Original ArticleDimensionality of the Whiteley Index: Assessment of hypochondriasis in an Australian sample of primary care patients☆,☆☆,★,★★
Introduction
Hypochondriasis is a relatively prevalent disorder in primary care, with prevalence estimates of between 3% and 6.3% [1], [2], [3]. The economic effects of hypochondriasis are tremendous [4]. Even at subclinical levels of severity, hypochondriacal worries significantly increase health care utilization at the level of primary care services, associated pathology testing, and secondary care services [5], [6]. Alongside this substantial community burden, the disorder has a major impact on interpersonal relationships, in general [7], [8], and on the doctor–patient relationship in particular. Despite the patient's experienced symptoms, often, no physical abnormalities can be found, resulting in consultations that are experienced by both doctor and patient as frustrating and unsatisfactory [4], [9].
Given the substantial negative impact of hypochondriasis for patients, doctors, and the community, it is surprising that this disorder remains extremely underdiagnosed in primary care [10], [11]. There appears to be need for a short screening instrument able to validly and reliably identify potential hypochondriacal patients in primary care.
Pilowsky [12] attempted to develop such a measure, the Whiteley Index (WI), by comparing responses of hypochondriacal and nonhypochondriacal patients on a range of items designed to tap general health worries. Those items discriminating significantly between groups were chosen for further analyses. The final scale comprised 14 items said to measure hypochondriacal fears and beliefs. Exploratory principal component analysis (EPCA) has yielded three factors, interpreted as ‘disease phobia, ‘bodily preoccupation’, and ‘disease conviction’ [12]. The factor disease phobia refers to the fear of having or developing a serious illness. The second factor, bodily preoccupation, describes the subjective impression of the patient as suffering from multiple bodily symptoms and pains. The third factor, disease conviction, is said to represent the strength of the patients' belief that they suffer from a serious illness.
The structural validity of the WI has been explored and challenged in several studies. A three-factor solution was found by Rief et al. [13], Hiller et al. [14], and Hinz et al. [15]. However these three factors did not correspond with the original factor solution of Pilowsky. Furthermore, a one-factor solution was proposed by Speckens et al. [16] based on investigations using three different samples. The latter four studies used EPCA. In another study, Fink et al. [17] identified a seven-item scale with good psychometric properties. The Whiteley-7 scale fitted into a modified Rasch model, which means that the slopes of the item–characteristic curve are equal and the pattern of responses to the items supports an additive scale. Table 1 gives a detailed overview of the range of differing factor solutions discussed.
Several reasons can be hypothesized for the contrary results. First, the study samples stem from dissimilar populations. Originally, Pilowsky [12] validated the WI in a sample of 200 inpatients of a psychiatric hospital, so that the three-factor solution might be a specific result of a tertiary care sample. Indeed, two of the studies that could replicate the three-factor solution were run in tertiary care [13], [14], although a third confirmation came from a general population survey [15]. Thus, the number of factors might be dependent upon the diagnostic compositions of the samples in study.
Second, different methods were employed. Whereas Fink et al. [17] used exploratory and latent trait methods to remove weak items and to confirm a short scale, all other studies made use of EPCA. Despite the frequent use of EPCA, it is assumed to be an inappropriate tool for the handling of dichotomous item responses, resulting in an underestimation of item intercorrelations, inconsistent estimates of parameters, and standard errors [18], [19], [20]. Weighted least squares (WLS) factor analysis employing the asymptotic covariance matrix of the tetrachoric correlations is recommended instead. Third, criteria for assigning items to factors differ between studies. For example, Speckens et al. [16] accepted factor loadings >.15 in their proposed one-factor model, although the authors flagged three items that contributed little to the common factor. Rief et al. [13] and Hiller et al. [14] accepted factor loadings >.40. Fink et al. [17] and Hinz et al. [15] employed higher standards, with loadings >.50.
The main aim of this study is to compare differing factor solutions to draw conclusions about the most valid scale model of the WI for the administration in primary care. Therefore, we firstly present endorsement frequencies, item–total correlations, and internal consistency for the WI on data from a primary care sample. Second, we compared seven different factor models of the WI by means of confirmatory factor analysis (CFA). Third, psychometric properties and a proposed cutoff score for the most valid scale are presented.
Section snippets
Participants and procedure
The sample consisted of 1929 primary care patients recruited from 29 general practices in and around Sydney, Australia. The 29 sites were chosen to reflect a range of cultural and socioeconomic backgrounds. Both rural and urban areas were represented in this sample. As a requirement of the project, each GP screened consecutive patients in their practice who were at least 18 years of age and able to read and understand a consent form. Exclusion criteria consisted of the inability to speak and
Psychometric properties of the WI
Table 2 presents the endorsement frequencies, part–whole corrected item–total correlations, and internal consistency coefficients. An examination of the endorsement frequencies found Item 3 (various things happening in your body) to be answered positively by 57% of the sample, followed by Items 2 (bothered by many aches and pains) and 14 (afraid of illness), with 38% and 35%, respectively. In contrast, only 8% of the participants answered positively to Item 5 (symptoms of very serious
Discussion
Several conclusions can be drawn from the different analyses, which were conducted with the WI with dichotomous answer categories for primary care patients. To the extent that the underlying assumptions hold, our results support a one-dimensional conceptualisation of the WI and suggest that a certain subscale of the WI, the WI-7 [17], had the best psychometric properties using the sample we collected. Of the seven models tested with CFA, the one-factor model by Fink et al. [17] performed best
Conclusions
In conclusion, of the various WI scales assessed in this study, the one-dimensional WI-7 proposed by Fink et al. [17] appears to constitute the most psychometrically sound scale for use as a screening instrument for hypochondriasis in primary care. The factor models underpinning the other scales assessed here were not supported by the results. In addition to psychometric considerations, the brevity and simplicity of the WI-7 also make it attractive as a screening tool in the context of primary
Acknowledgments
The authors wish to thank Prof. Dr. Ingeborg Stelzl for her help in analysing the data.
References (36)
- et al.
DSM-IV hypochondriasis in primary care
Gen Hosp Psychiatry
(1998) A cognitive–behavioural approach to hypochondriasis and health anxiety
J Psychosom Res
(1989)- et al.
Distress and attitudes in patients perceived as hypochondriacal by medical staff
Gen Hosp Psychiatry
(1988) - et al.
A validation study of the Whitely Index, the Illness Attitude Scales, and the Somatosensory Amplification Scale in general medical and general practice patients
J Psychosom Res
(1996) - et al.
Screening for somatization and hypochondriasis in primary care and neurological in-patients: a seven-item scale for hypochondriasis and somatization
J Psychosom Res
(1999) - et al.
The prevalence of hypochondriasis in medical outpatients
Soc Psychiatry Psychiatr Epidemiol
(1990) - et al.
Epidemiology of somatoform disorders—a community survey in Florence
Soc Psychiatry Psychiatr Epidemiol
(1997) - et al.
Medically unexplained symptoms in primary care
J Clin Psychiatry
(1998) - et al.
Hypochondriasis. An evaluation of the DSM-III criteria in medical outpatients
Arch Gen Psychiatry
(1986) - et al.
Transient and persistent hypochondriacal worry in primary care
Psychol Med
(1996)
A prospective 4- to 5-year study of DSM-III-R hypochondriasis
Arch Gen Psychiatry
Hypochondriasis, loneliness, and social functioning
Psychol Rep
Underdiagnosis of hypochondriasis in family practice
Psychosomatics
Dimensions of hypochondriasis
Br J Psychiatry
Hypochondrie: Erfassung und erste klinische Ergebnisse
Z Klin Psychol Forsch Prax
Dimensional and categorical approaches to hypochondriasis
Psychol Med
Hypochondrie in der Allgemeinbevölkerung: Teststatistische Prüfung und Normierung des Whiteley-Index
Diagnostica
Factor analysis in the development and refinement of clinical assessment instruments
Psycholog Assess
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All authors have agreed to authorship in the indicated order.
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The research was approved by an institutional review board.
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There has been no prior publication.
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There is no financial interest in the research.