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COVID-19 – high risk shielded patient list identification methodology

Rule logic

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. 

Rule Disease group Dataset used Inclusion criteria: HES (ICD10 & OPCS), MSDS, and BSA meds Inclusion criteria: GPES (SNOMED) with HES, BSA Meds
1 Solid organ transplant recipients who remain on long term immune suppression therapy HES, 
GPSPL
PCPM

Patient with ANY ICD-10/OPCS code falling within this disease group since 01/04/2006

AND

Recorded as having been prescribed medication during the past 6 months to manage post-transplant health

Patient has a code from Rule 1 in SNOMED_Flu_Subset_v2, solid transplants only

AND

Prescribed transplant medication (as identified in BSA Meds) in the last 6 months
2a

Cancer undergoing active chemo/ radiotherapy

or radical radiotherapy for lung cancer.
HES, 
GPSPL
PCPM

Patient with ANY ICD-10 code falling within this disease group AND coded with chemotherapy treatment within last 12 months

OR

Patient coded with neoplasm of lung AND radiotherapy within same episode of care since 2006

Patient has a code from Rule 2a in SNOMED_Flu_Subset_v2  in the last 12 months (up to extract date 16/03/2020)

AND

where patients have had chemotherapy treatment in the last 12 months (as identified in HES)
  People having immunotherapy or other continuing antibody treatments for cancer * None No coding available No coding available
  People having other targeted cancer treatments which affect the immune system, such as protein kinase or PARP inhibitors. * None No coding available No coding available
2b People with cancers of the blood or bone marrow such as leukaemia, lymphoma or myeloma at any stage of treatment HES, 
GPSPL
PCPM
Patient coded with ANY ICD-10 code falling within this disease group within the last 2 years (16 March 2018 onwards) Patient has a code from Rule 2b in SNOMED_Flu_Subset_v2  in the last 24 months (up to extract date 16 March 2020)
  People who have had bone marrow or stem cell transplants in the last 6 months, or still taking immunosuppression drugs HES, 
GPSPL
PCPM

All haematological transplants in last 6 months

OR

All haematological transplants since 1 June 2006 AND on immunosuppressant therapy

Patient has a code from Rule 2b in SNOMED_Flu_Subset_v2, Haematological transplants in last 6 months (up to extract date 16/03/2020)

OR

All haematological transplants ever AND on transplant immunosuppressant therapy
3 People with severe respiratory conditions including  severe asthma and severe COPD HES, MSDS,
GPSPL,
PCPM 

Patient with ANY ICD-10 code falling within this disease group since 1 April 2006

AND

  • For Asthma, those who have been prescribed a LABA or LABA/ICS or leukotriene over the past six months AND who have had four or more prescriptions for prednisolone over the six months
  • For COPD, those patients who are prescribed “triple therapy” inhalers and/or roflumilast

Patient has a code from Rule 3 in SNOMED_Flu_Subset_v2

AND

  • For Asthma, those who have been prescribed a LABA or LABA/ICS or leukotriene over the six months AND who have had four or more prescriptions for prednisolone over the six months
  • For COPD, those patients who are prescribed “triple therapy” inhalers and/or roflumilast within the last four months
  Cystic Fibrosis, idiopathic pulmonary Fibrosis, etc. Need to go straight through. Regardless of treatment. HES, MSDS,
GPSPL,
PCPM 
Patient coded with ANY ICD10 within this group since 1 April 2006

Patient has a code from Rule 3 in SNOMED_Flu_Subset_v2, those that are clinically flagged as to be included unconditionally

OR

Coded with 'Provision of Corticosteroid Safety Card' within the last 12 months (up to extract date 16 March 2020)
4 People with rare diseases and inborn errors of metabolism that significantly increase the risk of infections (such as SCID, homozygous sickle cell) HES, 
GPSPL,
PCPM
Patient coded with ANY ICD-10 code falling within this disease group since 1 April 2006 Patient has a code from Rule 4 in SNOMED_Flu_Subset_v2
  People on immunosuppression therapies sufficient to significantly increase risk of infection HES, 
GPSPL
All patients prescribed immunosuppression therapy in the last 6 months and NOT triggering in other disease categories All patients prescribed immunosuppression therapy in the last 6 months and NOT on triggering in other disease categories
5 People who are pregnant with significant congenital heart disease HES, 
GPSPL,
PCPM, MSDS

Patient with ANY ICD-10 code within this disease group since 1 April 2006

AND

(Having an estimated date of delivery of greater than, or equal to, the date of data extraction excluding (where possible) live births, terminations, stillbirths, and miscarriages (in MSDS) OR an open pregnancy SNOMED code (in GPES))
Patient has a code from both Rule 5 and Rule 6 (pregnant) in SNOMED_Flu_Subset_v2
Rule Disease group Dataset used Inclusion criteria: HES (ICD10 & OPCS), MSDS, and BSA meds Inclusion criteria: GPES (SNOMED) with HES, BSA Meds
C1A Immunodeficiency and immunosuppression: Children with risk of severe infection due to their primary immunodeficiency.

HES,
GPSPL,

PCPM
Patient with ANY ICD-10/OPCS code falling within disease group Patient has a code meeting PIN guidance
C2A Children at risk of severe infection due to immunodeficiency induced by their disease or their drugs as part of their therapy (i.e. post-transplant immunosuppression, severe vasculitis).  

HES,
GPSPL,

PCPM
All patients prescribed immunosuppression therapy in the last 6 months and NOT triggering in other disease categories All patients prescribed immunosuppression therapy in the last 6 months and NOT on triggering in other disease categories
C2B Children who are clinically vulnerable during the period before and after transplants. The duration of immunosuppression may differ for solid organ/ stem cell transplant.

HES,
GPSPL,

PCPM

Patient with ANY ICD-10/OPCS code falling within this disease group since 01/04/2006

AND

Recorded as having been prescribed medication during the past 6 months to manage post-transplant health
Patient has a code from Rule 1 in SNOMED_Flu_Subset_v2, solid transplants only
AND
Prescribed transplant medication (as identified in BSA Meds) in the last 6 months
 
C3A Children with very specific immunosuppression as part of their cancer therapy, e.g. receiving induction chemotherapy for acute lymphoblastic leukaemia (ALL) and Non-Hodgkins Lymphoma HES, 
GPSPL,
PCPM
 
Patient with ANY ICD-10 code falling within this disease group AND coded with chemotherapy treatment within last 12 months Patient has a disease code for condition in the last 12 months
C3B Receiving chemotherapy for acute myeloid leukaemia (AML)

HES,
GPSPL,

PCPM
Patient with ANY ICD-10 code falling within this disease group AND coded with chemotherapy treatment within last 12 months Patient has a disease code for condition AND coded with chemotherapy treatment within last 12 months
C3C Receiving chemotherapy for relapsed and/or refractory leukaemia or lymphoma

HES,
GPSPL,

PCPM
Patient with ANY ICD-10 code falling within this disease group Patient has a disease code for condition
C3D Received a donor stem cell transplant (allogeneic transplant) in the last 12 months  

HES,
GPSPL,

PCPM
Patient has a disease code for condition within last 12 months Patient has a disease code for condition within last 12 months
5 Children who are pregnant with significant congenital heart disease

HES,
GPSPL,

PCPM, MSDS

Patient coded with ANY ICD-10 code within this disease group  since 01/04/2006

AND

(Having an estimated date of delivery of greater than, or equal to, the date of data extraction excluding (where possible) live births, terminations, stillbirths, and miscarriages (in MSDS) OR an open pregnancy SNOMED code (in GPES))
Patient has a code from both Rule 5 and Rule 6 (pregnant) in SNOMED_Flu_Subset_v2

As this piece of work relied heavily on data linkage, the NHS Number was used as the main linkage, or index, key for the included datasets. In HES, if a patient’s NHS Number was not validated, the record was excluded from extracts to avoid false matching.

In addition, deceased patients were identified and removed from the final composite patient list using PDS – accepting one or both of the “informal” and “formal” notification of death markers.

Last edited: 7 October 2020 8:19 am