(51) Outcomes following SARS-CoV-2 infection among Canadians living with cystic fibrosis: Analyses using the Canadian Cystic Fibrosis Registry

Background: Two years into the COVID-19 pandemic, global studies, comprised mostly of data from the US and Europe, have identified risks of severe disease following SARS-CoV-2 (the virus that causes COVID-19) infection. However, literature on the impact of infection on clinical outcomes specific to the Canadian cystic fibrosis (CF) community is still lacking. The objectives of this study were to: 1) determine the risk of hospitalization among Canadians living with CF following SARS-CoV-2 infection, and 2) describe the change in lung function following infection.

Methods: Individuals with a confirmed SARS-CoV-2 infection between January 1, 2020, and December 31, 2021, were retrieved from the Canadian CF Registry, and followed until March 31, 2022. Age was defined as the age at the time of infection. Baseline clinical measurements were defined as the most recent measurement in the year prior to infection. Lung function was measured using FEV₁ percent predicted (ppFEV₁). Children under 6 years old were assumed to have ppFEV₁ ≥70%. Nutritional status was measured using body mass index (BMI) or BMI percentile. For objective 1, the outcome of interest was hospitalization for which SARS-CoV-2 infection was a precipitating event. Factors associated with hospitalization were assessed using logistic regression and presented as odds ratios (OR) with confidence intervals (CI). For objective 2, the outcome of interest was the change in ppFEV₁ from baseline to first measurement post-infection and was assessed using the Wilcoxon signed-rank test for matched pairs. For descriptive analyses, continuous variables were summarized using median and interquartile range (IQR), and categorical variables using frequency and proportion. Some results may be suppressed to reduce risk of identification of individuals.

Results: There were 145 individuals (44 children and 101 adults aged ≥18 years) with a positive test for SARS-CoV-2 recorded in the Canadian CF Registry during the study period. The characteristics of these individuals are summarized in Table 1, stratified by hospitalization status. Seven individuals were admitted to the intensive care unit and < 5 died during the follow-up period. After adjusting for sex, those post-transplant were significantly more likely to be hospitalized (OR: 33.5; CI: 10.1 to 111.0). In a subset of patients with at least 1 ppFEV₁ pre- and post-infection (N = 71), there was no significant difference in the median baseline ppFEV₁ between those hospitalized and those who weren’t. Furthermore, the change in ppFEV₁ was also not significant either in those hospitalized (median: -0.5%; IQR: -4.9% to 2.8%; p-value = 0.79) or those not hospitalized (median: 0.2%; IQR: -3.7% to 3.9%; p-value = 0.49). Ongoing analyses to assess the impact of baseline ppFEV₁ and time of infection on risk of hospitalization, and to calculate the rate of decline in ppFEV­₁ post-infection, will be available for NACFC.

Conclusions: Canadian CF patients who were transplant recipients were more likely to be hospitalized following SARS-CoV-2 infection. The change in baseline lung function was neither clinically nor statistically significant, however this relationship will need to be further explored as more follow-up data becomes available.

Acknowledgements: We would like to acknowledge the involvement and continued participation of those living with CF who consent to having their data submitted, and the contribution from CF clinic team members who enter the data.

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