Measuring quality of life in children with inflammatory bowel disease: the impact-II (NL)

Inflammatory bowel disease (IBD) is a chronic debilitating disorder. Measures of quality of life are only available for adult patient populations. We developed a new disease-specific health-related quality of life instrument in Dutch for pediatric patients with IBD, called Impact-II (NL). We translated and strongly modified the original (Canadian) Impact questionnaire. It comprises 35 items in six domains. Eighty-three children (66%) completed the questionnaire, 39 children were assessed twice. Disease symptoms were recorded and disease course severity assessed through chart review. Summated disease activity scores and disease course severity scores were dichotomized into two categories. Reliability coefficients were good for five out of six domains (Cronbach's alpha ranged from 0.57 to 0.86) and measures of test-retest stability in clinically stable patients were good for all domains (intra-class correlation coefficients ranged from 0.67 to 0.91). The instrument showed good discriminant validity between symptom groups and disease course severity on all domains. Convergent validity with a validated generic instrument [TNO-AZL Children's Quality of life questionnaire (Tacqol)] showed satisfactory coefficients. In conclusion, the developed questionnaire shows good psychometric properties. Test-retest stability and responsiveness to change should be further assessed in larger patient samples. Cross-cultural translation and validation procedures into other languages are being conducted to enable international use of Impact-II.