A national facility for small area disease mapping and rapid initial assessment of apparent disease clusters around a point source: the UK Small AreaHealth Statistics Unit

Background Reports of disease clusters are often received by district healt h authorities and are; in some cases, associated with concerns about a poll ution source. The Small Area Health Statistics Unit (SAHSU) has developed a Rapid inquiry Facility, which will produce an estimated relative risk for any given condition for the population within defined areas around a point source, relative to the population in a local reference region. The system can also facilitate the production of annual reports and other health studi es for Departments of Public Health Medicine through the creation of ward-l evel maps to illustrate disease variation across small areas. Methods The facility uses routinely collected morbidity, mortality and popu lation data at a small area scale, together with the computing facilities a nd expertise necessary to run such analyses quickly and efficiently. Using this facility SAHSU can supply a report within three working days. To aid i nterpretation, smoothed small area maps that account for sampling variabili ty in the observed data can also be produced. Results The paper reports on two case studies where the pilot system has be en utilized by health authorities for both point source analyses and small area disease mapping. Conclusions We believe that this facility would be of considerable use to d istricts. The local knowledge and expertise of the local public health spec ialist is essential in the interpretation and presentation of the facility' s output. Feedback from public health specialists is helping SAHSU refine t he output of the facility, so as to make the information presented as compr ehensive and as useful as possible.