Comorbidity burden and its impact on psychosocial morbidity in depressed outpatients

Background: Many studies have examined the co-occurrence of depression and one or two nondepressive disorders; however, little research has looked at broad spectrum comorbidity (i.e., comorbidity across several diagnostic cat egories) in depressed patients. Research on diagnostic practices in routine clinical settings - in which unstructured interviewing is the norm - sugge sts that comorbid conditions are often not detected [Zimmerman, M., Mattia, J. 1999. Psychiatric diagnosis in clinical practice: Is comorbidity being missed? Compr. Psychiatry, 40, 182-191]. In this study we examined the inde pendent impact of different comorbid diagnostic categories on psychosocial morbidity in psychiatric outpatients with Major Depressive Disorder (MDD). Methods: Participants were drawn from a pool of 1000 psychiatric outpatient s interviewed with the Structured Clinical Interview for DSM-IV diagnoses ( SCID-IV; [First, M.B., Spitzer, R.L., Williams, J.B.W., Gibbon, M., 1995. S tructured Clinical Interview for DSM-IV (SCID). American Psychiatric Associ ation, Washington, D.C.]). We compared the demographics, clinical character istics, and psychosocial functioning of depressed outpatients with and with out different axis I comorbidities, then conducted multivariate analyses to determine the respective impact of comorbid axis I disorders. Results: Thr ee hundred and seventy-three patients had a principal diagnosis of unipolar MDD. One hundred twenty-nine (34.6%) were diagnosed with MDD only, and 244 (65.4%) had MDD and at least one other axis I disorder. Comorbidity was as sociated with longer duration of index episode, more psychiatric morbidity, and more social and occupational impairment. There was also a significant relationship between increasing number of comorbid axis I disorders and gre ater psychiatric and psychosocial impairment. In regression analyses, comor bidity burden (i.e., the number of comorbid axis I disorders) showed the st rongest relation to psychiatric and psychosocial impairment. Limitations: T his is not a random sample of depressed outpatients and, thus, may not be g eneralizable to all outpatients with depression. Second, Axes II and III co morbidity were not assessed. Conclusions: Comorbidity burden showed the str ongest relation to impairment over and above the presence of any particular class of disorders. (C) 2001 Elsevier Science BY All rights reserved.