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Denver Developmental Screening Test (DDST), DENVER II Responsive to Change Over Time – Age specific norms provided. Content & Face Validity – Validity of Denver II established by the precision with which the ages corresponding to 25%, 50%, 75% and 90% passing for each item and subgroup have been determined - standardized on more than 2000.
MethodsAt first a precise translation of test was done by three specialists in English literature and then it was revised by three pediatricians familiar with developmental domains. Then, DDST-II was performed on 221 children ranging from 0 to 6 years, in four Child Health Clinics, in north, south, east and west regions of Tehran city. In order to determine the agreement coefficient, these children were also evaluated by ASQ test. Because ASQ is designed to use for 4–60 month- old children, children who were out of this rang were evaluated by developmental pediatricians.
Available sampling was used. Obtained data was analyzed by SPSS software. FindingsDevelopmental disorders were observed in 34% of children who were examined by DDST-II, and in 12% of children who were examined by ASQ test. The estimated consistency coefficient between DDST-II and ASQ was 0.21, which is weak, and between DDST-II and the physicians’ examination was 0.44.
The content validity of DDST-II was verified by reviewing books and journals, and by specialists’ opinions. All of the questions in DDST-II had appropriate content validity, and there was no need to change them. Test-retest and Inter-rater methods were used in order to determine reliability of the test, by Cronbach's α and Kauder-Richardson coefficients. Kauder-Richardson coefficient for different developmental domains was between 61% and 74%, which is good. Cronbach's α coefficient and Kappa measure of agreement for test-retest were 92% and 87% and for Inter-rater 90% and 76%, respectively. IntroductionDevelopmental disabilities can be seen in 10–15% of children in different populations. Early detection and appropriate referral of children with developmental delays or disorders is important in Pediatrics.
This is only possible by continuous developmental monitoring and assessment. Developmental assessment is made by early detection of problems through developmental surveillance and screening, precise evaluation by using standardized and formal diagnostic tools as well as evaluation of the medical, social, family history and physical examination of the child,. Developmental screening must be repeated periodically and incorporated into pediatrics practice ,.Developmental screening test is a brief standardized tool that is used for identifying children who need more detailed evaluation and if used appropriately is useful and cost benefit effective. Because screening is used for identifying the children who will receive the benefits of more professional evaluation or treatment, it is recommended that all children be screened for developmental delays.There are many developmental screening tools. The base of all of them is achieving developmental milestones at specific chronological ages. Denver Developmental Screening Test II (DDST-II) and Bayley are examples for such formal tools. For having ability to differentiate between abnormal children from those normal children who have slower rate of achieving developmental skills, these developmental screening tools must be reliable and valid, have acceptable sensitivity and specificity, be easy to perform and not expensive,.DDST-II is a formal developmental screening tool that assesses children from birth to 6 years of age.
First it was standardized on 1036 children (543 boys and 493 girls) from 2 weeks old to 6/4 years of age in Denver, Colorado as DDST. Then in 1992 it is revised and restandardized on 2096 children and is known as DDST-II. Test reliability on test-retest is 90% and its inter-rater reliability is 80–95%. The test is valid and there is a strong relationship between classification on the DDST and scores on the Stanford-Binet intelligence scales and the Previous edition of Bayley infant scales.DDST-II is a brief and validated screening tool that many of pediatricians are familiar with it. Although there is doubt about its limited specificity (43%) and risks of over referral , , it has high rate of sensitivity (83%) and identifies children with developmental delays,. DDST-II assesses child's development in 4 general areas: 1) personal–social (25 items), 2) fine motor- adaptive (29 items), 3) language (39 items), and 4) gross motor (32 items),. Screening by it produces 3 scores: normal, suspect and untestable (these children refused parti-cipating in some items that 95% of age matched children could pass them).
Sometimes DDST results are interpreted as normal, suspect, questionable (these children cannot pass some items that 75–95% of age matched children could pass them) and untestable. A study found sensitivity of 80% if 'questionable scores' were included with abnormal scores but specificity of 46%.
Alternatively, if 'questionable scores' were included with normal scores, sensitivity was 46% and specificity 80.By considering the importance of early detection of developmental disabilities and absence of an Iranian developmental screening test, this study was planned to determine the validity and reliability of Persian version of DDST-II (by translating to Persian and evaluating the cultural adaptation of the items) in Iranian children in order to provide an appropriate developmental screening tool for Iranian child health workers. Subjects and MethodsThis research is an action research that was performed from January to August 2008 in 4 Child Health Care centers located in north, south, east and west regions of Tehran city.These are primary health care centers which provide mainly general health services for people including children from different socio-economical classes of general population. Usually normal children visit such centers and services for growth monitoring, vaccination, vitamin supplements, etc).
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These centers are under the supervision of Deputy of Health, or Shahid Beheshti Medical University.At first test form and guiding sheet was translated precisely by 3 specialists familiar with English. Then the research team (4 pediatricians) read all 3 translated versions and for each item in form and sheet we chose the best translation (simple, short, easy to understand and culturally compatible).
Then we sent them along with original version to 3 other pediatricians who were familiar with developmental domains. The research team discussed their view points and implemented their opinions in the final form.
Healthy newborns, infants and children, 0–6 years old, in Tehran city could participate in this study. The inclusion criteria were: 1) age between birth to 6 years, 2) Iranian nationality, 3) living in Tehran city, and 4) parental cooperation. Exclusion criteria were: 1) having obvious developmental delay or disability (because including children with gross developmental disorders would lower the cutoff point for each developmental item in Iranian children), 2) parental refusal.The study was approved by the research committee and thereafter by the ethical committee of University of Social Welfare & Rehabilitation Sciences. Consent for participation was obtained from parents.
The parents whose children had developmental problems were informed and guided.Convenient sampling was used and 221 children (100 girls and 121 boys) in 13 age groups (0 to 2, 2.1 to 4, 4.1 to 6, 6.1 to 9, 9.1 to 12, 12.1 to 15, 15.1 to 18, 18.1 to 24, 24.1 to 30, 30.1 to 36, 36.1 to 48, 48.1 to 60 and 60.1 to 72 months), each age group containing 17 children, were examined. Demographic items included date of birth, sex, birth order, maternal education level, gestational age at birth (preterm or term; for preterm children up to 2 years we calculated corrected age), and history of disability of the child.Eight examiners were trained in a 1 day workshop for performing the DDST-II. A demographic questionnaire was completed for each child by parents and then DDST-II was done by the examiners. In order to determine the reliability of DDST-II, 25% of children in each age group (small children after 30–60 minutes, older children up to 2–3 days later) were re-examined by the same examiners (test-retest).Another 25% of children were retested by another examiner (inter-rater reliability).
In order to determine agreement coefficient, these children were also evaluated by ASQ (Ages and Stages Questionnaires) test. ASQ is not a diagnostic gold standard test. It is a developmental screening tool. Because we had no accessibility to any diagnostic tests we compared these two developmental screening tools to determine their agreement coefficient. Anyway, by another research team, ASQ was translated into Persian and was standardized on 11000 Iranian children. The results have not been published yet, but the general report exists and we have used the translated forms.
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Because ASQ is designed to use for 4–60 month-old children and each questionnaire can be used for one month before or after the specific age, children who were out of this range (3–61 months) were evaluated by developmental pediatricians. Also 10% of children of other age groups, after examining by DDST-II and completing the ASQ by parents, were evaluated by developmental pediatricians.As mentioned above, test-retest and inter-rater methods were used in order to determine reliability of the test by Cronbach's a and Kauder-Richardson coefficients.
We use Cronbach's a for reliability determining of each test item and Kauder-Richardson coefficient in 4 developmental domains. In test-retest and inter-rater tests we measured Cronbach's a and kappa measure of agreement for comparison of each developmental domain and final results of each test respectively. Content validity of the test was verified by reviewing texts and related articles, and by specialists’ opinions. Data was analyzed by SPSS software. FindingsIn this study 221 children were evaluated by DDST-II (100 girls and 121 boys) in 13 age groups (Appendix). Birth order of children were 73% first, 22% second, 3% third and 2% fourth child of family. Maternal educations of 85% of children were at high school or greater level.
95% of children were born at term and 5% of them preterm (for preterm children up to 2 years we calculated and considered corrected age).Children were selected from 4 different regions of Tehran city. Developmental screening of children by DDST-II showed that 143(65%) of them developed normally, 75(34%) had developmental delay (suspect) and 3(1%) were untestable according to test scoring method.Cautions and delays number in each developmental domains are 13 and 20 in Personal-social, 13 and 24 in Fine motor-adaptive, 21 and 16 in language and finally 10 and 23 in Gross motor areas. As it is seen number of cautions and delays are greater in language and fine motor– adaptive domains respectively. Children with developmental delays differed in number of affected domains.36 children had delay in 1, 27 children in 2 and 9 children in 3 developmental domains.In this study, reliability was evaluated by the Kauder-Richardson coefficients determination. The estimated coefficients were 0.74 for personal-social, 0.63 for fine motor-adaptive, 0.63 for language and 0.61 for gross motor domains. Test-retest and inter-rater methods were also used as other ways for reliability determination. Interclass Correlation Coefficients for test-retest and inter-rater methods are shown in.
DDST-II: Denver Developmental Screening Test II / ASQ: Ages and Stages QuestionnairesConsistency coefficient between DDST-II and ASQ was 0.21. Thus sensitivity and specificity of DDST-II could be calculated as shown below:Sensitivity = 21: 35 ×100 = 60%Specificity = 109:158 ×100 = 69%Comparison of DDST-II and results of pediatricians’ evaluation showed that 42 children passed and 4 children failed in both evaluations. Consistency coefficient between DDST-II and pediatricians’ evaluation was 0.44. Final translated version of DDST-II has been shown in appendix. DiscussionIn our study the content validity of DDST-II was verified by reviewing books and journals, and by specialists’ opinions.
All of the questions in DDST-II had appropriate content validity, and there was no need to change them.We evaluated the reliability of the test by the Kauder-Richardson coefficients determination. Determined Kauder-Richardson coefficients for all of developmental domains were “good”. Test-retest and inter-rater methods were also used as other ways for reliability determination. In test-retest examination the Cronbach's α coefficients for all developmental domain is very good and kappa measure of agreement is 87% ( P.
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