Syndromic Surveillance: The Boston Experience

Submitted By

Julia E Gunn
Infectious Disease Bureau/Boston Public Health Commission, Massachusetts
November 7, 2013

Boston is the largest city in Massachusetts with a diverse population of over 600,000 that doubles during workdays. The city is home to many colleges and universities, historic sites and sports teams. Boston also has an international airport and a harbor. The Infectious Disease Bureau first deployed a syndromic surveillance system in 2004 in preparation for the Democratic National Convention. Our system has evolved from a focus on detecting bioterrorism events to support all hazard event detection. The Boston Syndromic Surveillance System has been used to identify problems of public health significance and provides situation awareness.

In preparation for the 2004 Democratic Convention, the Boston Public Health Commission (BPHC) deployed a syndromic surveillance system using CDC's EARS application. The initial priority was to detect bioterrorism events. The city has nine acute care hospitals with ten emergency departments. The participation of all the Boston hospitals was critical for monitoring events of public health significance that may impact residents and non-residents alike. Less robust representation of healthcare facilities would result in a less complete picture.

The Boston Public Health Commission initally focused on the participation of all nine hospitals. Hospitals was asked to submit daily electronic files of all emergency department visits. Data elements included a unique identifier, visit date, chief complaints, age, gender, race/ethnicity, zip code and when available the first three ICD9 codes. A city regulation for syndromic surveillance reporting was passed to faciliate the implementation and receipt of data files. The system went live in July 2004. Experience with the system revealed that it had the potential to monitor other events of public health significance (influenza, injuries, carbon monoxide poisoning). A flexible chief complaint processing system was needed to support these other uses. We mapped 50,000 chief complaints into symptom categories that can be combined to make any needed syndrome that is then available for analysis. The creation of syndromes on the fly has allowed the Infectious Disease Bureau to provide valuable information during urgent situations.

The Boston Syndromic Surveillance System is routinely used for influenza surveillance. It provided critical information during H1N1 influenza pandemic in 2009. In 2012, illness associated with Coxsackie virus A6 was identified in the United States. The Boston Public Health Commission's Infectious Disease Bureau was notified of potential cases. We queried our syndromic surveillance system for ICD9 codes associated with Coxsackie infections and confirmed that Boston was seeing increased activity. This information facilitated the collection of samples that confirmed the presence to Coxsackie A6 and the development of guidance to schools and day care centers. When carbon monoxide visits are identified, referrals are made to BPHC evironmental health program. On several occasions this follow up identifed blocked chimneys or malfunctioning heating systems that endangered the lives of residents in those dwellings. In April, 2013, syndromic surveillance allowed BPHC to monitor issues of concern related to the Boston marathon bombing. In October, 2013, the syndromic surveillance system provided the same valuable situational awareness when the Boston Red Sox won the World Series.

Keys to the success of Boston's syndromic surveillance system include: local reporting regulations, adaptable and flexible chief complaint processes, an all hazards approach, and the daily use of the system. Understanding the local context (events, weather, populations, reported cases) is essential for evaluating syndromic surveillance findings. Meaningful use provides the opportunity to increase the efficiency of data processing. Systems that analyze multiple data streams have the potential to improve valuable information that can be used by local health departments.

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