DCR for Measuring Improved Symptoms, Lung Function After CFTR Triple Therapy

Diagnostic methods in medicine
Researchers analyzed the dynamic chest radiography and spirometry in patients with cystic fibrosis before and after starting triple combination CFTR modulator therapy.

Dynamic chest radiography (DCR) showed significant improvements in the hemidiaphragm excursion and projected lung area (PLA) in patients with cystic fibrosis (CF) who had initiated triple combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA). Results of the analysis were published in the Journal of Cystic Fibrosis.

For the observational study, researchers assessed the spirometry and DCR of 24 people with CF both prior to and following the initiation of ELX/TEZ/IVA. The use of DCR was able to track automatically the hemidiaphragm midpoints and PLA during both tidal and deep breathing maneuvers. Of the 24 patients with CF, 13 were women. Overall, 7 of the patients were taking TEZ/IVA before their first DCR, and an additional subsequently began taking TEZ/IVA prior to switching to ELX/TEZ/IVA before their second DCR. A total of 10 patients were naïve to CFTR modulator therapy at the time of ELX/TEZ/IVA initiation.

After commencing ELX/TEZ/IVA treatment, a significant improvement was observed in participants’ percent predicted forced expiratory volume in 1 second (ppFEV1; P<.001), percent predicted forced vital capacity (ppFVC; P<.001), FEV1/FVC (P=.007), and body mass index (P<.001). The utilization of DCR was associated with a significant increase in the deep breathing excursion of the right and left hemidiaphragms (P<.001 for both), as well as the maximum speed during inspiration (right: P=.03; left: P=.02).

Peak speed during expiration following a deep breath increased significantly on the right side (P=.02); although this measure increased on the left side as well, it was not statistically significant (P=.08). Further, PLA at end-expiration was reduced significantly (P<.001), and a significant increase in △PLA was also reported (P<.001).

“…[T]his work demonstrates that DCR is a straight-forward and useful tool to measure improvement in thoracic physiology and respiratory pump function following initiation of triple combination CFTR modulator therapy,” the study authors noted.

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.


FitzMaurice TS, McCann C, Nazareth D, Shaw M, McNamara PS, Walshaw MJ. Measuring the effect of elexacaftor/tezacaftor/ivacaftor combination therapy on the respiratory pump in people with CF using dynamic chest radiography. J Cyst Fibros. Published online January 28, 2022. doi:10.1016/j.jcf.2022.01.007