Approach
Age of onset of OCD is typically late adolescence to early twenties.[7] Late onset (i.e., after 35 years of age) is less common, and is often associated with a history of chronic subclinical symptoms.[7]
The Diagnostic and Statistical Manual of Mental Disorders, fifth edition, text revision (DSM-5-TR) criteria for obsessive-compulsive and related disorders (or World Health Organization [WHO] International Classification of Diseases 11th revision [ICD-11] criteria) should be used as a guide when making a diagnosis of OCD.[1][7]
In addition, structured interviews can be used to exclude comorbidities or similar psychiatric conditions that mimic OC symptoms but have different underlying neurocircuitries and treatments. Risk factors for OCD should be considered, such as the presence of a family history of OCD and history of paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS).
DSM-5-TR criteria
The American Psychiatric Association's DSM-5-TR offers operationalised criteria to be used in establishing a diagnosis of OCD. OCD is classified within the general chapter on "Obsessive-compulsive and related disorders".[1]
Must exhibit obsessions, compulsions, or both.
The obsessions or compulsions are time-consuming (e.g., take more than 1 hour per day) or cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
The obsessions and/or compulsions are not attributable to the physiological effects of a substance or other medical condition.
The disorder is not better explained by the symptoms of another mental disorder, such as excessive worries in the context of generalised anxiety disorder, or ritualised eating behaviour in the context of an eating disorder.
Obsessions are:
Recurrent and persistent thoughts, urges, or images experienced, at some time during the disturbance, as intrusive and unwanted and in most individuals cause marked anxiety or distress.
There is some effort by the affected person to ignore or suppress such thoughts, impulses, or images, or to neutralise them with some other thought or action (i.e., by performing a compulsion).
Compulsions are:
Repetitive behaviours (e.g., hand washing, ordering, checking) or mental acts (e.g., praying, counting, repeating words silently) that the person feels driven to perform in response to an obsession or according to rules that must be applied rigidly.
These behaviours or mental acts are performed in order to prevent or reduce distress, or prevent some dreaded event or situation. However, they are either clearly excessive or not connected in a realistic way with what they are designed to neutralise or prevent.
In diagnosis, specify level of patient insight. Note that this may vary over the course of the condition.
With good or fair insight: individual recognises that OCD beliefs are definitely or probably not true or that they may or may not be true.
With poor insight: individual thinks OCD beliefs are probably true.
With absent insight/delusional beliefs: individual is completely convinced that OCD beliefs are true.
Do not give these patients an additional diagnosis of a psychotic disorder unless their delusional beliefs involve content that extends beyond what is characteristic of their obsessive-compulsive and related disorder (e.g., an individual with body dysmorphic disorder who is convinced that his or her food has been poisoned).
Also specify if the disorder is tic-related (i.e., does the patient have a current or past history of a tic disorder). Up to 30% of those with OCD have a lifelong tic disorder, and may present with a different clinical course to those without a tic disorder in terms of symptoms, comorbidities, and pattern of inheritance.
Structured interviews
Typically in clinical settings, the diagnosis is determined by unstructured clinical interviewing and reviewing DSM-5-TR criteria. In addition, there are two empirically validated structured interviews with good reliability and validity that can be used to assess for an OCD diagnosis:
The Structured Clinical Interview for DSM-5 (SCID-5).[35]
The Anxiety Disorder Interview Schedule for DSM-5 (ADIS-5).[36]
The SCID and ADIS are not necessary in most cases and are largely used in research settings.
Yale-Brown Obsessive-Compulsive Scale (Y-BOCS)
The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) is the most widely used measure of OCD symptoms. It can be used as a self-report instrument or a semi-structured interview, and has been demonstrated to be valid in OCD. The Y-BOCS exists in both an adult and a child version.[37] This scale is not a diagnostic tool, but a reliable measure of symptom severity.
The Y-BOCS has both a symptom checklist and a severity rating scale. The Y-BOCS symptom checklist also provides the therapist with information about the problem areas that need further focus in treatment. The Y-BOCS severity scale consists of 10 questions: 5 about obsessions and 5 about compulsions. This scale should be administered to patients who are beginning treatment for OCD and should be re-administered periodically, perhaps every 6 months, in order to track treatment progress. The definition of response and non-response to treatment is based on the Y-BOCS.
Clinical Global Impression (CGI)
The CGI is used to assess the general clinical severity of any mental disorder.[38] It was developed for use in National Institute of Mental Health (NIMH)-sponsored clinical trials to provide a brief, single-item assessment of the clinician's view of the patient's global functioning prior to and after initiating a study medication. Subsequent to a clinical evaluation, usually requiring at least 1 hour, the CGI form can be completed in less than a minute by an experienced rater.
The CGI is composed of two companion one-item measures evaluating the following: a) severity of psychopathology from 1 to 7, and b) change from the initiation of treatment on a similar 7-point scale. These capture clinical impressions beyond mere symptom checklists, can include subthreshold comorbidity, and can take into account patient history, psychosocial circumstances, symptoms, behaviour, and the impact of the symptoms on the patient's ability to function. A patient self-assessment version of this has also been proposed.
The CGI is a useful tool for tracking clinical progress across time and has been shown to correlate with longer, more detailed and time-consuming rating instruments across a wide range of psychiatric diagnoses.[39][40][41]
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