Application of the Gross Motor Function Measure-66 (GMFM-66) in Dutch clinical practice: a survey study

The Gross Motor Function Measure-66 (GMFM-66) is an observational clinical measure designed to evaluate gross motor function in children with Cerebral Palsy (CP). It is a shortened version of the GMFM-88. A free computer program, the Gross Motor Ability Estimator (GMAE), is required to calculate the interval level total score of the GMFM-66. The aim of this study was to explore pediatric physiotherapists' experiences with the GMFM-66 and application of the measure in Dutch clinical practice.

An explorative cross-sectional survey study was performed. Dutch pediatric physiotherapists were invited to complete an online survey. Data-analysis merely consisted of frequency tables, cross-tabulations and data-driven qualitative analysis.

Fifty-six respondents were included in the analysis. In general, the therapists expressed a positive opinion on the GMFM-66, in particular regarding its user-friendly administration and benefits of the GMAE. The majority of questions revealed that therapists deviate from the guidelines provided by the manual to a greater or lesser extent though. The most worrisome finding was that 28.8% (15/52) of the therapists calculate the total score of the GMFM-66 using the score form of the GMFM-88 instead of the GMAE.

The consequences of the high number of therapists who stated that they calculate the total score of the GMFM-66 with the GMFM-88 score form are far-reaching; it has a misleading impact on the opinion of rehabilitation teams and parents on the development of the child, on decision-making in rehabilitation, and ultimately on the development of the child.

Information currently available on psychometric properties, motor growth curves and percentiles cannot be generalized to clinical practice in the Netherlands, as they were generated in highly controlled testing conditions, which do not hold in clinical practice.