Development and validation of an interpretive guide for PROMIS scores

Background Accurate score interpretation is required for the appropriate use of patient-reported outcome measures in clinical practice. Objective To create and evaluate figures (T-score Maps) to facilitate the interpretation of scores on Patient-Reported Outcome Measurement Information System (PROMIS) measures. Methods For 21 PROMIS (R) short forms, item-level information was used to predict the most probable responses to items for the range of possible scores on each short form. Predicted responses were then "mapped" graphically along the range of possible scores. In a previously conducted longitudinal study, 1594 adult participants with chronic conditions (e.g., multiple sclerosis) responded to four items each of a subset of these PROMIS short forms. Participants' responses to these items were compared to those predicted by the T-score Maps. Difference scores were calculated between observed and predicted scores, and Spearman correlations were calculated. Results We constructed T-score Maps for 21 PROMIS short forms for adults and pediatric self- and parent-proxy report. For the clinical population, participants' actual responses were strongly correlated with their predicted responses (r = 0.762 to 0.950). The majority of predicted responses exactly matched observed responses (range 69.5% to 85.3%). Conclusion Results support the validity of the predicted responses used to construct T-score Maps. T-score Maps are ready to be tested as interpretation aids in a variety of applications.