Flu a Consistent Threat to ESRD Patients

Influenza remains deadlier for patients with end-stage renal disease (ESRD), a researcher reported.

According to flu season data from 2010 to 2019, in-hospital mortality remained higher for ESRD patients with influenza compared with all flu patients, said Guangchen Zou, MD, of Danbury Hospital in Connecticut, in a presentation at the National Kidney Foundation Spring Clinical Meetings.

Overall, ESRD was associated with a 28% higher chance of in-hospital mortality each flu season (OR 1.28, 95% CI 1.17-1.40) in a model adjusted for age, gender, primary payer, heart failure, chronic lung disease, obesity, drug abuse, immunocompromised status, bacterial pneumonia, and the Charlson Comorbidity Index as covariates.

Based on data from the National Inpatient Sample, the study found that ESRD patients accounted for 2.91% to 3.65% of all hospital admissions that were coded with a primary diagnosis of influenza.

Among the 131,492 influenza hospital admissions included in the analysis, 2,081 patients (1.58%) died. However, the mortality rate among the 4,647 ESRD patients was 2.47% (115 patients).

Out of all flu seasons during this time, the deadliest seasons for people with ESRD were the 2010-2011 and 2014-2015 seasons. The 2016-2017 flu season had the lowest in-hospital mortality for not only ESRD patients, but also all influenza patients in general.

Zou told MedPage Today that these findings didn't come as much of a surprise, since "people with chronic medical conditions are often thought to be at higher risk of death from influenza, and infections of various kinds are a major cause of mortality for dialysis patients."

But when it comes to protecting this vulnerable population, the answer is clear: vaccination.

"Dialysis patients are at a higher risk of death when they get admitted for influenza and we should probably do more to encourage them to get vaccinated each year," Zou emphasized. "With so much focus on COVID, we should not forget that influenza is another potentially deadly virus for which vaccines are available."

In fact, he said, the pandemic -- at least in part -- inspired the study.

"After reading about the higher mortality for dialysis patients when they got COVID, I was trying to find previous research on outcomes of influenza in dialysis patients, but could not find much," said Zou. "This surprised us since influenza has been around for so long and causes significant mortality every year."

To tackle this question, the researchers identified all diagnoses using ICD-9/10-CM or ICD 10-PCS codes. ESRD was identified via a diagnosis or procedure code specifically for either ESRD or dialysis and excluded patients with acute kidney injury. Some conditions that were considered to make the patient immunocompromised included HIV, malignancy, and rheumatologic disorders, among others.

Zou added that study used an administrative database so it might have been affected by coding practices, and certain information such as vaccination status was lacking.

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