Extra ED Surveillance Doesn't Benefit Conventional Surveillance for Meningococcal Infection

Researchers in New South Wales, Australia report in the latest issue of BMC Infectious Diseases that use of an emergency department (ED) surveillance system to augment conventional surveillance of meningococcal infection did not demonstrate a benefit.

O'Toole and colleagues (2010) report that meningococcal infection causes severe, rapidly progressing illness and reporting of cases is mandatory in New South Wales (NSW), Australia. The NSW Department of Health operates near real-time ED surveillance that includes capture and statistical analysis of clinical preliminary diagnoses. The system can provide alerts in response to specific diagnoses entered in the ED computer system. The researchers' study assessed whether once daily reporting of clinical diagnoses of meningococcal infection using the ED surveillance system provides an opportunity for timelier public health response for this disease.

The study involved a prospective and retrospective component. First, reporting of ED diagnoses of meningococcal infection from the ED surveillance system prospectively operated in parallel with conventional surveillance which requires direct telephone reporting of this scheduled medical condition to local public health authorities by hospitals and laboratories when a meningococcal infection diagnosis is made. Follow-up of the ED diagnoses determined whether meningococcal infection was confirmed, and the time difference between ED surveillance report and notification by conventional means. Second, cases of meningococcal infection reported by conventional surveillance during 2004 were retrospectively matched to ED visits to determine the sensitivity and positive predictive value (PPV) of ED surveillance.

The researchers report that during the prospective evaluation, 31 patients were diagnosed with meningococcal infection in participating EDs. Of these, 12 had confirmed meningococcal disease, resulting in a PPV of 38.7 percent. All confirmed cases were notified earlier to public health authorities by conventional reporting. Of 149 cases of notified meningococcal disease identified retrospectively, 130 were linked to an ED visit. The sensitivity and PPV of the ED diagnosis for meningococcal infection was 36.2 percent and 37.5 percent, respectively.

O'Toole and colleagues (2010) conclude that based on prospective evaluation, it is reassuring that existing mechanisms for reporting meningococcal infection perform well and are timely. The retrospective evaluation found low sensitivity and PPV of ED diagnoses for meningococcal disease. Even if more rapid forwarding of ED meningococcal diagnoses to public health authorities were possible, the low sensitivity and PPV do not justify this. They add that in this study, use of an ED surveillance system to augment conventional surveillance of this scheduled medical condition did not demonstrate a benefit.

Reference: O'Toole L, Muscatello DJ, Zheng W and Churches T. Can near real-time monitoring of emergency department diagnoses facilitate early response to sporadic meningococcal infection? Prospective and retrospective evaluations. BMC Infectious Diseases 2010, 10:309doi:10.1186/1471-2334-10-309