Rationale: Children with Cerebral Palsy (CP) experience limitations in motor activities and participation in the community, predominantly caused by impairments in muscle function. Aside from abnormal posturing due to spasticity, muscle weakness can significantly contribute to impaired muscle function and there is increasing evidence that muscle weakness significantly impairs upper limb motor function and ability to perform manual tasks in children with CP. Studies in the last decade have shown that muscle weakness, not spasticity, is the greatest limiting factor of motor function in children with CP. Furthermore, there is increasing evidence that the strength in the upper extremities of children with CP is less compared to their typically developing peers (TDP). A systematic review focused on the psychometric properties of strength measurement instruments has shown that the number of studies investigating psychometric properties of strength measurement instruments is limited and that the methodological quality of these studies is low. Aim: The present study aims to investigate the reproducibility of the following three isometric strength measurements in the upper extremity of children and adolescents with unilateral CP as well as in TDP: Hand Held Dynamometry (HHD), pinch and grip strength using the E-link system and functional strength. To study to which extent upper extremity strength, both in the affected side and the non-affected side, differs from the strength in the upper extremities of TDP, these measurements will also be performed by children without neurological problems. Study Design: A cross-sectional study in which the reproducibility of three strength measurement instruments, i.e. HHD, E-link and Functional strength, will be investigated in children and adolescents with unilateral CP and TDP. Population: Children with unilateral spastic CP (with perinatal acquired hypoxic ischemic incidents), aged 7 to 18 years, Manual Ability Classification System (MACS) levels I-III, who are mentally able to perform the measurements will be included and TDP. Outcome measures: The most important psychometric property in strength measurement instruments is reproducibility. Reproducibility will be investigated using the following factors: Intraclass Correlation Coefficient (ICC), Limits of Agreement (LOA), Standard Error of Measurement (SEM) and the Smallest Detectable Difference (SDD). Reference values will be determined using the Generalised Additive Models for Location, Scale, and Shape (GAMLSS) method.
Study Type
OBSERVATIONAL
Enrollment
370
inter-rater reliability and test-retest reliability
Adelante
Hoensbroek, Limburg, Netherlands
Tolbrug
's-Hertogenbosch, Netherlands
Klimmendaal
Arnhem, Netherlands
Revant
Breda, Netherlands
Libra Zorggroep
Eindhoven, Netherlands
Rijnlands Revalidatie Centrum
Leiden, Netherlands
St. Maartenskliniek
Nijmegen, Netherlands
Sophie Revalidatie
The Hague, Netherlands
Viecuri Medical Centre
Venlo, Netherlands
Inter-rater and test-retest reliability of HHD expressed as ICC value
The intraclass correlation coefficient (ICC) is commonly used in the assessment of consistency or reproducibility of quantitative measurements made by different observers measuring the same quantity.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
Inter-rater and test-retest reliability of E-link expressed as ICC value
The intraclass correlation coefficient (ICC) is commonly used in the assessment of consistency or reproducibility of quantitative measurements made by different observers measuring the same quantity.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
Inter-rater and test-retest reliability of functional strength measurements expressed as ICC value
The intraclass correlation coefficient (ICC) is commonly used in the assessment of consistency or reproducibility of quantitative measurements made by different observers measuring the same quantity.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
Inter-rater and test-retest agreement of HHD expressed as Limits of Agreement
The limits of agreement (LOA) provide insight into how much random variation may be influencing the ratings. If the raters tend to agree, the differences between the raters' observations will be near zero. If one rater is usually higher or lower than the other by a consistent amount, the bias (mean of differences) will be different from zero. If the raters tend to disagree, but without a consistent pattern of one rating higher than the other, the mean will be near zero. Confidence limits (usually 95%) can be calculated for both the bias and each of the limits of agreement.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
Inter-rater and test-retest agreement of E-Link expressed as Limits of Agreement
The limits of agreement (LOA) provide insight into how much random variation may be influencing the ratings. If the raters tend to agree, the differences between the raters' observations will be near zero. If one rater is usually higher or lower than the other by a consistent amount, the bias (mean of differences) will be different from zero. If the raters tend to disagree, but without a consistent pattern of one rating higher than the other, the mean will be near zero. Confidence limits (usually 95%) can be calculated for both the bias and each of the limits of agreement.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
Inter-rater and test-retest agreement of functional measurements expressed as Limits of Agreement
The limits of agreement (LOA) provide insight into how much random variation may be influencing the ratings. If the raters tend to agree, the differences between the raters' observations will be near zero. If one rater is usually higher or lower than the other by a consistent amount, the bias (mean of differences) will be different from zero. If the raters tend to disagree, but without a consistent pattern of one rating higher than the other, the mean will be near zero. Confidence limits (usually 95%) can be calculated for both the bias and each of the limits of agreement.
Time frame: t1 (base-line) and t1 (2-3 weeks later)
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