Quality of life in inflammatory neuropathies: the IN-QoL.

BACKGROUND: No consensus exists which quality of life (QoL) measure should be used in patients with inflammatory neuropathies. Moreover, most QoL measures are ordinal-based scales with their known deficiencies. OBJECTIVES: To establish a new disease-specific interval-based QoL questionnaire in inflammatory neuropathies (IN-QoL) using the Rasch model and evaluate its scientific properties (validity, reliability and responsiveness). METHODS: 264 patients with inflammatory neuropathies completed six commonly used QoL questionnaires. The obtained data were stacked and subjected to Rasch analysis. Responsiveness was determined by using the concept of minimum clinically important differences related to varying individually obtained SEs (responsiveness definition: MCID-SE≥1.96 after 1-year follow-up compared with baseline). RESULTS: The IN-QoL fulfilled all Rasch's model requirements with high internal reliability values (patient separation index of 0.94), except being multidimensional. Additional factor analysis resulted in two (functional and mental) subsets that were unidimensional on their own. The IN-QoL showed good correlation with the EuroQol-health quality visual analogue scale (EQ-VAS) (Spearman's rho 0.72). It demonstrated acceptable responsiveness in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), as did the EQ-VAS. In patients with monoclonal gammopathy-related neuropathy and multifocal motor neuropathy, hardly any changes were seen over time. CONCLUSION: The IN-QoL questionnaire fulfils modern clinimetric requirements and correlates strongly with a patient's self-assessment of their own quality of health, while also showing responsiveness in patients with GBS and CIDP. We propose using the IN-QoL and the EQ-VAS for assessing the QoL of patients with inflammatory neuropathies in future studies.

Does ability to walk reflect general functionality in inflammatory neuropathies?

The "ability to walk" is considered a benchmark for good clinical recovery and prognosis, particularly in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). However, it has never been determined whether being "able to walk" represents general functionality. The purpose of this study was to examine whether the ability to walk outside independently reflects general functional improvement in patients with GBS, CIDP, and gammopathy-related neuropathy (MGUSP). A total of 137 patients with newly diagnosed (or relapsing) GBS (55), CIDP (59), and MGUSP (23) were serially examined (1-year). Predefined arbitrary cut-offs (so-called patients' Functional-Acceptable-Clinical-Thresholds [FACTs]) were taken at the 50th, 75th, and 90th percentile of the Inflammatory-Rasch-built-Overall-Disability-Scale (I-RODS(©) ). We determined the proportion of patients able to walk outside independently that reached the postulated cut-offs. A mean total of 85%, 39%, and 12% of all patients able to walk reached 50th, 75th, and 90th percentile thresholds, respectively. These findings were not neuropathy type related. Our findings show that assessing only one construct of functionality (e.g., walking ability) does not reflect the full scope of daily/social functional deficits perceived by patients. The ability to walk shows a patient is doing better, but not necessarily doing well. The I-RODS(©) bypasses these limitations.

Outcome measures in MMN revisited: further improvement needed.

The objectives of this study were to provide an overview of the outcome measures (OMs) applied in clinical trials in multifocal motor neuropathy (MMN) and to determine the responsiveness of a core set of selected OMs as part of the peripheral neuropathy outcome measures standardization (PeriNomS) study. The following OMs were serially applied in 26 patients with newly diagnosed or relapsing MMN, receiving intravenous immunoglobulin (assessments: T0/T3/T12 months): 14 muscle pairs MRC (Medical Research Council) scale, the Neuropathy Impairment Scale motor-subset, a self-evaluation scale, grip strength, and MMN-RODS© (Rasch-built overall disability scale). All data, except the grip strength, were subjected to Rasch analyses before determining responsiveness. For grip strength, responsiveness was examined using a combined anchor- (SF-36 question-2) and distribution-based (½ × SD) minimum clinically important difference (MCID) techniques, determining the proportion of patients exceeding both the identified cut-offs. For the remaining scales, the magnitude of change for each patient on each scale was determined using the MCID related to the individual SE (responder definition: MCID-SE ≥ 1.96). Overall, a great assortment of measures has been used in MMN trials with different responsiveness definitions. For the selected OMs, responsiveness was poor and only seen in one fourth to one third of the patients, the grip strength being more responsive. Despite the efforts taken to standardize outcome assessment, further clinimetric responsiveness studies are needed in MMN.

Impairment measures versus inflammatory RODS in GBS and CIDP: a responsiveness comparison.

This study aimed to 'define responder' through the concept of minimum clinically important differences using the individually obtained standard errors (MCID-SE) and a heuristic 'external criterion' responsiveness method in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). One hundred and fourteen newly diagnosed or relapsing patients (GBS: 55, CIDP: 59) were serially examined (1-year follow-up). The inflammatory Rasch-built overall disability scale (I-RODS), Rasch-transformed MRC sum score (RT-MRC), and Rasch-transformed modified-INCAT-sensory scale (RT-mISS) were assessed. Being-a-responder was defined as having a MCID-SE cut-off ≥1.96. Also, the correlations between patients' scores on each scale and the EuroQoL health-status 'thermometer' (external criterion) were determined (higher correlation indicated better responsiveness). In both diseases, the SEs showed a characteristic 'U'-shaped dynamic pattern across each scales' continuum. The number of patients showing a meaningful change were higher for the I-RODS > RT-MRC > RT-mISS and were in GBS higher than CIDP patients. The MCID-SE concept using Rasch-transformed data demonstrated an individual pattern of 'being-a-responder' in patients with immune-mediated neuropathies, and the findings were validated by the external criterion responsiveness method. The I-RODS showed greater responsiveness compared with the MRC and INCAT-sensory scales, and its use is therefore recommended in future trials in GBS and CIDP.

Grip strength comparison in immune-mediated neuropathies: Vigorimeter vs. Jamar.

The Jamar dynamometer and Vigorimeter have been used to assess grip strength in immune-mediated neuropathies, but have never been compared to each other. Therefore, we performed a comparison study between these two devices in patients with immune-mediated neuropathies. Grip strength data were collected in 102 cross-sectional stable and 163 longitudinal (new diagnoses or changing condition) patients with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), gammopathy-related polyneuropathy (MGUSP), and multifocal motor neuropathy (MMN). Stable patients were assessed twice (validity/reliability studies). Longitudinal patients were assessed 3-5 times during 1 year. Responsiveness comparison between the two tools was examined using combined anchor-/distribution-based minimum clinically important difference (MCID) techniques. Patients were asked to indicate their preference for the Jamar or Vigorimeter. Both tools correlated highly with each other (ρ = 0.86, p < 0.0001) and showed good intra-class correlation coefficients (Jamar [Right/Left hands]: ICC 0.997/0.96; Vigori: ICC 0.95/0.98). Meaningful changes were comparable between the two instruments, being higher in GBS compared to CIDP patients. In MGUSP/MMN poor responsiveness was seen. Significant more patients preferred the Vigorimeter. In conclusion, validity, reliability, and responsiveness aspects were comparable between the Jamar dynamometer and Vigorimeter. However, based on patients' preference, the Vigorimeter is recommended in future studies in immune-mediated neuropathies.

Comparing the NIS vs. MRC and INCAT sensory scale through Rasch analyses.

We performed a comparison between Neuropathy Impairment Scale-sensory (NISs) vs. the modified Inflammatory Neuropathy Cause and Treatment sensory scale (mISS), and NIS-motor vs. the Medical Research Council sum score in patients with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and IgM monoclonal gammopathy of undetermined significance-related polyneuropathy (MGUSP). The ordinal data were subjected to Rasch analyses, creating Rasch-transformed (RT)-intervals for all measures. Comparison between measures was based on validity/reliability with an emphasis on responsiveness (using the patient's level of change related to the individually obtained varying SE for minimum clinically important difference). Eighty stable patients (GBS: 30, CIDP: 30, and MGUSP: 20) were assessed twice (entry: two observers; 2-4 weeks later: one observer), and 137 newly diagnosed or relapsing patients (GBS: 55, CIDP: 59, and IgM-MGUSP: 23) were serially examined with 12 months follow-up. Data modifications were needed to improve model fit for all measures. The sensory and motor scales demonstrated approximately equal and acceptable validity and reliability scores. Responsiveness scores were poor but slightly higher in RT-mISS compared to RT-NISs. Responsiveness was equal for the RT-motor scales, but higher in GBS compared to CIDP; responsiveness was poor in patients with MGUSP, suggesting a longer duration of follow-up in the latter group of patients.

Changing outcome in inflammatory neuropathies: Rasch-comparative responsiveness.

OBJECTIVES: We performed responsiveness comparison between the patient-reported Inflammatory Rasch-built Overall Disability Scale (I-RODS) and the widely used clinician-reported Inflammatory Neuropathy Cause and Treatment-Overall Neuropathy Limitation Scale (INCAT-ONLS) in patients with Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and immunoglobulin M-monoclonal gammopathy of undetermined significance related polyneuropathy (IgM-MGUSP). METHODS: One hundred thirty-seven patients (GBS: 55, CIDP: 59, IgM-MGUSP: 23) with a new diagnosis or clinical relapse assessed both scales. Patients with GBS/CIDP were examined at 0, 1, 3, 6, and 12 months; patients with IgM-MGUSP at 0, 3, and 12. We subjected all data to Rasch analyses, and calculated for each patient the magnitude of change on both scales using the minimal clinically important difference (MCID) related to the individual standard errors (SEs). A responder was defined as having an MCID-SE ≥1.96. Individual scores on both measures were correlated with the EuroQoL thermometer (heuristic responsiveness). RESULTS: The I-RODS showed a significantly higher proportion of meaningful improvement compared with the INCAT-ONLS findings in GBS/CIDP. For IgM-MGUSP, the lack of responsiveness during the 1-year study did not allow a clear separation. Heuristic responsiveness was consistently higher with the I-RODS. CONCLUSION: The I-RODS more often captures clinically meaningful changes over time, with a greater magnitude of change, compared with the INCAT-ONLS disability scale in patients with GBS and CIDP. The I-RODS offers promise for being a more sensitive measure and its use is therefore suggested in future trials involving patients with GBS and CIDP.