15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License RESEARCH ARTICLE Assessing Dysferlinopathy Patients Over Three Years With a New Motor Scale Marni B. Jacobs, PhD ,1,2† Meredith K. James, PT ,3† Linda P. Lowes, PT, PhD ,4 Lindsay N. Alfano, DPT ,4 Michelle Eagle, PT, PhD,3 Robert Muni Lofra, PT,3 Ursula Moore, MBBChir,3 Jia Feng, MSc,1 Laura E. Rufibach, PhD,5 Kristy Rose, PT, PhD,6 Tina Duong, MPT, PhD,7,8 Luca Bello, MD, PhD ,9 Irene Pedrosa-Hernández, PT,10 Scott Holsten, PT,11 Chikako Sakamoto, PT,12 Aurélie Canal, PT,13 Nieves Sanchez-Aguilera Práxedes, PT,14 Simone Thiele, PT,15 Catherine Siener, PT, MHS,16 Bruno Vandevelde,17 Brittney DeWolf, PT, DPT, CCCE,7 Elke Maron, PT,18 Michela Guglieri, MD,3 Jean-Yves Hogrel, PhD ,13 Andrew M. Blamire, PhD ,19 Pierre G. Carlier, MD, PhD,20 Simone Spuler, MD, PhD,21 John W. Day, MD,22 Kristi J. Jones, MD, PhD,6 Diana X. Bharucha-Goebel, MD,23,24 Emmanuelle Salort-Campana, MD,17 Alan Pestronk, MD ,16 Maggie C. Walter, MD, MA,15 Carmen Paradas, MD, PhD,25 Tanya Stojkovic, MD,13 Madoka Mori-Yoshimura, MD, PhD,26 Elena Bravver, MD,11§ Jordi Díaz-Manera, MD, PhD,27,28 Elena Pegoraro, MD, PhD,9 Jerry R. Mendell, MD,4 The Jain COS Consortium, Anna G. Mayhew, PT, PhD,3‡ and Volker Straub, MD, PhD 3‡ View this article online at wileyonlinelibrary.com. DOI: 10.1002/ana.26044 Received Apr 24, 2020, and in revised form Feb 5, 2021. Accepted for publication Feb 5, 2021. Address correspondence to Professor Volker Straub, The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK. E-mail: volker.straub@newcastle.ac.uk † These authors should be considered co-first authors. ‡ These authors should be considered co-last authors. § Elena Bravver is deceased. From the 1Center for Translational Science, Division of Biostatistics and Study Methodology, Children’s National Health System, Washington, DC; 2 Pediatrics, Epidemiology, and Biostatistics, George Washington University, Washington, DC; 3The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Central Parkway, Newcastle upon Tyne, UK; 4The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH; 5The Jain Foundation, Seattle, WA; 6The Children’s Hospital at Westmead, The University of Sydney, Sydney, Australia; 7Cooperative International Neuromuscular Research Group (CINRG), Children’s National Health System, Washington, DC; 8Lucile Salter Packard Children’s Hospital at Stanford, Palo Alto, CA; 9Department of Neuroscience, University of Padova, Padova, Italy; 10Physical Medicine and Rehabilitation, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; 11Neuroscience Institute, Carolinas Neuromuscular/ALS-MDA Center, Carolinas HealthCare System, Charlotte, NC; 12Department of Physical Rehabilitation, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan; 13Institut de Myologie, AP-HP, GH Pitié-Salpêtrière, Paris, France; 14 Neurorehabilitation Unit, Rehabilitation Hospital Universitario Virgen del Rocío, Sevilla, Spain; 15Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians University of Munich, Munich, Germany; 16Department of Neurology Washington University School of Medicine, St. Louis, MO; 17 Service des Maladies Neuromusculaire et de la SLA, Hôpital de La Timone, Marseille, France; 18ELAN-PHYSIO, Praxis für Physiotherapie Maron, Berlin, Germany; 19Magnetic Resonance Centre, Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK; 20AIM & CEA NMR Laboratory, Institute of Myology, Pitié-Salpêtrière University Hospital, Paris, France; 21Charite Muscle Research Unit, Experimental and Clinical Research Center, a joint cooperation of the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine, Berlin, Germany; 22Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA; 23Department of Neurology Children’s National Health System, Washington, DC; 24National Institutes of Health (NINDS), Bethesda, MD; 25Neuromuscular Unit, Department of Neurology, Hospital U. Virgen del Rocío/Instituto de Biomedicina de Sevilla, Sevilla, Spain; 26Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan; 27 Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain; and 28Neuromuscular Disorders Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain Additional supporting information can be found in the online version of this article. © 2021 The Authors. Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association. 967 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License ANNALS of Neurology Objective: Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progres- sion using NSAD. Methods: We collected a longitudinal series of functional assessments from 187 patients with dysferlinopathy over 3 years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and non- ambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories. Results: The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3 to 8 years post symptom onset at baseline. Interpretation: The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clini- cal practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short-term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy. ANN NEUROL 2021;89:967–978 Abbreviations affected for decades.9,10 A number of factors that may influence the clinical phenotype and progression of dysferlinopathy have 6MWT 6 minute walk test been proposed, including exercise and the specific 10MWT 10 meter walk/run test mutation,6,11,12 although no clear pattern of decline or a-NSAA adapted North Star Ambulatory Assessment phenotype–genotype relationship has been established. ClinRO clinician reported outcome measure The variable progression of dysferlinopathy presents COS Clinical Outcomes Study of dysferlinopathy numerous challenges for clinical management and identifying DIF differential item functioning patient groups that could be targeted for clinical trials. The GEE generalized estimating equations lack of disease specific, validated clinician reported outcome ICC intraclass correlation coefficient measures (ClinRO) of motor performance specific to the LGMD limb girdle muscular dystrophy LGMD population has hampered interpretation when moni- MFM-20 Motor Function Measure-20 toring progression. Clinically meaningful, validated outcomes MM Miyoshi myopathy are essential to accurately evaluate change13,14 and response MMD1 Miyoshi myopathy dystrophy 1 to therapeutic interventions.15 Existing dysferlinopathy NSAA North Star Ambulatory Assessment research suggests the level of decline varies according to the NSAD North Star Assessment for limb girdle type current functional state and is not stable across short time muscular dystrophies periods.16 Showing efficacy in clinical trials is particularly dif- RFF timed Rise From Floor test ficult in slowly progressing and heterogeneous diseases.17,18 TUG Timed Up and Go test Thus, to appropriately power an interventional clinical trial aiming to slow or stabilize progression in a rare disease like dysferlinopathy, the natural history of the disease must be D ysferlinopathy is a rare, autosomal recessive, inherited form of muscular dystrophy caused by mutations in the DYSF gene, which encodes the skeletal muscle protein well-characterized using robust and meaningful outcomes, with a characterized population likely to progress over the dysferlin.1,2 The most common clinical diagnoses associated course of a defined clinical trial. with dysferlinopathy are limb girdle muscular dystrophy R2 The Jain International Clinical Outcome Study dysferlin related (formerly LGMD 2B) and Miyoshi myopathy (COS) of Dysferlinopathy was established to address the (MM or Miyoshi myopathy dystrophy 1 [MMD1]).3–5 lack of comprehensive natural history data for Although onset typically occurs during young adulthood, clini- dysferlinopathy and to identify and, if necessary, develop cal presentation is inconsistent, with a wide range of age at appropriate outcome measures for monitoring disease pro- onset, patterns of muscle weakness, and severity, despite a gression. Using data from 3 years of follow-up, the aims shared loss of dysferlin protein expression.1,6–8 Likewise, disease of this paper are: part 1) describe the development of the progression is variable; loss of ambulation occurs 5 to 35 years North Star Assessment for Limb Girdle Type Muscular after onset, whereas a minority of patients remain mildly Dystrophies (NSAD; formally the North Star Assessment 968 Volume 89, No. 5 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Jacobs et al: LGMDR2: Three-Year Progression and Trial Readiness for Dysferlinopathy),19 part 2) report on its ability to were selected16 alongside the newly developed NSAD detect change over a 1 year period, and part 3) describe assessment introduced at year 2. To evaluate the NSAD longitudinal disease progression to inform clinical prog- across all 3 years, scores prior to year 2 were calculated nostication and identify patients best suited for inclusion based on a-NSAA and MFM-20 items captured at previ- in clinical trials. ous study visits using a defined algorithm; new items were imputed based on item difficulty hierarchies. Outcome Methods measures selected showed consistently significant changes The Jain COS of dysferlinopathy is a multicenter, inter- over both 6 and 12 months with relatively high standard- national study of patients with a confirmed diagnosis of ized response means, including the 10 meter walk/run dysferlinopathy. Detailed study methods have been pub- (10MWT) and the ACTIVLIM patient report of daily lished previously.9,16 To be included in the Jain COS of function questionnaire. The ACTIVLIM is a validated dysferlinopathy, patients were required to have patient-reported outcome measure of functional ability 2 predicted pathogenic mutations in DYSF, or based on perceived difficulty in performing specific activi- 1 predicted pathogenic mutation plus either absent ties of daily living.24,25 Although the 6 minute Walk Test dysferlin expression on immunoblot or < 20% dysferlin (6MWT) was previously found to be less sensitive in the monocyte expression.20 Each participating site received dysferlinopathy population,16 it was included for compari- local ethics approval and written informed consent was son. Timed function tests were converted to velocity mea- obtained for all patients. The study was registered at sures (meters or task per second), and 0 m/s or 0 task/s ClinicalTrials.gov (NCT01676077). was assigned when the patient was unable to complete the Participants were evaluated 6 times over the course test due to disease progression. To appraise usefulness as of the study: screen, baseline, 6, 12, 24, and 36 months inclusion criteria, the Timed Up and Go (TUG) and Rise between November 2012 and March 2018. This multi- from Floor (RFF) tests were evaluated as predictors of part study includes data on: part 1 = 330 assessments from decline to determine whether they could better profile 154 patients, using available data from a data cut at baseline function. 20 months after the first patient enrolled. Part 2 = 309 assessments from years 2 and 3 and, part 3 = 187 patients Statistical Analysis at 14 sites over 3 years (one original site was excluded due Part 1: Development of NSAD Using a-NSAA and MFM-20 to the level of missing data). Three-year follow-up was Collected at Year 1 - Psychometric Evaluation Using high with 163 participants (87.2%) completing all study Rasch Analysis. A Rasch analysis examines the extent visits. to which the observed data (physiotherapists’ ratings of subject performance on items on the 2 scales) “fit” with Demographic Measures predictions of those ratings from the Rasch model (which Self-reported race and patient sex was recorded, and age at defines how a set of items should perform to generate each visit was calculated from the patient’s year of birth. reliable and valid measurements).26 The difference Symptom duration was calculated as the difference in between observed and expected scores indicates the years between patient-reported symptom onset (defined as degree to which a valid measurement is achieved.26,27 the onset of muscle weakness) and age at each visit. Rasch analysis has been used in the development and val- Patient-reported clinical diagnosis, as given by diagnosing idation of scales of motor performance in neuromuscular clinician, including LGMD2B and MM or other was disorders, including the North Star Ambulatory Assess- recorded. Maximum exercise level prior to disease onset ment (NSAA) and MFM.13,28 Rasch analysis examined was classified as none, low, moderate, or high.21 7 tests for reliable and valid measurement and compared the items of the 2 scales and their targeting ability on the Outcome Measures Jain COS of dysferlinopathy population. Available data A wide range of measures, including function and muscle from patients with between 1 and 4 assessments each strength, were performed in order to establish their useful- over the first year period were included in this analysis. ness in assessing disease progression over time.9 For part Data were entered into Rasch Unidimensional Measure- 1, two scales of motor performance, the adapted-North ment Model26 RUMM2030 software.29 Star Ambulatory Assessment (a-NSAA)22 and Motor Function Measure-20 (MFM-20),23 were evaluated with Part 2: Detecting Change Over 1 Year Using the Rasch analysis at year 1, which evolved into the NSAD NSAD. Following part 1 analysis, a proposed amalgam- used for parts 2 and 3. For part 3, the most sensitive out- ation and rescoring of items from the a-NSAA and come measures identified during the first year of the study MFM-20 was presented. The new scale, the NSAD, was May 2021 969 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License ANNALS of Neurology introduced at year 2 visits. The NSAD assessments at years 2 and 3 visits were examined using the Rasch analy- TABLE 1. Characteristics of the Study Sample (N = 187) sis, as described above, and the Wilcoxon signed rank for longitudinal change with SPSS 24. Inter-rater reliability Demographics No. % was assessed using intraclass correlation coeffi- cients (ICCs). Gender Male 87 46.5 Part 3: Longitudinal Disease Progression Over Female 100 53.5 3 Years. For part 3, the primary outcome was disease pro- gression over time, both since symptom onset in years, and Race/ethnicity time in months from baseline to subsequent study visits. To White 133 71.1 account for correlation between repeated measures of individ- Asian 32 17.1 ual patients, generalized estimating equations (GEEs) with Hispanic 12 6.4 sandwich variance estimation were used to evaluate change in functional measures over time. An exchangeable covariance Other 10 5.4 structure was assumed for all models based on quasi informa- Age at baseline, mean (SD), 38.5 (13.0) 11, 86 tion criteria measures suggesting best fit. For direct assessment min/max of demographic and clinical factors, a 2-tailed p < 0.05 was Clinical factors considered significant. Nonlinear associations were considered in symptom duration models by including a quadratic time Age at symptom onset, 21.8 (8.6) 0, 60 mean (SD), min/max term in models to evaluate any plateau effects. All models eval- uating progression controlled for age at baseline. For all demo- Symptom duration at 17.1 (10.5) 1, 51 graphic and clinical factors considered, a factor by time term baseline, mean (SD), was included in models to assess any differences in trajectories; min/max interaction terms significant at p ≤ 0.20 were noted. To better Clinical diagnosis visualize potential trajectory differences, continuous measures LGMD2B/R2 116 62.0 with notable interactions were categorized either through com- Miyoshi myopathy 54 28.9 monly used age groupings or study-derived quartiles for graph- ing. Predicted values above or below the possible values for a Other 17 9.1 given measure were bounded at the upper and lower limits Ambulant at baseline for plotting. All analyses were completed using SAS ver- Ambulatory 140 74.8 sion 9.4. Nonambulatory 47 25.1 Maximum exercise level Results during teen years Characteristics of the study patients included in the longitudinal None 46 25.4 analysis are presented in Table 1. Of the study subjects, 53.5% were women and most patients identified as non-Hispanic Low 17 9.4 white (71.1%). Age at baseline ranged from 11 to 86 years and Moderate 62 34.3 symptom duration at baseline from 1 to 51 years. Most of the High 56 30.9 patients were diagnosed as LGMDR2/2B, and three-quarters of the participants were ambulant at baseline. Mean follow-up Study follow-up time was 35.0 ± 5.8 months. Number of visits, mean 4.8 (0.5) 2, 5 (SD), min/max Part 1: Development of the North Star Follow-up time in months, 35.0 (5.8) 6, 44 Assessment for Limb Girdle Type Muscular mean (SD), min/max Dystrophies One hundred fifty-eight assessments were available for the a-NSAA and 172 assessments included in the MFM-20 Rasch analysis. Overall, the a-NSAA and MFM-20 per- Adapted North Star Ambulatory Assessment. The a-NSAA formed well against the battery of psychometric tests but item fit was excellent with good coverage of disease sever- were not without issue (Table 2). ity (ie, very few items measured the same level of ability). 970 Volume 89, No. 5 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Jacobs et al: LGMDR2: Three-Year Progression and Trial Readiness There was minimal floor effect, but some ceiling effect. Part 2: Ability of the NSAD to Detect Change in Three of 22 items had fit residuals outside the rec- 1 Year ommended range, and one item misfit with a significant We examined 309 NSAD assessments, 149 male patients v2 probability. Unidimensionality was acceptable (t test and 160 female patients from year 2 and year 3 visits. The 4.2%, binomial test lower 95% confidence interval NSAD performed well on Rasch analysis (see Table 2). [CI] proportion, < 0.01). Reliability was supported by a All but one of the items (Gets to sitting) clearly fit the high PSI (0.96), similar to Cronbach’s alpha. Six of construct with appropriate fit residual locations. Four 22 items displayed disordered item response (scoring) items at year 2, and 5 items at year 3, misfit with signifi- thresholds. Ten pairs of bilateral items (including stand on cant chi square values of p < 0.05. Reliability was demon- one leg, hopping, and climbing on and off box step) had strated by a high PSI of 0.97. Unidimensionality was residuals that were highly correlated (> 0.40), implying acceptable (binomial test lower 95% CI proportion, that a response to one influenced the response to the < 0.05). Although a ceiling effect still existed for the stron- other. When left-sided items were removed, the PSI gest and potentially asymptomatic subjects, the motor per- remained high (0.95), suggesting the dependency did not formance of both ambulant and nonambulant subjects artificially inflate reliability. There was no uniform or non- was targeted successfully by the items of the uniform differential item functioning (DIF) for gender, NSAD (Fig 1). indicating that gender did not influence performance on In the absence of a second independent rare disease this scale. population on whom to perform traditional scale valida- tion, Rasch analysis was repeated on 5 randomly generated MFM-20. Rasch targeting identified redundant items (too cohorts of 80% of the discovery population (see Table 2). easy for the population) and a ceiling effect, with a lack of The NSAD performed well in all of these analyses, con- items measuring stronger ambulant individuals. Eight of firming the scale is a fit for purpose instrument in this the 20 items had fit residuals outside the recommended population. range, and 4 items had a significant v2 probability. Thir- The NSAD as a whole detected a statistically signifi- teen of 20 items had disordered scoring thresholds. Reli- cant deterioration in the population over 1 year, with a ability was supported by a high PSI (0.94). mean change score of −1.73 points (Wilcoxon signed Unidimensionality was not achieved (t test 14.5%, bino- rank-sum test p < 0.0001, 95% CI = –2.33 to −1.14; mial test lower 95% CI proportion, > 0.05). One item Table 3). Inter-rater reliability was established with an expressed uniform DIF (ankle dorsiflexion), indicating ICC of 0.99. that the ability to dorsiflex the ankle may be influenced by gender. Part 3: Disease Progression With data for ambulant patients collected on both Disease Duration (Time From Symptom Onset). For all out- scales, it was possible to examine the interaction between comes assessed, a significant decline in function was seen the scales. The a-NSAA measures stronger patients more across disease duration (p < 0.0001), with nonlinear trajec- effectively with some items from the MFM-20 contribut- tories noted (Table SS1). Plots of the NSAD, 10MWT, ing to better measurement of weaker and nonambulant and 6MWT across symptom duration suggested disease individuals. Ordered response categories (thresholds) are progression for approximately 30 years, at which point paramount for accurate scale performance, as a higher decline reaches the measurement floor or levels off (data score on individual items must represent a higher level of not shown). A milder plateau effect was noted for the overall ability. The a-NSAA had 73% ordered thresholds. ACTIVLIM. The MFM-20 had only 35% of items with ordered Results of GEE models suggested that age at onset thresholds, with 4 scoring categories being too complex in may play a role in disease progression (Table SS1). Later 65% of items. age at onset was associated with better function according Following this review, 29 items were retained for the to the NSAD adjusting for disease duration (β = 0.26 NSAD (all 22 items from the a-NSAA and 7 items from points for each year later, 95% CI = 0.06–0.45, p = 0.03), the MFM-20) with a range from 0 to 54 (the higher the and patients with earlier age at onset showed faster pro- score the better the ability). The NSAD rescored the dis- gression than those with later onset (p = 0.04). Graphs ordered items, removed redundant and duplicate items suggested the steepest declines occurred during the first (available from the authors), and was re-ordered to 10 years post onset regardless of age at symptom onset, improve efficiency for patients and prevent unnecessary with earlier onset patients experiencing continued linear fatigue. The NSAD replaced the a-NSAA and MFM-20 decline compared with later onset patients who began to in years 2 and 3 of the Jain COS of dysferlinopathy. plateau (Fig 2A). Additionally, adjusted for disease May 2021 971 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License ANNALS of Neurology TABLE 2. Summary Rasch Results for Part 1 - a-NSAA and MFM-20 and Part 2 - NSAD Item Fit Person Fit Reliability Item Fit Item-trait interaction Number of Dependency Unidimensionality chi squared PSI with Ordered items with (number and DIF Mean (SD) Mean (SD) value (DF) extremes thresholds good fit* of pairs) (by gender) Part 1-a-NSAA and MFM-20 analysis a-NSAA n = −0.95 (1.41) −0.12 (0.42) 116 (44) 0.96 16/22 (73%) 19/22a (86%) 10 pairs Acceptable. No DIF 158 assessments 1 < p 0.01b for gender 10 extremes MFM-20 N = −0.85 (2.17) −0.25 (0.65) 524 (40) 0.94 7/20 (35%) 12/20a (60%) 1 pair Not acceptable. DIF 172 assessments 4 < p 0.01b present on 1 item 10 extremes (ankle dorsiflexion) Part 2- NSAD NSAD −0.27 (1.08) −0.26 (0.57) 243.5 (116) 0.97 28/29 (97%) 28/29a 14 pairs Acceptable (< 0.05) Year 2 N = 4 < 0.01b and no DIF for 153 assessments gender 7 extremes NSAD −0.51 (1.34) −0.34 (0.61) 350.4 (116) 0.97 28/29 (97%) 26/29a 19 pairs Acceptable (< 0.05) Year 3 N = 5 < 0.01b and no DIF for 156 assessments gender 6 extremes NSAD internal validation on discovery cohort Random cohort 1 −0.25 (1.06) −0.25 (0.60) 267.4 (116) 0.97 27/29 (93%) 29/29a 12 pairs Acceptable (< 0.05) N = 122 3 < 0.05b PSI 0.97 and no DIF for 4 extremes with one of gender pair removed Random cohort 2 −0.28 (0.97) −0.27 (0.57) 212.12 (116) 0.97 28/29 (97%) 29/29a 13 pairs Acceptable (< 0.05) N = 122 3 < 0.05b PSI 0.97 and no DIF for 4 extremes with one of gender pair removed Random cohort 3 −0.25 (1.01) −0.24 (0.59) 275.22 (116) 0.97 28/29 (97%) 28/29a 12 pairs Acceptable (< 0.05) N = 122 3 < 0.05b PSI 0.97 and no DIF for 5 extremes with one of gender pair removed Random cohort 4 −0.56 (1.22) −0.37 (0.72) 344.39 (116) 0.97 28/29 (97%) 26/29a 14 pairs Acceptable (< 0.05) N = 122 3 < 0.05b PSI 0.96 and no DIF for 2 extremes with one of gender pair removed Random cohort 5 −0.50 (1.18) −0.30 (0.54) 289.57 (116) 0.97 28/29 (97%) 27/29a 13 pairs Acceptable (< 0.05) N = 122 4 < 0.05b PSI 0.96 and no DIF for 2 extremes with one of gender pair removed * Fit: Defined as fit residual inside the recommended range (−2.50 to 2.50)a and nonsignificant chi squared probability (p < 0.01)b. a-NSAA = adapted North Star Ambulatory Assessment; DIF = differential item functioning; MFM-20 = Motor Function Measure-20; NSAD = North Star Assessment for Limb Girdle Type Muscular Dystrophies. duration, Asian patients performed worse on the 10MWT patients appearing to decline more quickly than Hispanic (β = −0.53 m/s, 95% CI = –0.89 to −0.16, p = 0.0005) and other patients (Fig 2B). Similarly, on average, women and 6MWT (β = −0.25, 95% CI = –0.42 to −0.08, had higher NSAD scores (β = 4.60 points, 95% p = 0.004) than White patients, on average, across the dis- CI = 0.90–8.31, p = 0.02) and slightly better 6MWT ease course. Slight differences in 10MWT trajectories by velocities (β = 0.12 m/s, 95% CI = –0.02 to 0.25, race were also noted (p = 0.11), with Asian and White p = 0.08) than male patients, controlling for disease 972 Volume 89, No. 5 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Jacobs et al: LGMDR2: Three-Year Progression and Trial Readiness FIGURE 1: Person–item targeting of North Star Assessment for Limb Girdle Type Muscular Dystrophies at year 2 and 3 visits, people are the top row and items are the bottom row. The strongest patients and the hardest items are on the right, and the weakest patients and the easiest items are on the left. Good coverage of ability of both ambulant and nonambulant. Ceiling exists for asymptomatic subjects. TABLE 3. Means and Change Scores for the NSAD over 12 Months, Years 2 to 3 Baseline NSAD Baseline 12 month changes Total scores Mean (ranges) 21.6 (0 to 54) −1.73 (−15.0 to 8.00) Whole cohort [95% CI] (n = 140) [−2.33 to −1.14] p value < 0.0001 (n = 123) Total scores Mean (ranges) 28.86 (7 to 54) −2.18 (−15 to 8) Ambulant [95% CI] (n = 97) [−0.296, −1.41] p value < 0.0001 (n = 87) Total scores Mean (ranges) 5.73 (0 to 15) −0.64 (−5 to 5) Nonambulant [95% CI] (n = 43) [−1.36 to 0.08] p value 0.0613 (n = 36) The patients whose visits fell outside the 12-month visit window for years 3 and 2 were excluded from the analysis (n = 13). CI = confidence interval; NSAD = North Star Assessment for Limb Girdle Type Muscular Dystrophies. duration. Some evidence that men progressed faster than follow-up time represented average monthly declines. For women was noted for the NSAD (p = 0.17; Fig 2C) and all outcomes, older age at onset and faster TUG and RFF 10MWT (p = 0.19), although differences in trajectories velocities at baseline were associated with better function, were not significant. Although absolute scores did not dif- whereas longer symptom duration was associated with fer based on teenage exercise levels, assessment of disease worse function, controlling for patient age (p < 0.001). trajectories suggested that patients with high exercise levels Compared with White patients, patients who identified as during the teenage years progressed slightly faster than Asian or “other” had lower 10MWT and 6MWT veloci- those in the none and moderate exercise groups (Fig 2D; ties (p < 0.05). p = 0.08). Age at baseline and symptom duration at baseline were significantly associated with disease progression dur- Three-Year Progression. All outcome measures showed ing the study period, primarily NSAD and 10MWT significant decline during the 3-year follow-up period decline. The greatest decline during the study period was (p < 0.0001; Table S1). Beta estimates (Table S1) for seen in patients who had been symptomatic for 3 to May 2021 973 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License ANNALS of Neurology FIGURE 2: Outcome trajectories across symptom duration by patient characteristic. Fitted regression lines with 95% confidence intervals from generalized estimating equation modeling for (A) North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) score by age at symptom onset, (B) 10 meter walk/run test (10MWT) by race/ethnicity, (C) NSAD score by sex, and (D) 10MWT by teen exercise level. 8 years (Fig 3A, B). Likewise, patients with earlier age at samples. Sample size was estimated using PASS 15 software symptom onset tended to show a greater decline during (Table 4). Mean decline and standard deviation for each the study period than those with later onset (p = 0.06). 6 and 12-month period (± 2 months) were calculated. Sam- Lower TUG velocity at baseline was associated with ple sizes for a hypothetical clinical trial targeting halting of greater decline in self-reported function on the ACTIVLIM progression with the NSAD as the outcome measure ranged during the follow-up period (p = 0.03), with some evidence from 14 using the strictest inclusion criteria to 32 based on of greater progression on timed function tests (p = 0.08). symptom duration at baseline alone for a 1-year trial and Likewise, patients with lower RFF velocity showed larger 32 to 52 for a 6-month trial based on the same criteria. declines on the ACTIVLIM (Fig 3C; p = 0.001) and 6MWT (Fig 3D’ p = 0.003), with some evidence of steeper progression on the 10MWT (p = 0.08). Quartile estimates Discussion suggested little decline over the 3-year study period for Part 1 of this study evaluated the suitability of the a- patients with high TUG velocity > 0.13 t/s (~ 7.7 seconds) NSAA and MFM-20 scales to measure motor performance or RFF velocity > 0.21 t/s (~ 4.7 seconds). in dysferlinopathy. The subsequent new scale, the NSAD, addressed the measurement issues within these 2 scales, Sample Size Estimation for Clinical Trial re-ordered items to improve efficiency and reduce patient Readiness. Outcome measures associated with decline over fatigue, and made the scale applicable for both ambulant a short time period identified in 3-year GEE models were and nonambulant patients. Analysis in part 2 confirmed selected to characterize possible clinical trial inclusion that the NSAD could detect change in clinical progression criteria. Sample size is highly dependent on estimated treat- of individuals with dysferlinopathy over 1 year and dem- ment effect and variability around the estimate, whereby onstrated excellent inter-rater reliability. This further sup- larger effects and decreased variability necessitate smaller ports the reported results for the first year of the Jain 974 Volume 89, No. 5 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Jacobs et al: LGMDR2: Three-Year Progression and Trial Readiness FIGURE 3: Functional outcome trajectories during the study period by patient characteristic. Fitted regression lines with 95% confidence intervals from generalized estimating equation modeling for (A) North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) score among symptom duration ≤ 10 years, (B) 10MWT among symptom duration ≤ 10 years, (C) ACTIVLIM by Rise from Floor velocity quartile, and (D) 6 minute walk test by Rise from Floor velocity quartile. COS of dysferlinopathy, where the a-NSAA was suggested an earlier disease onset may represent a more severe phe- as a possible primary outcome for ambulant patients.16 notype. Patients earlier on in their disease, particularly The NSAD tests the abilities of anterior and poste- those 3 to 8 years from symptom onset, showed the rior muscles of the leg and calf, which positions the assess- steepest rate of progression, particularly in the NSAD and ment well to measure change in motor function across 10MWT over 3 years of follow-up. This finding is other LGMDs and conditions involving the pelvic girdle, supported by a small study of 18 patients with such as Becker muscular dystrophy. The NSAD is cur- dysferlinopathy where patients progressed from normal rently being utilized in longitudinal natural history studies function to difficulty standing at an average of 8 years of LGMD types, including LGMDR1 Calpain3 related, after disease onset.11 Baseline TUG and RFF tests pro- LGMDR3 alpha-sarcoglycan related, and LGMDR4 beta- vided additional information, suggesting more noticeable sarcoglycan related.30,31 In these populations, the NSAD declines in other outcome measures among patients with was highly correlated to the 100 meter walk/run and RFF velocity measures below the highest quartile. tests, and differentiated rates of functional decline.30,31 It We previously estimated 46 moderately affected is also being utilized as an end point to demonstrate ambulant patients would be needed to show a halting of improvement in motor function in the ongoing phase I disease progression over 1 year on the a-NSAA.16 Limiting gene therapy trial for LGMD R4.15 Further work is being inclusion criteria to patients 3 to 8 years from onset, with undertaken to examine its relationship to patient-reported the NSAD as the outcome, could reduce this number to outcome measures and validation in other diseases. 32 and with timed function test criteria to 14. However, Results from part 3 suggested disease progression the necessary sample size must be balanced against the primarily occurs during the first 30 years after symptom available population that meets the inclusion criteria. In onset, at which point progression levels off. Patients with the present study, only 40 patients fell into the 3 to May 2021 975 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License ANNALS of Neurology TABLE 4. Sample Size Estimates for a 6-Month or 1-Year Placebo-Controlled Clinical Trial with Variable Patient Inclusion Criteria Target treatment effect Outcome Average 50% Reduction in 75% Reduction in Halting of 20% 50% measure change (SD)a progression progression progression Improvement Improvement Disease duration 3–8 yr 6 mo NSAD −1.53 (1.93) 202 92 52 38 26 ACTIVLIM −0.74 (1.61) 598 268 152 106 70 10MWT −0.14 (0.20) 260 116 68 48 32 6MWT −0.04 (0.07) 388 174 100 70 46 1 yr NSAD −2.81 (2.68) 116 54 32 22 16 ACTIVLIM −1.31 (2.03) 310 138 78 56 36 10MWT −0.20 (0.18) 104 48 28 20 14 6MWT −0.09 (0.09) 128 58 34 24 18 Disease duration 3–8 yr and either TUG velocity < 0.13 or Rise from Floor velocity < 0.21 6 mo NSAD −1.90 (1.91) 130 60 34 26 18 ACTIVLIM −1.33 (1.39) 140 64 38 26 18 10MWT −0.15 (0.21) 250 112 64 46 30 6MWT −0.04 (0.06) 286 128 74 52 34 1 yr NSAD −2.78 (2.66) 118 54 32 24 16 ACTIVLIM −2.14 (1.75) 86 40 24 18 12 10MWT −0.20 (0.13) 56 26 16 12 10 6MWT −0.11 (0.08) 70 32 20 14 10 Disease duration 3–8 yr and TUG velocity < 0.13 and Rise from Floor velocity < 0.21 6 mo NSAD −2.20 (2.14) 122 56 32 24 16 ACTIVLIM −1.39 (1.64) 178 80 46 34 22 10MWT −0.07 (0.08) 166 76 44 32 22 6MWT −0.03 (0.07) 684 306 174 122 78 1 yr NSAD −3.07 (1.79) 46 22 14 10 8 ACTIVLIM −1.80 (1.25) 64 30 18 14 10 10MWT −0.16 (0.10) 52 24 16 12 8 6MWT −0.12 (0.10) 90 42 24 18 12 a Calculations are based on an observed change in outcome score in untreated patients, representing the expected control effect. Numbers quoted repre- sent the total sample size based on equally sized treatment and control groups. 6MWT = 6 minute walk test; 10MWT = 10 meter walk/run test; NSAD = North Star Assessment for Limb Girdle Type Muscular Dystrophies; TUG = Timed Up and Go test. 976 Volume 89, No. 5 15318249, 2021, 5, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/ana.26044 by Readcube (Labtiva Inc.), Wiley Online Library on [08/03/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Jacobs et al: LGMDR2: Three-Year Progression and Trial Readiness 8 years post-onset criteria across 14 sites, whereas just functional ability throughout the course of the disease, 10 patients met the most stringent criteria, highlighting making it suitable for clinic, natural history studies, and the difficulty in meeting specific inclusion criteria for clin- interventional clinical trials. ical trials. In addition, caution should be taken when con- sidering years from symptom onset in inclusion criteria as onset of symptoms is often subjective, especially in retro- Acknowledgments spect. Although the 6MWT and ACTIVLIM remained The estimated US $4 million needed to fund this study sensitive measures of decline for more severely affected was provided by the Jain Foundation. (www.jain- patients, timed function tests based on walking, including foundation.org) The Jain COS consortium would like to the 6MWT, are unsuitable once a patient loses ambula- thank the study participants and their families for their tion, and are thus limited in terms of clinical and research invaluable contribution. utility. The John Walton Centre Muscular Dystrophy Although we think the development of the LGMD- Research Centre is part of the MRC Centre for Neuro- specific NSAD motor performance measure provides a muscular Diseases (Grant number MR/K000608/1). valuable assessment tool previously lacking in dysferlinopathy, a limitation in the present investigation Author Contributions was the change to the scale mid-study. To address this M.J., M.K.J., L.E.R., M.E., A.B., P.G., S.P., J.W.D., issue, a detailed conversion plan was developed by expert K.J.J., D.X.B.G., E.S.C., A.P., M.C.W., C.P., T.S., physiotherapists; average decline per year estimated by M.M.Y., E.B., J.D.M., E.P., J.M., A.M., and V.S. con- GEE models (−1.7 points/year) was similar to mean tributed to study concept and design. M.K.J., L.P.L., annual changes of directly collected NSAD scores from L.A., R.M.T., J.F., K.R., T.D., L.B., I.P.H., S.H., C.S., year 2 to year 3 (−1.8). A.C., J.B.M., S.T., C.S., B.V., B.D.W., E.M., M.G., The present study further supports results reported U.M., and the Jain COS Consortium contributed to data previously for the first year of study follow-up.16 Annual acquisition and analysis. M.J., M.K.J., L.P.L., L.A., change scores estimated from GEE models controlling for R.M.T., L.E.F., K.R., T.D., U.M., A.M., and age were similar to median change scores reported previ- V.S. contributed to drafting the text and preparing the fig- ously for the outcome measures considered. The use of ures. Members of the Jain COS Consortium can be found GEE modeling here allowed us to directly assess differ- in Supplementary Table 2. ences in rates of disease progression, which may have both clinical and trial implications. Potential Conflicts of Interest A major strength of the present study was the avail- ability of a large, diverse, multinational cohort, with char- The authors declared no conflict of interest. acterized long-term follow-up that permitted assessment of longitudinal progression and trends previously unavailable. However, despite this large sample, certain patient groups References remained small given the rarity of the disease; for example, 1. Bushby K, Straub V. 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