Cystic Fibrosis Patients' Vulnerability to COVID-19 Infection: Preliminary Data Ease Fears

Jim Kling, MDedge News

November 11, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Clinicians treating patients with cystic fibrosis (CF) have had to face the possibility that their patients may be particularly susceptible to SARS-CoV-2 infection and perhaps at greater risk of worse outcomes from COVID-19. But early results suggest that social distance measures and perhaps the younger average age of individuals with CF have prevented a severe impact on this patient population.

Not all of the news is good. Some research suggests that posttransplant individuals may be at greater risk of severe outcomes. However, researchers warned that the data are too sparse to draw firm conclusions, and ongoing analyses of patient registries and other sources should lend greater insight into the burden of COVID-19 among individuals with CF. Those were some of the conclusions presented at a session of the virtual North American Cystic Fibrosis Conference.

D.B. Sanders, MD, who is a pediatric pulmonologist at Riley Hospital for Children and the Indiana University, both in Indianapolis, presented data from the Cystic Fibrosis Foundation's Patient Registry, which includes patients in the United States. As in other populations, he showed that health care use has gone down among individuals with CF. From April to September 2019, 81% of clinical encounters were in the clinic and 12% in the hospital. Over the same period in 2020, those numbers dropped to 35% and 4%, respectively, with 30% by phone or computer. In-person health care use rebounded somewhat between July 1 and Sept. 16, with 53% of encounters at the clinic, 5% at the hospital, and 28% conducted virtually. There were also dips in forced expiratory volume in one second (FEV1) and microbiology testing, from about 90% occurring during health encounters at the end of 2019 to fewer than 10% of encounters by April.

As of Aug. 17, Sanders reported that 3,048 individuals with CF had been tested for COVID-19, with 174 positive results.

Racial and ethnic disparities in positive test results seen in other populations were also observable among individuals with CF. Several groups made up a higher proportion of COVID-19–positive CF patients than the general CF population, including Hispanics (18% vs. 9%), Blacks (7% vs. 5%), and individuals with FEV1 value less than 40% predicted (14% vs. 8%).

As of Sept. 17, there had been 51 hospitalizations and two deaths in the United States among 212 individuals with CF who tested positive for COVID-19, with increasing numbers that mirror trends in the U.S. population. One death occurred in a patient with advanced lung disease, the other in a post–lung transplant patient. "Thankfully [the numbers are] not higher, but this is being followed very closely," said Sanders during his presentation.

One encouraging bit of news was that hospitalizations among individuals with CF have dropped since the start of the pandemic. "I think this shows how good our families are at socially distancing, wearing masks, and now that they not being exposed to viruses, I think we're seeing the fruits of this with fewer hospitalizations," said Sanders. He noted that it's possible some of the decline could have been to reluctance to go to the hospital, and the introduction of triple combination cystic fibrosis transmembrane conductance regulator modulator therapy has also likely contributed. "We were already seeing fewer hospitalizations even before the pandemic hit," he said.

At the session, Rebecca Cosgriff, director of data and quality improvement at the Cystic Fibrosis Trust in the United Kingdom, presented an international perspective on COVID-19 cases among individuals with CF. At the beginning of the pandemic, the Cystic Fibrosis Global Registry Harmonization Group recruited country coordinators to collect anonymized data on infections, hospitalizations, and other outcomes. In April, the group published its initial findings from 40 cases in eight countries, which concluded that these cases generally resembled the broader population in clinical course, which assuaged initial fears.

Cosgriff reported on results from a second round of data collection with a cutoff date of June 19, which expanded to 19 countries and included many from South America and more in Europe. The network encompassed about 85,000 individuals with CF, and tallied 181 cases of COVID-19. A total of 149 cases were nontransplant, and 32 were posttransplant (28 lung only). Fully 15% of the nontransplant group were over age 40 years, compared with 41% in the transplant group. Homozygous F508del mutations were more common in the posttransplant group (59% vs. 36%). However, lung function, as estimated by the best FEV1 measured in the previous year prior to infection, differed between the nontransplant (73%) and posttransplant (80%) COVID-19 patients.

Across all age groups, hospitalizations were more common in patients with best FEV1 percentage predicted values less than 70% (P = .001). Cosgriff also expressed concern about the posttransplant group. "Across all outcomes that might be indicative of infection severity – hospitalization, ICU admission, new supplementary oxygen, and non-invasive ventilation – the proportion of the posttransplant group was higher across the board," she said during her presentation.

There were seven deaths. Cosgriff noted that there were too few deaths to analyze trends, but she presented a slide showing characteristics of deceased patients. "Factors like being post–lung transplant, being male, having less FEV1 than predicted, being over 40, or having CF-related diabetes, all appear pretty frequently amongst the cohort of people who died," she said.

Overall, the results of these surveys are encouraging, suggesting that early fears that COVID-19 cases could be more severe among individuals with CF may not have been borne out so far. Sanders noted in his talk that there aren't enough cases in the U.S. cohort to show links to risk factors with statistical significance. "But thankfully we're not seeing a host of negative outcomes," he said.

Sanders and Cosgriff have no relevant financial disclosures.

This article originally appeared in Chest Physician.

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