Development and assessment of the constipation-related disability scale S. L. Hart*, J. J. Albiani*, C. J. Crangle*, L. A. Torbit* & M. G. Varma   *Department of Psychology, Ryerson University, Toronto, ON, Canada.   Section of Colorectal Surgery, Department of Surgery, University of California San Francisco, San Francisco, CA, USA. Correspondence to: Dr S. L. Hart, 350 Victoria Street, Toronto, ON M5B 2K3, Canada. E-mail: stacey.hart@psych.ryerson.ca Publication data Submitted 9 June 2011 First decision 22 July 2011 Resubmitted 10 October 2011 Accepted 10 October 2011 EV Pub Online 17 November 2011 SUMMARY Background Chronic constipation is associated with impaired quality of life and physical discomfort. Although inability to engage in day-to-day activities has been significantly associated with psychological distress, limited research has examined this relationship in constipated samples. Aim To develop and validate the Constipation-Related Disability Scale (CRDS), which assesses the extent of disability caused by constipation. Methods A total of 240 constipated participants and 103 healthy controls completed the CRDS. Reliability was measured with Cronbach’s coefficient alpha and test–retest reliability was assessed with intraclass correlation coefficients. Convergent, divergent and predictive validity were assessed. Results Component and factor analyses were used to derive two factors: Work / Leisure Activities and Activities of Daily Living, as well as a total CRDS score. Good reliability was found, with alphas ‡0.87 and intraclass correlation coefficients ‡0.85. All scales were negatively correlated with the physical health subscales of the SF-36 (P < 0.001) and were not significantly correlated with the Epworth Sleepiness Scale and Social Desirability Scale, providing support for convergent and divergent validity, respectively. Evi- dence of predictive validity was supported by associations between the total CRDS with number of physician visits per year (P < 0.01), missed work in the last year (odds ratio [OR] = 1.11, 95% confidence interval [CI] = 1.06– 1.19, P < 0.001) and ER visits in the last year (OR = 1.08, 95% CI = 1.00– 1.16, P < 0.05). Conclusions The Constipation-Related Disability Scale is the first instrument that assesses the impact of constipation on daily activities. There is evidence of strong reliability and validity of the instrument. Aliment Pharmacol Ther 2012; 35: 183–192 ª 2011 Blackwell Publishing Ltd 183 doi:10.1111/j.1365-2036.2011.04910.x Alimentary Pharmacology and Therapeutics