Comorbidity of anxiety disorders and hypochondriasis considering different diagnostic systems

Comorbidity of Anxiety Disorders and Hypochondriasis Considering Different Diagnostic Systems Michael Bach, Detlev O. Nutzinger, and Lydia Hartl The influence of different hierarchical guidelines in various classification systems on the diagnosis of anxiety disorders and hypochondriasis was investigated. Using a semistructured polydiagnostic interview (including DSM-III, DSM-III-R, and the 1987 draft version of ICD-10), lifetime diagnoses were determined in 82 outpatients with a DSM.III-R anxiety disorder. In all diagnostic systems, half of our patients exhibited the descriptive features of hypochondriasis. As demonstrated, the formulation of restrictive hierarchical rules--as in DSM-IIl---contributes to the concept of "primary" hypochondriasis, while secondary

hypochondriasis remains underdiagnosed. Concordance rates for hypochondriasis were high between DSM-III.R and ICD.10, but not with DSM-III. Although hypochondriasis showed a strong association with the clinical course of panic disorder (PD), it could not be explained as a consequence of greater illness severity of PD with agoraphobia (AP). Our data underline the conceptualization of hypochondriasis as a phenomenologically homogeneous diagnostic category that may be differentiated from comorbid psychiatric conditions. Copyright © 1996by W.B. Saunders Company

A

have provided divergent exclusionary rules. For example, in DSM-II116 a diagnosis of hypochondriasis may be excluded by the presence of various anxiety disorders such as PD, generalized anxiety disorder, and obsessive-compulsive disorder, whereas in DSM-III-R 17 and ICD-10 (draft version) TM the co-occurrence of anxiety disorders and hypochondriasis may be considered two independent clinical conditions. In addition, unlike DSM-III-R criteria, DSM-III and ICD-10 exclude a diagnosis of hypochondriasis when depressive disorders precede the development of hypochondriacal symptoms. Furthermore, in contrast to DSM-III-R, the presence of (multiple) somatization disorder excludes a diagnosis of hypochondriasis in DSMIII and ICD-10. In all these diagnostic systems, a diagnosis of hypochondriasis is given only in the absence of any delusional or psychotic syndromes. As emphasized by several researchers, application of such hierarchical rules gives rise to substantial divergencies between different diagnostic systems and may obscure true relationships between psychiatric disorders such as anxiety disorders and hypochondriasis. 12,19 Therefore, the use of diagnostic criteria without consideration of exclusionary guidelines has been suggested especially for research in psychiatric comorbidity.2°-22 The purpose of the present study was (1) to evaluate the extent to which application of hierarchical guidelines provided in DSM-III, DSM-III-R, and ICD-10 may affect comorbidity rates of hypochondriasis in anxiety disorders, (2) to determine concordance rates for hypochondriasis according to these diagnostic sys-

SUBSTANTIAL PROPORTION of patients with anxiety disorders suffer from medically unexplained somatic symptoms, a,2 Based on bodily preoccupations and the person's misinterpretation of such physical signs and sensations, anxiety disorders are often associated with hypochondriacal complaints. 3-13Due to this fairly common coexistence of anxiety and hypochondriasis, hypochondriacal complaints may be regarded as associated features of anxiety disorders rather than defining a distinct diagnostic category. Consequently, several investigators have questioned the independence of hypochondriasis as a primary disorder. 5,12,14,15 Thus, although there is an overall agreement that hypochondriasis and anxiety disorders-namely panic disorder (PD)--are related, the nature of the relationship remains unclear.13 Research in psychiatric comorbidity attempts to determine the extent to which diagnostic groups overlap or can be distinguished on the basis of descriptive characteristics. With respect to the phenomenology of hypochondriasis, descriptive criteria do not vary across different diagnostic systems. However, for a diagnosis of hypochondriasis, different diagnostic systems From the Department of Psychiatry, University of Vienna, Vienna, Austria; the Klinik Bad Bramstedt-Centerfor BehavioralMedicine, Bad Bramstedt; and the Departmentof Psychology, Ludwig Maximilian University of Munich, Munich, Germany. Address reprintrequeststo MichaelBach, M.D., Department of Psychiatry, University of Vienna, WiihringerGartel 18-20, A-1090 Vienna, Austria. Copyright © 1996by W.B. Saunders Company 0010-440X/96/3701-0011503.00/0 62

Comprehensive Psychiatry, Vol. 37, No. 1 (January/February), 1996: pp 62-67

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ANXIETY DISORDERS AND HYPOCHONDRIASIS

tems, and (3) to assess the temporal relationship between PD, agoraphobia (AP), and hypochondriasis by the use of lifetime diagnoses according to DSM-III-R. METHOD The sample consisted of 82 psychiatric outpatients (49 women and 33 men) aged 38.7 _+ 10.0 (mean _+ SD) years (range, 21 to 68) attending the Department of Psychiatry in Vienna for participation in an outpatient treatment program for anxiety disorders. According to DSM-III-R, 66 subjects met criteria for PD with AP, 10 for PD without AP, and six for AP without history of PD. In all patients, lifetime diagnoses were determined by the use of a semistructured polydiagnostic interview. This instrument consisted of a Structured Clinical Interview for DSM-III-R (SCID, German version)e3and additional operationalized items from DSM-IIP 6 and the 1987 draft version of the ICD-10? s To ensure comparability between different diagnostic systems, all items were assessed in terms of written questions and were rated analogous to the SCID, followed by an algorithm for differential diagnosis according to DSM-III, DSM-III-R, and ICD-10. On the basis of lifetime diagnoses, a diagnosis has been excluded by a second one when its symptomatology was considered as part of broader phenomenological criteria represented by the second co-occurrent diagnosis. On the other hand, two or more diagnoses were assigned when times of onset and/or duration criteria could be regarded as independent. Interviews were performed by two of the authors (M.B. and D.O.N.) in that one rater conducted the interview while the other co-rated. When there was disagreement, diagnoses were made by consensus.

RESULTS

Regarding the comorbidity of hypochondriasis in anxiety disorders, application of hierarchical guidelines led to substantial divergencies between and within different diagnostic systems (Fig 1). Without applying hierarchical rules, 44 patients (53.7%) met criteria for hypochondriasis according to DSM-III and ICD-10, and 42 patients (51.2%) according to DSM-III-R. When applying particular hierarchical guidelines, only 12 patients (14.6%) met criteria for hypochondriasis according to DSM-III, whereas 42 patients (51.2%) fulfilled criteria according to DSM-III-R and ICD-10. Due to the co-occurrence of anxiety disorders and hypochondriasis in most patients, a diagnosis of hypochondriasis could not be given according to the exclusionary rules of DSM-III. In six of 42 patients with a DSM-III-R hypochondriasis, the onset was more than 6 months before that of DSM-III-R PD and/or AP, labeling these patients as "primary" hypochondriacs according to the proposal of Barsky et al. 12 Of these primary hypochondriacs, only one patient (16.7%) reported a history of a DSM-III-R major depression, whereas 24 of 36 patients (66.7%) with secondary hypochondriasis had a history of DSM-III-R major depression or dysthymia lifetime. Comparing diagnostic criteria for hypochon-

90

hierarchy-free

hierarchical

80

i

70 60 50 40 30 20 10

I

0

DSM-III

I DSM-III-R

I ICD-10

I--

I DSM-III

DSM-In-R

ICD- 10

Fig 1. Additional lifetime diagnosis of hypochondriasis: consideration of hierarchical guidelines. (11) Hypochondriasis; (D} no hypochondriasis.

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BACH, NUTZINGER, AND HARTL

driasis, concordance rates between DSM-III, DSM-III-R, and ICD-10 were as follows. Of 12 patients with DSM-III hypochondriasis, 10 (83.3%) met DSM-III-R criteria and all 12 (100%) also met ICD-10 criteria. Of 42 patients with DSM-III-R hypochondriasis, 10 (23.8%) met DSM-III criteria and 40 (95.2%) met ICD-10 criteria. Of 42 patients with ICD-10 hypochondriasis, 12 (28.6%) met DSM-III criteria and 40 (95.2%) met DSM-III-R criteria. In summary, 10 patients fulfilled criteria of all three diagnostic systems (concordance rates, 83.3% for DSM-III and 23.8% for DSM-III-R and ICD-10). Of these 10 patients, six were assigned a diagnosis of"primary" hypochondriasis according to DSM-III-R (concordance rates, 50.0% for DSM-III and 14.3% for DSM-III-R and ICD-10). DSM-III-R anxiety disorders at onset were PD with AP in 51 patients, PD without AP in 22, and AP without history of PD in nine. The diagnosis of PD with AP was given if the onset for both panic attacks and agoraphobic avoidance was within a range of 6 months. During the course of illness, 72.7% of patients with PD without AP at onset subsequently developed AP, whereas only 33.3% of patients with AP without history of PD at onset developed PD (Table 1). In addition, 92.2% of patients with a primary diagnosis of PD with AP exhibited a persistence of both panic attacks and agoraphobic avoidance. Patients with AP without PD at onset reported a significantly earlier disease onset as compared with patients with primary onset of panic attacks (mean age, 22.8 years in AP without history of PD, 28.7 in PD without AP, and 30.5 in PD with AP; one-way analysis of variance, P < .05). However, the total illness duration did not differ significantly between these three subsamples (one-way analysis of variance, P = .32). In addition, at the time of Table 1, Shifting in the Diagnostic Classification During the Course of Illness Principal DSM-III-RDiagnosisat Onset Lifetime DSM-III-R Diagnosis PD without AP PD with AP AP without PD

PD Without AP

PD With AP

AP Without PD

No.

%

No.

%

No.

%

6 16 0

27.3 72.7 0

4 47 0

7.8 92.2 0

0 3 6

33.3

*P < .01 (McNemar test).

0 66.7

the interview, the three subsamples did not differ significantly with regard to age (one-way analysis of variance, P = .25) and sex (×2, P = .14). During the course of illness, 28.5% of patients with an onset of AP without history of PD subsequently developed hypochondriasis, whereas 50.0% of patients with PD without AP and 56.9% of patients with PD with AP met additional criteria for DSM-III-R hypochondriasis. However, in all three subsamples, the age at disease onset was similar for patients with a lifetime prevalence of hypochondriasis as compared with those without hypochondriasis (analysis of variance: main effects, F = 2.28, P = .08; two-way interactions [hypochondriasis v no hypochondriasis], F = 0.02, P = .81). DISCUSSION

Comorbidity of Anxiety Disorders and Hypochondriasis: Effects of Different Hierarchical Guidelines Great similarities in the descriptive criteria for hypochondriasis in DSM-III, DSM-III-R, and ICD-10 led to the finding of similar lifetime prevalence rates for hypochondriasis when applying these diagnostic systems without exclusionary rules. There were only two patients in whom hypochondriasis was not diagnosed according to DSM-III-R due to a duration of less than 6 months. However, as a result of cooccurrence between anxiety disorders and hypochondriasis, the majority of hypochondriasis cases were excluded when applying hierarchical guidelines according to DSM-III. In contrast, only one hypochondriacal patient with a cooccurrent (multiple) somatization disorder and another patient with a co-occurrent major depressive episode remained undetected according to ICD-10. In addition, as expected, prevalence rates of DSM-III-R hypochondriasis remained unaffected, since DSM-III-R does not provide these exclusionary rules.

Concordance Rates for Hypochondriasis According to DSM-III, DSM-III-R, and ICD-IO High concordance rates were obtained for DSM-III-R and ICD-10. Only two patients with ICD-10 hypochondriasis failed to meet DSMIII-R criteria due to an illness duration of less than 6 months. Since most of our patients

ANXIETY DISORDERS AND HYPOCHONDRIASIS

exhibited a chronic course of hypochondriacal concerns, the more restrictive duration criterion of 6 months as defined in DSM-III-R does not substantially affect the diagnosis of hypochondriasis. However, since there is evidence for transient hypochondriacal reactions of less than 6 month's duration, namely in primary care patients, 24,25the formulation of more restrictive duration criteria may lead to diagnostic divergencies in such patient samples rather than in psychiatric patients. Most patients with hypochondriasis according to DSM-III-R and ICD-10 remained undiagnosed in DSM-III. On close examination, all patients with a primary onset of DSM-III-R hypochondriasis also met DSM-III criteria, whereas only a small proportion of secondary hypochondriasis fulfilled the diagnostic criteria of DSM-III. Therefore, it might be argued that DSM-III contributes to the concept of primary hypochondriasis, defining a probably more homogeneous diagnostic category of hypochondriasis as compared with other diagnostic systems. On the other hand, in subjects presenting with clinical features of both anxiety and hypochondriasis, DSM-III tends to eliminate hypochondriasis. As emphasized by Barlow et al., 2° this points to the question of whether researchers and clinicians should continue to act as if diagnostic categories were actual "entities" by choosing one category and excluding others, or whether they should attend more closely to presenting coexisting problems and the overall patterns of psychopathology.

Temporal Relationship Between PD, AP, and Hypochondriasis Most patients with PD at onset subsequently developed AP, underlining previous assumptions that the secondary development of AP may indicate a more severe variant of P D . 2628 However, the majority of patients with AP without history of PD at onset remained agoraphobic without developing panic attacks. This finding is consistent with previous studies giving evidence for the independence of agoraphobia at least in some anxiety disorder patients. 22,29-34 In addition, in our sample, primary agoraphobics reported a significantly earlier disease onset as compared with patients with primary onset of panic attacks. In these patients, devel-

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opment of phobic avoidance cannot be explained by aversive conditioning to panic. These findings are consistent with previous studies suggesting the primacy of agoraphobic symptoms with respect to panic attacks, 7,35,36which may therefore challenge the view currently represented in DSM-III-R that phobic avoidance is secondary to panic attacks. However, with regard to the conflicting results of previous studies on this question, it currently seems reasonable to assume different pathways for the development of panic attacks and phobic avoidance, allowing an interactive model of symptom progression toward the whole PD/AP syndrome by various r o u t e s . 32'33'37 In this study, hypochondriasis was strongly associated with PD, but not with AP. Lifetime comorbidity rates of hypochondriasis were approximately twice as high in panic patients as compared with primary agoraphobics. In addition, we found comparable comorbidity rates of hypochondriasis in patients with PD with AP, and PD without AP. These data are consistent with studies by Barsky et al., 12 who found that lifetime PD was more common in patients with DSM-III-R hypochondriasis, but current PD was not. However, our results are in contrast with the report by Starcevic et al., 13who found that hypochondriasis was specifically associated with AP in panic patients, leading to the assumption that hypochondriacal concerns may be explained as a consequence of a greater illness severity of PD patients with secondary AP. 13,14,38 In contrast, Barsky et al. 39 recently pointed out that hypochondriasis and PD are phenomenologically and functionally differentiable disorders. Therefore, in our view, the application of hierarchical rules that tend to choose anxiety disorders and exclude hypochondriasis in subjects with co-occurrent symptom clusters remains questionable. In six of 42 patients with DSM-III-R hypochondriasis, the onset of hypochondriasis was more than 6 months before that of the anxiety disorders. Of these, five patients had no history of depressive disorders. These findings are comparable to those of Barsky et al., 12'39 adding further evidence to the concept of "primary" hypochondriasis. 4°-42 However, since in most patients hypochondriasis was assigned as an additional diagnosis rather than as the primary

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disorder, it seems unreasonable to consider hypochondriasis as a prodromal syndrome of PD, as suggested previously.5,7,9

Limitations of the Study Several limitations may restrict the generalizability of this study. First, due to the retrospective nature of our data, conclusions on the temporal relationship of disorders should be used with caution. In particular, evidence was found that people tend to remember salient apparent events such as the experience of their first panic attack rather than the less severe discomfort resulting from primary phobic avoidance or hypochondriacal concerns. 43 Therefore, the retrospective assessment of primary AP or hypochondriasis may lead to false-negative resuits. Consequently, only low prevalence rates were found for these diagnostic categories in the present study, which further limits the generalizability of results. In addition, with regard to previous research in primary care, 12,44 our data may not allow conclusive assumptions on the comorbidity of anxiety disorders and hypochondriasis in nonpsychiatric patient samples.

Conclusions Although there is growing evidence of natural discontinuities between related syndromes, underlining their discriminative validity, research needs to continue to establish sufficient empirical support for the formulation of restrictive hierarchical guidelines for particular diagnostic categories, such as anxiety disorders and hypochondriasis. As demonstrated in this study, the application of restrictive exclusionary rules as

provided by DSM-III may contribute to the dichotomization of "primary" versus "secondary" hypochondriasis. 4° However, differentiation of hypochondriacs without comorbid disorders from those with comorbid anxiety or depressive disorders on the basis of descriptive criteria remains unclear so far. 12 In our sample, too, primary and secondary hypochondriacs displayed comparable phenomenological features as provided by DSM-III-R and ICD-10, adding further weight to the conceptualization of hypochondriasis as a phenomenologically homogeneous diagnostic category that may be differentiated from co-occurrent psychiatric conditions. However, regarding discriminant and predictive validity of hypochondriasis, prospective studies are still needed to address the longitudinal course of hypochondriasis in anxiety disorder patients. As suggested in this study, use of a hierarchy-free diagnostic assessment in addition to application of hierarchical guidelines may be helpful for evaluating the temporal relationship between associated disorders without premature elimination of coexisting psychopathological conditions. In addition, further investigations should address the responsiveness to treatment of comorbid conditions. Although there is some evidence that successful treatment of anxiety disorders may also reduce co-occurrent hypochondriacal concerns, 14 controlled treatment studies comparing patients with anxiety disorders and hypochondriasis with patients displaying only one of these disorders are still warranted, n,12,15 In addition, comparative evaluation of the usefulness of various treatment approaches in these patients will be required.n,42, 43

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