Screening instruments for anxiety and depression in patients with irritable bowel syndrome are ambiguous.

INTRODUCTION Psychiatric disorders are common among patients with irritable bowel syndrome (IBS) which may make a psychiatric evaluation appropriate. The Hospital Anxiety and Depression Scale (HADS) has been recommended internationally for screening. The Common Mental Disorder Questionnaire (CMDQ) is a novel Danish instrument recommended for use in general practice, but it lacks validation. The objective of this study was to test the reliability and the convergent validity of the anxiety and depression subscales of the CMDQ and the HADS in patients with IBS. MATERIAL AND METHODS A total of 149 patients with IBS completed the CMDQ and the HADS twice in a year. Data were analysed with respect to internal consistency (Cronbach's alpha), agreement on case identification (κ) and correlation between scores (Spearman's rank correlation coefficient). RESULTS All subscales showed satisfactory internal consistency. Cases identified by the CMDQ's anxiety and depressions subscales differed considerably from those identified with the HADS with only fair-moderate agreement, while the correlation between the scores on the CMDQ and the HADS was only moderate for both anxiety and depressions. CONCLUSION The subscales for anxiety disorder and depression on the CMDQ showed internal consistency, but only fair to moderate agreement and correlation, which yielded an unsatisfying convergent validity compared to the HADS. More studies in different populations and research on the cut-off values for possible cases could make the CMDQ more useful. FUNDING Danish Council for Independent Research; Region Zealand's Health Sciences Research Foundation; Councils for Quality Assurance in Primary Care in Region Zealand. TRIAL REGISTRATION NCT00659763.