ABSTRACT
This chapter explores a definition of a small-area study and reviews the different types of small-area epidemiological enquiry. One definition of a small-area study is an analysis carried out at sub-national or perhaps sub-regional level. Computer systems for carrying out small-area analyses of routine data offer the possibility of undertaking automatic surveillance in order to detect areas of high disease incidence. A major problem in the interpretation of analyses of disease rates in small areas is the issue of socio-economic confounding. A major constraint is the availability of appropriate health data at the small-area level, such as cancer registrations, often because of reasons of data confidentiality; indeed, the proposed European Community directive on confidentiality could have a devastating effect on the ability of bona fide researchers to use national or regional registries for epidemiological purposes. Environmental pollution data tend to be collected at a small number of fixed monitoring sites across a country.
