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Canadian Journal of Cardiology
Research Letters|Articles in Press

A Comparison of COVID-19 and Influenza in Heart Transplant Recipients: A Nationwide Study in the United States

Published:February 23, 2023DOI:https://doi.org/10.1016/j.cjca.2023.02.015
      Prior studies have established the increased susceptibility of patients with cardiovascular comorbidities to COVID-19 and associated worse outcomes.

      Isath A, Malik AH, Goel A, et al. Nationwide Analysis of The Outcomes and Mortality of Hospitalized COVID-19 Patients. Curr Probl Cardiol 2022:101440. (In eng)

      ,
      • Satterfield BA
      • Bhatt DL
      • Gersh BJ
      Cardiac involvement in the long-term implications of COVID-19.
      Heart transplant (HT) recipients often have an increased burden of comorbidities and are also on chronic immunosuppressive therapies. Immunosuppression can increase susceptibility to infections but has also been hypothesized to blunt the cytokine storm in COVID-19 patients. Further, recipients of solid-organ transplants have been proven to be at greater risk for complications from viral respiratory infections such as seasonal influenza than the general population. However, the impact of COVID-19 on HT recipients remains to be fully elucidated.
      We aimed to evaluate the demographics, clinical characteristics, and impact of COVID-19 compared with influenza infection in HT recipients in a large, nationally representative database.
      We queried the National Inpatient Sample from 2019 to 2020 for all adult (≥18 years) hospitalizations for COVID-19 or influenza in patients with prior history of HT. The primary outcome of interest was in-hospital mortality. Secondary outcomes included respiratory failure, length of stay, and hospitalization costs. A 1:1 propensity score-matched analysis was performed to adjust for possible confounders. STATA 16.0 was used for analysis.
      HT patients hospitalized with COVID-19 in comparison to influenza were more likely to be older [median age 62 vs 55 years, p<0.001] and had a higher prevalence of comorbidities such as diabetes (53.0% vs 39.3%, p=0.01), chronic kidney disease (70.5% vs 58.9%, p=0.04), dementia (3.9% vs 0%, p=0.04), and obesity (22.2% vs 9.3%, p=0.004). There was no significant difference in chronic obstructive pulmonary disease between the two groups (18.7% vs 17.1%, p=0.72).
      After propensity score matching, there were 390 hospitalizations in each group. The in-hospital mortality was significantly higher among HT patients with COVID-19 infection compared with influenza infection (20 (5.1%) vs. <10 (0%), p =0.02). Respiratory failure requiring intubation >24 hours was also more common in HT patients with COVID-19 (8.9% vs. 1.3%, p=0.03). Myocarditis was low and comparable in both groups [COVID-19 5 (0.43%) vs influenza 0 (0%), p=0.50 (propensity matching could not be performed due to low numbers)], as was rejection [10 (2.5%) vs 0 (0%), p=0.10].
      The median length of stay was significantly higher in HT patients with COVID-19 compared with influenza [5 (3-9) vs. 3.5 (2-5) days, p=0.01], as was the median cost of hospitalization [$12620 (6561-24912) vs. $8208 (5590-16456), p=0.01].
      The prevalence of HT patients with concomitant COVID-19 increased through the year in 2020 while a decrease in influenza infection in HT recipients was noted (Figure 1). The highest mortality was noted in the initial phase of the pandemic with a significant decrease through the year.
      Figure thumbnail gr1
      Figure 1A – Propensity matched outcomes of COVID-19 vs influenza in heart transplant recipients, B – Trends in hospitalizations and mortality
      To the best our knowledge, this is the first study to directly compare outcomes of COVID-19 and influenza infection in HT recipients.
      HT recipients under chronic immunosuppressive medications might have greater viral burden, heightened infectivity, and worse outcomes. Elevated cytokine production and systemic inflammatory state play a critical role in COVID-19 infection while the interaction between immunomodulators and the inflammatory state is poorly understood.
      • Alfishawy M
      • Elbendary A
      • Mohamed M
      • et al.
      COVID-19 Mortality in Transplant Recipients.
      Prior reports have demonstrated a worse mortality with COVID-19 in HT recipients - as high as 20-30%.
      • Alfishawy M
      • Elbendary A
      • Mohamed M
      • et al.
      COVID-19 Mortality in Transplant Recipients.
      ,
      • Ahmed F
      • Abid M
      • Maniya T
      • et al.
      Incidence and prognosis of COVID-19 amongst heart transplant recipients: a systematic review and meta-analysis.
      In comparison to our study, most of these studies were done in the early phases of the pandemic and are comparable to mortality noted in the earlier phase of our study.
      • Alfishawy M
      • Elbendary A
      • Mohamed M
      • et al.
      COVID-19 Mortality in Transplant Recipients.
      ,
      • Ahmed F
      • Abid M
      • Maniya T
      • et al.
      Incidence and prognosis of COVID-19 amongst heart transplant recipients: a systematic review and meta-analysis.
      The American Society of Transplant recommends annual influenza vaccination for HT recipients given the higher mortality in this vulnerable population. Prior studies have reported worse mortality with COVID-19 compared with influenza in the general population.
      • Khan MS
      • Shahid I
      • Anker SD
      • et al.
      Cardiovascular implications of COVID-19 versus influenza infection: a review.
      This was also evident in our study of HT recipients, in whom COVID-19 was associated with a significantly higher mortality after propensity matching for co-morbidities.
      Our study utilized a national database overcoming the biases seen with single center studies, however, there may be misclassification errors and potential confounding. Further, the differential in the vaccination rates of both groups likely also affects outcomes given COVID-19 vaccination was not available in 2020. In summary, among patients hospitalized with a history of HT, COVID-19 was associated with an increased risk of mortality and respiratory failure, and healthcare utilization when compared with influenza infection.

      References:

      1. Isath A, Malik AH, Goel A, et al. Nationwide Analysis of The Outcomes and Mortality of Hospitalized COVID-19 Patients. Curr Probl Cardiol 2022:101440. (In eng)

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