Evaluating the Validity and Reliability of PDQ-II and Comparison with DDST-II for Two Step Developmental Screening

This research was designed to identify the validity and reliability of the Prescreening Developmental Questionnaire 2 (PDQ-II) in Tehran in comparison with the Denver Developmental Screening Test-II (DDST-II). After translation and back translation, the final Persian version of test was verified by three pediatricians and also by reviewing relevant literature for content validity. The test was performed on 237 children ranging from 0 to 6 years old, recruited by convenient sampling, from four health care clinics in Tehran city. They were also evaluated by DDST II simultaneously. Interrater methods and Cronbach's α were used to determine reliability of the test. The Kappa agreement coefficient between PDQ and DDST II was determined. The data was analyzed by SPSS software. All of the questions in PDQ had satisfactory content validity. The total Cronbach's α coefficient of 0-9 months, 9-24 months, 2-4 years and 4-6 years questionnaires were 0.951, 0.926, 0.950 and 0.876, respectively. The Kappa measure of agreement for interrater tests was 0.89. The estimated agreement coefficient between PDQ and DDST II was 0.383. Based on two different categorizing possibilities for questionable scores, that is, "Delayed" or "Normal", sensitivity and specificity of PDQ was determined to be 35.7-63% and 75.8-92.2%, respectively. PDQ has a good content validity and reliability and moderate sensitivity and specificity in comparison with the DDST-II, but by considering their relatively weak agreement coefficient, using it along with DDST-II for a two-stage developmental screening process, remains doubtful.