Developmental Screening Tools for Motor Developmental Delay in High Risk Preterm Infants

Address for correspondence: Selvam Ramachandran, Assistant Professor Physiotherapy, School of Allied Health Sciences, Manipal University, Manipal, Udupi Dist, Karnataka 576104, India E-mail: rs79physio@gmail.com Tel: +91 96867 38297 1Selvam Ramachandran, Assistant Professor (Selection Grade) Physiotherapy, School of Allied Health Sciences, Manipal University, Manipal, Udupi Dist, Karnataka, India. 2Dr. Sudip Dutta, Professor and Head Paediatrics, Sikkim Manipal Institute of Medical Sciences, Tadong, Gangtok, East Sikkim, India. Abstract


Introduction
Need for standardized developmental screening tool T he adverse neurodevelopmental outcomes are o en associated with prematurity 1,2 .The preterm infants are nursed in Neonatal Intensive Care Units (NICU) as there is an invariable diffi culty in coping up with environmental demands owing to its early exposure to the environment.The survival rates of such preterm infants have increased with due NICU care; on the contrary these infants presents with neuro-developmental disorder at later stages of which motor developmental delay is common.The environmental eff ects of NICU have also been reported to add to the adversity of prematurity associated neuro-developmental disorder 3 and scien fi c evidence of developmental care interven ons are inconclusive ll date 4,5 .The developmental disorder shall present as a developmental delay, dissocia on, devia on and regression 6 .Developmental delay refers to a signifi cant delay in the acquisi on of milestones in various developmental domains; devia on refers to atypical acquisi on sequence of developmental milestones; dissocia on refers to diff ering rate of development across developmental domains; and regression refers to the loss of previously acquired developmental milestones.
The iden fi ca on of the actual or impending risk of motor developmental disorder are essen al to remediate op mal neurodevelopmental outcomes through appropriate early developmental care interven on.Such iden fi ca on of risk is done through developmental surveillance and screening 6,7 .Dworkin 8 defi ned developmental surveillance as "a fl exible, con nuous process whereby knowledgeable professionals perform skilled observa ons of children during the provision of health care.The components of developmental surveillance include elici ng and a ending to parental concerns, obtaining a relevant developmental history, making accurate and informa ve observa ons of children, and sharing opinions and concerns with other relevant professionals."Developmental screening 9 is the administra on of a brief standardized tool that aids the iden fi ca on of children at risk of a developmental disorder.Developmental screening does not result in either a diagnosis or treatment plan but rather iden fi es areas in which a child's development diff ers from same-age norms.The American Academy of Pediatrics has issued the policy statement and algorithm on developmental surveillance and screening 9 .The AAP recommends surveillance and screening of all infants to iden fy established disabili es or risks of delayed development following the AAP algorithm.The algorithm contains recommenda ons to perform surveillance at all well-child visits and administra on of a standardized screening tool at the 9 and 18 month visits and again at either the 24 or 30 month visit.Further it recommends administra on of appropriate developmental screening tools for those infants with reported concerns of developmental surveillance.

Characteristics of developmental screening test
Theore cal framework: The content and constructs of the item set in a developmental screening tool shall be based on neuro-matura onal perspec ve or an ecological perspec ve 10 .The tool based on biological neuro-matura onal perspec ve assumes that acquisi on and performance of motor skills are based on the hierarchical matura on of central nervous system.The tool tes ng the motor performance based on ecological perspec ve assumes that the acquisi on, performance and matura on of motor skills involve complex interac ons of the environmental infl uences on the developing infant.

Types of test:
The screening tests are basically referred as criterion or norm referenced test 11 .The performance score with reference to the a ainment of minimum score on the item set tested on specifi c competencies that marks the pass or fail in the test is termed as criterion referenced test.The performance score when compared with the scores of the norma ve sample of the similar and larger popula on is termed as norm referenced test.Care should be taken to draw meaningful inference when using the norm referenced test while comparing the performance score with the norma ve popula on as development of motor skills vary amongst diverse social, cultural and ethnic groups.
Test purpose: The clinical examina on of preterm infants should include specifi c and standardized developmental screening tools to discriminate, predict and evaluate motor func ons and/or performance.Kirshner B and Guya G 12 have described a methodological framework for assessing health indices.Based on this framework the developmental screening tool can be classifi ed on basis of test purpose.The discrimina ve screening tool should be able to dis nguish the performance of the subject with or without the func on on the specifi c domain.The norm referenced screening tool will help to discriminate the performance func ons of the test group with the norma ve sample.The predic ve screening tool should be able to categorize the test subjects based on the actual or expected performance lags at present or in the future.An evalua ve screening tool is used to measure the magnitude of infl uence of therapeu c interven ons on the changes in the performance in a specifi c domain over a period of me; it helps the health professional to evaluate prognosis on the developmental index as well as the effi cacy of early interven on program services.
Test administrator: The administra on of test items on a screening tool shall be either a professional with adequate training, exper se and experience or parent / caregiver ini ated with li le or no training requirement 13 .The test items may be assessed by expert observa on or comprehensive elicited examina on by the trained health professional.

Age and developmental domains:
The appropriateness and u lity of the developmental screening tool depends on the age range of subject being tested and the inclusion of constructs of specifi c developmental domains that are tested 14 .

Challenges of administering standardized developmental screening tool
The administra on of standardized developmental screening tool for motor developmental delay for preterm infants is complex and challenging for the following factors: Infant factors: The motor development during fi rst year of life follows exponen al and non-linear pa ern; the unusual and atypical NICU exposure of preterm infants would nega vely infl uence the rapid and cri cal phase of brain development thus aff ec ng the pa erns of motor development.The growth and development of preterm infants is atypical of term infants and follows variable motor trajectories 11 .Further the motor development are being infl uenced and molded by complex psycho-social-cultural factors in the biological milieu of preterm infants.

Screening procedural factors:
The use of ageadjusted scores in developmental screening tools remains debatable ll date 15 .Some authors recommend that conceptual age (adjusted age) should be taken into account while others maintain that chronological age (no adjustment) should be preferred.Siegel 16 maintains that "the use of correc on will reduce and some mes remove the apparent diff erence between the pre-terms and full-terms… it will not necessarily result in the most accurate predic on" of later func oning.The appropriateness of age adjustment depends on the specifi c domain skills assessed, the degree of prematurity, and the chronological age of the child.The item sets included in the screening tool are clustered within the broad range of items and are placed in correla on to child's age.The ceiling and basal rules are applied to indicate whether the child's performance have reached lower and upper limits.Washington et al 17 noted that the clinician's choice of start age item set will increase the chance of under and overes ma on of the child's developmental level.

Implementa on factors:
Countering the test items of the developmental screening tool itself is unnatural for the infant.The test items are administered by the persons (professionals) who are totally unfamiliar with the infant and expec ng the infant to remain a en ve and carryout adult-directed instruc ons.Further test items do not engage play-oriented ac vi es during screening.Addi onal barriers to screening includes lack of confi dence / exper se of the health professional, consensus lack on the choice of appropriate screening tool, requirements of tool specifi c infrastructure and related costs, me constraints, compe ng clinical demands, cost burden, staffi ng requirements and logis c issues of working parents in case of longitudinal assessments requiring mul ple visits 13,18 .

Use of age-adjusted scores in developmental screening tool
There are two theore cal viewpoints on the use of age adjustment in preterm infants 15 .From the biological perspec ve of infant growth and development, the matura on proceeds as a temporal factor since concep on.It is ra onal to infer that there will be lag in one or more developmental domains associated with prematurity; and therefore there is a requirement of age adjustment with a no on that preterm infants will "catch up" with their full term counterparts.From the ecological perspec ve of infant growth and development, the matura on proceeds as a spa al factor and are infl uenced by the environmental variables.The parental care, parental s mula on and the parent-child interac on all are said to have infl uence in growth and development 19,20 .
The preterm birth is not only quan ta vely diff erent from full-term birth but also diff ers qualita vely because of invariable co-morbidi es associated with prematurity.Mohr & Bartelme 21 introduced the concept of conceptual age also referred to as corrected or adjusted age to overcome the quan ta ve lag of preterm infants.The performance of preterm infants on a developmental screening tool a er age adjustment need not necessarily match with the performance on specifi c a ributes of full term infants.Most of the developmental screening tools for preterm infants encourage use of adjusted age over chronological age.
If preterm infant is being assessed by corrected age, then such infant is being deprived of scores of higher age item set.Hence the standard score may not refl ect the appropriate developmental index given the variability in the type of items passed by the preterm infant.The start item set is an important determinant of developmental index on the basis of both chronological and corrected age.The conven onal procedure of using the developmental screening tool is that the start item set and the norma ve group selected should correspond to the chronological age.For preterm infants the items that belong to 'interval' age group (diff erence in chronological and corrected age) should also be administered.The cumula ve use of chronological and corrected age will enable conver ng the raw score to the standard score in having a meaningful interpreta on of achieved developmental index.On one hand, the clinician shall choose the item sets of corrected age and the derived scores shall be compared with the scores of the norma ve sample of corrected age; on the other, the item sets of chronological age shall be chosen and the derived scores shall be compared with the scores of the norma ve samples of corrected or chronological age.
In conven on and also in several studies, the use of age adjusted developmental screening in clinical prac ce for at least fi rst two years of life is been recommended.Some researchers also advocate age adjusted correc on only for the fi rst year of life.It is further stated that "as the child becomes older, this correc on factor becomes propor onately smaller compared with total age".Several authors reports the signifi cance of use of age adjusted scores for assessing motor skills in preterm infants for varying periods.Lems et al 22 recommends age adjustment for the fi rst six months of the fi rst year while assessing motor skills.Ross 23 advocated the full age adjustment in assessing motor skills during fi rst year of life as growth and development of motor skills predominates and has a greater impact than on mental skills.Palisano 24 advocates the use of age adjustment for motor skills un l 18 months.

Clinimetric and psychometric standards for eff ective screening tests
Developmental screening has become an integral part of quality health care in Developmental Care Interven ons (DCI).The health professionals in developmental care of preterm infants should have sound knowledge on the intended purpose of developmental screening tools.The good developmental screening tool should meet the standards of clinimetric and psychometric proper es 11,13,18,25 .Such tools should poses varied characteris cs such as; Reliability: It refers to how consistently screening tool iden fi es children with delays and/or disabili es.It also refers to the consistency of scores and so do the performance of the child with change in screening se ngs, evaluators and the repeat measures.Instruments should be selected with reliability coeffi cients greater than.80 and preferably greater than.90 Validity: It refers to how well a tool measures what it intends to measure.Concurrent validity indicates how well the constructs of the developmental screening tool correlates with the same construct of other screening tool.The construct validity indicates the measurement of item in alignment with a theore cal concept.Criterion validity refers to infl uence of other variables (criterion).
U lity: It refers to clinical u lity of the tool viz. the applicability of the appropriate screening tool specifi c to the age range and the domains that are being tested.
Specifi city and Sensi vity: Specifi city refers to the property of tool in correctly iden fying the infants developing typically and performing at the expected level of standardized assessment.Sensi vity refers to the ability of the screening tool in detec ng small diff erences in between and within groups of test subjects.AAP 9 recommends the standard screening tool should have specifi city and sensi vity at least in the range of 70 -80% or higher.

Developmental disorder specifi c screening tools
The developmental disorders shall include delays in the development of speech and language, fi ne motor, gross motor, social, and problem-solving skills.Those developmental delays are markers for specifi c developmental condi ons that include cerebral palsy, speech and language disorders, learning disabili es, cogni ve disability (mental retarda on), au sm spectrum disorders and vision or hearing impairment.

Ages and Stages Questionnaire (ASQ)
Ages and Stages Ques onnaire (ASQ), is a set of 19 parent completed ques onnaire that are used to evaluate the following developmental domains: communica on, gross motor, fi ne motor, problemsolving, and personal adap ve skills, for children 4 to 60 months old.Domain scores are obtained by the sum of the item scores.Children with ASQ score below the cut off (<2SD) in any of the domain are taken as screen failed.Juneja M et al 27 reports that ASQ has strong test characteris cs for detec ng developmental delay in Indian children and reaffi rms the value of ASQ as an eff ec ve developmental screening tool.The sensi vity of ASQ is higher in the high risk group, whereas specifi is higher in low risk group.

Developmental Assessment Scale for Indian Infants (DASII)
It assesses development in the age range of birth to 30 months and provides a measure of motor and mental development as Motor Developmental Quo ent (MoDQ) and Mental Developmental Quo ent (MeDQ), respec vely.Developmental delay is defi ned on DASII as DQ score ≤70 (≤2SD) in either the mental or motor scale 27,28 .

Trivandrum Developmental Screening Chart (TDSC)
The TDSC was designed by selected 17 test items from BSID (Baroda Norms).It was validated both at hospital community level against the standard Denver Developmental Screening Test.TDSC had a sensi vity of 66.7% and specifi city of 78.8% which makes it an acceptable simple screening tool even for the community level worker 29 .

Disability Screening Schedule (DSS):
It is a broad based one me screening schedule for all the major disabili es, viz., locomotor, visual, hearing and intellectual in early childhood (0-6 years).DSS has a sensi vity of 0.89 and a specifi city of 0.98 30 .

Implications for clinical practice
There is a strong need for primary care provider modulated 31 mul -disciplinary, community oriented and family centered early interven on developmental care services 32 .The informa on on the developmental index of preterm infants should be drawn from both the professionally generated developmental screening and with the anecdotal observa ons of parents / caregivers.The parent completed screening assessment should precede a professionally directed screening as the former one includes observa on in a natural environment and specifi c to socio-cultural prac ces of family.The appropriate diagnos c tests should be carried out concurrent to developmental screening assessment to make the early interven on services eff ec ve 33 .The age-adjusted developmental screening of preterm infants should be done at least in the fi rst year and if there are associated issues of birth weight / co-morbidi es, the prac ce of age-adjustment shall be extended to the second year; therea er there is no signifi cance of age-adjustment 23 .The longitudinal assessment of at risk infants should follow the AAP algorithm of surveillance during well-child visits and screening at 9, 18 and 24 months 9 .The health professional should choose appropriate screening tool with good clinimetric and psychometric standards while performing the developmental screening tests conforming to the best evidence available 34 Globally various developmental screening tools are being used.The screening tests / tools are either completed by parent or the therapist.The parent completed screening tools include responses to ques onnaires based on parental observa on of the ac vity performance.The therapist completed screening tools include specifi c elicited responses or based on therapist observa on of ac vity performance.The widely used therapist completed mul -domain screening tools include Denver Developmental Screening Test (DDST), Bayley Scale of Infant Development (BSID), Bayley Infant Neurodevelopmental Screener (BINS), Ba elle Developmental Inventory Screening Test (BDIST), Milani-Compare Development Screening Test (MCDST).The parents completed screening tools include Ages and Stages Ques onnaire (ASQ), Kent Inventory of Developmental Skills (KIDS) and Parents' Evalua ons of Developmental Status (PEDS) 26 .
. Council on Children with Disabili es, Sec on on Developmental Behavioral Pediatrics, Bright Futures Steering Commi ee and Medical Home Ini a ves for Children with Special Needs Project Advisory Commi ee.Iden fying Infants and Young Children with Developmental Disorders in the Medical Home: An Algorithm for Developmental Surveillance and Screening.Pediatrics.2006; 118(1):405-20.