Series details: CRDA/24

The Public Health Common Dataset (PHCDS) has been commissioned annually by the Department of Health (DoH) for the National Health Service (NHS) since 1988/89. The purpose of the PHCDS has developed from helping directors of public health agencies produce their annual reports, to encompass monitoring progress in achieving Health of the Nation (HoN) targets, 1 and subsequently Our Healthier Nation targets. 2 This is available on-line at the archive website for official documents at http://www.archive.official-documents.co.uk/. The PHCDS also monitors clinical outcomes. The Public Health Common Data Set (known as the Compendium of Clinical and Health Indicators since 1998) provides health authorities with a 'common currency' for studying and comparing information about health.

The PHCDS includes many hundreds of health indicators calculated from individual health and local authorities (where possible) in England and Wales. A health indicator is a characteristic of an individual, population or an environment which can be measured and used to describe one or more aspects of the health of an individual or population. The PHCDS has been commissioned annually by the DoH for the National Health Service (NHS) since 1988/89. The PHCDS has developed substantially in content and scope since its original appearance.

The Compendium of Clinical and Health Indicators, 1998 onwards

As stated above the Public Health Common Data Set has been known as the Compendium of Clinical and Health Indicators since 1998. In 1995, after a period of consultation, the Central Health Outcomes Unit (CHOU) of the Department of Health rationalised clinical and health indicators from a variety of national data sets into one structured data set. This became the Compendium of Clinical and Health Indicators (the Compendium). The Compendium brought together indicators from a number of datasets developed by the Department of Health. This included included a categorisation of indicators by health topic (e.g. disease entity) rather than by type of data set, as hitherto. The CHOU subsequently moved away from the Department to become jointly based at the London School of Hygiene and Tropical Medicine and the Institute of Health Sciences, University of Oxford. It became known as the National Centre for Health Outcomes Development (NCHOD).

The PHCDS has been commissioned annually by the Department of Health (DoH) for the National Health Service (NHS) since 1988/89. Within the DoH, the Public Health Group has responsibility for the development of the Our Healthier Nation public health strategy across government. Within the NHS Executive (NHSE), the NHS Public Health Development Unit (PHDU) is responsible for public health strategy and functions in the NHS.The Public Health Common Data Set (PHCDS) is a compendium of data across a range of nationally identified items with a relevance to public health. The DoH commissions external organisations to create the PHCDS on its behalf.

The 1988 PHCDS was produced by the Epidemiology and Public Health Research Unit at the University of Surrey. By the 1991 PHCDS this organisation had changed its name to the Institute of Public Health, and by the 1996 PHCDS it had become the National Institute of Epidemiology. The 1998 PHCDS was produced by the Centre for Public Health Monitoring at the London School of Hygiene and Tropical Medicine (LSHTM).

Further information on the history of the DoH can be found in the Administrative History of the Health Departments.

Each PHCDS dataset consists of a number of indicators on topics such as demography, fertility, mortality, morbidity, and the decennial census. Indicators are aggregated statistical measures describing a group of patients or a population, compiled from measures or assessments made on people in the group or population. Indicators are available for administrative areas within the NHS in England from 1996, data is also available for local authority areas.

The data within the PHCDS is by administrative areas, therefore it is important to understand the administrative structure of the NHS. However, the administrative areas of the NHS have undergone significant re-organisation during the years that the PHCDS has been produced. In 1988 the DoH was responsible for the NHS, NHS Regional Health Authorities (RHAs), District Health Authorities (DHAs), and Family Health Service Authorities (FHSAs). In 1996 DHAs and FHSAs were merged and replaced by Health Authorities (HAs). The structure of the NHS includes HAs and Primary Care Groups (PCGs).3

The scope and content of the PHCDS has changed and developed since its inception. In 1998, the PHCDS itself was absorbed into the Compendium of Clinical and Health Indicators which are based on mortality data. In addition some indicators look at hospitalisation for specific causes, some screening activities and regional data on health and lifestyle. The set also includes some basic social and demographic indicators, mainly derived from the 1991 census. As regards its use the PHCDS was distributed to Health Authorities (HAs) on digital media. The HAs were required to install the PHCDS on their personal computers (PCs). (For further information, see the relevant User Guides, in the Dataset Documentation Catalogue, references CRDA/24/DD/1-10.)

Further transfers of data from the Compendium of Clinical and Health Indicators by the Department of Health are anticipated.

The PHCDS dataset and related dataset documentation are public records under the Public Records Acts 1958 and 1967. The National Archives has assigned these datasets and dataset documentation the series reference JA 5.

The Public Health Common Datasets are deemed closed on transfer for 5 years. However all of the datasets currently available within this series are open without restriction. Data is available for browsing on demand by users of NDAD and does not have to be booked in advance.

The PHCDS and related dataset documentation are subject to Crown Copyright. Copies may be made for private study and research purposes only.

The PHCDS is not subject to registration under the Data Protection Act.

The language of the materials is English.

Documents and publications relating to the Public Health Common Datasets have been transferred to NDAD and can be consulted via the Dataset Documentation Catalogue.

The Public Health Common Data Set data definitions and user guide for computer files are available via the Dataset Documentation Catalogue. Various Health Authority public health reports were also published.

For the 1988 to 1996 PHCDS the data was distributed on 3.5 inch floppy disks. (The 1990 User Guide states that HAs could request the data on 5.25 inch disks.) The number of disks per year differed depending on the number of files. For the 1997 and 1998 PHCDS the data was distributed on a CD-ROM.

The system requirements for PCs to read the PHCDS were for 1988 to 1995:

• IBM or compatible microcomputer
• 3.5 inch 720K or 1.44MB disk drive
• Random access memory (RAM) of at least 640K

For 1996 the system requirements are not described other than up to 3Mb of hard disk space was required to load the data from one floppy disk. (There were thirty-six disks in total for the 1996 PHCDS.)

For 1997-1999 no system requirements are described.

Microsoft DOS (MS-DOS) and Microsoft Windows.

For 1988 to 1995 the data was distributed in Symphony (WR1) spreadsheets. To read the data a copy of Symphony (version 1.1 or upwards), or Lotus 1-2-3 or a spreadsheet package that could import Lotus files was required.

For 1996 the data was distributed as compressed (ZIP) files. These files had to be copied onto the hard disk of a PC and then uncompressed. The uncompressed files were Lotus 1-2-3 (WK3) files.

For 1997 the data was distributed as Lotus 1-2-3 (WK3) files.

For 1998 and 1999 the PHCDS data was distributed as Lotus 1-2-3 (WK4) files; the Compendium data was supplied in two formats, Lotus 1-2-3 (WK3) and Microsoft Excel 97.

Symphony and Lotus 1-2-3 are Lotus software packages.

Each PHCDS dataset originally consisted of data in a number of spreadsheet files. Within NDAD the data are held in tables. One table has been created for each spreadsheet file. The structure of each table reflects the structure of the original file. Each dataset consists of the tables relating to that year of the PHCDS. Within each year tables are grouped by topic, e.g. tables on population are grouped together. Some topics are only available for some years, which reflects the development of the PHCDS. Since the data was held as a series of standalone spreadsheets, these were not inter-linked (as they would perhaps have been within a database). To allow users to combine fields from more than one file, relationships have been set up within NDAD between all tables (for the same type of NHS administrative area) within a topic. For example in the 1988 dataset, all tables within the first topic (Population and Demography) are linked. In the 1992 dataset, the data for an indicator is, in general, held in two tables, one covering Regional and District Health Authorities and the second covering Regional and Family Health Services Authorities; In this case all Regional and District Health Authorities tables within a topic have been inter-related, and separately all Regional and Family Health Services Authorities tables within a topic have been linked.

Further details for each year are available in the sub-series catalogues. See Links to sub-series catalogues

The PHCDS datasets are closed in that once entered the data was archived and was not subsequently overwritten by other data.

The data that was used to create the PHCDS came from a number of sources and was collected via many different systems. The organisations that supplied the data to the PHCDS producers (as described above in the Aim and purpose and Statement of responsibility sections) are usually listed for each indicator in the relevant User Guides for each year. For example, data for indicator B3, Number of live births occurring in the calendar year 1989 (from the 1990 PHCDS, reference CRDA/24/DS/1990/2/2) was provided by the Office of Population, Censuses and Surveys (OPCS). However, this data was originally collected by OPCS from the NHS via the statistical form VS1 (Vital Statistics 1).

The organisations that provided data for the PHCDS include OPCS's successor, the Office for National Statistics (ONS), the DoH and the NHS via RHAs, HAs and hospitals.

The major data collection/statistical systems that provide source data for the PHCDS include:

• Vital Statistics - data on population, births, deaths, fertility and mortality
• Death certification - registration of deaths and medical certificate of cause of death
• Census - count of all people and households (usually every 10 years)
• General Household Survey - continuous survey of a sample of people resident in private households
• Health Survey for England - survey designed to monitor the nation's health
• National Food Survey - continuous survey of a sample of people resident in private households
• Cancer registration minimum data set - collected via regional and national cancer registries
• British Isles Network of Congenital Anomalies Register (BINOCAR) and National Down Syndrome Cytogenetic Register
• KC50 - statistical return on vaccinations against communicable diseases
• Hospital Episodes System (HES) - holds data on consultant episodes for hospital in-patients

Generally, the data used in the PHCDS was validated by the original data collectors before being used. Issues regarding interpretation of data are described in the User Guides (see the Dataset Documentation Catalogue), either in the introduction section of each User Guide or in comments on individual indicators.

The source data for the PHCDS was usually processed by the organisations producing the PHCDS to create the indicators. Many indicators are a rate per population, so that HAs can be compared. The processing methodology of each indicator is described in the User Guides which can be seen via the Dataset Documentation Catalogue.

There are a small number of tables in which some figures are displayed as percentages within the original spreadsheet (when viewed via Excel) but are exported to CSV as figures between 0 and 1, and are therefore held as such within the NDAD archive. An example of this is the 'Response rate' column(s) in tables CRDA/24/DS/1996/6/14 and CRDA/24/DS/1997/5/26 (hob4).

Details of the content and transformation validation checks performed by NDAD on each dataset are recorded in the catalogues of individual datasets. To view these catalogues, please go to the Sub-series catalogue from where you can access the dataset catalogues. See Links to sub-series catalogues.

Subseries catalogues provide more detailed information about individual subseries, and are currently available for the following subseries:

1. The Health of the Nation: a strategy for health in England, Department of Health, 1992, London, HMSO

2. Saving Lives: Our Healthier Nation (OHN) White Paper Cm 3852, Department of Health, 1999, HMSO,

3. See the web site for 'How the NHS works', http://www.nhs.uk