'Silent voices' in health services research: ethnicity and socioeconomic variation in participation in studies of quality of life in childhood visual disability.

Purpose. To investigate patterns of participation of visually impaired (VI) children and their families in health services research. Methods. The authors compared clinical and sociodemographic characteristics of children and their families who participated with those who did not participate in two studies of quality of life (QoL) of VI children. In Study 1, the authors interviewed VI children and adolescents, aged 10 to 15 years, about their vision-related quality of life (VRQoL) as the first phase of a program to develop a VRQoL instrument for this population. One hundred seven children with visual impairment (visual acuity in the better eye LogMar worse than 0.51) were invited to participate in the interviews. Study 2 investigated health-related quality of life (HRQoL) of VI children using an existing generic instrument, administered in a postal survey. 151 VI children and adolescents, aged 2 to 16 years, with hereditary retinal disorders were invited to participate in the survey. Results. The overall participation level was below 50%. In both studies, participants from white ethnic and more affluent socioeconomic backgrounds were overrepresented. Participation did not vary by age, sex, or clinical characteristics. Conclusions. The authors suggest that there are barriers to participation in child- and family-centered research on childhood visual disability for children from socioeconomically deprived or ethnic minority groups. They urge assessment and reporting of participation patterns in further health services research on childhood visual disability. Failure to recognize that there are "silent voices" is likely to have important implications for equitable and appropriate service planning and provision for VI children.