Introduction to New NSSP–ESSENCE Data Quality Filters

For some time, the community of practice has tried to improve (and maintain) data quality. However, the completeness of reporting some variables fundamental to syndromic surveillance practice, such as chief complaint and discharge diagnosis, can vary across and within sites over time and complicate how surveillance data are interpreted.

Such variance among data explains why some community of practice members are cautious when they compare syndromic trends across sites. For example, an analysis of NSSP–ESSENCE emergency department encounters nationwide showed, on average, that the daily percentage of discharge diagnoses considered informative (i.e., are not null or do not simply include terms like “unknown”) was 45% in 2016, 54% in 2017, 65% in 2018, and 70% in 2019 (figure 1). This is an improvement of about 56% from 2016 to 2019. Yet, if a user’s multiyear query relies on the discharge diagnosis for results, differentiating the surveillance trend from the influence of longer term improvements in data quality is still complicated.

Percent of Daily Emergency Department Encounters with Informative Discharge Diagnoses

Figure 1. Percent of Daily Emergency Department Encounters with Informative Discharge Diagnoses


New functionality has been added to NSSP–ESSENCE that makes controlling for this variation easier. In the Query Portal interface, within the list of Available Query Fields, users will notice a set of variables in the Data Quality Filters folder (figure 2).

Menu Options in NSSP–ESSENCE


Figure 2. Menu Options in NSSP–ESSENCE

The options for each variable are binary, Yes/No selections. For example, if a user selects Discharge Diagnosis Informative (DDI) equals Yes, then the query will only include encounters with an informative discharge diagnosis. Additionally, if the query is run as a percentage of all visits, then the numerator and denominator will only include encounters where the DDI is Yes, which helps control for the influence of improvements in discharge diagnosis completeness on surveillance trends. By requiring DDI equals Yes, keep in mind that encounters with chief complaint text that could have matched your query might be excluded.

Check out the June 19, 2019, ESSENCE Q &A number 5 webinar (~minute 51:27) for a discussion of this and other features.