Iron infusions put to the test against stubborn restless legs

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age ≥ 18 years; * Weight ≥ 50 kg; * Drug-resistant RLS; * Severe to very severe RLS (IRLSSG-Q score \> 20), persistent or recurrent for more than one month; * Treatment with dopamine agonists without exceeding the recommended doses (ropinirole ≤ 2 mg/day, pramipexole ≤ 0.54 mg/day, rotigotine ≤ 3 mg/day); * Treatment with dopamine agonists and/or α2δ ligands and/or opioids that has been stable for at least 3 months; * In cases of sleep apnea syndrome, treatment with continuous positive airway pressure (CPAP); * Participants were required to be fluent in spoken and written French, be enrolled in a health insurance plan, agree to the automated processing of anonymized confidential data, and have provided written, informed consent for the study. Exclusion Criteria: * Iron supplementation (oral or intravenous) within 3 months prior to enrollment and throughout the study period * Serum ferritin \< 50 µg/L or \> 300 µg/L; * Transferrin saturation \< 20% or \> 45%; * Hemochromatosis; * RLS augmentation syndrome ; * Treatment with neuroleptics or antidepressants; * Allergy to iron; * Severe infectious or inflammatory disease within the past 3 months; * RLS associated with chronic kidney disease, pregnancy, or a clinically significant neurological or psychiatric disorder; * Severe sleep apnea syndrome (AHI \> 30/h) that is untreated, or in cases where treatment is refused or has failed; * Known allergy, inflammatory, or immune disorder; * History of severe asthma, eczema, or any other atopic allergy; * Pregnancy or breastfeeding; * Also excluded are patients participating in another research study, those deprived of their liberty by judicial or administrative order, those living in a medical facility, those subject to a legal protection order, or those from whom consent could not be obtained.