Development and validation of new disease-specific measures of somatization and comorbidity in IBS

OBJECTIVE

To create and validate empirically derived questionnaires that measure non-gastrointestinal symptoms and disorders that co-exist with irritable bowel syndrome (IBS).

METHODS

A systematic review of the world literature identified all non-GI symptoms and diagnoses known to have excess frequency in IBS patients. These data were used to create the Recent Physical Symptoms Questionnaire (RPSQ), which measures somatization (the psychological tendency to report multiple physical symptoms), and the Comorbid Medical Conditions Questionnaire (CMCQ). The psychometric properties of these questionnaires were assessed in two studies: 109 IBS patients in Study I; 286 IBS patients and 67 healthy controls in Study II.

RESULTS

In Study I, the RPSQ and CMCQ showed high test-retest reliability (r=.88 and .95) and good internal consistency (Cronbach alphas: .86 and .70, respectively). In Study II, principal components analysis demonstrated that the RPSQ is a homogeneous somatization scale, but the CMCQ could be divided into 4 subscales: one for psychiatric disorders and 3 for different types of somatic disorders. Concurrent validity of the RPSQ was shown by strong correlations with the Cornell Medical Index (CMI) and the Brief Symptom Inventory-18 (BSI-18) somatization scales. The validity of CMCQ responses was not assessed. Discriminant validity was modest: the BSI-18 anxiety and depression scales were less strongly correlated with the RPSQ than the BSI-18 somatization scale. The RPSQ and CMCQ scores of IBS patients were significantly higher than the scores of healthy controls (P<.001).

CONCLUSIONS

The RPSQ and CMCQ are psychometrically sound measures of somatization and medical comorbidities in IBS.

A preliminary investigation of the effects of cognitive behavioral therapy for panic disorder on gastrointestinal distress in patients with comorbid panic disorder and irritable bowel syndrome

BACKGROUND

High comorbidity between panic disorder with/without agoraphobia (PD/A) and irritable bowel syndrome (IBS) has been identified in the literature. These findings have resulted in the recent development of neurobiological models to explain their overlapping symptoms and related origins. This study was a preliminary investigation of the influence of cognitive behavioral therapy (CBT) for PD/A on PD/A patients with and without comorbid IBS.

METHODS

All patients completed a thorough intake assessment, brief waitlist period, and a 12-week CBT group for PD/A.

RESULTS

The results demonstrated significant reductions in the symptoms of anxiety, depression, and overall impairment in both patient groups (ts>2.3; Ps<.05). In addition, PD/A patients with comorbid IBS also experienced reductions in the disability and distress associated with their gastrointestinal symptoms of IBS (ts>1.9; Ps<.07).

CONCLUSIONS

Although additional research still is needed, these preliminary findings suggest that CBT for PD/A can be used to simultaneously treat comorbid symptoms of PD/A and IBS. Implications for the neurobiological models for these comorbid conditions were discussed.

Frequency and severity of the symptoms of irritable bowel syndrome across the anxiety disorders and depression

High rates of irritable bowel syndrome (IBS) symptoms have been reported in individuals diagnosed with anxiety and depressive disorders. However, most studies have investigated these relations in a single disorder, rather than a heterogeneous group of patients, thereby not allowing for comparisons across anxiety disorders and depression, or for considering the effects of comorbidity. Thus, the present study investigated the symptoms of IBS in a diverse group of patients (N=357) by administering questionnaires and a diagnostic interview. A high frequency of IBS symptoms was found in patients with panic disorder, generalized anxiety disorder, and major depressive disorder. However, the frequency of IBS symptoms in patients with social anxiety disorder, specific phobia, and obsessive-compulsive disorder was comparable to rates found in community samples. In addition, anxiety sensitivity and illness attitudes and intrusiveness were predictive of elevated IBS symptomatology. Together, these findings emphasize the role physiological symptoms of anxiety and worry in the co-occurrence of the anxiety disorders and IBS.