Analysis of nonresponse in the assessment of health-related quality of life of childhood cancer survivors.

The aim of this study was to compare the characteristics of respondents and nonrespondents in a survey of childhood cancer survivors recorded in the Childhood Cancer Registry of Piedmont and their current primary care general practitioners. Eligible subjects were identified from the Childhood Cancer Registry of Piedmont and the referring general practitioners were traced through the National Health Service. A postal questionnaire was sent both to childhood cancer survivors and to their general practitioners. Prevalence odds ratios were estimated for demographic and clinical characteristics in survivors and for demographic characteristics in general practitioners. A total of 1005 childhood cancer survivors and 857 general practitioners (132 of them had two or more cancer survivors in care) were included in the study. Completed questionnaires were obtained from 691 survivors (69%) and 615 general practitioners (72%). For survivors, the only associations with nonresponse were for age 35-44 years [prevalence odds ratio: 0.53 (95% confidence interval: 0.33-0.85)], being married [prevalence odds ratio: 1.45 (95% confidence interval: 0.96-2.18)] and diagnosis after 1977 [prevalence odds ratio: 0.66 (95% confidence interval: 0.42-1.03)]. For general practitioners, the only associations were for male sex [prevalence odds ratio: 1.62 (95% confidence interval: 1.13-2.32)] and place of work outside of the city of Turin [prevalence odds ratio: 1.93 (95% confidence interval: 1.07-3.47)]; furthermore associations were relatively weak. An association was also found between nonresponse in survivors and nonresponse in their general practitioners [prevalence odds ratio: 3.40 (95% confidence interval: 2.54-4.56)]. In conclusion, apart from age, marital status and period of diagnosis, there were little differences between respondent and nonrespondents, for the considered clinical and demographical characteristics. Participation of survivors and their general practitioners correlated, suggesting that involvement of the general practitioners in the study may be a method to increase participation of survivors of childhood cancers.