Treatment of patients with multifocal motor neuropathy with immunoglobulins in clinical practice: the SIGNS registry

Abstract

Objectives: The management of patients with multifocal motor neuropathy (MMN) under everyday clinical conditions has been insufficiently studied. We therefore collected comprehensive observational data on patients with MMN who received intravenous (IV) or subcutaneous (SC) immunoglobulins (IGs) as maintenance therapy.

Methods: This was a prospective, noninterventional study (registry) in neurological centres (hospitals and offices) throughout Germany.

Results: As of 1 December 2015, 80 patients with MMN were included (mean age 55.4 ± 9.8 years, 67% males, mean disease duration 10.7 ± 10.2 years). The affected limb regions were predominantly distal muscle groups of the upper extremities. On the inflammatory neuropathy cause and treatment (INCAT) scale, 94% of the patients had some disability in the arms and 61% in the legs. At inclusion, 98.8% received IVIG and 1.3% SCIG. Substantial variation was observed between IVIG treatment intervals (every 0.7 to 17.3 weeks) and dosage (0.2-2.1 g/kg body weight received during a single administration; mean monthly dosage, 0.9 g/kg body weight). However, the mean monthly dosage was steady over time. At 1-year follow up, improvement was seen in muscle strength, INCAT and quality of life (QoL) scores (SF-36 questionnaire).

Conclusions: The management of patients with MMN in everyday clinical practice demonstrates a wide range of absolute dosages and treatment intervals of IG, supporting the recommended practice of determining treatment dose on an individual patient basis. The improvements in muscle strength and reduction in disability, accompanied by increased QoL, strengthen the case for use of IG as a maintenance treatment for MMN.

Keywords: autoimmune disease; disability; neuroimmunology; neurology; observational; patient-related outcomes; quality of life; routine care; therapy.

Figure 1.

Muscle strength according to Medical Research Council (MRC) criteria. BL, baseline.

Figure 2.

Degree of disability on the INCAT scale in MMN patients documented in SIGNS. INCAT, inflammatory neuropathy cause and treatment. Arm disability 0 No upper limb problems 1 Symptoms, in one or both arms, not affecting the ability to perform any of the following functions: doing all zips and buttons; washing or brushing hair; using a knife and fork together; handling small coins 2 Symptoms, in one arm or both arms, affecting but not preventing any of the abovementioned functions 3 Symptoms, in one arm or both arms, preventing one or two of the abovementioned functions 4 Symptoms, in one arm or both arms, preventing three or all of the functions listed, but some purposeful movements still possible 5 Inability to use either arm for any purposeful movement Leg disability 0 Walking not affected 1 Walking affected, but walks independently outdoors 2 Usually uses unilateral support (stick, single crutch, one arm) to walk outdoors 3 Usually uses bilateral support (sticks, crutches, frame, two arms) to walk outdoors 4 Usually uses wheelchair to travel outdoors, but able to stand and walk a few steps with help 5 Restricted to wheelchair, unable to stand and walk a few steps with help Source: Merkies et al. [2002].

Figure 3.

IV Dosing of intravenous immunoglobulin (IVIG) preparations in patients with MMN at baseline and at follow up. (a) Per patient. IVIG, intravenous immunoglobulin; BW, body weight. Each line represents an individual patient. (b) In dosage categories. IVIG dosage at inclusion: 0.9 ± 0.7 g/kg BW/4 weeks, range 0.1–2.9, median 0.6 [interquartile range (IQR), 0.3–1.3]. IVIG dosage at 1 year: MMN: 0.9 ± 0.7 g/kg BW/4 weeks, range 0.1–3.0, median 0.6 (IQR, 0.4–1.3). MMN, multifocal motor neuropathy; IQR, interquartile range.

Figure 4.

Dosing changes at 1-year follow up compared with at inclusion. Values are %.

Figure 5.

Quality of life in Short Form-36 at the time of inclusion. Higher values indicate better status, range [0–100]. Norm control from German representative sample for normative comparison.

Figure 6.

Global health as measured with the Short Form-36. (a) At baseline: ‘In general, would you say your health is?’. For comparison, values derived from the German population for this question are displayed [Morfeld et al. 2005]. For the German version of the SF-36, translation of this question deviates from the original English version; shown here are back-translated German answer categories. (b) At follow up: ‘Compared with one year ago, how would you rate your health in general now?’. Values are %.