News Release

H1N1 influenza can cause substantial illness and death in transplant recipients, but early antiviral therapy might offer protection

Peer-Reviewed Publication

The Lancet_DELETED

The global influenza A H1N1 (swine flu) pandemic caused substantial disease and death in solid organ transplant (SOT) patients during 2009-10. But early treatment (within 48 h) with antiviral therapy resulted in lower rates of hospitalisation and reduced the number of admissions to intensive care by almost two-thirds. Wherever possible, early antiviral treatment for symptomatic patients during future outbreaks along with preventive measures such as vaccination might offer protection for this high risk population. These are the conclusions of the first large multicentre epidemiological study examining influenza in transplant patients, published in an Article* Online First in The Lancet Infectious Diseases.

SOT patients might have higher flu infection rates and are potentially at greater risk of complications due to the immunosuppressant drugs they take to prevent organ rejection. As such, transplant recipients infected with H1N1 are probably more likely to develop severe disease than the general population. Although many guidelines document the importance of influenza infection in organ transplantation, studies on the impact of influenza and the use of antiviral treatment in SOT patients are lacking. Additionally, conflicting outcomes have been reported about the severity of disease resulting from influenza infection.

To provide more evidence on clinical outcomes in people who have had a SOT, Deepali Kumar from the University of Alberta in Canada and international colleagues assessed 237 transplant recipients infected with the pandemic H1N1 influenza A strain to identify factors leading to admission to hospital and intensive care unit (ICU), and other complications.

The researchers surveyed 154 adults and 83 children from 26 transplant centres in the USA, Canada, and Europe who had received organ transplants (kidney, heart, lung, liver, and others) and had influenza A infection between April and December 2009. Information on type of transplant, symptoms, diagnosis, and treatment were collected and factors leading to pneumonia, admission to hospital and ICU were calculated using statistical models.

Patients received their transplant a median 3.6 years before being infected with H1N1. Overall, 167 (71%) of 237 patients were admitted to hospital, 37 (16%) were sent to the ICU (of whom 21 needed mechanical ventilation), and ten (4%) died.

Importantly, findings showed that early antiviral treatment (primarily oseltamivir [Tamiflu]) was linked with a reduced likelihood of ICU admission (7 [8%] of 90 patients treated within 48 h vs 28 [22%] of 125 patients treated after 48 h), admission to hospital, need for mechanical ventilation, and death.

Additionally, the results confirmed previous research showing a high risk of pneumonia, with almost a third of patients in this study contracting pneumonia. Interestingly, children were less likely to present with pneumonia compared with adults (13 (16%) of 81 children vs 60 (40%) of 149 adults).

The authors say: "Pandemic influenza A H1N1 resulted in a spectrum of illness ranging from mild and self-limiting to severe disease in recipients of solid-organ transplants…starting treatment with antiviral drugs early is important for reduction of morbidity and mortality in this highly susceptible population. For example, during periods of transmission, transplant patients presenting with signs and symptoms that are compatible with influenza should probably start empirical treatment with antiviral drugs before the diagnosis is confirmed."

They continue: "Almost a third of the patients in our cohort reported contact with an ill household member before their own illness. In this setting, postexposure chemoprophylaxis might be an option…Vaccination of both transplant patients and their household contacts is probably an important preventive measure since vaccine responses might be suboptimum after transplantation."

In an accompanying Comment, Per Ljungman from Karolinska University Hospital and Karolinska Institutet in Sweden says that these findings support the use of antiviral therapy in immunocompromised individuals and points out that: "Although the rates of oseltamivir [Tamiflu] resistance have, until now, been low with the pandemic H1N1 strain, the development of new anti-influenza drugs should be a priority." He concludes by emphasising the importance of annual influenza vaccination for transplant recipients.

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*PLEASE ENSURE YOU CREDIT THE LANCET INFECTIOUS DISEASES AS THE SOURCE OF THIS MATERIAL*

Dr Deepali Kumar, University of Alberta, Edmonton, Canada. T) +1 780 492 3885 E) deepali.kumar@ualberta.ca

Professor Per Ljungman, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden. T) +46 70 760 3577 (mobile) E) per.ljungman@ki.se (Please note that Professor Ljungman is currently in the USA)

For full Article and Comment see : http://press.thelancet.com/tlidorganflu.pdf

Notes to Editors: This is the first original research article to be published by The Lancet Infectious Diseases.


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