New research shows that during more than one-third of outpatient visits to psychiatrists in the 1990s, patients with bipolar disorder did not receive a mood stabilizer—even though these medications have been proven to ameliorate the devastating effects of the manic and depressive phases of the illness.

Columbia University researcher Carlos Blanco, M.D., Ph.D., and colleagues evaluated national data on the treatments being used for outpatients with bipolar disorder over an eight-year period in the 1990s in order to measure physician conformance to recommendations in APA’s Practice Guideline for the Treatment of Patients With Bipolar Disorder.

Blanco, an assistant professor of psychiatry at Columbia University and assistant director of the Columbia University Anxiety Disorders Clinic, analyzed 865 visits to psychiatrists by patients with bipolar disorder from the National Ambulatory Medical Care Survey using a random sample of physicians in office practice. The survey is conducted each year by the National Center for Health Statistics.

To track trends in treatment of bipolar disorder over time, Blanco and his colleagues analyzed patient visits from 1992 to 1995 and from 1996 to 1999. The results of their analysis appear in the June American Journal of Psychiatry.

Blanco found that there was a significant difference in the diagnostic subtype of patients diagnosed with bipolar disorder from one study period to the next. For instance, researchers noted that patients diagnosed with a manic subtype of bipolar disorder accounted for just 8.4 percent of the 593 visits examined during the first study period, but that this proportion rose to 17 percent of 272 patients visits studied during the second study period.

Patients with mixed subtype of bipolar illness made 20 percent of outpatient visits during the first study period, but the proportion jumped to 36 percent during the latter part of the 1990s. Blanco told Psychiatric News that the shift in diagnoses as reflected by the study data may be due to the fact that increasing numbers of psychiatrists learned about the characteristics and diagnosis of mixed and manic subtypes of bipolar disorder as more scientific literature on the subject became available.

Blanco also found distinct differences in types of medications psychiatrists prescribed for patients with bipolar disorder during the two study periods. For instance, physicians prescribed lithium during 51 percent of visits examined during the first study period, but just 30 percent of the visits during the second study period. Conversely, visits characterized by the prescription of valproic acid, a newer mood stabilizer, rose dramatically, from 11 percent to 26.6 percent.

Blanco said that research on the efficacy of valproic acid for bipolar disorder and subsequent marketing by the pharmaceutical industry during the 1990s may have boosted prescription rates of the drug by physicians. In addition, physicians may have found that some patients tolerated and responded better to valproic acid as compared with other mood stabilizers.

But for a surprising number of patient visits, psychiatrists prescribed no mood stabilizer. Patients received mood stabilizers during just 64 percent of the 593 patient visits in the first study period, and this proportion decreased to 59 percent during the next study period in the late 1990s.

"I was very concerned about the fact that for more than a third of patient visits in our sample, there was no prescription for a mood stabilizer, which should be considered the first line of treatment in patients with bipolar disorder," Blanco said. "Our data indicate that a great many people with bipolar disorder involved in these visits were placed at risk for relapse."

In addition, in just over 44 percent of patient visits during both study periods, physicians prescribed an antidepressant without a mood stabilizer, a treatment scenario that could induce mania in patients with bipolar disorder.

Blanco’s analysis did not address why, during a relatively large proportion of patient visits, there were no prescriptions for mood stabilizers. He speculated that a number of factors could have dissuaded psychiatrists from prescribing mood stabilizers to patients with bipolar disorder. Some patients, for example, may not have improved on a mood stabilizer in the past, may have suffered from side effects from a previous mood stabilizer, or were unwilling to take a mood stabilizer when it was suggested by their psychiatrist.

"I think these data call for more research on clinical decision making by psychiatrists," said Blanco, "to help us better understand the factors that inform psychiatrists’ treatment decisions."

Blanco received funding for the study through grants from NIMH and NIDA, the National Alliance for Research on Schizophrenia and Depression, and APA’s Van Amerigen Health Services Scholars Program.

"Trends in the Treatment of Bipolar Disorder by Outpatient Psychiatrists" is posted on the Web at http://ajp.psychiatryonline.org/cgi/content/full/159/6/1005?. ▪

Am J Psychiatry  20021591005