Using nationally representative percentiles to interpret PROMIS pediatric measures.

PURPOSE: This study's aim was to use a representative sample of the US pediatric population to estimate percentiles for several PROMIS pediatric measures: Anger, Anxiety, Depressive Symptoms, Family Relationships, Fatigue, Global Health, Life Satisfaction, Meaning and Purpose, Pain Behavior, Pain Interference, Physical Activity, Physical Function Mobility, Physical Function Upper Extremity, Physical Stress Experiences, Positive Affect, Psychological Stress Experiences, Sleep Disturbance, Sleep Impairment, and Peer Relationships.
METHODS: We used two separate, nationally representative samples of parents and children aged 5-17 years drawn in different years from the GfK Knowledge Panel, a dual-frame online probability panel.
RESULTS: All measures that were developed using a representative sample had a median at or near the expected value of 50. For the other measures, the 50th percentile was often 10 points or more from 50. Several domains had high floors or low ceilings. No domain's percentiles completely corresponded to the percentiles associated with a normal distribution with a mean of 50 and standard deviation of 10.
CONCLUSIONS: This work allows users to interpret a child's self-reported quality of life relative to children in the US general population. When attempting to evaluate whether a child falls above or below other children in the US, one should use the values presented in this study. In addition, we recommend that users should focus on whether a child's score falls into one of a few broad severity groups rather than on specific percentile scores.