Diagnosis is relevant for patient care, research and policy. When an accurate and ‘timely’ diagnosis is made, a patient has the best opportunity for a positive health outcome because clinical decision-making will be tailored to a correct understanding of the patient’s health problem (Balogh et al., 2015). During the development of the 11th version of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) and the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the World Health Organization and the American Psychiatric Association (APA) made efforts towards harmonising the two classification systems: (1) for a more accurate collection of national health statistics and design of clinical trials aimed at developing new treatments, (2) to increase the ability to replicate scientific findings across national boundaries and (3) to rectify the issue of DSM-IV and ICD-10 diagnoses not agreeing (Bridley & Daffin, 2023).