New pharmacological and therapeutic interventions during the past three decades contributed to a longer survival of people with Muscular Dystrophy (MD).1,2 Therefore, the number of non-ambulatory people with upper limb dysfunction has increased, as has the demand for more accurate assessment protocols.2 The lack of instruments to quantify upper limb functional impairments is a challenge faced by health professionals who work with people with MD.3

Some tests evaluate upper limb motor function in MD or specifically in Duchenne Muscular Dystrophy (DMD), but none evaluate timed performance. The Brooke Scale classifies upper limb active movements in DMD and Becker muscular dystrophy (BMD) with a six-point scale.4 However, Brooke Scale did not quantify functional performance. Dimension 3 of the Motor Function Measure (MFM) has six items referring to upper limb function.5 However, in people with less severe MD, the Motor Function Measure might not detect early stage disabilities and might show scoring ceiling effects. ABILHAND questionnaire points to the subject's perception of difficulty performing activities of daily living involving upper limb functions.6 ABILHAND classifies the tasks as fully or partially performed, or not performed at all. Upper limb performance is inferred according to the subject's report and not specifically tested. The Performance of Upper Limb Test assesses shoulder, elbow and hand functions in DMD. Four items of this scale measure timed performance only as additional qualitative information, with no impact on the total score.7

Timed performance is an accurate functional measure in people with DMD.8,9 This evaluation strategy has been used in DMD for functional performance of the lower limbs, for example, the six-minute walk test,10 in the North Star Ambulatory Assessment11 and in the Functional Evaluation Scale for Duchenne Muscular Dystrophy.12 The Jebsen–Taylor Test evaluates upper limbs timed performance in seven subtests that represent everyday activities, such as writing, turning cards, picking up objects or beans with a spoon, stacking checkers, and picking up light or heavy cans. The subtests assess the distal and proximal upper limb performance. Materials are standardized and have low-cost. Assessment requires about 35min.13

The Jebsen–Taylor Test was translated and cross-culturally adapted into Brazilian Portuguese and showed excellent intra and inter-rater reliability in people with stroke, cerebral palsy and Parkinson disease.14–17 Scores are determined by timed performance on functional activities, which differentiates this test from others. The test has normative data for healthy people18 and was previously applied in boys with DMD and considered as a sensitive method to assess DMD progression. However, measurement properties were not tested and people with other types of MD were not evaluated.19

We hypothesized that Jebsen–Taylor Test would generate accurate measures20 of upper limb motor function in people with MD. First, we aimed to analyze the reliability, internal consistency and validity of Jebsen–Taylor Test in people with Muscular Dystrophy. Second, we aimed to describe and classify upper limb timed performance in people with MD.

Sample characteristics are displayed in Table 1.

Participants with severe upper limb disability (scored as 7–8 on the Vignos Scale) showed difficulty during subtests 3 and 4, which required inserting objects or beans into the can. In these cases, subtests 3 and 4 were considered complete when six small objects or five beans were placed on the table, near the can.

The present study described upper limb timed performance and analyzed the reliability, internal consistency and validity of the Jebsen–Taylor Test in people with Muscular Dystrophy. The good measurement properties found indicated that timed performance could be used to measure the progression of muscle weakness14 and upper limb motor function in participants with MD. The Jebsen–Taylor Test was previously applied in people with DMD by Hiller and Wade,19 who identified that short times were indicators of upper limb muscles preservation, internal consistency, reliability and validity. The times on the Jebsen–Taylor Test were correlated to the Performance of Upper Limb Module scores. Considering that the Performance of Upper Limb Module is the standard assessment for upper limb function, the Jebsen–Taylor Test could be considered valid for measuring timed performance. A previous pilot study also found a strong correlation between the Jebsen–Taylor Test and Performance of Upper Limb Module.31

The Jebsen–Taylor Test showed high ICC values, which reflected high agreement between raters. For ICC calculation, the variation between participants was divided by the total variation, which included the variation between participants and the not intended variation (i.e. “error”). As the study design involved the evaluation of time by means of filming, the authors believe the error was lower. The coefficients of variation varied from 0.59 to 1.42. Many high values were found to be due to the variation of the performance of each participant and not due to the variation of the instrument or rater. Even though the participants showed high variability in the tests, the raters had high agreement and the test showed good internal consistency.

Participants could perform all subtests of the Jebsen–Taylor Test and did not demonstrate any pain or discomfort during the procedures. Subtest 1 (i.e. writing) was previously considered unsuitable for people with DMD, because it might be influenced by cognitive and/or learning difficulties, often associated with MD, mainly DMD.19 The present study showed that this activity could be used with people with DMD (and other types of MD), as long as the subjects could read and write. The assessment of writing, which has motor and cognitive demands, is important for better understanding of upper limb function. Subtests 3 and 4 required adaptations for people with severe upper limb disability (i.e. scored as 7–8 on the Vignos Scale). They were asked to place the six small objects or the five beans on the table, near the can, instead of inserting objects or beans into the can.

All DMD participants and non-ambulatory MD participants showed increased times to perform subtests of the Jebsen–Taylor Test in comparison with the normative data.18 However, ambulatory MD participants exhibited similar times when performing the non-dominant and the dominant attempts of subtests 2, 3, 5 and 6 compared to controls. DMD non-ambulatory participants showed higher times in turning over cards, picking up small objects, simulating feeding, and picking up large light objects. For the other MD type groups, non-ambulatory participants showed longer times in turning over cards, picking up small objects, stacking checkers, and picking up large light objects. Therefore, these tasks were more sensitive in detecting differences in upper limb performance, as they showed increased times even in less severe participants. Very few biomarkers involving upper limb functions are currently available for decision making in research and clinical practice. The description of timed performance and the establishment of performance categories could help clinicians develop clinical treatment strategies. Quantitative information involving motor function is useful for monitoring MD progression.

Subtests instructions did not determine specific upper limb movements or positions, just the task aims. Compensatory movements were observed, because muscle weakness impairs upper limb performance and restricts movements, which elicits the selection of new motor strategies.32,33 Compensatory movements increase as motor function decreases with MD progression.33,34 However, a high number of compensatory movements could result in variability in performance, not only in people with DMD, but also with other types of MD. Our sample showed high standard deviations in all subtests, which exemplified such variability. Besides, subtests involved gripping and holding and required proximal stability. Functional motor loss in MD usually occurs from proximal to distal and the lack of proximal stability might impair upper limbs timed performance.9 Future studies should evaluate whether some proximal upper limb assistance would help performance on the Jebsen–Taylor Test in people with MD.

The present study has some limitations. It was not possible to compare timed performance between people with MD and healthy participants due to the absence of a control group. However, the normative data for the Jebsen–Taylor Test was available in the literature18 for such comparisons and analyses. Another important point is that the Jebsen–Taylor Test should not be used to evaluate people with severe upper limb impairment (e.g. Vignos score of 9) because of ceiling effects. Participants scored as 9 by Vignos would have much difficulty performing the tasks and show very long times, which could be improper in clinical practice. Additionally, people with severe upper limb disability might need adaptations to enable them to pick up small common objects and to simulate feeding testing. Finally, the lack of compensatory movement assessment must be mentioned. The description of compensatory movements could contribute to a better understanding of functional independence. Many people with MD employ compensatory movements to perform tasks that become difficult as muscle weakness progresses.10,33

The Jebsen–Taylor Test is a reliable and valid method for evaluating upper limb performance in people with MD (DMD, LGMD, BMD, MD and FSH). The description and classification of timed performance provides normative data for clinical practice and research. Timed performance is a reliable measure for upper limb function in this population.

The authors declare no conflicts of interest