Functional Mobility in Pediatric and Young Adult Hematopoietic Cell Transplant Patients: A Comparison of the Functional Mobility Score (FMS) and the Karnofsky Performance Status Scale and Lansky Play Performance Scale

Introduction Hematopoietic cell transplants (HCT) are often associated with profound physical deconditioning and decreased functional mobility with resulting decreased participation in mobility and play. Accurately reporting a patients’ functional mobility is paramount to identify impairments and provide appropriate intervention. The established standard for evaluating an HCT patient's level of function, based on age, is the Karnofsky Performance Status Scale and the Lansky Play Performance Scale; both report functional capacity and performance of activities of daily living. The functional mobility score (FMS) is a therapist-developed, objective outcome measure for pediatric and young adult HCT patients incorporated into the Transplant Energize Me Patient Outcome (TEMPO) quality improvement project. Objective The aim is to investigate the relationship between the FMS and the Karnofsky Scales and Lansky Scales, including the rating of functional status. Methods The FMS and Karnofsky Scale or Lansky Scale are completed at defined time points during HCT admission and follow-up for HCT. The FMS is a composite score of six functional skills, each scored on a 7-point ordinal scale, completed for patients who are ≥42 months old (Table 1). The cumulative score is converted to a percentage; a higher score represents greater independence with functional mobility and functional skills, similar to the Karnofsky and Lansky scales. This retrospective study investigates those scores completed pre-transplant. Data was analyzed using nonparametric statistics. Results 52 patients transplanted from 2016 to 2019 were included in analysis. The mean ± standard deviation for Karnofsky Scale or Lansky Scale scores at initial assessment were 95.8±6.3%, while the mean FMS score was 91.1±12.0%. There was a significant, but weak, positive correlation between the two measures (r=0.306, p=0.027) (Figure 1). Conclusion The FMS and Karnofsky or Lansky Scales show a weak relationship.  Based on preliminary results, additional time point comparisons between the measures may provide further information about functional capacity of this population. Specifically, further investigation is needed to determine if FMS might be a more sensitive measure for capturing functional impairment then the Karnofsky or Lansky Scales.