ABSTRACT
X-linked hypophosphatemia (XLH) is a rare genetic phosphate disorder caused mainly by PHEX mutations. Unlike for children, knowledge of the disease's manifestations in adults is limited. Musculoskeletal symptoms are the main feature of the disease in young adults associated with a heavy burden on patients' life. They include fractures and pseudofractures, pain, joint stiffness, osteoarthritis, enthesopathies, and muscle weakness, eventually leading to impaired quality of life. Conventional treatment with phosphate supplements and vitamin D analogs is indicated in symptomatic patients. Appropriate rehabilitation is also a key to the management of the disease to improve physical function and decrease pain, stiffness, and fatigue. Regarding the incidence and consequences of musculoskeletal features in XLH, all patients should be assessed by a bone disease specialist and, if necessary, managed by a multidisciplinary team.
Subject(s)
Familial Hypophosphatemic Rickets/complications , Familial Hypophosphatemic Rickets/therapy , Enthesopathy/etiology , Enthesopathy/physiopathology , Familial Hypophosphatemic Rickets/physiopathology , Humans , Mutation/genetics , Osteoarthritis/etiology , Osteoarthritis/physiopathology , PHEX Phosphate Regulating Neutral Endopeptidase/geneticsABSTRACT
OBJECTIVE: To investigate effectiveness of systematic switching treatment from innovator infliximab to biosimilar infliximab, and its associated factors. METHODS: In this prospective observational study, all adult patients receiving maintenance therapy with innovator infliximab in Cochin University Hospital were systematically switched to biosimilar infliximab. Effectiveness was assessed by the retention rate of biosimilar infliximab at the time of the third infusion. Sensitivity analyses for effectiveness included changes of disease activity parameters and infliximab trough levels between baseline and the last visit as well as the occurrence of adverse events leading to drug discontinuation. Factors associated with biosimilar infliximab discontinuation at the last visit were explored. RESULTS: A total of 260 patients fulfilled the inclusion criteria, including 31 rheumatoid arthritis (RA), 131 axial spondyloarthritis (axSpA) and 64 inflammatory bowel diseases. The retention rate was 85% (221/260 patients) at the time of the third biosimilar infusion. Between baseline and the last visit (mean follow-up of 34 weeks), 59 patients (23%) discontinued biosimilar infliximab, mainly due to experienced inefficacy (n = 47, 80%). No clinical or biological factors were associated with biosimilar discontinuation. No serious adverse events occurred. No change in objective disease activity parameters or infliximab trough levels was detected. However, a significant increase of BASDAI (2.94 ± 2.20 vs. 3.18 ± 2.21, P = 0.046, before vs. after switch, respectively) was observed in patients with axSpA. Innovator infliximab was re-established in 47/59 patients (80%). CONCLUSION: No changes in drug trough levels or objective parameters were observed after the systematic switch to biosimilar infliximab in a real clinical practice setting. Only changes in patient-reported outcomes were observed, suggesting attribution effects rather than pharmacological differences.
