Quantifying Treatment-Related Fluctuations in CIDP

Abstract

ObjectiveThe objective of this study was to explore the extent of IV immunoglobulin (IVIG) treatment-related fluctuations (TRFs) by using home collection of daily grip strength in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and to use that information to develop evidence-based treatment optimization strategies.MethodsThis prospective observational study included 25 patients with well-defined CIDP. Participants recorded grip strength daily for 6 months. Disability and gait metrics were collected weekly. Serum immunoglobulin G levels were obtained at peak, trough, and midcycle IVIG intervals. Day-to-day grip strength changes <10% were considered random. To identify patients with TRFs, 3-day averaged grip strength was calculated on each consecutive day after an IVIG infusion. TRFs were defined as ≥10% 3-day averaged grip strength difference compared to the pre-IVIG baseline.ResultsParticipants successfully recorded grip strength on all but 9% of recordable days. Twelve patients (48%) were classified as low/no fluctuaters and 13 (52%) as frequent fluctuaters. In the frequent fluctuating group, grip strength improved over 1 week and thereafter was relatively stable until the third week after infusion. Grip strength was significantly correlated with measures of disability.ConclusionsGrip strength collection by patients at home is reliable, valid, and feasible. A change in grip strength by ≥10% is a useful, practical, and evidence-based approach that may be used to identify clinically meaningful TRFs. From these data, we propose a treatment optimization strategy for patients with CIDP on chronic IVIG that may be applied to routine clinic care during both face-to-face and virtual video or telephone patient encounters.Trial Registration InformationClinicalTrials.gov Identifier: NCT02414490.

European Academy of Neurology/Peripheral Nerve Society guideline on diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy: Report of a joint Task Force—Second revision

“…Some examples of disability and impairment scales are given: Disability can be assessed by the Inflammatory Rasch‐built Overall Disability Scale (I‐RODS) 94–96 and the Inflammatory Neuropathy Cause and Treatment (INCAT) disability scale 97,98 Impairment can be assessed by the MRC sum score, 96,98,99 the Modified INCAT Sensory Sum scale (mISS), 98,100 the Neuropathy Impairment Score, 101 and by measuring grip strength using handheld dynamometry 98,102–104 The changes required to define improvement have not been adequately validated.…”

“…The changes required to define improvement have not been adequately validated. The following which have been used in clinical trials can serve as a guide: I‐RODS: + ≥4 centile points INCAT disability scale: − ≥1 point mISS: − ≥2 points MRC sum score (0‐60): + ≥2 to 4 points* Grip strength: Martin Vigorimeter: + ≥8 to 14 kPa* Jamar hand grip dynamometer: + ≥10%** *higher values may improve diagnostic specificity.**values averaged over 3 consecutive days improve diagnostic specificity 104 …”

“…97,98 Impairment can be assessed by the MRC sum score, 96,98,99 the Modified INCAT Sensory Sum scale (mISS), 98,100 the Neuropathy Impairment Score, 101 and by measuring grip strength using handheld dynamometry. 98,[102][103][104] • The changes required to define improvement have not been ade- **values averaged over 3 consecutive days improve diagnostic specificity. 104 T A B L E 3 Sensory nerve conduction criteria (1) CIDP…”

“…98,[102][103][104] • The changes required to define improvement have not been ade- **values averaged over 3 consecutive days improve diagnostic specificity. 104 T A B L E 3 Sensory nerve conduction criteria (1) CIDP…”

“…Evidence summary: According to high certainty evidence (5 trials, 269 participants), 104 induction treatment with IVIg produced more shortterm improvement than placebo. Adverse events were more common with IVIg than placebo (high certainty evidence), but serious adverse events were not observed (moderate certainty evidence, 3 trials, 315 participants).…”