Limitations of Syndromic Surveillance

What are some limitations of syndromic surveillance data?

• Computer algorithms interpret the chief complaint for an emergency department visit and assigns a symptom complex or syndrome to that visit. A chief complaint is not a diagnosis. It captures the patient’s primary reason for seeking medical care and is commonly recorded as a free text field, which may include misspellings or abbreviations.
• The number of hospitals providing data to AlaSyS has increased over time, leading to improved coverage in recent years. This increase should be considered when interpreting trends across years. It is also important to consider that planned or unplanned interruption in data transmission will create fluctuations in data volume.
• The quality of data has improved over time as national standards and definitions now specify what information hospitals should provide. Changes in data quality should be taken into consideration when interpreting trends across years.
• An individual could have more than one emergency department visit during a reporting period making per capita or population rate calculations tricky to interpret.
• No exposure, risk factor, or outcome data are available.
• Like all surveillance data, syndromic surveillance data are not unbiased and not a representative sample of the population. Therefore, descriptive statistics are best applied and the use of analytic or inferential statistics may not be appropriate.

Contact AlaSyS

Questions and comments about ADPH syndromic surveillance activities can be emailed to [email protected] or you can contact us by phone Monday through Friday 8:00 a.m. to 4:30 p.m. by calling 334-206-5971.