Additions and subtractions
Overview
Version 3 introduced a mechanism whereby General Practice and NHS Trusts can “add” patients and Version 4 allowed General Practice to “subtract” individuals from the SPL. This is independent of disease coded data picked up by the rule set and, for example, supports professional and clinical judgement by a GP or by a speciality consultant in a NHS Trust.
The mechanism for the additions and subtractions for hospitals, is by marking an individual record as either addition or subtraction in the appropriate field of the SPL Trust data collection template submitted via the Strategic Data Collection Service (SDCS) solution.
Additions and subtractions to the SPL from General Practice is managed through the use of the appropriate SNOMED CT Code as entered into the patients record, as follows:
| Code | Description |
|---|---|
| 1300591000000101 | Low risk category for developing complication from COVID-19 infection (finding) |
| 1300571000000100 | Moderate risk category for developing complication from COVID-19 infection (finding) |
| 1300561000000107 | High risk category for developing complication from COVID-19 infection (finding) |
The most recent code (determined by date of event where risk code is applied) will be used to determine a patient’s entry to, or removal from, the SPL.
Therefore, the methodology now follows the process below:
- Data sources: GP clinical, hospital commissioning, primary care (dispensed medicines), maternity
- Baseline SPL (algorithm only)
- Additions and subtractions
- Composite SPL
From version 44 patients identified by the COVID-19 Population Risk Assessment have been added to the SPL, applying the following business rules:
1. For patients who have never been present on the SPL AND do not have a Moderate or Low risk code on their GP clinical record:
Action: Addition to SPL with SNOMED-CT code:
“1300561000000107 - High risk category for developing complication from coronavirus disease caused by severe acute respiratory syndrome coronavirus infection (finding)”
2. For patients who are present on the SPL.
Action: No action required. Patient will remain on SPL.
3. For patients who have been previously on the SPL but have subsequently been removed by application of moderate or low risk code OR patients who have never been present on the SPL but have a Moderate or Low risk code on their GP clinical record.
Action: No action required. NHS Digital will uphold clinical decision and the moderate or low risk flag, i.e. “subtraction” will be remain in place.
The COVID-19 Population Risk Assessment will calculate based on assumed data as well as data from the patient record. Specifically assumed values relate to sex, ethnic category, BMI measure and postcode.
Where an assumed value has been captured, this will be picked up by SPL processing through indicator in the COVID-19 Population Risk Assessment data. This indicator will be used when processing outputs for the patients GP clinical record and the free text will vary accordingly.
How additions and subtractions will be calculated to produce the composite SPL
In the first instance, a date stamp (or event date) is attached to each record from source data that has triggered an addition to the baseline SPL. These data are collated in a fact table, or audit log.
The fact table includes 3 new data items, data source, risk flag and date. The risk flag is calculated as “High”, “Medium” or “Low”; or “H”, “M” or “L” for ease.
For any record that triggers inclusion through the algorithm, the risk flag is set to “H” with appropriate data source and data also recorded.
Subsequent (non-algorithmic) additions and subtractions will be processed, by date, as follows:
| Action | Outcome |
|---|---|
| GP marks a new SPL patient as low risk | The patient is not included in the composite SPL |
| GP marks a new SPL patient as medium risk | The patient is not included in the composite SPL |
| GP marks a new SPL patient as high risk | The patient is added to the composite SPL |
| GP marks an existing SPL patient as low risk | The patient is removed from the composite SPL |
| GP marks an existing SPL patient as medium risk | The patient is removed from the composite SPL |
| GP marks an existing SPL patient as high risk | The patient is retained in the composite SPL |
| NHS Trust “adds” a new SPL patient | The patient is added to the composite SPL |
| NHS Trust “adds” an existing SPL patient | The patient is retained in the composite SPL |
| NHS Trust “subtracts” an existing SPL patient | The patient is removed from the composite SPL |
| NHS Trust “subtracts” a non-SPL patient | The patient is not included in the composite SPL |
| COVID-19 Population Risk Assessment "adds" a new SPL patient | The patient is added to the composite SPL |
| COVID-19 Population Risk Assessment "adds" an existing SPL patient | The patient is retained in the composite SPL |
| COVID-19 Population Risk Assessment "adds" a patient who has been previously on the SPL but since removed by moderate or low risk code | The patient is not included to the composite SPL |
| COVID-19 Population Risk Assessment "adds" a patient who has never been present on the SPL but has a moderate or low risk on their GP clinical record | The patient is not included to the composite SPL |
In formulaic terms, actions and outcomes can be presented as follows:
| Source | Current risk flag | Action | New risk flag | SPL outcome |
|---|---|---|---|---|
| GP | <BLANK>, L or M | L | L | Not included |
| GP | <BLANK>, L or M | M | M | Not included |
| GP | <BLANK>, L or M | H | H | Added |
| GP | H | L | L | Removed |
| GP | H | L | L | Removed |
| GP | H | H | H | Retained |
| NHS Trust | <BLANK>, L or M | Addition | H | Added |
| NHS Trust | H | Addition | H | Retained |
| NHS Trust | H | Subtraction | L | Removed |
| NHS Trust | <BLANK>, L or M | Subtraction | L | Not included |
| QCOVID | <BLANK> | Addition | H | Included |
| QCOVID | H | Addition | H | Retained |
| QCOVID | L or M | Addition | L or M | Not included |
The GP Clinical decision will always take priority in terms of subtractions and only newer eligible coded diagnoses will override this existing clinical decision. In practice this will only ever be from General Practice data, as HES data will generally be a period of time behind.
If there is a conflict in the SPL fact table between same dated methodology, a hospital or a GP update record, (i.e. diagnostic codes or risk codes have been applied with an identical date) the priority will be the GP clinical decision.
Notes
Movement of paediatric patients to the adult rule set will be applied from the point of the patient’s 18th birthday. Therefore application of conditions included in Table 2, but not Table 3, (found in Rule Logic chapter) will occur from this point forward, but will reflect clinical coding captured prior to the patient’s 18th birthday.
Patient opt-outs will be applied via General Practice.
As a final process step, when linking to the NHS Personal Demographic Service (PDS) dataset, the following adjustments will take place:
- deceased patients, both formally and informally marked, will be removed
- address and contact detail changes will be applied, based on latest demographic data
- individuals marked with a “Sensitive” flag in PDS will have all contact details removed from downstream data dissemination activity. However, these patients will remain present in the SPL
- if a date stamp is not attached to an event, then this will always concede precedence to dated events
- for congenital heart defects and pregnancy, the date for calculation will be the date of the defect
- no dates for drug data will be used for addition or subtraction processing i.e. GP or Hospital additions/ subtractions will always override groups which are modified by drugs, i.e. issuing a drug alone will not trigger re-entry onto the SPL
Last edited: 2 March 2021 5:35 pm