Strengths and limitations
HES data covers all NHS-funded hospital activity in England. As such
they are the most complete and detailed record of hospital activity in
England related to COVID-19. The eight-month study period allowed us to
look at temporal trends over an extended period.
However, as with any administrative dataset, there are limitations in
using HES data. HES relies on individual hospital trusts compiling data
accurately and in a consistent manner. As such, some patients who
underwent a tracheostomy may not have been coded as such and so number
of tracheostomies reported here is likely to be an under-estimate.
Furthermore, tracheostomy complications are likely to be underreported
due to coding limitations.19 However, we have no
reason to suspect that our data are systematically biased in terms of
temporal trends or the profile of patients receiving tracheostomy.