ValidatioN of the caNadiaN NormS for the alberta iNfaNt motor Scale for iNfaNtS iN a SoUth africaN regioN aged foUr to twelVe moNthS; a Pilot StUdy

Correspondence Author: Mrs Marlette Burger Division of Physiotherapy, Department of Interdisciplinary Health Science, Faculty of Medicine and Health Science, Stellenbosch University, PO Box 19063, Tygerberg, 7505, Cape Town South Africa Email: mbu@sun.ac.za AbSTrAcT: The Alberta Infant motor scale (AIms) is a norm referenced, performance based, observational tool that assesses motor development in infants from birth up to the age of eighteen months. The AIms has been widely used by researchers and clinicians around the world, but only a few attempts were made to validate the Canadian norms for infants residing outside Canada. The purpose of the study was to validate the Canadian norms of the AIms for infants within the Cape metropolitan region, south Africa. A longitudinal study was conducted using the AIms to assess the gross motor development of 67 healthy full term infants at 4, 8 and 12 months respectively. At 4 months the mean percentile ranking was significantly higher than the Canadian norm (p=0.01), while no statistical significant differences were found at 8 and 12 months of age. The AIms is a valid assessment tool for healthy infants aged 8 and 12 months within the Cape metropole, south Africa. The infants at four months of age scored higher than the Canadian norm. Further validation which incorporate larger, random samples are required to enable generalisation of the findings for the South African infant population.

to the age of eighteen months (Piper & Darrah, 1994).Spittle et al (2008) concluded in their systematic review of the clinimetric properties of nine infant neuromotor assessments tools that the AIMS demonstrated the strongest psychometric properties and the best clinical utility.The AIMS is the only infant motor assessment tool that eva luates the qualitative aspects of the infants' acquired gross motor skills as well as the functional aspects of gross motor development (Majnemer & Snider 2005).
The AIMS has sound psychometric properties, is extremely cost effective and has been widely used by researchers and clinicians around the world (Valentini & Saccani, 2012;Uesugi et al, 2008), but after an extensive lite rature search, only two attempts to validate the Canadian norms for infants residing outside Canada were found (Syrengelas et al 2010;Fleuren et al 2007a).The most recent and, so far,

INtRODuCtION
Information on the normal gross motor skills in a healthy population is impor tant since normative data provides a benchmark for health professionals to evaluate deviations from the norm and to provide early intervention (Piper & Darrah 1994;Mayson et al 2007).The early identification of infants with gross motor delays necessitates a reli able discrimination tool that has been standardized on a normative sample representative of the population (Mayson et al 2007).In Canada, normal referenced values for gross motor development has been established in young infants and the Alberta Infant Motor Scale (AIMS) was developed in the early 1990's by Piper & Darrah (1994) to assist with the motor assessment of young infants from birth through to independent walking.The AIMS is a norm referenced, per formance based, observational measure that is used to record spontaneous move ment abilities of infants from birth up largest study conducted on 424 healthy full term Greek infants, found that except for the 23 month age group the mean AIMS score did not differ significantly between Greek and Canadian infants (Syrengelas et al 2010).Fleuren et al (2007a) assessed the motor performance of a 100 full term Dutch infants, aged 0 12 months, and found that 75% of the Dutch infants scored below the 50 th percentile and concluded that new AIMS test reference values needs to be established for Dutch children.Fleuren et al (2007a) was criticized for using a small sample (Haastert et al 2007), but argued that normative data should be applicable to small or large sample sizes (Fleuren et al 2007b).
The AIMS can easily be used in SouthAfrican government hospitals, clinics as well as rural settings since it does not require extensive training, expensive equipment or a large venue to assess the infants (Piper & Darrah 1994), however, it is not known whether the AIMS norms are appropriate for South African infants from different cul tural and socioeconomic backgrounds.Rosenbaum et al (1990) and Mayson et al (2007)cautioned against the inter pretation of results from discriminative motor developmental assessment tools on a population that is not the same as that on which it was validated until there is sufficient information regarding the appropriateness of comparisons amongst children of different ethnic origins.The purpose of the study was to ascertain the crosscultural validity of the Canadian norms of the AIMS for infants aged four to twelve months within the Cape Metropolitan region.This research pro ject served as a preliminary study for a future AIMS validation study on a larger sample of infants from all socio economic and ethnic groups within the Western Cape, South Africa.

Instrumentation
The AIMS consists of 58 items which measure three key components of motor control namely weight bearing, postural alignment and antigravity movement in the following four positions: prone (21 items), supine (9 items), sitting (12 items) and standing (16 items).Scoring entails a dichotomous option for each of the 58 items, scored as "observed" (one point) or "not observed" (no points).The sum of total raw scores, ranging from 0 to 58, can then be converted into an agebased percentile ranking according to the normative data in the manual (Piper & Darrah, 1994).The reliability and validity of the AIMS have been well established and reported in the literature (Piper & Darrah 1994;Jeng et al 2000;Darrah et al 1998;Blanchard et al 2004;Uesugi et al 2008).

Assessment of the video recordings
The principle researcher, who received training in administrating and scoring of the AIMS, assessed and scored the infants motor capabilities while view ing the video clips directly after each of the assessments.In order to determine the interrater reliability a random sub sample of 80% of each age group (4, 8 and 12 months) was assessed and scored by a second researcher (MB) with 18 years experience in the assessment and treatment of paediatric patients.Scoring was administrated exactly as specified in the AIMS administrative guideline manual (Piper & Darrah, 1994).

Statistical analysis
The infants' demographic data and their raw scores and percentile rankings were entered on an Excel spreadsheet.For interrater reliability, the intraclass cor relations (ICC) were calculated.For comparison of percentile ranks against a fixed 50% percentile, onesample ttests were conducted.Mixed model repeated measures ANOVAs with post hoc Bonferreni analyses were done to compare 4, 8 and 12month rankings, taking into account gender and the clinic from which the infants came.The mixed model approach does not require complete measurements over all time points for the subjects.Thus, all data time points were included in the mixed physiotherapist and/or medical doctor screened infants and only healthy full term infants with a typical motor deve lopment were included.The following exclusion criteria applied: infants born preterm (< 37 weeks gestation); birth weight of < 2500gram; infants exposed to and/or infected by HIV; infants with congenital and/or genetic disorders; infants using baby walkers as this may influence the development of milestones such as independent sitting and crawl ing (Burrows & Griffiths 2002;Garret et al 2002) and infants who were hos pitalized for more than 25% of their lives (since prolonged hospitalization could temporarily delay gross motor development).Ethics approval was pro vided by the Stellenbosch University's Ethics Committee for Human Research (Ethics number: N07/09/196) and writ ten informed consent was also obtained from the parents / legal guardians of the infants who participated in the study.

Method of data collection and procedure
A longitudinal study was conducted and incorporated three AIMS assessments opportunities to assess all infants at 4, 8 and 12 months old respectively.At both Baby Well Clinics, the assessments took place in a private room with a 1x1 metre padded mat, toys, a low table and a plinth.The infants were dressed lightly and comfortably to avoid restriction of movements.A digital video camera was used to record the infants' gross motor repertoire in four different posi tions, namely prone, supine, sitting and standing.The AIMS does not require the assessor to handle the infant or to facilitate movement (Piper & Darrah, 1994), but some infants were encour aged and prompted with toys to move in and out of the prone, supine, sitting and standing position.Testing procedures for the AIMS took approximately 1520 minutes per infant, part of which was used for the infant to adapt to its sur roundings.If the infant started crying, the video recording was temporarily interrupted to allow the infant to be con soled.If the infant did not settle down the mother was asked to bring the infant back and the remainder of the assess ment was recorded within a week.model analysis.A significance level of 5% (p< 0.05) was used as guidance for determining significant differences.Assumptions of normality were assessed and found to be appropriate (results not included as this is not relevant to the objectives of this study).

Demographic profile and the AIMS score results at 4, 8 and 12 months of age
At the 4 month assessment the sample size consisted of 67 infants; of these, 20 infants participated in the study from the Private Baby Well Clinic and 47 infants participated from the Public Baby Well Clinic.At the 8 month AIMS assessment 50 infants were assessed and 17 infants were lost to follow up.A further nine infants were lost to follow up and 39 infants were assessed at 12 months.The majority of infants at four months were Coloured (80%) followed by White (12%) and Black (8%) infants.The infants' mean percentile rankings for the Private and Public Baby Well Clinics were combined at 4, 8 and 12 months.The mean percentile ranking at 4 months was significantly higher than the Canadian norm (p=0.01)(Table 1).

Age and percentile rankings of female and male infants
From the mixed model analysis, a sig nificant interaction effect (p=0.03) for gender and age was found.Post doc analysis revealed that at the 4 month percentile rank, female infants scored  significantly higher than their male counterparts (p=0.01).Although the male infants scored slightly higher at 8 and 12 months, the difference was not statistical significant (Figure 1).

Age and percentile rankings of infants attending the Private and Public Baby Well Clinics
The interaction between age and clinic was insignificant (p=0.9) which implies that any possible clinic dif ferences were the same at all the age time points.The clinic main effect (thus ignoring age) was not statistically significant (p=0.18),but did show a trend for the Public Baby Well Clinic to score lower (Figure 2).

Relationship between race and percentile rankings on the AIMS
The mixed model ANOVA analysis indicated an insignificant interaction between race and age (p=0.35).

DISCuSSION
The main purpose of the current study was to serve as a preliminary study to validate the AIMS as a gross motor developmental assessment tool in a cohort of infants from different ethnic and socioeconomic backgrounds in the Cape Metropolitan region of the Western Cape, South Africa.The overall AIMS scores of the infants included in this study compared well to the Canadian normative sample.The four month old infants (n=67), in particular the female infants, performed significantly better (p=0.01)than the Canadian norms, while the 8 and 12 month age groups did not differ significantly from the Canadian 50 th percentile rank (p=0.95 and p=0.70 respectively).The reasons for the signi ficant difference between the Canadian and South African infants at 4 months of age are not clear.One could also argue that although the mean percentile rank of the South African sample was sig nificantly higher than the Canadian 50 th percentile rank, the mean percentile dif ference was small (6.97%) and may not be of clinical significance.Syrengelas et al ( 2010) also found that the Greek infants (2< 3 months) scored signifi cantly (0=0.02)higher than Canadian infants, while there were no significant differences for the other age levels from birth to 18 months.They also ques tioned the clinical significance of the 2< 3months score and postulated that the differences seen between Greek and Canadian infants at 2< 3months could be due to possible differences in parental care and child rearing activities during this age period (Syrengelas et al 2010).Although comparisons were also carry out between gender, clinics and race groups these correlations were not pri mary objectives of this study and were exploratory to ascertain whether further investigation into these factors are war ranted.A statistical significant difference was found between the motor perfor mance of males and females at 4 months, with female infants scoring significantly better than males, while the percentile ranks of the male infants were slightly higher than the female infants at the 8 and 12 month assessments.Our results are inconsistent with reports that no gender differences could be detected for gross motor development in infants aged 4 60 months (Richter & Janson 2007); 6 11 months (de Lourdes Drachler et al 2007) and 018 months (Syrengelas et al 2010;Piper & Darrah 1994:198).Piper & Darrah (1994:198) initially planned to developed separate developmental AIMS norms for boys and girls, but since they found no significant gender differences at any age period, the scores for the entire sample were combined and analyzed according to age only.The largest study so far assessing sex differ ences and heterogeneity in motor mile stone attainment amongst healthy infants from Ghana, India, Norway, Oman and the USA found that girls tended to achieve gross motor milestones at ear lier ages than did boys, but stated that the magnitude of observed differences was too small and sporadic to justify sexspecific motor developmental norms (WHO Multicentre Growth Reference Study Group 2006).
The infants from the Private Baby Well Clinic scored slightly higher percentile ranks (p=0.90)than the infants from the Public Baby Well Clinic.The Public Baby Well Clinic predominantly serves a mixed race lower socioeconomic popu lation while Private Baby Well Clinic serves middle to high income residents.After an extensive search of the litera ture, only one report (Capute et al 1985) could be found assessing the influences of socioeconomic status (SES) on gross motor development in fullterm healthy infants.Findings by Capute et al (1985) differ from our results by indicated an overall moderate inverse trend between SES and gross motor function; where higher SES infants tend to score lower on gross motor gradients.
The current study reflects excellent interrater reliability values for the AIMS assessments at 4, 8 and 12 months between two experienced and trained therapists.These findings concur with the results of previous studies using the AIMS in healthy full term infants (Piper & Darrah 1994;Syrengelas et al 2010) as well as infants born preterm (Pin et al 2010) and at risk for developmental delay (Jeng et al 2000).Blanchard et al (2004) found that the AIMS manual provides sufficient information to attain high interrater reliability amongst untrained early intervention providers from diverse professional backgrounds, but recommend that cutoff points for abnormal motor development must be established at monthly intervals.This monthly cutoff points will be extremely useful in the SouthAfrican context to assists inexperienced clinicians from diverse professional backgrounds uti lizing the AIMS to identify infants who are at risk of developmental delays.
The main limitation of the study was the loss to follow up of infants resulting in only 39 infants assessed at 12 months of age.The following reasons for the lost to followup were given (telephonic correspondence with the parents): parent(s) had to go back to work after 4 months maternity leave and enrolled their infants with a crèche or day mother who in turn was not able to bring the infant for the assessments; infants who participated in the study were also healthy and therefore some parent(s) did not see the necessity to participate in follow up assessments.Infants were also lost to follow up because parent(s) changed contact details such as telephone num bers and addresses and did not notify the principal researcher or leave forward ing details of their whereabouts.Loss to followup is unfortunately a reality in SouthAfrica due to inadequate com munications systems (with only a few of the mothers being contactable by phone) and migrant families frequently having to change their address details, as well as the insufficient and expensive public transport that is often the only means of accessing the relevant healthcare resources (Kirsten et al 1995).
The second limitation of the study was that the infants were assessed quarterly up to 12 months instead of monthly.We strongly recommend future South African validation studies follow the methodology described by Syrengelas et al (2010).Rather than follow the same group of infants over time, with the risk of loss to followup, a large group of ethnical diverse infants can be divided based on their age into 18 parts (month 118) for each month from birth up to 18 months.This will be a feasible way to determine if new normative data and reference values need to be established for SouthAfrican infants, particularly around the 4 month, since the current study found significant differences between the Canadian and South African cohort at 4 months of age.Due to the loss of followup of infants at the 8 and 12 month assessments as well as the small race group sample for black and white infants, the influences of gender, race and SES on gross motor development were not clear, but did show trends for possible differences between the groups.Further research is necessary to verify and explain the role of gender, SES and race on gross motor development in SouthAfrican infants.

CONCluSION
The results yielded by this pilot study demonstrate that the AIMS can be uti lized as a reliable and costeffective tool by paediatric health care professionals in the Cape Metropole, South Africa to assess the gross motor acquisition of infants at 8 and 12 months of age.Care should be taken when comparing infants at 4 months of age to the Canadian normative sample, since SouthAfrican infants, especially the female infants may score significantly higher.Further research also needs to be undertaken to determine if the AIMS is valid for the greater South African infant population and to verify and explain the role of gender, ethnicity and SES on gross motor development.

Figure 1 :
Figure 1: Relationship between age and percentile rankings of female and male infants Factors such as socioeconomic status (Capute et al 1985), in addition to cul turespecific care and rearing practices (WHO Multicentre Growth Reference Study Group 2006) and ethnicity (Kelly et al 2006) have been suggested to affect infant's gross motor development.However, it was beyond the scoped of this pilot study to determine potential factors that could have led to differences between the SouthAfrican and Cana dian cohort.

Figure 2 :
Figure 2: Relationship between age and the percentile ranks of infants attending Private and Public Baby Well Clinics