Abstract
Background Although preliminary studies have established a good psychometric foundation for the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) for a broad population of youth with disabilities, additional validation is warranted for young children.
Objective The study objective was to (1) examine concurrent validity, (2) evaluate the ability to identify motor delay, and (3) assess responsiveness of the PEDI-CAT Mobility domain and the Alberta Infant Motor Scale (AIMS).
Methods Fifty-three infants and young children (<18 months of age) admitted to a pediatric postacute care hospital and referred for a physical therapist examination were included. The PEDI-CAT Mobility domain and the AIMS were completed during the initial physical therapist examination, at 3-month intervals, and at discharge. A Spearman rank correlation coefficient was used to examine concurrent validity. A chi-square analysis of age percentile scores was used to examine the identification of motor delay. Mean score differences from initial assessment to final assessment were analyzed to evaluate responsiveness.
Results A statistically significant, fair association (rs=.313) was found for the 2 assessments. There was no significant difference in motor delay identification between tests; however, the AIMS had a higher percentage of infants with scores at or below the fifth percentile. Participants showed significant changes from initial testing to final testing on the PEDI-CAT Mobility domain and the AIMS.
Limitations This study included only young patients (<18 months of age) in a pediatric postacute hospital; therefore, the generalizability is limited to this population.
Conclusions The PEDI-CAT Mobility domain is a valid measure for young children admitted to postacute care and is responsive to changes in motor skills. However, further item and standardization development is needed before the PEDI-CAT is used confidently to identify motor delay in children <18 months of age.
Computer adaptive testing merges computer technology with modern measurement theory, and its use is still new to the field of physical therapy.1,2 Validity of any new measurement tool requires research demonstrating its relationships with other existing tests intended for similar purposes. In addition, of particular interest to clinicians is the ability of a new test to meet its measurement objectives and thus aid in clinical judgments regarding prognosis and intervention planning. The computer adaptive test version of the Pediatric Evaluation of Disability Inventory (PEDI),3 the PEDI-CAT, was released in October 2012. Although initial studies have supported the psychometric foundation for the PEDI-CAT for a broad population of youth with disabilities,4 additional study for age-specific validation is warranted, especially in infants and young children.
The PEDI-CAT is a judgment-based measure and requires no special environment, materials, or activities to administer other than the test software installed on a computer (Microsoft Windows operating system, Microsoft Corp, Redmond, Washington) or iPad (Apple Inc, Cupertino, California). The focus on typical functional performance at the present time is assessed, and, as such, the child's parent(s) or professionals who currently provide services for the child are the most likely respondents. No physical testing is required. The PEDI-CAT can be completed on multiple occasions for the same child (eg, admission, interim assessment, discharge, and follow-up), and there is no minimum time that must pass between assessments.4
Completed by using preinstalled software on a personal computer or iPad, the PEDI-CAT uses statistical models to estimate a child's abilities from a minimal number of the most relevant items or from a predetermined number of items within each of its domains. All respondents begin with the same item in each functional domain in the middle of the range of difficulty, and the response to that item then dictates which item will appear next (a harder or easier item), thus customizing the items to the child and minimizing the number of irrelevant items. With administration of each subsequent item, the score is re-estimated along with the confidence interval, and the computer algorithm determines whether the predetermined set number of items has been administered or an acceptable level of measurement precision has been met. Once either of these stopping rules has been satisfied, the assessment ends. The PEDI-CAT program then displays the score results instantly.4 The PEDI-CAT is purported to provide an accurate, precise, and efficient assessment of childhood function.4–6
Developed for use across all diagnoses and settings, the PEDI-CAT can be used by physical therapists to identify functional delay, to examine improvement for an individual child after intervention, or to evaluate and monitor group progress in program evaluation and research. The PEDI-CAT measures abilities in the 3 functional areas of Daily Activities, Mobility, and Social/Cognitive, and a fourth domain, the Responsibility domain, reports whether the child or caregiver takes responsibility for multifaceted daily tasks.4
Content validity of the PEDI-CAT was established through a review of existing adult and pediatric functional assessments and input from practicing clinicians, parents of children with and without disabilities, and experts in the field of rehabilitation.7 Discriminant validity was demonstrated in a 2012 study in which the PEDI-CAT was able to differentiate between groups of children with and without disabilities based on parent responses in all 4 domains.5 In addition, the scores of the PEDI-CAT Mobility domain were shown to differentiate the functional mobility status between groups of children who used a walking aid (higher scores) or wheelchair (lower scores).8 In the one study of concurrent validity that we are aware of, strength of association between the PEDI-CAT Mobility domain and the PEDI Functional Skills Mobility domain scaled scores was good to excellent (r=.82, P<.001).9 Test-retest reliability results also have been reported as high (intraclass correlation coefficient=.96–.99) for all 4 domains when parent respondents completed the PEDI-CAT twice within 1 month.5
No studies, to date, have examined the PEDI-CAT's ability to identify functional delay or the responsiveness of the PEDI-CAT to identify change over time in functional mobility for infants or young children receiving physical therapy intervention. In addition, evidence of concurrent validity for the PEDI-CAT is limited. Conversely, the Alberta Infant Motor Scale (AIMS) is a well-known performance-based, norm-referenced, observational tool for the motor assessment of infants and young children up to 18 months of age used by physical therapists to identify motor delays and evaluate motor skills over time.10 The AIMS has been used to identify gross motor delay in infants with diagnoses such as univentricular heart defects,11 treated idiopathic clubfoot,12 and positional plagiocephaly.13 In a 2013 study, the AIMS was noted to better detect the effects of early intervention physical therapy on the motor development of infants with very low birth weight at 12 months of age compared with the Bayley Scales of Infant Development–Dutch second edition (BSID-II-NL).14 In addition, there is significant evidence of concurrent validity for the AIMS. Scores on the AIMS have been compared with gross motor raw scores of the Peabody Developmental Gross Motor Scale–2,15 the Harris Infant Neuromotor Test,16 the Bayley Scales of Infant Development,17,18 and the Infant Motor Profile19—all producing strong correlations and evidence of concurrent validity.
Although the PEDI-CAT is described as a measure of function and the AIMS is identified as a measure of motor development, both the PEDI-CAT and the AIMS measure the ability to engage in distinct motor activities. The PEDI-CAT's Mobility domain includes items that depend heavily on the performance of gross physical movement abilities and includes items for foundational motor skills, such as rolling, sitting, crawling, and walking, similar to those found in the AIMS. Thus, the purpose of this study was to (1) examine concurrent validity of the PEDI-CAT Mobility domain and the AIMS; (2) evaluate the ability of the PEDI-CAT Mobility domain to identify motor delay compared with the AIMS; and (3) assess the responsiveness of the PEDI-CAT Mobility domain and the AIMS in examining change over time for infants and young children (<18 months' chronological age) admitted to a pediatric postacute care hospital and referred for a physical therapist examination.
Method
Participants
Fifty-three infants and young children were included in the study sample. Infants and children were included if they were inpatients at Franciscan Hospital for Children, Boston, Massachusetts, at the time of the study; referred for a physical therapist examination; and <18 months of age. Mean age at initial PEDI-CAT assessment was 175.32 days (SD=126.54, range=5–452), and mean age at initial AIMS assessment was 173.77 days (SD=126.37, range=5–453). Table 1 provides additional characteristics of the participants, including age groups and clinical program groups, which have been previously established to describe infants and children admitted to pediatric postacute care hospitals.20
Characteristics of the Study Samplea
All participants were transferred to Franciscan Hospital for Children, a pediatric postacute care hospital, from an acute care hospital, as they required a hospital level of care for an extended period of time. The pediatric postacute care hospital provides ongoing medical care and rehabilitation services for children with a wide variety of medical diagnoses, medical device dependence, and therapeutic needs. Average length of stay in the pediatric postacute care hospital for the study group was 90.47 days (SD=103.04, range=9–462).
Procedure
Physical therapy staff at Franciscan Hospital for Children had been trained in the administration, scoring, and interpretation of the PEDI-CAT by 2 of the PEDI-CAT's authors via in-service presentation, case review, and practice administration upon introduction of the PEDI-CAT in October 2012. Additionally, physical therapy staff participated in training in the use of the AIMS via review of the test's intended population, psychometric properties, setting and materials, procedures, time requirements, scoring, and score interpretation. Three video cases of infants 10 weeks, 7 months, and 8.5 months of age were used to practice scoring.
For each participating infant or child, the physical therapist completed the AIMS during the initial physical therapist examination or during an additional physical therapy session (if needed) at the patient's bedside (crib). The PEDI-CAT Mobility domain (Speedy, version 1.3.6) was completed based on observation and caregiver report from the initial physical therapist examination. Test order was determined by the physical therapist. The mean number of days between the completion of the initial PEDI-CAT Mobility domain and the AIMS initial assessment was 1.59 days (SD=3.0). At discharge or at 3-month intervals until discharge, the child's primary physical therapist again completed the PEDI-CAT Mobility domain (Speedy version) and the AIMS. For one child who remained in the hospital, final testing was done when the child turned 18 months of age.
Hospital institutional review board approval was obtained to retrospectively examine the results of both assessments and collect demographic data on the participants. PEDI-CAT and AIMS scores obtained between July 2013 and April 2014 were included for analysis. Data (demographics and test scores) were entered into a project-specific database and analyzed using SPSS version 22 (SPSS Inc, Armonk, New York).
Measures
The PEDI-CAT Mobility domain has 4 content areas (basic movement and transfers, standing and walking, steps and inclines, and running and playing), in which items range from foundational motor skills of rolling over and sitting unsupported to more advanced skills of jumping, running, or carrying heavy objects. There are additional items specifically for children who use mobility devices such as walking aids (canes, crutches, walkers) or wheelchairs. Pictures accompany each item to further depict the activity being assessed. Respondents score items as “unable,” “hard,” “a little hard,” or “easy.” An “I don't know” option also is available and, when chosen, prompts the PEDI-CAT software to choose another item to be administered.
There are 2 versions of the PEDI-CAT: Speedy and Content-Balanced. The Speedy version utilizes no more than 15 items per domain and is the fastest way to obtain a score. For the Content-Balanced version, approximately 30 items per domain are administered, which include a balance of items from each of the content areas within each domain. Because the algorithm for the Content-Balanced version requires that a minimum number of items be administered in each content area and most of the items in the PEDI-CAT content areas of steps and inclines, and running and playing were not appropriate to include for infants and young children <18 months of age and especially for the majority of the infants and young children who had been hospitalized since birth, the Speedy version (Mobility) was used for this study. The PEDI-CAT Mobility domain (Speedy) can be completed in 5 to 10 minutes.4
The PEDI-CAT is both norm-referenced and criterion-referenced, as the computer program generates a score report containing a normative score represented as a T-score and age percentile range (eg, <5th, 5th–25th), as well as a scaled score (recommended for use to assess change over time). An exact age percentile, rather than a percentile range, is not shown on the score report but can be accessed by exporting the data to Microsoft Excel (Microsoft Corp).4
The AIMS is also a norm-referenced measure and was designed to provide a measure of motor development for infants at risk for motor delay. The AIMS can be used to assess infants from birth to 18 months of age and consists of 58 test items administered in 4 different positions: prone (21 items), supine (9 items), sitting (12 items), and standing (16 items). The items are arranged according to the developmental sequence of motor skills in each position. Items are scored based on observation of the child's motor skills and are recorded as “observed” or “not observed.” A total score is calculated by summing the number of observed skills within each subscale plotted on the provided graph, and an age percentile is determined. An estimated time of 20 to 30 minutes is needed to administer the entire assessment.10 A summary of test features for the PEDI-CAT Mobility domain and the AIMS is presented in Table 2.
General Features of the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) Mobility Domain and the Alberta Infant Motor Scale (AIMS)
Data Analysis
Demographic and test data for 1 year were analyzed. Standard descriptive statistics were used to summarize the demographic and clinical characteristics of the sample. To examine the concurrent validity of the PEDI-CAT Mobility domain (Speedy version) and the AIMS, Spearman rank correlation coefficients were used (significance level of P<.05) to ascertain the relationship among the individual age percentiles generated on the initial assessments.
To analyze the identification of delay (scoring ≤5th percentile), we compared the age percentiles for the PEDI-CAT Mobility domain and AIMS initial assessments. To achieve this objective, we recoded the age percentile for each child into 1 of 4 categories: ≤5th percentile (2 SD below the mean), >5th to ≤10th percentile (1.5 SD below the mean), >10th to ≤20th percentile (1 SD below the mean), and >20th percentile. A chi-square analysis was used to compare the percentage of infants and young children in each group for the 2 assessments. Also, we descriptively examined the percent agreement for each child's age percentile on the PEDI-CAT and AIMS.
In addition to the use of age percentiles for the total sample, we calculated the percentage of participants with a T-score <30 (2 SD below the mean) on the PEDI-CAT Mobility domain and descriptively compared this percentage with the percentage of participants in the ≤5th percentile (2 SD below the mean) using the AIMS. To further understand the ability of the measures to identify motor delay in infants and young children, we converted the PEDI-CAT and AIMS percentiles to z scores for comparison with a normal distribution (mean of 0 and SD of 1). Lastly, for the 25 children born prematurely (47% of total sample), we calculated corrected age and compared each child's age percentile on the AIMS using the corrected and chronological ages.
To assess the responsiveness of the PEDI-CAT Mobility domain and the AIMS in examining change in motor skills over time for infants and young children (<18 months of age) admitted to a postacute care hospital and referred for physical therapy, we calculated change scores for both the PEDI-CAT and the AIMS. We used PEDI-CAT scaled scores and the AIMs total raw score and calculated a change score by subtracting the admission/initial score from the discharge/final score for each child for each assessment. We then calculated the mean and standard deviation for the group and compared the mean admission/initial score with the mean discharge/final score for each test using a paired t test. We also calculated the percentage of children with a positive change score (>0.0). Twenty of the participants did not receive an interim or discharge physical therapist examination because physical therapy intervention was not indicated upon initial examination or the infant or child was receiving physical therapist services but was still in the hospital at the time of the study completion (not yet discharged) and had not yet been in the hospital for 3 months (time frame for interim testing). As such, only admission/initial scores were used in the analysis for study objectives 1 and 2, and admission/initial and interim/discharge scores (final assessment), if available, were used to assess responsiveness for study objective 3.
Results
In examining the concurrent validity of the PEDI-CAT Mobility domain and the AIMS, the Spearman rank correlation was statistically significant but showed only a fair association between the 2 assessments (rs=.32, P=.02).21
There was no statistically significant difference (χ2=10.446, P=.32) in the identification of motor delay between the 2 assessments; however, the AIMS had a higher percentage of infants identified with motor delay (scoring below the 5th percentile [n=46, 86.8%]) than the PEDI-CAT for both PEDI-CAT ≤5th age percentiles (n=15, 28.3%) and T-scores of <30 (n=23, 43.4%) (Tab. 3). For the total sample, 18 (34%) of the 53 children scored in the same age percentile on the PEDICAT and on the AIMS. Using the PEDI-CAT as the reference test (denominator), the agreements were as follows: age percentile <5th, 15/15 (100%) same; 2/23 (9%) for >5th–≤10th percentile; 0/6 (0%) for >10th–≤20th percentile, and 1/9 (11%) for >20th percentile. For 7 (28%) of the 25 children born prematurely, using the child's corrected age on the AIMS would change the infant's age percentile score from <5th to >5th percentile and indicate they did not demonstrate motor delay. The age percentile score did not change for the remaining 18 children born prematurely when using corrected age. The Figure illustrates that the distribution of scores was shifted to the left and that the majority of the children demonstrated scores on the low end of the normal range or below the normal range on both assessments. We would anticipate the normal distribution of scores would be between −2 and 2 or within the curve.
Infants and Young Children Identified as Having Motor Delay Upon Initial Assessment on the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) Mobility Domain and the Alberta Infant Motor Scale (AIMS)
Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) and Alberta Infant Motor Scale (AIMS) mean z scores and percentiles and PEDI-CAT mean T-score compared with normal distribution.
When examining responsiveness, 24 (75%) of the 32 children for whom 2 or more PEDI-CAT scaled scores were available (initial and interim/final scores) showed a positive change in scaled score on the PEDI-CAT, whereas 7 children (22%) had no change and 1 child (3%) demonstrated a 5-point decrease in scaled score. Twenty-nine (91%) of the 32 children showed a positive change on the AIMS, and 3 (9%) showed no change. For this subsample (n=32), a statistically significant change from mean initial/admission scores to mean discharge/final scores on both the PEDI-CAT Mobility and the AIMS was noted (Tab. 4).
Admission/Initial, Discharge/Final, and Mean Change Scores for the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) Mobility Domain and the Alberta Infant Motor Scale (AIMS)
Discussion
Evaluation of the psychometric properties of the PEDI-CAT, a new pediatric functional assessment, is needed. Specifically, in this study, we examined the concurrent validity of the PEDI-CAT Mobility domain and the AIMS, compared the percentage of children identified as demonstrating motor delay using the PEDI-CAT Mobility domain and the AIMS, and assessed the responsiveness of the PEDI-CAT Mobility domain and the AIMS in examining change in motor skill over time for infants and young children (<18 months age) admitted to a postacute care hospital and referred for a physical therapist examination.
Concurrent Validity
Comparing a new assessment against a criterion “gold standard” is a common method for examining concurrent validity and establishing the legitimacy of a new measure. Concurrent validity indicates how well 2 measures that evaluate the same skills or traits of the individuals and are administered at roughly the same time correlate with one another.21 Whereas the PEDI-CAT was developed as a measure of daily function, the AIMS examines motor development (including quality of movement). Both the PEDI-CAT and the AIMS, however, measure early, basic movement and motor skills. Both tests provide clinicians with an age percentile based on a normative standardization sample, and these percentiles were used for comparison. Although the correlation between the 2 measures was statistically significant, and thus unlikely to be due to chance, it was still only a fair association. Therefore, using the results of one assessment to predict the results of the other assessment should be done with caution.
In addition to an age percentile, the PEDI-CAT provides a T-score, and the AIMS provides a raw score. A raw score can be calculated for the PEDI-CAT by counting the number of items scored as “easy” and using the item maps in the PEDI-CAT manual to determine how many additional items were scored as easy in the scoring algorithm of the program software to produce the T-score. We examined a small subsample of cases (n=5, 10% of sample) by calculating a raw score and compared the raw scores from the PEDI-CAT with the AIMS raw score and found that this approach provided a close comparison. Although this method increases our comfort with the concurrent validity of the PEDI-CAT, it reveals that there is a likely discrepancy with the age percentiles. As the lack of need for score calculation is one of the benefits of the PEDI-CAT and not expected to be done by clinicians, we did not fully explore this method but rather stress caution when using the PEDI-CAT age percentiles for children under 18 months of age.
Identification of Delay
Normative data, presented as age percentiles or as T-scores in various assessments, provide what is needed to identify infants and young children whose motor skills are atypical for their age. The PEDI-CAT Mobility domain is a measure of gross physical movement capacities (gross motor activity and functional mobility), whereas the AIMS is a measure of motor development based on neuromaturational theory and dynamic motor theory.10 There is overlap, however, in the content of the PEDI-CAT items on the lower end of the scale with the items of the AIMS. For example, the PEDI-CAT Mobility domain's basic movement and transfer content area includes items such as “When lying on belly, pushes up on elbows,” “Rolls over in bed or crib,” and “Sits on floor without support.” These items are almost identical to items found on the AIMS and are appropriate for identifying motor delay in infants and young children.
For the total sample, there was no statistically significant difference between the PEDI-CAT Mobility domain and the AIMS for identification of motor delay using age percentiles. The AIMS, however, did identify more children as having motor delay than the PEDI-CAT. The greatest difference is in the number of children identified in the <5th percentile, where the AIMS identified 3 times the number of children as the PEDI-CAT when comparing age percentiles. Combining the children who scored in the >5th–≤10th percentile or those with a T-score <30 on the PEDI-CAT (n=23), however, increases the number of children with “lower” normative scores and more closely matches the number of children identified by the AIMS.
A T-score of <30 is equivalent to the <5th age percentile, and the PEDI-CAT provides both T-scores and age percentiles. In our sample, however, the use of T-scores generated by the PEDI-CAT identified a greater number of infants and children (n=23) as having motor delay than the age percentiles (n=15). The manual for the PEDI-CAT states, “The percentile ranges were developed using a different methodology than that used to derive the T-scores, i.e. growth curve analysis, therefore, there may be occasions when the two types of scores do not correspond exactly. When using PEDI-CAT scores for service eligibility decisions, we strongly recommend that the child be identified as eligible if EITHER the T-score OR the percentile range is below the criterion.”4 It is common for clinicians to use z scores as an alternative to the use of a T-score to determine eligibility for physical therapist services, with scores falling 1.5 to 2 standard deviations below the mean as an eligibility criterion.22
It is important to note that chronological ages (not corrected ages) were used (unless otherwise noted) for this study. The PEDI-CAT does not allow for use of a corrected age, and it is recommended in the PEDI-CAT manual to use either the normative score (T-score) or the percentile for identification of delay along with the clinician's judgment when identifying motor delay.4 Also, fewer than half of the study participants were born prematurely. Using a corrected age on the AIMS for the 25 infants who were born prematurely would have decreased the number of children in the <5th percentile group by less than one-third. All infants in this small group were ≤2 months of age (chronologically) and will likely be in the hospital for an extended period of time. Due to their significant medical needs and considerable environmental restrictions limiting opportunity for play and exploration utilizing independent mobility, and thus prohibiting the attainment of motor milestones, it is expected that any identified motor delay will likely last beyond the typical 2-year correction period.23 Therefore, due to the varied diagnoses in the study sample, the limitations of the PEDI-CAT in correcting for prematurity and the anticipated motor limitations for infants and young children with an extended hospitalization, chronological ages were used for comparison.
Seven participants were not identified as having a delay in motor skills according to the AIMS. Four of the 7 participants were very young infants (3–38 days of age at admission) with a diagnosis of neonatal abstinence syndrome who were referred for a physical therapist examination due to hypertonicity, risk of motor skill delay due to prolonged hospitalization, and assessment of parent or caregiver teaching needs for positioning, play, and equipment. These 7 infants did not receive physical therapist intervention.
The PEDI-CAT Mobility domain item bank consists of a total of 75 items normed in 1-year increments for the assessment's entire age range from birth to 21 years of age.4 Although the intent is for the most appropriate items to be presented to the respondent based on the child's age and ongoing responses about motor function, the number of items available to assess the motor skills of very young infants and children is limited. In contrast, the AIMS has 58 items solely focused on the motor development of children <18 months of age.10 This discrepancy may have had an impact on the strength of the association between the 2 measures. Additional items to reflect the rapid developmental motor changes in the first 2 years of life of very young children could improve the PEDI-CAT's ability to identify delay in this age group.
Responsiveness
To examine the responsiveness of the PEDI-CAT Mobility domain and the AIMS, we used the PEDI-CAT Mobility domain scaled scores and the AIMS total scores. The PEDI-CAT's scaled scores are based on a 20–80 scale metric that does not take into account the age of the child but rather represents an interval level of measurement that places items along the metric based on equal units of item difficulty. Scaled scores thus provide a mechanism to examine a child's mobility skills and the change in skills over time. Scaled scores have been particularly helpful in documenting improvements in children who are not expected to regain or “catch up” to a level of function within their age range while an inpatient in postacute care.24,25 Scaled score distribution for the PEDI-CAT Mobility domain also has been shown to be adequate for use with children with varied diagnoses and ages.9
The AIMS may be used to monitor the course of motor development for infants within the first 18 months of life, including those who are deemed “at risk” and those who have a clinical diagnosis.10 It has been recommended that to maintain the highest specificity (ruling in of motor delay with a high degree of confidence), the cutoff should be the 5th percentile; however, if the assessment is intended to identify the greatest number of infants with abnormal motor delay, the 10th percentile may be used.26 More than 80% of the sample in this study with available discharge scores on the AIMS continued to score in the <5th percentile. Thus, we used the total raw score of the AIMS rather than the percentile ranking for a change over time comparison, as we did not expect participants to “catch up” to their same-age peers while in the hospital. In addition, for the 32 children with discharge scores for both measures, the AIMS continued to identify more children (n=26, 81%) than the PEDI-CAT (n=13, 41%) as delayed (<5th percentile), confirming that the AIMS did not overidentify children at admission. Both assessments, however, were responsive to change over time. Using a raw score that is a sum of the items scored as “observed” may once again be a reflection of the number of items in the scale versus equal increments of change in function as observed with a scaled score. The AIMS mean change score had a large standard deviation, indicating variability in the amount of change among the group.
An advantage of the PEDI-CAT is that it can be used for infants, children, and youth up to 21 years of age, which allows for tracking of function for children with disabilities over a longer period of time. Based on this work, we recommend further standardization for the PEDI-CAT with the development of normative scores in 1-month intervals for children <2 years of age rather than in 1-year increments, as the achievement of new skills is typically very rapid in these early years. Additional items to assess basic movement skills (eg, head control, reciprocal kicking) and early transfers (eg, transitioning into and out of a prone position) also are likely needed. A benefit of a computer adaptive test is that it is not a fixed paper-and-pencil format, and revisions can be made more easily by updating the software. In addition, the PEDI-CAT was developed on a 20–80 metric to allow items to be easily added at either end of the scale.4,8
Study Limitations
Although the same tester completed both the PEDI-CAT and the AIMS for a single child, several therapists collected scores for the total sample. Participants in this study were infants and young children admitted to a pediatric postacute care hospital, and although they had a variety of diagnoses, reasons for hospital admission and length of admission varied. Therefore, these findings may not be generalizable to children receiving physical therapy who are not in a postacute hospital. In addition, the majority of children were less than 6 months of age at initial testing (with a very limited number of children [n=5, 10%] being older than 9 months at initial testing). Additional study is needed to increase the number of participants in each diagnostic category, with a wider age range and in varied practice settings.
Although this study provides evidence indicating that the PEDI-CAT is a valid measure of mobility function for infants and children <18 months of age admitted to pediatric postacute care, is suitable to identify infants and young children with motor delay, and is responsive to changes in motor skills over time, further study is needed. The PEDI-CAT Mobility domain can be used with infants and young children in postacute hospital settings to measure change in mobility skills. It also identifies children with significant motor delays but should be used with caution for children with mild motor delays. It is recommended that the PEDI-CAT Mobility domain normative data be re-evaluated for children <18 months of age to best identify motor delay.
Footnotes
All authors provided concept/idea/research design, writing, and consultation (including review of manuscript before submission). Ms Rosen, Dr Lombard, and Dr Farrell provided data collection. Ms Dumas and Dr Fragala-Pinkham provided data analysis and project management. Ms Rosen provided study participants. Ms Dumas provided facilities/equipment, institutional liaisons, and administrative support.
- Received August 1, 2014.
- Accepted May 21, 2015.
- © 2015 American Physical Therapy Association
References
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