PedsQL™ 4.0 Generic Core Scales       
The 23-item PedsQL™ 4.0 Generic Core Scales were developed specifically for application in both healthy and patient populations, and have resulted from an extensive iterative process involving numerous patient and parent focus groups and individual focus interviews, item generation, cognitive interviewing, pre-testing, and subsequent field testing [13].  With international data on over 35,000 healthy children and children with pediatric chronic health conditions published or in press in over 170 peer-reviewed journals since 2001 (see Publications, www.pedsql.org), the PedsQL™ 4.0 Generic Core Scales have been shown to distinguish between healthy children and children with pediatric chronic health conditions [13, 17, 19, 27, 28], demonstrated sensitivity to disease severity, responsiveness through patient change over time [15, 17, 28], shown significant intercorrelations with disease-specific symptom scales (based on the conceptualization of disease-specific symptoms as causal indicators of generic HRQOL)[13, 27, 29], and demonstrated an impact on clinical decision making, showing significant associations with quality of healthcare, barriers to healthcare, and prediction of healthcare costs over time [28, 30-32].  Thus, the PedsQL™ 4.0 Generic Core Scales have demonstrated the feasibility, reliability, validity, and responsiveness necessary for patient self-report for children ages 5 to 18 years and parent proxy-report for ages 2 to 18 years for pediatric clinical research and practice.  The PedsQL™ 4.0 is the only empirically validated generic pediatric HRQOL measurement instrument that we are aware of to span this broad age range for child self-report and parent proxy-report while maintaining item and scale construct consistency.