Prevalence and clinical correlates of medical comorbidities in patients with bipolar I disorder: analysis of acute-phase data from a randomized controlled trial.

OBJECTIVE: We studied the relationship between number of medical comorbidities in patients with bipolar I disorder and their demographic and clinical characteristics.

METHOD: Data were from 174 patients in the acute phase of the Pittsburgh Maintenance Therapies in Bipolar Disorder (MTBD) study, a randomized controlled trial comparing Interpersonal and Social Rhythm Therapy to an intensive clinical management approach for individuals with a lifetime diagnosis of bipolar I disorder or schizoaffective disorder, manic type, according to Research Diagnostic Criteria, who were receiving adjunctive protocol-driven pharmacotherapy. Patients entered the MTBD study from 1991 to 2000. We examined the acute-phase Hamilton Rating Scale for Depression (HAM-D) and Bech-Rafaelsen Mania Scale scores, demographics, clinical history, and medical comorbidities.

RESULTS: Patients with a high number of medical comorbidities had longer duration of both lifetime depression (p = .02) and lifetime inpatient depression treatment (p = .04), had higher baseline HAM-D score (p = .01), and were more likely to be treated for a depressed clinical state during the acute phase of the MTBD study (p = .05). Moreover, higher severity of baseline medical comorbidities predicted slower decreases in HAM-D score among depressed (p = .004) and mixed/cycling (p = .003) patients even after controlling for baseline HAM-D score.

CONCLUSIONS: Medical illness is correlated with several indicators of poorer prognosis and outcome in bipolar I disorder. Not only do preventing and treating medical comorbidities in bipolar patients decrease the morbidity and mortality related to physical illness, but they could also enhance psychological well-being and possibly improve the course of bipolar illness. Identification of characteristics in bipolar I patients that are correlated to increased risk for medical comorbidities is a fundamental step in understanding the nature of the relationship between bipolar disorder and medical illness.