Risk Factors Emerge for Treatment-Resistant Depression
Paula Moyer, MA
Oct. 27, 2005 (Amsterdam) — Concurrent anxiety disorder, a poor response to the initial antidepressant used, and a current risk of suicide increase the risk that a patient will develop treatment-resistant depression (TRD), according to a team of Belgian psychiatrists who presented their findings here at the 18th congress of the European College of Neuropsychopharmacology.
"These issues, singly or in combination, are all risk factors for [TRD]," said Pierre Oswald, MD, during his presentation. He is an assistant psychiatrist in the psychiatry department of Erasme Hospital, an appointment at the University Clinic of Brussels in Belgium.
Dr. Oswald stressed the urgency of identifying the risks of TRD because "as many as 50% of depressed patients do not respond to first-line treatment, even at presumably adequate doses." Until recently, investigators did not agree on the definition of TRD; therefore, competing definitions have led to conflicting findings regarding the predictors, he said.
Fortunately, a consensus has developed. Investigators now agree that TRD is an inadequate response at least two consecutive antidepressants from different classes, given at presumably adequate doses. As a result of this consensus, Dr. Oswald and coinvestigators initiated a large European study involving seven centers and 996 patients with major unipolar depression.
The patients in the study had received at least one antidepressant treatment at adequate doses during their last depressive episode. Each patient was evaluated using a structured diagnostic interview, the Mini-International Neuropsychiatric Interview. They also responded to a questionnaire investigating their demographic, psychosocial, psychiatric, and somatic characteristics. The investigators then developed a checklist of previous treatments that included drug class, duration of treatment, dose, and patient adherence, as well as the exact sequence of antidepressants that patients had received, in case they had participated in multiple trials.
The investigators defined the last depressive episode as resistant if the patient had not responded to at least two consecutive antidepressant trials. According to this definition, 356 patients (35.7%) were treatment-resistant; 346 patients (34.7%) were responsive, and the remaining 294 patients (29.6%) had issues that put them at risk of developing TRD.
In a two-step logistic regression analysis, certain factors predicted the development of TRD: comorbid anxiety disorder, a poor response to the initial antidepressant treatment, a depression with features of melancholia, and current suicidal risk.
ECNP 18th Congress: Abstract S.07.07. Presented Oct. 24, 2005.
European Neuropsychopharmacol. 2005;15(suppl 3):S326
Reviewed by Gary D. Vogin, MD
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