mg per day) until his serum acid rate reached a target level of <5 mg/dl. The patient failed to achieve target uric acid level; therefore, allopurinol was stopped and febuxostat (titrated up to 80 mg per day) was prescribed. Again, the patient failed to achieve target acid levels and his symptoms worsened.
At this point, insurance approval was obtained to initiate PEG therapy. In order to decrease the risk of developing anti-pegloticase antibodies, 15 mg per week of methotrexate was prescribed prior to initiation of PEG therapy. As febuxostat was discontinued and PEG therapy was initiated, the patient’s uric acid level became undetectable and remained so throughout the course of treatment (uric acid <0.2 mg/dL).
In addition to PEG therapy, the patient was prescribed 0.6 mg of colchicine and 2.5mg of prednisone per day. The patient demonstrated significantly improved joint pain and stiffness within 2 months of beginning PEG therapy. After 11 months, a repeat DECT scan of the feet and ankles showed a marked decrease of the MSU crystal deposition with persistent erosive changes.
Chronic gouty arthritis can be difficult to diagnose; it can be easy to overlook symptoms and misdiagnose patients with other types of inflammatory diseases. The reported case represents some of the challenges that healthcare providers. It also highlights the benefits of DECT scanning in diagnosing gout and assessing the MSU crystal burden. PEG acted as an effective therapy for this patient’s refractory polyarticular gout.
The authors of the case report emphasized that “Unless contraindicated, it should be used concomitantly with immunosuppressive therapy (methotrexate in our case) to decrease the likelihood of developing anti-pegloticase antibodies.”
