Screening for somatization and hypochondriasis in primary care and neurological in-patients: A seven-item scale for hypochondriasis and somatization

The aim of this study was to investigate the internal and external validity of the Whiteley Index as a screening instrument for somatization illness. A 14-item version of the Whiteley Index for hypochondriacal traits was give n to 99 of 191 consecutive primary care patients, aged 18-65 years, and to 100 consecutive patients, aged 18-60 years, admitted for the first time to a neurological ward. The primary care sample was, in addition, interviewed by means,of the SCAN (Schedules for Clinical Assessment in Neuropsychiatry) psychiatric interview. The GPs and the neurologists were asked to rate var ious characteristics of the patients that might indicate somatization. The internal validity of the Whiteley Index was tested by means of latent struc ture analysis. On this basis, a reduced seven-item scale (Whiteley-7 scale) and two subscales (i.e., an Illness Conviction and Illness Worrying scale, each with three items) were constructed. All three had a high internal val idity fitting into the very restricted Rasch statistical model (p>0.05) and an acceptable transferability between most of the subpopulations investiga ted. In the primary care population, the Whiteley-7 and the Illness Convict ion scales at cut-point 0/1 showed 1.00 and 0.87 sensitivity and 0.65 and 0 .87 specificity, respectively, using as "gold standard" the fulfillment of criteria for at least one ICD-10 somatoform disorder, and 0.71 and 0.63 sen sitivity and 0.62 and 0.87 specificity, respectively, as gold standard for the fulfillment of criteria for at least one DSM-IV somatoform disorder, ex cluding the NOS diagnostic group. The Illness Worrying subscale showed less impressive performance in this respect. The agreement between the Whiteley -7 scale including the two subscales and neurologists' rating and the GPs' rating and the somatization subscale on the SCL-90 was modest or worse. It may be concluded that the Whiteley-7 scale and the Illness Conviction subsc ale had acceptable psychometric profiles, and both seem to be promising scr eening tools for not only hypochondriasis but also for somatoform disorders in general. (C) 1999 Elsevier Science Inc.