Switching From Intravenous to Subcutaneous Immunoglobulin Maintenance Treatment in Chronic Inflammatory Demyelinating...

Subcutaneous immunoglobulin (SCIg) is an alternative maintenance therapy to intravenous immunoglobulin (IVIg) in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The CIDP guideline considers switching from IVIg to SCIg at an equivalent dosage reasonable; however, the optimal dosing strategy is unknown. This case series examines whether a 1:1 IVIg-to-SCIg switch maintains clinical stability.

IVIg-dependent, clinically stable CIDP patients who switched from IVIg to SCIg in the Erasmus Medical Center were retrospectively evaluated. Clinical deterioration was defined as a decline in grip strength or muscle strength, or an increase in disability based on minimal clinically important difference criteria within 4 months after the switch.

A total of 10 consecutive CIDP patients on stable IVIg regimens switched to an equivalent (1:1) SCIg dose. One patient remained clinically stable, while nine patients deteriorated. Three of these became clinically stable after increasing the SCIg dose to 1:1.3 or 1:1.5, whereas three patients did not regain stability despite a dose increase to 1:1.3. Clinical stability was maintained in the patient receiving a low dose (0.4 g/kg every 3 weeks), whereas patients receiving higher doses (≥ 1 g/kg every 3 weeks) deteriorated. Five patients switched back to IVIg, while five remained on SCIg throughout follow-up.

A 1:1 IVIg-to-SCIg switch was insufficient to maintain clinical stability in most CIDP patients, including those on higher IVIg maintenance doses. Some but not all patients regained stability after increasing the SCIg dose. Optimal dose adjustment strategies, including whether temporary higher dosing is required, remain to be determined in future studies.