The World Health Organization (WHO) is currently revisiting the ICD. In the 10th version of the ICD, approved in 1990, hypochondriacal symptoms are described in the context of both the primary condition hypochondriacal disorder and as secondary symptoms within a range of other mental disorders. Expansion of the research base since 1990 makes a critical evaluation and revision of both the definition and classification of hypochondriacal disorder timely. This article addresses the considerations reviewed by members of the WHO ICD-11 Working Group on the Classification of Obsessive-Compulsive and Related Disorders in their proposal for the description and classification of hypochondriasis. The proposed revision emphasizes the phenomenological overlap with both anxiety disorders (e.g., fear, hypervigilance to bodily symptoms, and avoidance) and obsessive-compulsive and related disorders (e.g., preoccupation and repetitive behaviors) and the distinction from the somatoform disorders (presence of somatic symptom is not a critical characteristic). This revision aims to improve clinical utility by enabling better recognition and treatment of patients with hypochondriasis within the broad range of global health care settings.
The article reviews the historical background and symptoms of body dysmorphic disorder (BDD) and olfactory reference disorder, and describes the proposals of the WHO ICD-11 Working Group on the Classification of Obsessive-Compulsive and Related Disorders related to these categories. This paper examines the possible classification of BDD symptoms in ICD-10. Four different possible diagnoses are found (hypochondriacal disorder, schizotypal disorder, delusional disorder, or other persistent delusional disorder). This has led to significant confusion and lack of clear identification in ICD-10. Olfactory reference disorder can also be classified as a delusional disorder in ICD-10, but there is no diagnosis for non-delusional cases. The Working Group reviewed the classification and diagnostic criteria of BDD in DSM-5, as well as cultural variations of BDD and olfactory reference disorder that include Taijin Kyofusho. The Working Group has proposed the inclusion of both BDD and olfactory reference disorder in ICD-11, and has provided diagnostic guidelines and guidance on differential diagnosis. The Working Group's proposals for ICD-11 related to BDD and olfactory reference disorder are consistent with available global evidence and current understanding of common mechanisms in obsessive-compulsive and related disorders, and resolve considerable confusion inherent in ICD-10. The proposals explicitly recognize cultural factors. They are intended to improve clinical utility related to appropriate identification, treatment, and resource allocation related to these disorders.