The Small Area Health Statistics Unit: a national facility for investigating health around point sources of environmental pollution in the United Kingdom.

STUDY OBJECTIVE: The Small Area Health Statistics Unit (SAHSU) was established at the London School of Hygiene and Tropical Medicine in response to a recommendation of the enquiry into the increased incidence of childhood leukaemia near Sellafield, the nuclear reprocessing plant in West Cumbria. The aim of this paper was to describe the Unit's methods for the investigation of health around point sources of environmental pollution in the United Kingdom. DESIGN: Routine data currently including deaths and cancer registrations are held in a large national database which uses a post code based retrieval system to locate cases geographically and link them to the underlying census enumeration districts, and hence to their populations at risk. Main outcome measures were comparison of observed/expected ratios (based on national rates) within bands delineated by concentric circles around point sources of environmental pollution located anywhere in Britain. MAIN RESULTS: The system is illustrated by a study of mortality from mesothelioma and asbestosis near the Plymouth naval dockyards during 1981-87. Within a 3 km radius of the docks the mortality rate for mesothelioma was higher than the national rate by a factor of 8.4, and that for asbestosis was higher by a factor of 13.6. CONCLUSIONS: SAHSU is a new national facility which is rapidly able to provide rates of mortality and cancer incidence for arbitrary circles drawn around any point in Britain. The example around Plymouth of mesothelioma and asbestosis demonstrates the ability of the system to detect an unusual excess of disease in a small locality, although in this case the findings are likely to be related to occupational rather than environmental exposure.

Improving the quality of data in randomized clinical trials: the COMPACT computer package. COMPACT Steering Committee.

One crucial component for a successful clinical trial is that the data gathered have a high level of reliability and completeness. This paper reviews some problems of data management and describes the computer package COMPACT which has been developed to deal with such problems. The package allows range and consistency checks and can monitor complex follow-up schedules. A unique feature of the package is a PROBLEMS file which has use both for identification of queries about the data and of patients with particular characteristics of interest. The ability to monitor drug dosages and to signal deviations from the protocol is of particular value. COMPACT has the syntax necessary to create a 'flat' file for transfer to statistical packages for analysis, and the variable description files for SAS, SPSS and MINITAB. The package is written in standard FORTRAN which enables transfer to different types of mini and micro computer systems.

The derivation of reference ranges adjusted for age, sex and other variables.

A method for deriving reference ranges has been developed that has wide applications in clinical medicine. Data that is not homogenous but has subgroups (e.g. age, sex or social class) can be analysed and mean values for the subgroups determined. Facilities are included which enable outliers to be identified and the form of the distribution to be examined.