Ulla Werlauff Methods to assess physical functioning - Danske ...

Assessments at impairment level
Gender and ages were recorded and reported in all studies. Influence of gender was calculated in
study IV. In study I, the patients’ age was used as cut points to describe characteristics in different
age groups and to calculate differences among young and old patients.
Antropometrics (study I)
Since all patients in study I were non-ambulant, height in meters was measured as full length of arm
span between finger tips by a flexible measuring tape [Hepper 1965, Miller 1992]. Weight was
recorded in kilos using a scale for lifts.
Measurement of dynamic muscle strength (study I, II, III)
Muscle strength was tested by manual muscle testing (MMT) based on the Medical Research
Council (MRC) method [1943]. MRC scores 0-5 were modified to a 0-10 score to make the scale
more sensitive according to the modification of Brooke et al. [1981]. Manual muscle testing of 38
muscle groups of the whole body was measured in study I, and based on our findings in this study,
we decided to focus on muscle strength of the upper limbs in study II, in which nine muscle groups
were measured. In study III, we calculated the change over time in seven muscle groups of the
upper limbs in patients with SMA II and III, and for SMA III also in six muscle groups of the lower
limb. All muscle tests were performed bilaterally. MRC score was calculated as percentage of
maximal possible score by the fraction used by Scott et al [1982]: MRC% = sum of graded scores x
100/ (number of muscle tested x 10).
The reliability of the manual muscle test increases when performed by a clinically experienced
evaluator and when followed by a standardized protocol [Cuthberth 2007, Escolar 2001]. Inter-rater
reliability is also improved when testing weak muscles and when tested by a limited number of
experienced evaluators [Kleyweg 1991, Florence 1992, Mahony 2009].
These criteria were all met in our studies: Patients with SMA II have very limited muscle strength
ranging from 1 to 3 on the MRC scale. All assessments were performed by one of four trained and
clinically experienced evaluator and training sessions were arranged over the years to ensure
consistency and agreement among evaluators. At the last training session, agreement among four
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