LA CONCEPCIÓN ECONÓMICA

The Hospital Episode Statistics (HES) are held in a central data store and include details of all patient admissions to NHS hospitals in England. Data for NHS hospitals in Northern Ireland, Scotland and Wales are collected separately by respective national offices. HES data contain information on each hospital episode (Liffen et al., 1988). Data are available for every financial year from 1989-90 onwards, and each record holds around 100 personal, medical and administrative details of each patient admitted to hospital in England. This includes geographical information about the location of treatment and where the patient lived. Around 12 million new records are added to the dataset each year, with most of the variables collected at point of contact

from the Patient Administration System (PAS). However, there are also ‘derived’

variables which are imputed from other information contained within the HES.

Access to HES data can be achieved through the HESonline website (http://www.hesonline.nhs.uk/), however the use of HES microdata (episode level) is strictly controlled due to high risk of disclosure. Requests for this data in the form of database extracts or custom tabulations are currently made to the NHS Information Centre through their external data custodians, Northgate Information Solutions. If requests are made for data items of increased sensitivity (such as OA code of patient

78

residence), approval is needed from the Security and Confidentiality Advisory Group (SCAG) and/or the Patient Information Advisory Group (PIAG).

If permission is granted by the advisory groups, it should be possible to obtain data for patients relating to their residential location (which could be as detailed as postcode unit or OA) and their location of treatment (which in theory could be as detailed as hospital postcode – this information, however, would need to be derived

externally by users from the ‘site’ or ‘provider’ code of treatment featured in the

database). These interaction data can be further disaggregated by variables including gender, age, ethnicity, admission/discharge date, length of treatment spell and illness/diagnoses/operation type. Disaggregation could also be by maternity or psychiatric identifier variables which may be seen as different from the standard variables due to the nature of admittance (i.e. non-standard medical admittance).

As stated previously, for the purposes of studying interaction flows it is necessary to access either database extracts or custom tabulations. Aggregated HES data are

available to download ‘off-the-shelf’ from the HES website, although these tables are

of very limited use for studying interaction. The only geographical data available from this source identifies either the strategic health authority of residence for patient episodes, or the hospital care provider/HA location for patient episodes. These geographical data do represent aggregated origin and destination statistics, but it is not possible to link the tables (for example through a common identifier) to obtain flow information.

In addition to the main HES dataset (which is concerned with in-patient episodes), outpatient data has been recorded on the IC (HES) Outpatients dataset since 2003. This dataset has more than 40 million new records added to it each year and features records for all outpatient attendances in England. At present the dataset is labelled

‘experimental’ as there are a number of known weaknesses in the data. These

weaknesses principally relate to significant local variations in data completeness (The Information Centre, 2006), with some local administration centres providing far more complete patient records to the central dataset than others. As with the main HES dataset, the HES outpatients dataset also contains information about the location of

79

treatment and residence for each patient. Again, it is possible to directly identify the postcode or OA of residence for patients, while the location of treatment (if required at a level lower than HA or PCT) would need to be derived for the site of treatment or provider code – an external exercise, but not one that would prove too difficult as provider codes are included in downloadable information from the HESonline website.

A certain amount of care needs to be exercised when using HES data, especially when comparing years. There are fluctuations in the data which, as stated by HESonline

(2007), may have occurred as a result of ‘organisational changes, reviews of best

practice within the medical community, the adoption of new coding schemes and data quality problems that are often year specific.’ With this being the case, any observations of changes over time need to be carefully checked.

Little, if any, research appears to have been done on the ‘commute to hospital’. This

data set provides the potential to investigate hospital catchment areas for different types of operation and to compute average distances to hospital for different types of treatment across the country, for example.

Negotiations are currently in progress with Pam Hughes, Dean White and Chris Roebuck at the NHS Information Centre, to provide CIDER with access to HES data on a permanent basis. It has been agreed in principal that providing CIDER with HES data that could be incorporated into WICID should be possible. As yet, negotiations relating to the outpatient dataset have not taken place, but it is envisaged that once access to the primary HES dataset is established, negotiations relating to the outpatients data set could commence.