Personality disorder not otherwise specified

Personality disorder not otherwise specified (PD-NOS) is a subclinical diagnostic classification for some DSM-IV Axis II personality disorders not listed in DSM-IV.

The DSM-5 does not have a direct equivalent to PD-NOS. However, the DSM-5 other specified personality disorder and unspecified personality disorder are substantially comparable to PD-NOS.

Additionally, the DSM-5 introduced the diagnosis Personality disorder - trait specified (PD-TS) as an alternative to let clinicians define the presentation in detail in terms of "impairment of personality functioning" and "pathological personality traits".

Diagnostic criteria
In all cases of non-specific diagnoses it is a requirement that the person meet the general criteria for personality disorders.

DSM-IV-TR
Clinicians may give this diagnosis when no other personality disorder in the DSM fits the patient's symptoms.

The DSM-IV-TR excluded four personality disorders, but this diagnosis may be used instead. The four excluded personality disorders are:
 * Sadistic personality disorder
 * Self-defeating personality disorder
 * Depressive personality disorder
 * Passive–aggressive personality disorder

DSM-5
The DSM-5 split PD-NOS into two diagnoses: Other Specified Personality Disorder and Unspecified Personality Disorder. They share the general criteria for personality disorders, but let clinicians specify why the presentation does not meet the criteria for any specific personality disorder (e.g. mixed personality features).

ICD-10
The World Health Organization's ICD-10 defines two conceptually similar diagnoses:
 * Other specific personality disorder for personality disorders that don't have a separate code. This diagnosis allows the following type specifiers: "eccentric", "haltlose", "immature", "narcissistic", "passive-aggressive", and "psychoneurotic".
 * Personality disorder, unspecified for general personality disorder diagnoses.

ICD-11
ICD-11 uses general diagnoses with specifiers to fully describe a condition. The closest diagnosis to PD-NOS would be Personality disorder, severity unspecified.

Epidemiology
The National Comorbidity Survey Replication estimated the prevalence of PD-NOS in the general population at around 1.6% (0.3-2.9%). Comorbidity measures indicated a strong association with antisocial personality disorder (and generally Cluster B), moderate association with obsessive-compulsive personality disorder, and strong negative association with schizoid and dependent personality disorders.

A 2004 meta-analysis estimated the prevalence of PD-NOS in patient samples between 8-13%. In structured interview studies it is the third most common diagnosis given, in unstructured studies it is the single most frequent diagnosis. Half the studies did not give further definition for the diagnosis, and those that did used "mixed" most often.

In another study out of 1760 psychotherapy referrals 21.6% was diagnosed exclusively with PD-NOS. In terms of severity patients with PD-NOS fall between a formal personality disorder diagnosis and no personality disorder. Patients who received PD-NOS as an additional diagnosis to their formal personality disorder diagnosis had the most severe problems.