A new approach to assess illness behaviour

The aim of this study was to develop a scale to assess the different aspects of illness behaviour and to evaluate the measure in depressive and somatising patients.

The psychometric properties of the scale were assessed in the following diagnostic groups: patients with major depression (n=36), major depressives with an additional somatisation syndrome (n=40), patients with somatisation syndrome (n=37), and a control group (n=37). After multiple test construction procedures and factor analysis, we developed the Scale for the Assessment of Illness Behaviour (SAIB).

The scale included 26 items (originally 58 items) and comprised five factors: (1) verification of diagnoses, (2) expression of symptoms, (3) medication, (4) consequences of illness, and (5) scanning. The intercorrelations between these factors were low confirming the multidimensional structure of illness behaviour. Physicians' rating partially confirmed the factors. All patient groups had elevated scores for illness behaviour. Correlational analyses demonstrated that illness behaviour was closely related to anxiety (such as health worries and phobic anxiety), even after controlling for other factors. Somatisation had medium associations with some aspects of illness behaviour. Symptom Checklist (SCL) results revealed that illness behaviour is not associated with the distress of single symptoms, but with the general number of symptoms.

A suitable instrument to assess illness behaviour has been developed and should be further analysed in subsequent studies.