Reliability and validity of health status measurement by the TAPQOL.

BACKGROUND In addition to clinical measures in the evaluation of paediatric interventions, health related quality of life (HRQoL) is an important outcome. The TAPQOL (TNO-AZL Preschool children Quality of Life) was developed to measure HRQoL in preschool children. It is a generic instrument consisting of 12 scales that cover the domains physical, social, cognitive, and emotional functioning. AIMS To evaluate the feasibility, score distribution, internal consistency, test-retest reliability, and discriminative and concurrent validity of the TAPQOL multi-item scales in preschool children, aged 2-48 months. Also to evaluate the feasibility, reliability, and validity separately for infants (2-12 months old) and toddlers (12-48 months old). METHODS Parents of a random general population sample of 500 preschool children were sent a questionnaire by mail. A random subgroup of 159 parents who participated received a retest after two weeks. RESULTS The response rate was 83% at the test and 75% at the retest. There were few missing answers. Six scales showed ceiling effects. Nine scales had Cronbach's alphas >0.70. In general, score distributions and Cronbach's alphas were comparable for infants and toddlers. Test-retest showed no significant differences in mean scale scores; two scales had intra-class correlations <0.50. Five scales showed significant differences between children with no conditions versus children with two or more parent reported chronic conditions. CONCLUSION Results showed that the TAPQOL is a feasible instrument to measure HRQoL and support the reliability and discriminative validity of the majority of its scales for infants as well as toddlers.