Test for Respiratory and Asthma Control in Kids (TRACK): Clinically meaningful changes in score

Background: The Test for Respiratory and Asthma Control in Kids (TRACK) is the first validated questionnaire to assess respiratory and asthma control exclusively in young children. Objective: We sought to determine the minimally important difference (MID) for interpreting meaningful changes in individual patients' TRACK scores. Methods: In this prospective, nonrandomized, longitudinal study conducted at 20 US pediatric sites, TRACK was administered at 2 separate clinic visits (4-6 weeks apart) to caregivers of children aged less than 5 years with symptoms consistent with asthma. Anchor-based methods were used to determine the MID from mean score differences between patients based on multiple criteria measures: physician guidelines-based respiratory control rating, physician-recommended changes to therapy, episodes of symptoms lasting more than 24 hours in the past 3 months, oral corticosteroid use for respiratory tract illnesses in the past year, physician-assessed change in control status at follow-up, and caregiver-reported change in respiratory status. The MID also was determined from distribution-based methods. Results: TRACK scores were assessed at baseline (426 caregivers) and follow-up (396 caregivers). Mean differences in TRACK scores between patients differing on criteria measures ranged from 3.4 to 16.4 points (mean, 11.1 points). Distribution-based techniques confirmed these findings. Based on logistic regression analyses, scoring 10 or more points less than 80 on TRACK was associated with an approximately 2-fold increased odds of having uncontrolled asthma or respiratory symptoms. Conclusion: Changes in TRACK scores of 10 or more points represent clinically meaningful changes in respiratory control status in individual young children with respiratory symptoms consistent with asthma and should alert health care providers to re-evaluate asthma management.