Abstract
OBJECTIVE: Our objective was to assess the operating characteristics of the Psychological Development Questionnaire-1 (PDQ-1), an autism screener for use with young children. METHODS: In Phase 1, we evaluated the concordance of the PDQ-1 with established autism scales, determined test-retest reliability, and identified a risk threshold score. In Phase 2, a population of 1959 toddler-age children was prospectively screened through multiple pediatric practices in a diverse metropolitan region, using the new instrument. Screen-positive children were referred for diagnostic evaluation. Screened children received follow-up at age 4 years to identify autism cases missed by screening and to specify the scale's psychometric properties. RESULTS: By screening a diverse population of low risk children, age 18 to 36 months, with the PDQ-1, we detected individuals with autism who had not come to professional attention. Overall, the PDQ-1 showed a positive predictive value (PPV) of 88%, with a sensitivity of 85% and specificity of 99% in a low risk population. High specificity, good sensitivity, and PPV were observed across the 18 to 36 month age-range. CONCLUSION: The findings provide preliminary empirical support for this parent report-based indicator of toddler psychological development and suggest that the PDQ-1 may be a useful supplement to developmental surveillance of autism. Additional research is needed with high risk samples and large, unselected populations under real-world conditions.