Agreement among three instruments for measuring functional health status and quality of life in pediatric orthopaedics.

The Child Health Questionnaire (CHQ), Pediatric Outcomes Data Collection Instrument (PODCI), and Pediatric Evaluation and Disability Inventory (PEDI) are the 3 instruments commonly used to measure function and quality of life in pediatric orthopaedics. This study compared answers to specific questions on the CHQ, PODCI, and PEDI given by the parents of 66 children with cerebral palsy, who completed all 3 questionnaires. Both Spanish- and English-speaking subjects were included. No overlapping questions were found between the CHQ and PEDI. Of the 8 questions that overlapped between the CHQ and PODCI, 2 questions (general health and change in health) had weighted kappa greater than 0.70, with responses within +/-1 point for more than 95% of respondents. These 2 questions had almost exactly the same wording on both questionnaires. The other 6 questions had fair to poor agreement between questionnaires (kappa, 0.10-0.55). All 5 questions that were addressed by both the PODCI and PEDI also had poor agreement (kappa < 0.40). There was little correspondence between the preconceived match quality and the actual matching results (r=0.41; P=0.16). These results suggest that differences in wording have a significant and unpredictable effect on parents' responses; this should be considered when selecting from among different instruments. Of the instruments used in this study, the CHQ is the easiest to administer and is a good general quality of life measure; however, the PODCI or PEDI may be preferred if information about more specific functional activities is desired.