Principally, high-level disease groups were provided by the Chief Medical Officer in the “CMO Readout list” (Table 1) and converted into the appropriate ICD-10 diagnoses codes and OPCS-4 procedure codes, as recorded in Hospital Episode Statistics.
Further, the CMO Readout list was converted into the appropriate SNOMED-CT coding structure, as recorded in GPFLU.
In addition, medications used to treat these diseases were identified and patients recorded as being prescribed these were isolated in the PCPM dataset.
Finally, open pregnancies were identified in MSDS. These data were combined to formulate a rule set that identified patients at very high risk of complications from COVID-19 infection. A list of diagnosis codes and procedure codes can be found in Annex B and the medications used within this work can be found in Annex C.
This table shows the exact processing rules used to identify high-risk patients in the datasets shown in this document.