78 Apfeldorf et al. © 2000 WILEY-LISS, INC. DEPRESSION AND ANXIETY 12:78–84 (2000) MORBIDITY OF COMORBID PSYCHIATRIC DIAGNOSES IN THE CLINICAL PRESENTATION OF PANIC DISORDER William J. Apfeldorf, M.D., Ph.D., 1 * Lisa A. Spielman, Ph.D., 1 Marylene Cloitre, Ph.D., 1 Leora Heckelman, Ph.D., 2 and M. Katherine Shear, M.D. 3 This study seeks to determine how panic disorder patients with anxiety and de- pression comorbidity differ from panic disorder patients without comorbidity at the time of presentation for treatment. One-hundred seventy-one panic disorder patients presenting for their initial assessment and treatment at the Payne Whitney Anxiety Disorders Clinic agreed to participate and completed self-re- port and diagnostic assessments. Sixty-seven percent of panic disorder subjects were found to have at least one comorbid anxiety or depression diagnosis. Age and gender ratio were not affected by the presence of comorbid diagnoses. Comorbidity significantly contributed to psychological distress and symptom load, overall impairment, and interpersonal impairment. Depression and Anxiety 12:78–84, 2000. © 2000 Wiley-Liss, Inc. Key words: panic disorder; anxiety disorder; depression; comorbidity 1 Department of Psychiatry, Joan and Sanford I. Medical Col- lege of Cornell University, White Plains, New York 2 Department of Psychiatry, St. Luke’s-Roosevelt Medical Center, New York, New York 3 Department of Psychiatry, University of Pittsburgh, Pitts- burgh, Pennsylvania Contract grant sponsors: the Reader’s Digest Foundation (WJA); the Charles H. Revson Foundation (WJA); and a Public Health Service Grant (MKS). *Correspondence to: William Apfeldorf, M.D., Ph.D., Department of Psychiatry, Joan and Sanford I. Weill Medical College of Cornell University, 21 Bloomingdale Road, White Plains, NY 10605. E-mail: wapfeldo%westnyh@nyh.mail.cornell.edu Received for publication 8 July 1999; Accepted 5 May 2000 INTRODUCTION Panic disorder is associated with increased risk of both major depression and agoraphobia. Based on life- time rates, the odds ratios of comorbidity of panic dis- order with agoraphobia range from 7.5 (ECA study) to 21.4 (Cross-National Study [CNS]), and the odds ra- tios of panic disorder and major depression range from 3.8 to 20.1 (CNS). In a multicenter anxiety study, uncomplicated panic disorder was seen as a sole diagnosis for 55% of subjects presenting with primary panic at intake, and panic with agoraphobia was seen as a sole diagnosis for 47% of subjects presenting with primary panic at intake [Goisman et al., 1995]. Como- rbid disorders complicate the scientific identification of clinical populations by exhibiting functional effects on the patient and diagnostic effects on the clinician [Feinstein, 1970]. A comorbid condition may affect a patient’s clinical course so that the outcomes antici- pated for the index disorder may differ according to the amounts and types of comorbidity present before treatment. Diagnostically, a comorbid condition may produce manifestations that simulate those of the in- dex disease, so the pretherapeutic state of the disorder is difficult to identify. DSM-II and its successors at- tempt to tackle the diagnostic issues posed by psychi- atric comorbidity but do not address the functional issue. Schemes for assessing these aspects of prethera- peutic taxonomy have been developed for chronic dis- eases and are now being applied successfully in psychiatry [Angold and Costello, 1993]. The current study examines the functional effects of comorbid psy- chiatric conditions of the clinical presentation of panic disorder. A comorbid disorder may affect the age of presenta- tion, the outcome to be anticipated with and without treatment, the choice of treatment, and the level of functional impairment to be expected [Feinstein, 1970]. Detection of panic disorder results from a stimulus or event that leads the patient to seek exami- nation. Although panic disorder patients may seek help for symptoms arising from the disorder, many do not self-identify panic attacks or panic disorder [Ka- ton, 1989]. In this group, a comorbid condition may act as the stimulus for seeking help. If the comorbid condition exists prior to and early in the course of panic disorder, it may lead to earlier detection at a younger age and in a gender ratio reflecting the