Marten J. Poley - Erasmus Universiteit Rotterdam

Cost-Effectiveness of Treatment for Congenital Anorectal Malformations 29This again implies that the cost-effectiveness ratio is likely to be a conservativeestimate that possibly underestimates the cost-effectiveness of treatment forARM.The study had an adequate response rate (69%), considering the long periodbetween the treatment and the date of the investigation. It is unlikely that thenonresponse influenced the calculated treatment costs because, from a medicalpoint of view, the severity of the malformation does not noticeably differ betweennonresponders and responders. However, we cannot be certain that the quality oflife of the nonresponders does not differ from the responders. Because wefollowed our initial contact with a telephone reminder, we had some opportunityto investigate the reasons for nonresponse, but the results were ambiguous.Some nonresponders seemed to indicate that they had a lower quality of life,citing reasons for nonresponse as 'various health problems', 'nonacceptance','avoidance', and 'behavioral and family problems'. Other nonresponders,however, suggested that quality of life was underestimated. Some stated thatthey were not participating in the investigation because they had no healthproblems. Although no firm conclusions can be drawn, it seems likely that thequality of life of the nonresponders did not differ considerably from theresponders.Remarkably, the results suggest that quality of life of ARM patients does not differgreatly from the general population. The mean EQ-5D index score for their healthstate is 0.88 compared with 0.93 in the general population. On the basis of theliterature, we expected a more severe impairment of quality of life. 4-8 It could ofcourse be argued that the EQ-5D is not sufficiently sensitive to detect stooldifficulties. However, former research in this patient group confirmed thesensitivity of the EQ-5D to clinical differences in all age groups where it wasadministered (i.e., from 5 years on). 23Because of difficulties that small children have with notions of abstract conceptsand language, we used the parents as proxies to answer the disease-specificquestionnaire and the EQ-5D. We are conscious of the variety of factors that caninfluence a parent's rating of his or her child's quality of life and the equivocalfindings reported in the literature. 24-29 Nevertheless, recent research findings inchildren 30-36 seem to suggest that a parent is able to report appropriateinformation regarding his or her child's quality of life, especially when observable,concrete questions are asked (e.g., about mobility, usual activities). Furthermore,when the parent and the child disagree about the child's quality of life, the parenttends to rate the child as having a poorer quality of life than the child does him orherself. In this investigation, such a tendency would result in a more conservativeestimate of cost-effectiveness. Moreover, we also compared the proxy version ofthe EQ-5D in these patients with another proxy questionnaire, the TACQOL,whose validity in children has been confirmed previously. 37 The EQ-5D showedgood validity from 5 years and over. 23 We consider, therefore, that the favorable