Among the pilot study cohort (n=122), the mean age was 11.5 years, mean age at diagnosis was 6.7 years, and mean A1c was 8.4%. The study participants were 71.1% white, 9.9% Hispanic, 11.6% Black, and 7.4% other race. Most participants (91.1%) were from families with two or more adults in the home, 45.4% of parents had a college degree, and 77.4% of families reported an annual income of $50,000 or greater. Among the main study cohort (n=325), the mean age was 12.5 years, mean age at diagnosis was 6.8 years, and mean A1c was 8.5%. The study participants were 76.5% white, 10.3% Hispanic, 7.1% Black, and 6.1% other race. Most participants (90.4%) were from families with two or more adults in the home, 46.9% of parents had a college degree, and 76.9% of families reported an annual income was of $50,000 or greater.
Principal components factor analysis extracting five factors did not result in the diabetes QOL items loading the specified diabetes QOL subscales for either child or parent report. For the child report, items within each subscale loaded across multiple factors, and the resulting factors did not represent conceptually meaningful distinct constructs (). For the parent-proxy report, items from the diabetes symptoms subscale loaded two different factors. Items in the treatment adherence, worry, and communication subscales formed individual factors; however, items from the treatment barriers subscale also loaded two of these factors. Analysis of the child-data scree plot suggested that either a one- or two-factor solution would best represent the data (eigenvalues of 6.79 and 2.07); analysis of the parent-data scree plot indicated a two-factor solution (eigenvalues of 6.02 and 2.28). As such, both one-factor and two-factor solutions were tested. Loadings of the items on the factors for each solution are presented in . In the one-factor solution, most items loaded for both parent-proxy and child data. Reported problems with hypoglycaemia did not load for children or parents, and problems wearing identification did not load for parents. In the two-factor solution with child data, all items on the symptom subscale loaded one factor, and all remaining items except worry about hypoglycaemia loaded the second factor. For parent-proxy data, all items on the symptoms and worry subscales loaded one factor, and all but two of the remaining items (problems with needle pain and problems wearing identification) loaded the other. Correlation between the two factors was .49 and .45 for child and parent data respectively.
Factor pattern of the diabetes quality of life measure; 5-factor solution (n=447)
Factor pattern of the diabetes quality of life measure; 1-factor and 2-factor solutions (n=447)
Psychometric properties of the generic and diabetes QOL scales and subscales are provided in . There were no significant differences in means, and internal consistency of the measures was similar across the two cohorts, with total score alphas ranging from .84 to .90. Alphas for parent and child treatment barriers, treatment adherence, and worry subscales were less than .70. Correlations between parent and child report of quality of life were modest, ranging from nonsignificant to .43 (). Generic and diabetes QOL were moderately to highly related. Among children, the correlation between generic and diabetes QOL was .71 for cohort 1 and .74 for cohort 2. Among parents, the two measures were correlated .65 for cohort 1 and .56 for cohort 2.
Quality of life scale and subscale properties
Parent-child correlations for quality of life scales and subscales
Bivariate relations of the QOL total scores and subscale scores with depression, adherence, and A1c are presented in . Both generic and diabetes QOL were associated with depression, though more strongly for child report of QOL (r = -.63 generic and -.54 diabetes-related) than parent report (r = -.37 generic and -.24 diabetes-related). Parent report of diabetes QOL was most strongly associated with parent report of adherence (r = .42 cohort 1 and .36 cohort 2), while child report of both generic and diabetes QOL were associated with child report of adherence (r ranging from .21 to .37). Associations of all the QOL measures with A1c were small and less consistent across the two cohorts.
Correlation of quality of life scales with general emotional functioning and diabetes-related outcomes