Mental retardation (MR) is a generalized disorder, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors that appears before adulthood. It has historically been defined as an Intelligence Quotient score under 70.
Coding mental disorders is complicated by the availability of another set of widely used codes, the Diagnostic and Statistical Manual, Fourth Edition (DSM-IV). According to this latest edition three criteria must be met for a diagnosis of mental retardation:
1. an IQ below 70,
2. significant limitations in two or more areas of adaptive behavior (as measured by an adaptive behavior rating scale, i.e. communication, self-help skills, interpersonal skills, and more), and
3. evidence that the limitations became apparent before the age of 18.
Coders are advised to use DSM-IV as a reference aid to arrive at a diagnosis, but ICD-9-CM should be used for the actual coding. The Mental Disorders section of ICD-9-CM was developed with the assistance of the American Psychiatric Association in an effort to help coders apply these diagnostic codes accurately. The codes are recognized by payers and help avoid confusion and claim denials.
ICD – 9 – CM codes for Mental disorders (290 – 319)