Does psychological treatment help only those patients with severe irritable bowel syndrome who also have a concurrent psychiatric disorder?

Objective: We have previously reported improved health-related quality of life in patients with severe irritable bowel syndrome (IBS) following psychological treatments. In this paper, we examine whether this improvement was associated with improvement in psychological symptoms and was confined to those patients who had concurrent psychiatric disorder. Method: Two hundred and fifty-seven patients with severe IBS entering a psychological treatment trial were interviewed using the Schedules for Clinical Assessment in Neuropsychiatry. At entry to the trial and 15 months later, patients were also assessed using the Hamilton Depression Rating Scale, Symptom Cheecklist-90 (SCL-90) and Short Form-36 (SF36) physical component summary score as the main outcome measure. Partial correlation was used to compare changes in SF36 score and changes in psychological scores while controlling for possible confounders, treatment group and baseline scores. Multiple regression analysis was used to examine whether changes in psychological scores, changes in pain and a history of abuse could account for most of the variance of change in SF36 physical component score. Results: Of 257 patients with severe IBS, 107 (42%) had a depressive, panic or generalized anxiety disorder at trial entry. There were moderate but significant correlations (0.21-0.47) between change in the psychological scores and the change in SF36 physical component scores. The correlation coefficients were similar in the groups with and without psychiatric disorder. The superiority of psychotherapy and antidepressant groups over treatment as usual was similar in those with and without psychiatric disorder. Multiple regression found significant independent effects of change in depression, anxiety, somatization and abdominal pain but there was still variance explained by treatment group. Conclusions: In severe IBS improvement in health-related quality of life following psychotherapy or antidepressants is correlated with, but not explained fully by reduction of psychological scores. A more complete understanding of how these treatments help patients with medically unexplained symptoms will enable us to refine them further.