DEVELOPMENT OF A HEALTH-RELATED QUALITY-OF-LIFE INSTRUMENT FOR USE INCHILDREN WITH SPINA-BIFIDA

The objective of this study was to develop a spina bifida health-relat ed quality of life (HRQOL) instrument. Items were generated through se mistructured interviews, and reduced by frequency-importance product r anking. Validity was assessed by correlating the HRQOL score with a gl obal question concerning the child's well-being using the Spearman's r ank coefficient, and the Piers-Harris Children's Self-Concept Scale (P -H) using the Pearson correlation coefficient. Reproducibility was ass essed at P-week intervals using the intra-class correlation coefficien t (ICC). Field testing was undertaken in a larger sample to evaluate i tem-total correlation, internal consistency and construct validity. Pa tients taking part in the study were 329 children and adolescents with spina bifida attending two treatment centres. Over 600 items were gen erated. These were reduced to 47 questions and 50 questions, for child ren and adolescents respectively. The correlation between the HRQOL sc ore and the global question was r= 0.57, and with the P-H was 0.26 (ch ildren). These values for adolescents were 0.63, and 0.89, respectivel y. Reproducibility was ICC = 0.78 (children) and 0.96 (adolescents). F ollowing field testing, the questionnaire was further reduced to 44 qu estions (children) and 47 questions (adolescents) by eliminating quest ions with an item- total correlation less than 0.20. Cronbach's alphas for the final instrument were 0.93 (children) and 0.94 (adolescents), and construct validity correlations were 0.63 (children) and 0.37 (ad olescents). The spina bifida HRQOL instrument has good measurement pro perties and may be used as a discriminative instrument. Assessment of responsiveness is necessary before using it to evaluate therapy in cli nical trials.