Primary diagnoses and Covid patients

The disease is the primary diagnoses in most patients with positive tests.

The Telegraph claimed:

More than half of Covid hospitalisations are patients who only tested positive after admission, leaked data reveal.

The article continued:

However, the patterns shown in the leaked figures — with the vast majority of hospital Covid cases being diagnosed after admission, in some cases weeks later — suggest it includes large numbers likely to have been admitted for other reasons.

There are two separate concepts here:

• Covid-19 surveillance admissions: A count of people with a positive SARS-CoV-2 in the 14 days before admission, or had a positive test after admission.
• Primary diagnoses: The reason the patient goes to hospital. That could be with Covid-19, or another reason.

The article’s thrust is the surveillance definition overstates Covid-19 impacts on hospitals. Sir Graham Brady MP (Altrincham and Sale West) says it is “inevitably misleading”.

We can think about statistical issues with some hypothetical patients.

Patient A: One person begins to experience severe coughing. They do not have a SARS-CoV-2 test before going to hospital. The routine testing identifies they are positive. Hospital staff start treatment for Covid-19.