Introduction: A common approach to the surveillance of emerging infectious diseases and agents of bioterrorism is to analyse electronically captured data for disease syndromes. The Patient Care Enhancement System (PACES) is a form of electronic medical records presently in service in the Singapore Armed Forces (SAF). We assess the feasibility of PACES data for surveillance, describe time-trends, and identify methods of sub-analysis which could improve performance. Materials and Methods: Medical consults from July 2000 to June 2003 were extracted. Diagnosis codes were mapped to 7 infectious disease syndromes according to the categorisation in the Electronic Surveillance System for the Early Notification of Communitybased Epidemics (ESSENCE): gastrointestinal (GI), fever (FEVER), respiratory, (RESP), coma (COMA), neurological (NEURO), dermatologic-haemorrhagic (DERMHEM) and dermatologic-infectious (DERM-INF). Results: A total of 732,233 episodes of care were analysed. Weekly periodicity was observed, with decreased weekend consults; there were no obvious seasonal trends in any of the syndromes. RESP, FEVER and GI syndromes were common events. Sub-analyses, either by restricting to cases with a repeated consultation, or grouping the data by medical centres, could dramatically lower thresholds used to flag outbreaks. Conclusion: In spite of the level of background noise inherent in a system consisting mainly of primary care consults, sub-analysis by medical centre, or restriction to cases with repeated consults were able to yield sensitive thresholds for outbreak detection.
There is growing awareness of the need for efficient, real-time identification of infectious disease outbreaks. The bioterrorism attacks involving anthrax bacilli, 1 and the sudden emergence of the Severe Acute Respiratory Syndrome (SARS), 2 a previously unknown infectious disease, have emphasised the reality of both intentional and naturally occurring outbreaks. Early detection of an outbreak is important for both outbreak control and the clinical management of cases. 3 Disease notifications, which rely on physicians to notify suspicious cases, often occur after the definitive diagnosis, and hence may be unable to provide early warning for novel infectious agents.
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