This thesis describes the assessment of depression and anxiety by questionnaire and visual analogue scale in patients with irritable bowel syndrome (IBS). It examines the relationship between such assessments and self- reported symptoms before and after a placebo controlled, double -blind trial of fibre supplementation in 49 IBS patients, and finds that a high depression score at outset may be a predictor of continuing symptoms regardless of treatment. The treatment itself was no better than placebo, though there was a substantial 'placebo' effect
I consider the use of putative biochemical markers of 'stress' in such patients, but find that neither salivary IgA nor urinary metanephrine correlate well with symptoms, symptom response, or psychometric assessment scores. Platelet serotonin levels did not distinguish IBS subjects from those with other chronic gastrointestinal complaints. It seems unlikely that any of these parameters will be helpful in routine diagnosis or management of IBS.
A second cohort of IBS subjects was studied five years after initial diagnosis, using similar psychometric assessments. The chronic nature of the disorder was confirmed. The results suggest that anxiety levels might be an important influence on the longer-term maintenance of the symptom complex. Finally the thesis examines aspects of the general practitioner consulting behaviour of a group of IBS patients. Such behaviour seems relatively stable over the longer term although there was a very high prevalence of diagnoses of depression or anxiety, both before the IBS diagnosis and during the five years to review.
The studies are considered to support a holistic approach to IBS; its pathogenesis, management, and natural history. The symptom complex is forged by the action of several factors, notably psychological, physical and circumstantial (life events). The behavioural and emotional elements of the symptom complex are best considered as one product, and the doctor - patient relationship plays an important modulating role. There is some evidence that depressed mood may be more important in determining short term responses, such as consulting behaviour, and anxiety in maintaining the perception of 'symptoms' in the longer term. Simple assessment of depression and anxiety, perhaps by 'user friendly' visual analogue scales, might usefully be incorporated in the routine assessment of IBS patients.