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Publication, Part of

Hospital Admitted Patient Care Activity 2019-20

National statistics

National Statistics

Current Chapter

Hospital Adult Critical Care Activity - Technical Guide


Hospital Adult Critical Care Activity - Technical Guide

Background to Critical Care Data

An Intensive Care Unit (ICU) or High Dependency Unit (HDU) ward in a hospital, known as a critical care unit, provides support, monitoring and treatment for critically ill patients requiring constant support and monitoring to maintain function in at least one organ, and often in multiple organs. Medical equipment is used to take the place of patients’ organs during their recovery. 

Some critical care units are attached to condition-specific treatment units, such as heart, kidney, liver, breathing, circulation or nervous disorders. Others specialise in neonatal care (babies), paediatric care (children) or patients with severe injury or trauma.

The Critical Care Minimum Dataset (CCMDS)  is submitted by hospitals to the Secondary Uses Service (SUS) . The CCMDS contains 34 data items on periods of care in adult critical care units, of which 14 data items are mandatory for submitters. Each month, record-level data extracts are taken from SUS to populate the Hospital Episode Statistics (HES)  data warehouse which is used to produce this publication. Figure 1 illustrates this process.

 

Figure 1: Data acquisition process

Critical care records contain information on:

  • the organ support that the patient received; and
  • the method, source and location of admission and discharge.

In addition, data in the associated HES APC records contain further details including:

  • patient demographics, including sex and age; and
  • diagnosis and treatment details.

HES critical care data now includes Neonatal and paediatric critical care data however, they have been filtered out and only adults are included in this report. 


Selection of Data for Analysis

Adult care units only

Data for paediatric and neonatal care is collected principally through separate data sets which are not comparable to the adult critical care data set; analysis is therefore limited to those records which identify the critical care unit function (the principal clinical service provided in the ward) as predominately one for the treatment of adults. Nevertheless, some neonatal and paediatric patients will have been treated in these critical care units and their data are included for analysis.

Data range

For coherence with other HES-derived publications, records have been included for analysis only where the discharge date is within the 2019-20 financial year.

Best match

Most raw critical care records in the data set are associated with only one record of an APC episode  but some are associated with multiple episodes in an APC spell; to avoid multi-counting these critical care records, an algorithm has been applied to link each critical care record to the APC episode record against which it is the ‘best match’. Because of limitations in the algorithm, a small number of raw critical care records are identified as a ‘best match’ with more than one APC episode and the final presented numbers of critical care records slightly over-count the true number of critical care periods.

The best match methodology and its impact are laid out in more detail in the Best Match Methodology section. 

Data cleaning

Certain records have been excluded from analysis, including:

  • records exhibiting illogical critical care dates (i.e. an end date prior to the start date); and
  • critical care records which have not been able to be linked to a hospital APC record  owing to its having been removed from the APC data-set during a data cleaning process. These cleaning processes may include the removal of duplicate records, activity which occurred outside of the relevant date range or removal on specific request of a data provider.

Best Match Methodology

A given raw record of critical care in the data set may be associated with more than one APC episode record. Reporting on the number of matches between critical care records and APC episodes would therefore represent an overstatement of critical care periods because some would be duplicated. To avoid this, an attempt has been made, for reporting purposes in this publication, to link each critical care period to one APC episode.

A multi-step algorithm is applied to identify the APC record that is the best match to each critical care period.

Step 1: Critical care to APC relationship

The first step is an examination of the relationship between each critical care to APC association and to assign these relationships a ranking in a thirteen-point hierarchy (see Figure 2). A determination has been made that the lower the cardinal number of the rank in the hierarchy, the better the relationship between the critical care record or records with the most senior rank.

Step 2: Number of support activities

Where step 1 of the algorithm identified more than one APC episode per critical care record as a best match candidate, the record or records with the maximum number of critical care support activities are retained.

Step 3: Tie-breaker

Where two or more records remain as best match candidates, the record with the lowest record ID (a unique but arbitrary record identifier) is retained.

Remaining duplicates

Where a single critical care period record is associated with more than one APC episode with different identifiers and with equally good hierarchy rank, each such association will be flagged by the match algorithm as a best match. As a result, a small number of duplicates will remain in the final data-set for analysis; a summary is shown in Appendix 1 of the Summary Report. These duplicates can arise from there being duplicate episodes in the APC data-set or from the APC records with which the critical care period was associated being of equally poor quality.


Best Match Examples

Example 1: Two different critical care periods occur within an inpatient episode; both rows retained as best matches

Critical care to APC relationship

Critical care to APC relationship description

Patient ID

Critical care start date

Critical care discharge date

Episode start date

Episode end date

Best Match flag

4

Start dates match, CC end before episode end

111

17/05/2019

07/07/2019

17/05/2019

14/07/2019

Y

 

3

End dates match, CC

start after episode start

111

07/07/2019

14/07/2019

17/05/2019

14/07/2019

Y

Example 2: Critical care period is present three times, associated with three different episodes; one row is retained as best match

Critical care to APC relationship

Critical care to APC relationship description

Patient ID

Critical care start date

Critical care discharge date

Episode start date

Episode end date

Best Match flag

1

Start and end match

222

01/04/2019

01/04/2019

01/04/2019

01/04/2019

Y

3

End dates match, CC

start after episode start

222

01/04/2019

01/04/2019

31/03/2019

01/04/2019

N

4

Start dates match, CC end before episode end

222

01/04/2019

01/04/2019

01/04/2019

06/04/2019

N

Example 3: Two critical care periods are present, one of which is associated with 2 inpatient episodes; one row retained as best match for each critical care period

Critical care to APC relationship

Critical care to APC relationship description

Patient ID

Critical care start date

Critical care discharge date

Episode start date

Episode end date

Best Match flag

4

Start dates match, CC end before episode end

333

23/05/2019

26/05/2019

23/05/2019

29/05/2019

Y

8

CC starts during episode, ends after

333

23/05/2019

26/05/2019

22/05/2019

23/05/2019

N

2

CC within episode

333

26/05/2019

27/05/2019

23/05/2019

29/05/2019

Y

Example 4: Three critical care periods are present, associated with a total of three inpatient episodes; one row retained as best match for each critical care period

Critical care to APC relationship

Critical care to APC relationship description

Patient ID

Critical care start date

Critical care discharge date

Episode start date

Episode end date

Best Match flag

3

End dates match, CC

start after episode start

444

10/06/2019

11/06/2019

09/06/2019

11/06/2019

Y

12

CC before Episode

444

10/06/2019

11/06/2019

13/06/2019

16/06/2019

N

3

End dates match, CC

start after episode start

444

12/06/2019

13/06/2019

11/06/2019

13/06/2019

Y

6

CC starts before, ends during episode

444

12/06/2019

13/06/2019

13/06/2019

16/06/2019

N

4

Start dates match, CC end before episode end

444

13/06/2019

13/06/2019

13/06/2019

16/06/2019

N

3

End dates match, CC

start after episode start

444

13/06/2019

13/06/2019

11/06/2019

13/06/2019

Y

Example 5: One critical care period is present, associated with four different inpatient episodes; each is retained as a best match

Critical care to APC relationship

Critical care to APC relationship description

Patient ID

Critical care start date

Critical care discharge date

Episode start date

Episode end date

Best Match flag

12

CC before Episode

555

26/07/2019

31/07/2019

15/01/2020

15/01/2020

Y

12

CC before Episode

555

26/07/2019

31/07/2019

17/01/2020

24/01/2020

Y

12

CC before Episode

555

26/07/2019

31/07/2019

17/01/2020

17/01/2020

Y

12

CC before Episode

555

26/07/2019

31/07/2019

24/01/2020

24/01/2020

Y



Last edited: 18 November 2020 2:17 pm