Methods used to produce this data

This page describes the methodologies used to produce the figures contained in this release. It includes details on what data are presented, the data sources, how groups are defined (if applicable) and how calculations are carried out.

1. Outpatients

The following information on outpatient appointments (for consultant-led activity only) is presented:

  • Number of new and return attendances
  • Did Not Attend (DNA) rates.

Information on new attendances and DNA rates are taken from the SMR00 database. Return appointments are taken from ISD(S)1. Please refer to the Data Quality page for further information.

Statistical Disclosure Control has been applied to this analysis.

1.1 New and Return Appointments

New and return appointments are defined by referral types.

New appointments:

  • Referral Type = 1
  • Referral Type = 2

Return appointments:

  • Referral Type = 3

See the PHS Data Dictionary entry on Referral Type (external website) for further information on what this means.

1.2 Did Not Attends

DNAs are identified from the attendance status on SMR00 records. DNA rates are calculated from new appointments only and are presented as a percentage of the total number of new outpatient appointments.

Did Not Attends:

  • Attendance Status = 8 (Patient did not attend and gave no prior warning)

See the PHS Data Dictionary entry on Attendance Status (external website) for further information on what this means.

2. Inpatient and Daycase Admissions

The following information on Inpatient and Daycase Admissions (for acute specialties only) is presented:

  • The number of episodes and stays by NHS Board, hospital, council area, admission type, age + sex, deprivation and specialty
  • Average length of stay

All of this information is taken from the SMR01 database. Please refer to the Data Quality page for further information.

Statistical Disclosure Control has been applied to this analysis.

2.1 Inpatient and Daycase Activity

Inpatient admissions are defined by admission types.

Elective (Routine) admissions:

  • Admission Type = 10-12 and 19

Emergency admissions:

  • Admission Type = 20-22, 30-36, 38-39

Transfers:

  • Admission Type = 18

Daycases are defined by the Inpatient/daycase marker:

  • IPDC = 'D'

See the PHS Data Dictionary entry on Admission Type (external website) for further information on what this means.

Table 1: Example patient flow

Episode Admission
Episode Discharge
NHS board
Hospital
Continuous Inpatient Stay
Episode Length of Stay
Specialty
01/10/2017
01/10/2017
A
A
1
0
A1
01/10/2017
05/10/2017
A
A
1
4
A1
05/10/2017
10/10/2017
A
A
1
5
A2
10/10/2017
20/10/2017
A
A
1
10
A2
20/10/2017
21/10/2017
B
B
1
1
C1
31/10/2017
01/11/2017
B
C
2
1
A1

2.2 Episodes 

This data release would calculate episodes from table 1 as follows:

  • Episodes by NHS board – Four episodes for board A with an average length of stay of 4.75 days and two episodes for board B with an average length of stay of 1 day
  • Episodes by hospital – Four episodes for hospital A with an average length of stay of 4.75 days, one episode for hospital B with an average length of stay of 1 day and one episode for hospital C with an average length of stay of 1 day
  • Episodes by specialty – Three episodes for general medicine (A1) with an average length of stay of 1.7 days, two episodes for cardiology (A2) with an average length of stay of 7.5 days and one episode for general surgery (C1) with an average length of stay of 1 day

2.3 Stays

A stay is a continuous, unbroken period of time a patient spends as an inpatient in an acute facility. A patient may change specialty, consultant, significant facility, NHS board and/or hospital during a continuous inpatient stay. Because of this, information used to assign a stay to a specific hospital or NHS board has to be taken from a single episode within a stay. The rules to decide what data is taken from which episodes are defined as follows:

  • Age – Taken from first episode
  • NHS board – Taken from first episode
  • Hospital – Taken from first episode
  • Date of Discharge – Taken from last episode
  • Emergency/Elective/Transfer - Taken from first episode

A stay which has a mix of inpatient and daycase episodes is counted once as an inpatient stay. For example, if a stay begins as a daycase but then is subsequently admitted as an inpatient then this will be classed as an inpatient stay. If all of the episodes in a stay are daycase episodes, then it is counted as a daycase.

Using the above rules, this data release would calculate stays using the information from Table 1 above as follows:

  • Stays by NHS board – One stay for board A with a length of stay of 19 days and one stay for board B with a length of stay of 2 days
  • Stays by hospital – One stay for hospital A with a length of stay of 20 days and one stay for hospital C with a length of stay of 1 day

2.4 Specialty Spells

A specialty spell is an unbroken period of time within a continuous inpatient stay that a patient spends in a specific specialty in a specific location. There has been a change in how a specialty spell has been calculated to be consistent with the annual publication. The new method better describes the number of admissions to a given specialty in a given location.

There can be multiple specialty spells within a larger continuous inpatient stay and as such the episodes are grouped by link number, cis marker, specialty and NHS Board. The inclusion of NHS Board in the aggregation is to account for any movements out of the board. The other assumptions in the spell calculation follow similar rules to continuous inpatient stays:

  • Date of Discharge – Taken from last episode within specialty
  • Emergency/Elective/Transfer - Taken from first episode within stay

This change in methodology means that figures pre November 2020 are not comparable with this publication. For more information on the specialty spells methodology please see the Specialty Spells Methodology paper (PDF).

3. Beds

The following information on hospital beds is presented:

  • Total number of available staffed bed days over the quarter
  • Total number of occupied bed days over the quarter
  • Average number of available staffed beds per day
  • Average number of occupied beds per day
  • Percentage occupancy

All of this information is taken from the ISD(S)1 data returns. Please refer to the Data Quality page for further information.

3.1 Estimation

NHS Highland was unable to submit beds information from quarters ending March 2014 until September 2015. Beds figures have been estimated for this period using a straight line. A straight line is fitted between the last quarter before the estimation period and the first quarter after the estimation period. The estimated values are taken as the points along this line at each quarter.

In other cases, estimation is carried out using the previous three months of known data.

The order for aggregating and estimating all available staffed beds and total occupied bed days has been updated since the November 2020 quarterly publication. Estimations are now applied after aggregation by specialty and location but before aggregation to specialty groups and NHS Boards, so that the totals now match the individual tallies. The estimation function used itself has not been changed.

3.2 Beds Calculation

Bed figures are calculated based on the ISD(S)1 data returns.

Total number of available staffed beds (aasb) over the quarter Allocated  Beds   +  Borrowed  Beds   –  Lent  Beds   +  Temporary  Beds

Average number of available staffed beds per day (asb) = aasb / number of days in the quarter

Total number of occupied bed days (tobd) = Sum of the number of occupied beds for each day of the quarter

Average number of occupied beds per day (aob) = tobd / number of days in the quarter

Percentage occupancy = (aob / asb) x 100

Please refer to the Glossary page for more information about the terms used.

4. Other points to note

ISD(S)1 also does not record information on the age or sex of patients, nor the deprivation of the area in which they live.

Specialties have been assigned a specialty grouping based on their specialty code. Acute specialty grouping includes the medical and surgery groupings combined. Further information on which specialty codes are assigned to which specialty groupings is available in the specialty grouping file (XLS).

The quarterly publication should not be used to approximate yearly figures as NHS Boards can update and submit their data monthly which may result in changes in the recent data shown from one publication to another. This means that there will likely be more variation in the quarterly data which would level off over the year when presenting annual data within the annual publication. Also, it should be noted that the quarterly publication includes acute hospitals only. In addition, only acute specialties are included in the inpatient and daycase figures.

Last updated: 07 October 2022
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