Chapter 29

Epidemiology

WHAT IS EPIDEMIOLOGY?

Epidemiology is the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to control diseases and other health problems [1]. It is concerned with studying the presence of disease in a community, country or region, and can help to ascertain the size, severity, spread and origin of a particular disease.

An epidemiologist deals with diseases in groups of people (whereas a clinician deals with disease in individuals). From epidemiological studies, decisions can be made on the allocation or targeting of resources in a population.

Epidemiology is the foundation upon which governments and local authorities plan preventive measures for future generations, including oral health, such as the fluoridation of water and how many dentists will need to be trained in 20 or 30 years time to meet demand. The oral health educator (OHE) needs to know how dental surveys are used in epidemiology, as well as indices, which are used to measure data in populations and individuals.

SURVEYS

Surveys are systems used to collect and record data vital to epidemiology and future planning of oral health.

Often, hundreds or thousands of subjects have to be surveyed, and the data must be recorded and analysed. Surveys must therefore be simple, reproducible and non-time-consuming.

As mentioned throughout this book, two surveys are of particular significance to the OHE:

• Adult Dental Health Survey (ADHS) 2009.
• Dental Health Survey of Children and Young People 2003.

The main purposes of these surveys, which are carried out every 10 years, are to get a picture of the dental health of the population and how this has changed over time in order to assess changes in health and to plan for the future.

For example, some of the aims of the 2009 ADHS were to:

• Establish the condition of natural teeth and supporting tissues.
• Investigate dental experiences.
• Gain knowledge about attitudes towards dental care and oral hygiene.
• Examine changes in dental health over time.
• Monitor the extent to which dental health targets set by the government are being met.

For the ADHS, 11,380 individuals were interviewed and 6,469 dentate adults were examined, making it the largest adult epidemiological survey ever in the United Kingdom.

The survey was commissioned by the NHS Information Centre for Health and Social Care, the Welsh Assembly Health Department and the Department of Health, Social Services and Public Safety in Northern Ireland. It was managed principally by the Office for National Statistics (ONS). (Scotland decided not to participate.)

The 2009 survey consisted of a questionnaire interview for adults aged over 16 years at all sampled households, and an oral examination of the mouth and teeth of all those adults who had at least one natural tooth. Statistics were collected and recorded by community dental officers (often assisted by dental nurses), who examined sections of the population in their areas and charted results.

These statistics were sent to the ONS where they were analysed, collated and published in report form [2, 3]. Reports can then be used by area authorities considering, for example, whether to fluoridate their water supply or implement procedures to control drinks sold in school tuck shops.

Survey terminology

The OHE should be familiar with four terms that are used in the context of epidemiological surveys:

INDICES

An index (plural indices) is a numerical method of measuring data in a survey or in individuals.

Before indices were devised, oral hygiene and the extent of disease were graded by terms, such as good, average or poor. Obviously, this was unsatisfactory as one person’s idea of good may differ from another. Factors such as the extent of plaque and calculus were not recorded.

Examples of where indices can be used

Examples of data that can be gathered using indices include:

• Extent of caries – how many in a population are affected?
• Extent of periodontal disease – how wi/>
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