by Jeff Minerd, Contributing Writer, MedPage Today July 14, 2022

Patients requiring dialysis were more likely to die in the month following a hurricane, likely because of storm-related disruptions to dialysis services, researchers said.

In an analysis that combined storm-tracking data with information from the U.S. Renal Data System, all-cause mortality among dialysis patients in hurricane-affected areas was increased 13% in the 30 days following storms, relative to periods when there were no hurricanes (95% CI 5%-22%, P<0.001), Matthew Blum, MD, of the Johns Hopkins University School of Medicine in Baltimore, and colleagues reported online in the Journal of the American Society of Nephrology.

Risk of death was highest immediately following a hurricane and waned over time. The day after a storm, mortality risk was doubled (HR 2.02, P<0.001). Three days after, risk was more than 50% higher (HR 1.59, P<0.001). By 60 days post-storm, however, the risk was no longer significant (HR 1.04, P=0.16), Blum's group found.

"Recent work has highlighted the range of disruption to dialysis services brought forth by natural disasters, including loss of power, water, transportation, and communication systems along with evacuations and hospital surges," Blum and colleagues wrote.

"This is consistent with observations from Hurricane Katrina," they added, "in which 44% of patients in the affected area missed at least one dialysis session, 17% of patients missed at least 3 sessions, and 23% of patients were hospitalized within a month of the storm." A total of 94 Gulf Coast dialysis units were closed for at least a week following Katrina, they noted.

The retrospective study included 187,388 patients from the U.S. Renal Data System who were registered as requiring maintenance dialysis from 1997 through 2017. All patients lived in one of 108 hurricane-affected counties in the United States. Their median age was 65 and 43.7% were female.

The study also used data from the federal government's revised Atlantic hurricane database (HURDAT2) and the independently run hurricaneexposure database, which maintains county-level storm tracking information. There were 27 hurricanes during the study period. Overall 29,849 patients were exposed to at least one hurricane, with some 530,000 patient-years of follow-up.

Death from any cause was the main outcome. There were 105,398 deaths during the study period. The researchers estimated the risk of death after a hurricane using time-varying Cox proportional hazards model, adjusted for age, sex, race and ethnicity, year of dialysis initiation, educational attainment, poverty level, and monthly housing costs.

Blum and colleagues noted that missed dialysis sessions due to hurricanes could allow potassium, fluid, and uremic toxins to accumulate and make patients more susceptible to cardiovascular events. In addition, hurricanes have been linked with higher death rates from infectious, respiratory, neuropsychiatric, and injury-related causes. Furthermore, tropical storms often bring extreme heat, which has been linked with higher mortality among patients with end-stage renal disease, they said.

Organizations that support dialysis-dependent patients during natural disasters are one way to address this problem, Blum and colleagues indicated. For example, the Kidney Community Emergency Response (KCER) coalition was established after Hurricane Katrina in 2006. This multidisciplinary group offers preparatory guidance for dialysis care during natural disasters.

One of the coalition's recommendations is to administer early dialysis treatment prior to anticipated disruptions, the researchers said. When this recommendation was employed during Superstorm Sandy, 60% of patients in affected areas received early dialysis, and this was associated with lower odds of emergency department visit, hospitalization, and 30-day mortality compared to those who did not receive early dialysis, a 2015 study found.

"Given the possibility of increasing severity of tropical cyclone events, dialysis units and public health professionals should continue to enhance contingency plans to safeguard the welfare of dialysis-dependent patients," Blum and colleagues said.

Joseph Vassalotti, MD, chief medical officer at the National Kidney Foundation, who was not involved in the study, said his organization also offers resources and information, including the online document Planning for Emergencies -- a Guide for People with Kidney Disease.

Vassalotti also recommended KCER as an important resource. "The Chief Medical Officers of Dialysis Programs work collaboratively to address natural disasters, such as hurricanes," he said in an email to MedPage Today. "The COVID-19 pandemic also had a silver lining of fostering care coordination and collaboration across systems."

One limitation of the study was that it relied on wind speed and precipitation to determine hurricane exposure. It did not take the effects of flooding and storm surges into account, Blum's group acknowledged. "Consequently, our analysis may not include the mortality risk of storms that caused heavy flooding without hurricane-force winds," they said.

"Future work should consider cause-specific mortality, additional storm features associated with higher mortality, and the comparative effectiveness of different storm response protocols. Efforts to model climate change-related health effects and mortality should consider the dialysis-dependent population," Blum and colleagues concluded.

Jeff Minerd is a freelance medical and science writer based in Rochester, NY.

The study was supported by the National Institutes of Health.

One co-author reported extensive relationships with industry. Vassalotti reported no conflicts of interest.

Journal of the American Society of Nephrology

Source Reference: Blum M, et al "Hurricanes and mortality among patients receiving dialysis" JASN 2022; DOI: 10.1681/ASN.2021111520.

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