Background
Fetal alcohol spectrum disorder (FASD) is an umbrella term used to describe a combination of neurodevelopmental impairments and physical characteristics that result from prenatal alcohol exposure (PAE) [
1]. The prevalence in Canada is estimated to be 0.79% of the population, although few Canadian prevalence studies have been conducted [
2]. The severity of FASD varies with the frequency, timing, and amount of PAE [
3,
4] and while PAE is a required criterion for the diagnosis of FASD, not all individuals with PAE meet criteria for an FASD diagnosis [
5]. In addition to confirmed PAE,
Fetal alcohol spectrum disorder: a guideline for diagnosis across the lifespan (Canadian Guideline) requires evidence of pervasive brain dysfunction defined by severe impairment in at least 3 of 10 neuro-developmental domains [
5]. Diagnostic evaluation is completed by a multi-disciplinary team who conduct thorough developmental assessments, which include physical and neurological examination, to investigate pervasive brain dysfunction [
5].
Occupational and/or physical therapists are often included on diagnostic teams for the purpose of assessing the motor domain which include gross motor, fine motor and visual-motor integration skills [
5]. Gross motor skills use the large muscles of the body for balance, coordination, and strength to perform activities such as throwing, running and riding a bike. Fine motor skills use the small muscles of the hands for strength and dexterity to perform activities such as opening containers, drawing, and tying shoelaces. Visual motor skills use both the visual and motor systems combined (i.e., eye-hand coordination) to complete activities such as copying shapes and catching a ball. Difficulties with these motor skills can negatively impact day to day function (e.g. participation in gym, independence in dressing, and completing school work). It is well documented that motor skills are commonly impaired in children with PAE and FASD [
3‐
9], yet this area is not always evaluated in assessment for FASD diagnosis.
The Canadian Guideline [
5], lists a variety of motor assessment tools that are commonly used in FASD assessment for children aged 7–18 years including the Movement Assessment Battery for Children, Second edition (MABC-2) [
10], the Beery-Buktenica Developmental Test of Visual-Motor Integration, Sixth Edition (BeeryVMI-6) [
11], the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2) [
12] and the Rey Complex Figure Test (RCFT) [
13].
The Australian Guide to the diagnosis of FASD (Australian Guide) lists the same assessment tools as the Canadian Guideline with the exception of the RCFT [
13]. Other international FASD guidelines [
14‐
16] did not include lists of motor assessment tools for use in FASD diagnosis. Research investigating sensitivity and specificity of assessment tools for use in FASD diagnosis is lacking.
The Canadian Guideline recommends using either total motor scores or multiple subtest scores from standardized motor assessments for confirmation of motor impairment [
5]. However, it is unclear whether the use of total motor (fine and gross motor combined) or subtest scores (fine, gross and visual-motor separated) are more accurate. Recent literature suggests that fine and gross motor scores should be considered separately to support the diagnostic criteria for FASD, as they involve different neurodevelopmental areas and pathways [
3,
4,
6]. Individuals with FASD present with heterogeneous impairments that may affect some areas of fine motor skills, gross motor skills, or both [
3,
4,
6]. Recent literature supports the use of subtest scores in motor evaluation for FASD, to provide a more specific profile of motor impairments [
17‐
19]. Further, complex gross and fine motor skills that involve multiple neural pathways are more likely to be impaired after PAE than basic motor skills [
3,
6,
7,
20].
The Canadian Guideline uses 2 or more standard deviations below the mean (−2SD), as a cut-off to indicate a severe impairment in all of the neuro-developmental domains [
5]. This cut-off is the standard for defining a severe deficit for many diagnoses, and is used in other scales and guidelines including the Diagnostic and Statistical Manual of Mental Disorders [
21]. However, this cut-off is considered conservative and may not identify all children who have significant impairments. The -2SD cut-off was reviewed during the latest update of the Canadian Guideline. While a cut off of − 1.5 SD was considered, [
5] it was decided that there was no empirical data to support the change [
5] and there was concern about over-identification. Research in this area is needed to investigate which cut-off score is the most accurate (i.e., optimizing the balance between sensitivity and specificity).
Existing international FASD diagnostic guidelines [
5,
13‐
16] vary considerably in regards to cut-off scores and use of subtests (Table
1). Cut off scores range from -2SD to −1SD (2nd to 16th percentile), indicating a wide variance in accepted impairment levels [
5,
13‐
16]. Direct comparisons between these guidelines are difficult due to variability in the diagnostic criteria. The Australian Guide [
13] and the Canadian Guideline [
5] are unique in their use of subtests, though the terminology differs making direct comparison difficult.
Table 1
Comparison of FASD guideline features that relate to the neurodevelopmental assessment
Canadian Guideline (2016) [ 5] | FASD with Sentinel Facial Features, FASD without Sentinel Facial Features | -2SD | Composite score or multiple subtest scores | Severe impairment in 3 or more of 10 neurodevelopment domains |
Australian Guide (2016) [ 13] | FASD with 3 Sentinel Facial Features, FASD with < 3 Sentinel Facial Features | -2SD | Composite score or 1 or more major subdomain scores | Severe impairment in at least 3 neurodevelopmental domains |
Updated Clinical Guidelines (2016) [ 15] | FAS, Partial FAS, ARND, ARBD | -1.5SD | Not specified | Impairment in at least 1 neurodevelopmental domain |
University of Washington 4 Digit Code (2004) [ 14] | FAS, Partial FAS, ARND | -2SD | Not specified | Severe dysfunction in 3 or more domains of function |
CDC Diagnostic Guidelines (2004) [ 16] | FAS | -1SD | Not specified | Deficit in 3 or more functional domains |
In order to clarify diagnostic criteria regarding motor impairment in FASD, the following objectives of the study were identified:
1)
Determine the diagnostic accuracy of motor assessment tools and subtests listed in the Canadian Guideline;
2)
Determine if a severe motor impairment can be more accurately identified by using multiple subtest scores or total motor scores;
3)
Investigate which cut-off is most accurate in identifying a motor domain impairment when assessing for FASD.
Discussion
The Canadian Guideline for diagnosis of FASD lists the BOT-2, MABC-2 and BeeryVMI-6 for motor assessment in children with suspected FASD [
5]. The findings of this study indicate the BOT-2SF is not an accurate assessment tool for evaluating motor impairment in this population, identifying only 2% of children with FASD as having a severe motor impairment. Since 2% is the prevalence expected in the general population, one would expect the rate would be higher among children and youth with FASD. We suggest that use of the BOT-2SF in FASD diagnostic assessment should be reconsidered. Appropriateness of the complete and short forms should be considered separately, as our study did not investigate the BOT-2 complete form. There is some evidence that the complete form is able to detect motor impairments in this population as it was previously found to identify 9.5% of children with FASD as having a severe motor impairment [
4]. The BeeryVMI-6 identified 16% of children with FASD with a severe motor impairment, suggesting it has clinical value. We found the MABC-2 to have the highest accuracy, identifying 30% of children with FASD as having a severe motor impairment. It may have identified more children because it assesses more complex motor skills (e.g., constructing a triangle using nuts and bolts and hopping on one leg in a specific pattern) which require coordination of multiple motor sub-systems [
7]. The literature suggests that complex motor skills are more often affected than basic motor skills in individuals with FASD [
6,
7].
The Canadian Guideline recommends the use of total motor or multiple subtest scores at − 2 SD to provide evidence of a severe motor impairment [
5], resulting in a more conservative diagnostic criteria compared to other guidelines [
15,
16]. The BeeryMC subtest was found to have the highest sensitivity at -2SD (0.38), which supports its use in FASD diagnostic assessment. Our findings are in line with other research which also detected high levels of motor impairment in this population using the BeeryMC subtest [
17]. Previous research found the -2SD cut-off to be too restrictive and evaluated prevalence of motor impairment at -1SD (16th percentile cut-off) in children with FASD [
17‐
19]. Our results demonstrated that although the total motor score of the MABC-2 had the highest accuracy using current recommendations, this value is still low. Our results suggest that diagnostic accuracy for the motor domain is improved when using the cut-off score of − 1.5 SD, particularly using the BeeryMC subtest. This altered criterion resulted in correctly identifying more children as having a motor impairment without increased false identification, resulting in overall greater accuracy compared to current guideline recommendations. This finding highlights that the recommendations for motor assessment in the current Canadian Guideline do not have sufficient statistical accuracy to identify motor impairment. Our results demonstrated that while sensitivity increased further at -1SD (16th percentile), optimal balance with specificity was not attained which could result in over-identification. Further investigation of the inclusion of single subtests and/or use of a -1.5 SD cut-off level in the Canadian Guideline is warranted to confirm these findings.
Prevalence rates of fine and gross motor deficits among children with FASD and PAE support that motor skills should regularly be assessed when considering an FASD diagnosis. In a meta-analysis of children with moderate to high PAE, gross motor skills were found to be 2.9 times more likely to be impaired [
3] and significant fine motor impairments are also reported in children with PAE [
6,
8,
9]. Our findings of the prevalence of both fine and gross motor impairments and functional difficulties found in children with PAE and FASD were consistent with these studies. Involvement of both occupational therapy and physical therapy is warranted as part of a multi-disciplinary team to provide input towards diagnosis and recommendations in FASD diagnostic clinics.
Limitations
This study had several limitations. PAE was reported by mothers retrospectively, which may have led to recall bias. However, PAE was also confirmed, when possible, by other reliable sources as listed in the Canadian Guideline. In addition, activity of daily living abilities were based on parental report and clinician observation, and not a standardized, norm-referenced assessment tool. Clinicians were not masked to PAE, as all children in our study had PAE (i.e. they are referred to our clinic when FASD is suspected due to PAE). However, knowledge of FASD diagnosis was unknown at the time of assessment.
Acknowledgements
The authors would like to sincerely thank Sandra Taylor, Kathryn Graff, Lorraine McPhee, Crystal Klassen, Tara Lynn Kruger and Kristen Skagen from the Camrose Pediatric Specialty Clinic for assistance with data collection and clinical expertise for this study.