(1) Change in DEXA scan values in children with Cystic Fibrosis, after starting Elexacaftor-Tezacaftor-Ivacaftor and optimizing physical activity and calcium intake
Physical Therapist Valley Childrens Hospital, United States
Background: Cystic Fibrosis related bone disease is a common complication of Cystic Fibrosis (CF), it is characterized by low bone mineral density and an increased risk of fracture. CF related bone disease is common in Cystic Fibrosis patients due to many factors including malabsorption of fat-soluble vitamins, poor nutritional status, lack of physical activity, delayed puberty, and chronic lung inflammation.
In October 2019, the triple combination CFTR modulator Elexacaftor-Tezacaftor-Ivacaftor (ELX/TEZ/IVA) was approved by the FDA. With partially restored function of the chloride channels, patients on ELX/TEZ/IVA have showed improvements in lung function, CFQR score, sweat chloride, and in BMI. With these results it is expected that CF patients’ nutritional status will improve both in BMI and the ability to absorb vitamins including vitamin D, vitamin K, and calcium.
Over the last 2 years this institution’s CF Clinic has worked to improve patients DEXA scan scores (Z-score). This included ensuring all qualified patients receive ELX/TEZ/IVA, exercise counseling, and optimized calcium intake. The purpose of this study is to determine if there is a correlation between treatment with ELX/TEZ/IVA and improvement in bone density as well as evaluate other factors that may influence bone health.
Methods: This study is a single-center, retrospective chart review of CF patients with low baseline Z-scores and concurrently on ELX/TEZ/IVA, managed by Valley Children’s Hospital Pulmonology Clinic between January 2018 and March 2022.
Primary
Objective: Compare the change in Z-scores in CF patients before and after starting ELX/TEZ/IVA
Secondary
Objective: Analyze other variables that could impact Z-scores including time on ELX/TEZ/IVA, amount of physical activity per day, and optimized calcium intake.
Results: A total of 18 patients were included in this study. All patients were on ELX/TEZ/IVA prior to having their 2nd DEXA scan. Median change in DEXA scan from 1st DEXA scan to 2nd DEXA scan was 0.15, with 67% of patients seeing an improvement in Z-score on their 2nd DEXA scan. Of those patients with an improvement in Z-scores, patients were on ELX/TEZ/IVA for a mean of 13.4 months compared to a mean of 12 months for patients who showed a decrease in Z-scores. Median activity level for patients that showed an improvement in Z-scores was 2.8 (meeting 70% of physical activity) compared to a median level of 2.17 (meeting 54.5% of physical activity) for patients with a decrease in Z-scores. Lastly, 58% of patients who had an improvement in Z-scores were on supplemental calcium (enteral shakes or prescribed calcium) compared to 83 % of patients with a decrease in Z-scores being on supplemental calcium. Of those patients maximized on all 3 (ELX/TEZ/IVA, calcium, and meeting activity recommendations), the average improvement in DEXA scan scores was 0.07. 80% of patients fully meeting their activity score showed improvements in DEXA scores.
Conclusions: There was a positive correlation between improvement in Z-score and treatment with ELX/TEZ/IVA, and those meeting the recommended physical activity score. Of interest, the improved group had a less optimized calcium intake than the group that did not show improvement. This had to do with patients in this group having had their 2nd DEXA scan before we had an opportunity to optimize their calcium. The main limitation of this study is a small sample size. We aim to continue to include more patients in this study as subsequent DEXA scans are collected.
