BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) are considered a global threat; the mortality rate is high and infections are difficult to treat. CRE became a reportable condition in Alaska in December 2013. Infections with CRE can be caused by various species of bacteria and cause different types of infection, which makes this a unique reportable condition. Because CRE identification and classification are complex and reporting is relatively new, in 2015 the Section of Epidemiology (SOE) sought to evaluate the CRE suveillance system. The goals of the evaluation were to assess the quality and completeness of CRE reporting and gauge the impact of proposed changes to the case definition.
METHODS: The CDC’s Updated Guidelines for Evaluating Public Health Surveillance Systems were applied to the Alaska CRE surveillance system, which is the same as the state’s standard disease reporting system. This system relies on passive reporting by required entities. Case data from December 2013-2015 were reviewed. Staff within SOE who investigate CRE cases were interviewed. All prior suspect and probable CRE case reports were reviewed to determine how many would have been classified differently with a proposed case definition change.
RESULTS: Eight cases of CRE were confirmed from Dec. 29, 2013 - Dec 31, 2015. The current case defintion is not compatible with updated CRE testing, so a new definition has been proposed, which would increase the case count to 22 cases. The predictive value postive (PVP), defined as the proportion of confirmed cases out of all reported cases, was estimated to be 25%. Only one non-hospital provider reported a possible case. Data were not available to assess timeliness. Data collection on cases is uneven and primarily stored as notes, which made analysis difficult.
CONCLUSIONS: The system appears effective at identifying CRE cases and enabling followup. However, CRE is a complex disease and this system may not be effective over the long term or as the number of cases increases. Particularly, issues of how to deal with long-term CRE colonization and how to store case data for varying species, antibiograms, and infection types are not yet resolved. Pending changes to increase carbapenemase testing will make the system more useful. Planned case definition changes will increase the number of cases, and will increase alignment with national definitions. Lab outreach would likely improve the PVP. Outreach to non-hospital providers may also be necessary. Improving data collection and storage would make the system more amenable to analysis.