Is one trial enough for repeated testing? Same-day assessments of walking, mobility and fine hand use in people with myotonic dystrophy type 1

Walking test outcomes in adults with genetic neuromuscular diseases: a systematic literature review of their measurement properties

INTRODUCTION

Neuromuscular diseases (NMDs) include a large group of heterogeneous diseases. NMDs frequently involve gait disorders, which affect quality of life. Several walking tests and tools have been described in the literature, but there is no consensus regarding the use of walking tests and tools in NMDs or of their measurement properties for walking outcomes. The aim of this review is to present an overview of walking tests, including their measurement properties when used in adults with inherited or genetic NMDs. The aim is to help clinicians and researchers choose the most appropriate test for their objective.

EVIDENCE ACQUISITION

A systematic review was conducted after consulting MEDLINE (via PubMed), EMBASE, Science direct, Google Scholar and Cochrane Central Register of Controlled Trials databases for published studies in which walking outcome measurement properties were assessed. The validity, reliability, measurement error and responsiveness properties were evaluated in terms of statistical methods and methodological design qualities using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines.

EVIDENCE SYNTHESIS

We included 46 studies in NMDs. These studies included 15 different walking tests and a wide variety of walking outcomes, assessed with six types of walking tools. Overall, the 6MWT was the most studied test in terms of measurement properties. The methodological design and statistical methods of most studies evaluating construct validity, reliability and measurement error were "very good." The majority of outcome measurements were valid and reliable. However, studies on responsiveness as minimal important difference or minimal important change were lacking or were found to have inadequate methodological and statistical methods according to the COSMIN guidelines.

CONCLUSIONS

Most walking outcomes were found to be valid and reliable in NMDs. However, in view of the growing number of clinical trials, further studies are needed to clarify additional measurement properties.

Outcome measures frequently used to assess muscle strength in patients with myotonic dystrophy type 1: a systematic review

Measurement of muscle strength is fundamental for the management of patients with myotonic dystrophy type 1 (DM1). Nevertheless, guidance on this topic is somewhat limited due to heterogeneous outcome measures used. This systematic literature review aimed to summarize the most frequent outcome measures to assess muscle strength in patients with DM1. We searched on Pubmed, Web of Science and Embase databases. Observational studies using measures of muscle strength assessment in adult patients with DM1 were included. From a total of 80 included studies, 24 measured cardiac, 45 skeletal and 23 respiratory muscle strength. The most common method and outcome measures used to assess cardiac muscle strength were echocardiography and ejection fraction, for skeletal muscle strength were quantitative muscle test, manual muscle test and maximum isometric torque and medical research council and for respiratory muscle strength were manometry and maximal inspiratory and expiratory pressure. We successfully gathered the more consensual methods and measures to evaluate muscle strength in future clinical studies, particularly to test muscle strength response to treatments in patients with DM1. Future consensus on a set of measures to evaluate muscle strength (core outcome set), is important for these patients.

Intrarater reliability and validity of outcome measures in myotonic dystrophy type 1

OBJECTIVE

To investigate intrarater reliability and concurrent and construct validity of muscle strength, balance, and functional mobility measures in individuals with noncongenital myotonic dystrophy type 1 (DM1).

METHODS

Seventy-eight adults with noncongenital DM1 participated in visit 1, and 73 of the them participated in visit 2 separated by 1 to 2 weeks. The assessments consisted of muscle strength tests with handheld dynamometry (HHD) and stationary dynamometry in the lower limb. The balance tests consisted of the step test, Timed Up and Go test, feet-together stance, tandem stance, 1-leg stance, and modified Clinical Test of Sensory Integration and Balance on a balance platform. The functional mobility tests consisted of the 10-m walk test (10mWT) and 10-times Sit-to-Stand test.

RESULTS

The HHD and stationary dynamometry had sufficient intrarater reliability for most muscle groups on a group (SEM_% ≤15%) and individual (minimal detectable difference [MDD_95%] ≤30%) level, but the HHD was most reliable. Stationary dynamometry measured a higher torque than HHD for all extensor muscles, but for single individuals, none of the devices were favored. Overall, intrarater reliability and validity were sufficient only for the dynamic balance tests, not the static balance tests. Both functional mobility tests were sufficiently reliable and valid, but the 10mWT was most reliable.

CONCLUSION

Overall, HHD is recommended as a reliable and valid tool for single individuals and for flexor muscles on a group level. For balance assessments, the dynamic balance tests are recommended as the most valid and reliable balance tests. Both functional mobility tests are recommended for valid and reliable outcomes, but the 10mWT was superior for reliability.

Strength-training effectively alleviates skeletal muscle impairments in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a multisystemic disease characterized by progressive muscle weakness. The aim of this project is to evaluate the effects of a 12-week lower limb strength training program in 11 men with DM1. Maximal isometric muscle strength, 30-second sit-to-stand, comfortable and maximal 10-m walk test (10 mwt) were evaluated at baseline, 6 and 12 weeks, and at 6 and 9 months. The one-repetition maximum strength evaluation method of the training exercises was completed at baseline, 6 and 12 weeks. Muscle biopsies were taken in the vastus lateralis at baseline and 12 weeks to evaluate muscle fiber typing and size (including atrophy/hypertrophy factors). Performance in strength and functional tests all significantly improved by week 12. Maximal isometric muscle strength of the knee extensors decreased by month 9, while improved walking speed and 30 second sit-to-stand performance were maintained. On average, there were no significant changes in fiber typing or size after training. Further analysis showed that individual abnormal hypertrophy factor at baseline could explain the different changes in muscle size among participants. Strength training induces maximal isometric muscle strength and lasting functional gains in DM1. Abnormal hypertrophy factor could be a key component to identify high and low responders to hypertrophy in DM1.

Analysis of the functional capacity outcome measures for myotonic dystrophy

Objectives

Defining clinically relevant outcome measures for myotonic dystrophy type 1 (DM1) that can be valid and feasible for different phenotypes has proven problematic. The Outcome Measures for Myotonic Dystrophy (OMMYD) group proposed a battery of functional outcomes: 6‐minute walk test, 30 seconds sit and stand test, timed 10 m walk test, timed 10 m walk/run test, and nine‐hole peg test. This, however, required a large‐scale investigation,

Methods

A cohort of 213 patients enrolled in the natural history study, PhenoDM1, was analyzed in cross‐sectional analysis and subsequently 98 patients were followed for longitudinal analysis. We aimed to assess: (1) feasibility and best practice; (2) intra‐session reliability; (3) validity; and (4) behavior over time, of these tests.

Results

OMMYD outcomes proved feasible as 96% of the participants completed at least one trial for all tests and more than half (n = 113) performed all three trials of each test. Body mass index and disease severity associate with functional capacity. There was a significant difference between the first and second trials of each test. There was a moderate to strong correlation between these functional outcomes and muscle strength, disease severity and patient‐reported outcomes. All outcomes after 1 year detected a change in functional capacity except the nine‐hole peg test.

Conclusions

These tests can be used as a battery of outcomes or independently based on the shown overlapping psychometric features and strong cross‐correlations. Due to the large and heterogeneous sample of this study, these results can serve as reference values for future studies.

Relationships between Lower Limb Muscle Strength Impairments and Physical Limitations in DM1

BACKGROUND

Although adult and late-onset DM1 phenotypes DM1 present distinct lower limb weaknesses portraits, resulting physical limitations have never been described separately for each phenotype.

OBJECTIVE

To characterize the lower limb weaknesses and physical limitations among the DM1 adult and late-onset phenotypes separately and to document the contribution of weaknesses on mobility to optimize the management of this population.

METHODS

The strength of four muscle groups among 198 participants was quantified. Participants were categorized according to the severity of their muscular involvement using the Muscular Impairment Rating Scale (MIRS). Physical limitations were assessed using the Timed up-and-go (TUG), Berg Balance Scale (BBS) and 10 meters comfortable walking speed (10MWT). Multiple linear regressions were performed to identify the contribution of each muscle group to the mobility tests scores.

RESULTS

Late-onset demonstrated less weakness and physical limitations (p < 0.001 - 0.002) than the adult phenotype, but 21.9-47.5% of participants with this phenotype showed mobility scores below reference values. Physical limitations were observed in the first two MIRS grades (37.5-42.1% of the participants) for the TUG and 10MWT. Ankle dorsiflexors and knee extensors were the two muscle groups that showed the strongest relationships with mobility scores.

CONCLUSION

Although less impaired, the late-onset phenotype shows significant lower limb muscle weakness associated with physical limitations. The surprising presence of quantitative lower limb muscle weakness in the first two MIRS grades needs to be considered when using this scale. Both ankle dorsiflexors and knee extensors appear to be good indicators of physical limitations in DM1.

Validation of the Nine Hole Peg Test as a measure of dexterity in myotonic dystrophy type 1

We aimed to validate the Nine Hole Peg Test as a measure of dexterity in myotonic dystrophy type 1 (DM1). Fifty patients with adult-onset, genetically confirmed DM1 were evaluated by Nine Hole Peg Test and re-evaluated at one week. Myotonia was not a limiting factor. The first test was compared with that performed by normal subjects (n = 28). Contextually, patients underwent handgrip and three-finger pinch assessments by handheld dynamometer. The Nine Hole Peg Test showed high intra-rater and inter-rater reliability in DM1 [ICC 0.86/0.83 for dominant and 0.90/0.88 for non-dominant hand, respectively]. Inverse correlation with handgrip and pinch strength values (r = -0.4; p < 0.01) and direct correlation with Muscular Impairment Rating Scale (r = 0.4; p < 0.01) were found for both DH and NDH. The test was able to differentiate severe DM1 patients, stratified by extent of muscle impairment, from mildly affected and normal controls, with a sensitivity of 97% and 95% for dominant hand and non-dominant hand, respectively (p < 0.0001). In conclusion, we showed that the Nine Hole Peg Test is a reliable, valid and sensitive test of dexterity in DM1, and that it can be considered as a candidate outcome measure to monitor natural history of disease and, possibly, therapeutic response in clinical trials.