Differentiating hypochondriasis from panic disorder

Abstract

Hypochondriasis and panic disorder are both characterized by prevalent health anxieties and illness beliefs. Therefore, the question as to whether they represent distinct nosological entities has been raised. This study examines how clinical characteristics can be used to differentiate both disorders, taking the possibility of mixed symptomatologies (comorbidity) into account. We compared 46 patients with hypochondriasis, 45 with panic disorder, and 21 with comorbid hypochondriasis plus panic disorder. While panic patients had more comorbidity with agoraphobia, hypochondriasis was more closely associated with somatization. Patients with panic disorder were less pathological than hypochondriacal patients on all subscales of the Whiteley Index (WI) and the Illness Attitude Scales (IAS) except for illness behavior. These differences were independent of somatization. Patients with hypochondriasis plus panic had higher levels of anxiety, more somatization, more general psychopathology and a trend towards increased health care utilization. Clinicians were able to distinguish between patient groups based upon the tendency of hypochondriacal patients to demand unnecessary medical treatments. These results confirm that hypochondriasis and panic disorder are distinguishable clinical conditions, characterized by generally more psychopathology and distress in hypochondriasis.

Introduction

Health anxieties are frequently experienced by patients with medical illness or mental disorders. They are perceived as plausible emotional reactions if a serious or life-threatening disease exists. In other cases, health anxieties may develop despite absence of organic pathology, especially when patients tend to misinterpret minor bodily sensations as signs of a serious disease or mistrust their doctors. If strong health anxieties persist over long periods of time and have negative consequences for the psychosocial functioning of the person, the diagnosis of hypochondriasis can be made. This diagnosis is included in categorical classification systems such as DSM-IV (American Psychiatric Association, 1994) and can be quantified by worldwide used hypochondriasis scales such as the Whiteley Index or the Illness Attitude Scales (Hiller, Rief, & Fichter, 2002).

However, hypochondriacal disorder is not the only clinical condition defined by predominant health anxieties. Patients with panic disorder usually report many intense somatic symptoms during their panic attacks such as palpitations and accelerated heart rate, shortness of breath, chest pain, nausea, paresthesia or dizziness. They also tend to attribute these symptoms to organic causes, such as heart or pulmonary disease. As a consequence, panic patients frequently demand extensive medical examinations or consult numerous specialists in the hope that the organic causes of their symptoms can be detected. Thus, the emotional, cognitive, and behavioral reactions of panic patients are very similar to those typically described for hypochondriacal disorder.

Despite these similarities, hypochondriacal and panic disorder can be well distinguished through use of structured interviews or diagnostic checklists (Barsky, Wyshak, & Klerman, 1992; Fava & Grandi, 1991). The major difference is the episodic nature of the symptoms in panic disorder versus the more or less persisting complaints in hypochondriasis. Panic patients usually experience their symptoms only during discrete periods that have a sudden onset and build to a peak within a few minutes, although worries concerning development of new attacks may persist in the intervals between the attacks. Hypochondriasis, on the other hand, is defined as fears or ideas of having a serious disease for more than 6 months. The exclusion criterion for hypochondriasis in DSM-IV (F) specifies that the disorder is not to be diagnosed if the symptomatology is fully accounted for by panic disorder. However, this does not generally exclude co-existence of hypochondriasis and panic disorder because patients may suffer from both episodic panic attacks (mostly attributed to cardiac dysfunction) as well as from more chronic fears related to diseases other than those associated with heart dysfunction.

Although DSM-IV provides valuable guidelines for differential diagnosis, overlaps and boundaries of hypochondriasis and panic disorder have rarely been studied. Barsky, Barnett, and Cleary (1994) compared “pure” hypochondriasis and panic disorder by selecting only hypochondriacal patients without comorbid panic disorder and panic patients without comorbid hypochondriasis. Patients with hypochondriacal disorder had more symptoms and higher distress on scales measuring health anxieties, disease conviction, bodily preoccupation, somatization and disability, they expressed less satisfaction with medical care, and were rated by their physicians as more demanding and help-rejecting. While patients with panic disorder received more comorbid diagnoses of depression and phobias, patients with hypochondriasis had a higher rate of comorbid generalized anxiety disorder. There was a trend for hypochondriacal patients to use more medical care than patients with panic disorder.

Other studies evaluated how often the specific comorbidity between hypochondriasis and panic disorder occurs and whether patients with and without this comorbidity can be distinguished. Only studies using reliable and valid diagnostic interviews will be cited here. Bach, Nutzinger, and Hartl (1996) examined panic disorder patients of a psychiatric outpatient department and diagnosed additional hypochondriasis in 51%. They also demonstrated that hypochondriasis is more closely linked to panic disorder than to agoraphobia. Of patients with primary panic disorder, more than 50% later developed hypochondriasis, in contrast to only 28.5% of patients with primary agoraphobia. Furer, Walker, Chartier, and Stein (1997) reported a similarly high rate of 48% for co-existing hypochondriasis in panic patients seen in an anxiety disorder clinic. Co-existence of both diagnoses was associated with increased hypochondriacal fears and concerns, anxiety, somatization and general psychopathology. In the samples recruited by Barsky et al. (1994) from a general medical clinic, 25% of the patients with panic disorder also fulfilled criteria of hypochondriasis, and 13% of the patients diagnosed with hypochondriasis had an additional panic disorder. Patients with this specific pattern of comorbidity showed generally more symptomatology and disability on a variety of measures. Somewhat contrary to these findings, Benedetti et al. (1997) found no marked differences between panic patients with and without hypochondriasis, although there was evidence that illness phobia before the onset of panic disorder increased the likelihood of developing the full clinical picture of hypochondriasis.

In the present study, we attempted to clarify in more detail the similarities and differences between hypochondriasis and panic disorder. Although we built on previous research, some methodological improvements were introduced. These improvements include (a) evaluation of different psychometric dimensions describing health anxieties and associated affective, cognitive and behavioral components, and (b) control of somatization as a crucial variable that could account for group differences. A comorbid group consisting of patients fulfilling the diagnostic criteria of both hypochondriasis and panic disorder was included to examine whether this “mixed condition” represents something like a third diagnostic group in addition to both “pure” groups.