Accuracy of diagnostic classification and clinical utility assessment of ICD-11 compared to ICD-10 in 10 mental disorders: findings from a web-based field study.

In this web-based field study, we compared the diagnostic accuracy and clinical utility of 10 selected mental disorders between the ICD-11 Clinical Descriptions and Diagnostic Guidelines (CDDG) and the ICD-10 CDDG using vignettes in a sample of 928 health professionals from all WHO regions. On average, the ICD-11 CDDG displayed significantly higher diagnostic accuracy (71.9% for ICD-11, 53.2% for ICD-10), higher ease of use, better goodness of fit, higher clarity, and lower time required for diagnosis compared to the ICD-10 CDDG. The advantages of the ICD-11 CDDG were largely limited to new diagnoses in ICD-11. After limiting analyses to diagnoses existing in ICD-11 and ICD-10, the ICD-11 CDDG were only superior in ease of use. The ICD-11 CDDG were not inferior in diagnostic accuracy or clinical utility compared to the ICD-10 CDDG for any of the vignettes. Diagnostic accuracy was consistent across WHO regions and independent of participants' clinical experience. There were no differences between medical doctors and psychologists in diagnostic accuracy, but members of other health professions had greater difficulties in determining correct diagnoses based on the ICD-11 CDDG. In sum, there were no differences in diagnostic accuracy for diagnoses existing in ICD-10 and ICD-11, but the introduction of new diagnoses in ICD-11 has improved the diagnostic classification of some clinical presentations. The favourable clinical utility ratings of the ICD-11 CDDG give reason to expect a positive evaluation by health professionals in the implementation phase of ICD-11. Yet, training in ICD-11 is needed to further enhance the diagnostic accuracy.