Health related quality of life in disorders of defecation: The Defecation Disorder List

Background: Constipation and encopresis frequently cause problems with respect to emotional wellbeing, and social and family life. Instruments to measure Health Related Quality of Life (HRQoL) in these disorders ill are not available. Methods: A disease specific HRQoL instrument, the "Defecation Disorder List"(DDL) for children with constipation or functional non-retentive faecal soiling (FNRFS) was developed using accepted guidelines. For each phase of the process, different samples of patients were used. The final phase of development included 27 children. Reliability was assessed in two ways: internal consistency of domains with Cronbach's alpha, and test-retest reliability with intra-class correlation coefficients (ICC). To assess validity, comparable items and domains were correlated with Tacqol, a generic HRQoL instrument for children (TNO-AZL). Results: In the final phase of the development, 27 children completed the instrument. It consisted of 37 items in four domains. The response rate was 96%. Reliability was good for all domains, with Cronbach's alpha values ranging from 0.61 to 0.76. Measures of test-retest stability were good for all four domains with ICCs ranging from 0.82 to 0.92. Validity based on comparison with the Tacqol instrument was moderate. Conclusion: The DDL is promising as a measure of HRQoL in childhood defecation disorders.