COMMENTARY

DSM-5's Validity: Non Sumus Angeli!

Ronald W. Pies, MD

Disclosures

June 12, 2013

In This Article

Many Measures of Validity

Dr. Bernard Carroll's description[3] of convergent validity should be required reading for all psychiatry residents. He explains that our disease constructs take shape through a process of "convergent validation." This entails "...iterative attention to signs, symptoms, course of illness, response to treatments, family history, and laboratory data." He adds that "laboratory tests are not the automatic gold standard of evidence for validity." Indeed, as Dr. Carroll[3] pointedly observes,

We need to be clear that the existence of disease is not predicated on having a biological test. It's nice when we do have one, but there are many areas in medicine where there is no conclusive diagnostic test. Think migraine. Think multiple sclerosis. Think chronic pain. Indeed, clinical science correctly recognized many diseases long before lab tests came along for confirmatory diagnostic application. Think Parkinson's disease, Huntington's disease, epilepsy...it's a long list.

Furthermore, validity is not a single or simple construct. Thus, discriminant validity refers to the ability of a set of diagnostic criteria to distinguish one condition from another: for example, how well does our construct of schizophrenia allow us to distinguish this condition from autistic spectrum disorders or bipolar disorder? Predictive validity is a measure of how well a diagnostic category allows us to make accurate predictions of course of illness, episode recurrence, degree of impairment, morbidity and mortality, and response to treatment.

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