Pain predicts longer time to remission during treatment of recurrent depression

Introduction: Pain and depression are mutually exacerbating. We know that both of these syndromes predict the future occurrence of the other. It has not been shown, however, whether the presence of pain slows the effect of treatment for depression. We hypothesized that greater pain and somatic scores prior to treatment with imipramine and interpersonal psychotherapy would predict a slowed time to remission from depression. Method: We performed secondary data analyses of an archived study. Subjects (N = 230) were between 21 and 65 years of age and were enrolled in a study of maintenance treatment for recurrent unipolar depression. Patients had to meet Research Diagnostic Criteria (RDC) for a major depressive episode and historical requirements for at least 3 prior episodes and clear remissions (according to RDC). Patients were also required to have a minimum Hamilton Rating Scale for Depression score of 15 and a minimum score of 7 on the Raskin Severity of Depression Scale. This report describes the acute treatment phase, during which all subjects received combination therapy consisting of imipramine hydrochloride (150 to 300 mg) and interpersonal psychotherapy. Pain and somatization were measured with the Hopkins Symptom Checklist. Results: Higher levels of both pain and somatization predicted a longer time to remission. After controlling for baseline severity of depression, only pain was still significant in predicting a longer time to remission. Headache and muscle soreness were the 2 variables from the pain index whose presence independently predicted a slower remission. Both pain and somatization improved during acute treatment. Subjects with more pain and somatization, after controlling for severity of depression, reported more suicidality. Women reported more pain than men. Conclusions: Pain, but not somatization, predicted a longer time to remission and may be a marker of a more difficult-to-treat depression. Adults with recurrent depression should be screened for the presence of pain prior to treatment, as the presence of these symptoms may require more aggressive treatment or may be a marker for suicidality or the use of dual-mechanism antidepressants.