Thursday, 2 January 2014

H7N9 median time between events: the story of average disease

Click on image to enlarge.
From Clinical Findings in 111 Cases of Influenza A (H7N9) Virus Infection, Gao et al, Volume No 368, Page No. 2277-85. Copyright © (2013) Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.
This is a supplementary figure from the New England Journal of Medicine article entitled "Clinical Findings in 111 Cases of Influenza A (H7N9) Virus Infection" published May 2013 by Gao and colleagues working at a host of Chinese institutions around Eastern China.

It presents key median times between virus acquisition through to death among 62 influenza A(H7N9) virus-infected patients.

It struck me as a very clear way of summarizing the timeline to death among those with this outcome ascribed to infection by H7N9 earlier in 2013.

It is noteworthy that the median time for antiviral therapy to commence was 7-days, ostensibly too late to have an effect on severe infection and disease....but then a definite diagnosis took 8-days on average so antiviral treatment would have to have been commenced without lab confirmation, in order to be most effective. 

It seems that quite a few H7N9 patients present to at least 2 facilities once they become symptomatic. From the figure above, antiviral treatment is usually started at the second, tertiary care facility. Could it be started earlier?

This really stresses the key role of the first Doctor an H7N9 patient presents to, an event which itself occurs 48-hours after symptoms develop. The high end of when antiviral treatment needs to be administered to have its greatest impact.