Ebola Survivors Experience Increased Mortality Risk in Year Following Recovery
Investigators observed that, when compared with the general population of Guinea, survivors of Ebola had a 5-fold increased risk of mortality over a mean of 1 year of follow-up after discharge.
It’s no secret that Ebola is a highly pathogenic and deadly disease. In the ongoing Ebola outbreak in the Democratic Republic of the Congo, the blood-borne virus has an overall case fatality ratio of 67%. Although the risk of death during acute infection phase is common knowledge, information on subsequent mortality after recovery has been widely unknown, until now.
In a new article published in The Lancet Infectious Diseases, investigators report their findings from a retrospective cohort study that followed survivors from the 2013-2016 west Africa Ebola outbreaks.
During the west African outbreak, a record number of individuals survived Ebola. The overall mean case fatality ratio was 62.9% Although a range of post-Ebola sequelae have been noted in survivors, the authors of the study reported the lack of information about subsequent mortality. Therefore, the authors used information from the Guinean national survivors monitoring program to attempt to contact and follow up with survivors who received treatment in Ebola treatment units.
Of the 1270 survivors who were discharged from treatment centers in Guinea, information was retrieved for 1130 or 89%. The survivors were followed from December 8, 2015, through September 30, 2016, with deaths during this time period recorded.
The investigators interviewed family members of the survivors who subsequently passed away during the study period to gain insight about their deaths. Additionally, the team calculated an age-standardized mortality ratio compared with the general Guinean population, and assessed risk factors for mortality using survival analysis and a Cox proportional hazards regression model.
Among the survivors, 59 deaths were reported during the study period, with the cause of death “tentatively attributed” to renal failure in 37 cases.
Through these methods, the team observed that, when compared with the general population of Guinea, survivors of Ebola had a 5-fold increased risk of mortality over a mean of 1 year of follow-up after discharge (age standardized mortality ratio 5·2 [95% CI 4·0—6·8]).
After the 1-year period, the investigators note, “mortality did not differ between survivors of Ebola virus disease and the general population. (0·6 [95% CI 0·2—1·4]).”
It was also observed that patients who had longer stays in the Ebola treatment centers had an increased risk of late death when compared with patients who had shorter stays in the facilities (adjusted hazard ratio 2·62 [95% CI 1·43—4·79]).
“Mortality was high in people who recovered from Ebola virus disease and were discharged from Ebola treatment units in Guinea,” the authors wrote in their report. “The finding that survivors who were hospitalized for longer during primary infection had an increased risk of death, could help to guide current and future survivors' programs and in the prioritization of funds in resource-constrained settings.”
According to investigators, future research should focus on the possible effects that Ebola has on kidney function. Additionally, the duration of Ebola virus disease and persistence in bodily fluids should be investigated as risk factors for long-term effects.
The team also concludes that similar studies should be conducted in Ebola survivors from the Democratic Republic of the Congo, Liberia, and Sierra Leone to gain more insight on how to prevent late deaths after recovery from Ebola virus disease.