LAMFit: A Digital Fitness Program for Individuals with Lymphangioleiomyomatosis

Abstract

Background: Daily physical activity is reported to be substantially reduced in individuals with the rare lung disease lymphangioleiomyomatosis (LAM). This important modifiable risk factor can be reduced using proven behavioral change and exercise interventions. Using a digital health platform with remote monitoring to deliver a structured exercise regimen in the home setting may be feasible and safe for individuals with LAM that are medically appropriate to participate.Methods: In this dissertation, we describe the design and pilot testing of 'LAMFit,' a fully remote, digital fitness program for individuals with LAM living in the United States. First, we convened a group of experts in LAM and conducted a 2-round, modified Delphi study to develop an expert consensus LAMFit exercise preparticipation screening tool for providers to use to determine medical appropriateness prior to patient enrollment in LAMFit. Next, we conducted a retrospective analysis of in-person clinical exercise testing during two prior exercise studies our research team as conducted among patients with interstitial lung disease (ILD) [n=15 LAM and n=15 idiopathic pulmonary fibrosis (IPF)]. To determine the utility of using peak heart rate (HR) on six minute walk test (6MWT) for exercise prescription in higher-functioning individuals with ILD in the absence of maximal cardiopulmonary exercise test (CPET), we evaluated the agreement between peak HR on 6MWT and HR at the first ventilatory threshold on CPET, the criterion standard for aerobic exercise prescription. We identified a 'cutoff' threshold at or above 85% pred. 6MWT distance where it becomes inappropriate to use of peak HR on 6MWT to estimate aerobic exercise threshold in ILD. Lastly, we pilot tested LAMFit over a period of 6 months using LAM medical provider prescreening, a custom digital health platform with a fitness tracker, a medical-grade pulse oximeter, a novel, in-app remote 6MWT, and patient-reported outcome measures administered during baseline, midpoint, and final remote study visits. Results: All 25 participants with LAM (100%) completed the first 12-week exercise program of the LAMFit pilot study, including baseline, and midpoint study visits. Twenty-two participants (88%) completed the second 12-week exercise program and final study visit, with 3 discontinuations for reasons unrelated to the study intervention. No serious or non-serious study-related adverse events occurred. High adherence to aerobic exercise during the two 12-week intervention periods of LAMFit was achieved (intervention period 1: 81±18%; intervention period 2: 79±18%). In the first 12 weeks of the exercise program, the mean daily minutes of moderate-to-vigorous physical activity (MVPA) increased by an average of 51% (25.6 ± 32.6 min to 52.5 ± 59.2 min; p=0.0318) compared to the run-in period. Distance achieved in 6MWT increased by an average of 7.1% (36.2 ± 9.1m, p=0.0021) from baseline to midpoint, and continued benefit was seen after completion of the second exercise intervention, with an average increase of 8.5% distance walked on 6MWT (43.4 ± 10.9, p=0.0021) at final study visit compared to baseline. Significant improvements in fatigue, health-related quality of life, and dyspnea were observed after participation in the first 12 weeks. Participants expressed a high level of satisfaction and acceptability of the LAMFit digital fitness program. Conclusion: A fully-remote approach to delivering a home-based exercise program in LAM is feasible and safe. The pilot feasibility study of LAMFit was a noteworthy success. Stakeholder interest in the LAM community is very high for continuing to scale access to the LAMFit program nationally and internationally.