Cardiopulmonary exercise testing (CPET) provides key prognostic information for patients with advanced CF and is a promising marker for lung transplantation referral, according to a retrospective analysis of international data.

The team showed the peak work rate (Wpeak) was the most significant predictor of death or lung transplantation for patients with advanced CF lung disease (ACFLD) two years after undergoing testing.

The investigators analysed health-related data from patients with ACFLD aged ten years and above with FEV1 up to 40% predicted, who had performed a CPET between January 2008 and December 2017 and for whom follow-up information on death and lung transplantation was available two years after CPET.

The final analysis, published in the Annals of the American Thoracic Society (link here), included data on 174 CF patients (41% female) from 20 Asian, Australian, European and North American centres.

Eleven patients died during the two-year follow-up period, and 33 underwent lung transplantation; these patients had worse lung function, lower exercise capacity, more frequent Pseudomonas aeruginosa infections, and more frequently had CF-related diabetes, the researchers noted.

The team found that both VO₂peak and Wpeak provided prognostic information for people with advanced CF: for each additional 10% predicted increase in either, the cumulative two-year probability of death/LTX dropped by 40%.

However, further analysis revealed that Wpeak was most strongly associated with this outcome: with data showing a probability of death or LTX of 45.2% for those with a Wpeak of up to 49.2% predicted versus 10.9% for those with a Wpeak of more than 49.2% predicted (P<0.001).

There were key study limitations, including the potential for selection bias and a lower than expected recruitment rates.

However, the authors stressed that the findings “provide a compelling rationale for the prospective evaluation of Wpeak as a promising marker for LTX referral and candidate selection”.

Also of note, “an important practical implication is that Wpeak can be measured using a maximal cycle ergometer test without the need for gas exchange measurements, which offers several advantages in a clinical setting,” they stressed.