Many doctors are not referring to predefined criteria when diagnosing major depressive disorder, according to a study by Mark Zimmerman, associate professor of psychiatry and human behavior and director of outpatient psychiatry at Rhode Island Hospital.
Zimmerman administered a survey to 291 psychiatrists and 40 "non-psychiatrist physicians" prior to speaking at a number of medical conferences. One of the questions asked participants how often they used the criteria outlined in the fourth edition of the Diagnostic and Statistical Manual for Mental Disorders when diagnosing depression. The participants were then asked to select "less than 25 percent of the time," "26-50 percent of the time," "51–75 percent of the time" or "more than 75 percent of the time."
The results showed that 10.7 percent of the psychiatrists and 45 percent of the other physicians indicated that they consult the criteria less than 25 percent of the time.
"The concern is that individuals are being treated with medicine unnecessarily," Zimmerman said.
Both Zimmerman and Katherine Sharkey, assistant professor of medicine at the Alpert Medical School, agreed there is a limited effect of drug treatment on milder cases of depression. Monitoring the possible effects of an incorrect diagnosis becomes difficult because of the "so-called placebo response," Zimmerman said.
Zimmerman said doctors are not using the guidelines outlined in the DSM-IV because they are too long for clinicians to remember and include points that are "difficult to apply in medically ill patients." Sharkey added that the reasons may have more to do with the doctors' desire to diagnose and successfully treat the patient.
"Doctors say, ‘Well, this isn't going to change what my treatment is going to be anyway,'" Sharkey said.
There are nine criteria included in the DSM-IV to classify a major depressive episode, of which the patient must present five or more. The manual notes not to "include symptoms that are clearly due to a general medical condition." Zimmerman has recently published a paper suggesting a shorter definition, leaving out the physical symptoms that cause confusion for medically ill patients.
Sharkey highlighted the importance of having criteria agreed upon by the psychiatric community to ensure consistent diagnoses across the country and to allow for advancements to be made in the way of treatments.
"Making accurate diagnoses in psychiatry is really dependant on using the criteria," she said.
"The hope is, by shortening the definition, the criteria will be applied more rigorously in clinical practice," Zimmerman said.
