Diagnostic Validity of Autism Diagnostic Observation Schedule, Second Edition (K-ADOS-2) in the Korean Population

Abstract Background Although the Korean version of the Autism Diagnostic Observation Schedule-2 (K-ADOS-2) is widely being used to diagnose autism in South Korea, no previous study has examined the validity and reliability of all modules of K-ADOS-2 across a wide age range, particularly older children, adolescents, and adults. Method Data from 2,177 participants were included (mean age = 79.2 months; 73.5% male); 1480 participants with autism and 697 participants without autism (Module-T, n = 296; Module-1, n = 654; Module-2 n = 574; Module-3 n = 411; Module-4, n = 233). Participants completed a battery of tests, including the K-ADOS or K-ADOS-2 and other existing diagnostic instruments. Sensitivity, specificity, area under the receiver operating characteristic (ROC) curve, positive predictive value (PPV), negative predictive value (NPV), Cohen’s kappa (k), and agreement with existing diagnostic instruments were computed. Cronbach’s α values were also calculated. Results All five modules of the K-ADOS-2 showed sufficient ranges of sensitivity 98.2–100.0%; specificity, 83.1–93.5%; area under the ROC curve, .91-.97; PPV, 88.1–97.6%; NPV, 87.3–100.0%; and k values, .83–.92. The kappa agreement with existing diagnostic instruments ranged from .20 to .90. Cronbach’s α values ranged from .83 to .90 across all modules. Limitation : The best-estimate clinical diagnoses made in this study were not independent of the K-ADOS-2 scores. Some modules did not include balanced numbers of participants in terms of gender and diagnostic status. Conclusion The K-ADOS-2 is a valid and reliable instrument in diagnosing autism in South Korea. Future studies exploring the effectiveness of the K-ADOS-2 in capturing restricted, repetitive behaviors and differentiating autism from other developmental disabilities are needed.