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. 2022 Mar 2;19(5):2898.
doi: 10.3390/ijerph19052898.

Evaluating Completeness of Foodborne Outbreak Reporting in the United States, 1998-2019

Yutong Zhang  1 , Ryan B Simpson  1 , Lauren E Sallade  1 , Emily Sanchez  1 , Kyle M Monahan  2 , Elena N Naumova  1
Affiliations

Evaluating Completeness of Foodborne Outbreak Reporting in the United States, 1998-2019

Yutong Zhang et al. Int J Environ Res Public Health. .

Abstract

Public health agencies routinely collect time-referenced records to describe and compare foodborne outbreak characteristics. Few studies provide comprehensive metadata to inform researchers of data limitations prior to conducting statistical modeling. We described the completeness of 103 variables for 22,792 outbreaks publicly reported by the United States Centers for Disease Control and Prevention’s (US CDC’s) electronic Foodborne Outbreak Reporting System (eFORS) and National Outbreak Reporting System (NORS). We compared monthly trends of completeness during eFORS (1998−2008) and NORS (2009−2019) reporting periods using segmented time series analyses adjusted for seasonality. We quantified the overall, annual, and monthly completeness as the percentage of outbreaks with blank records per our study period, calendar year, and study month, respectively. We found that outbreaks of unknown genus (n = 7401), Norovirus (n = 6414), Salmonella (n = 2872), Clostridium (n = 944), and multiple genera (n = 779) accounted for 80.77% of all outbreaks. However, crude completeness ranged from 46.06% to 60.19% across the 103 variables assessed. Variables with the lowest crude completeness (ranging 3.32−6.98%) included pathogen, specimen etiological testing, and secondary transmission traceback information. Variables with low (<35%) average monthly completeness during eFORS increased by 0.33−0.40%/month after transitioning to NORS, most likely due to the expansion of surveillance capacity and coverage within the new reporting system. Examining completeness metrics in outbreak surveillance systems provides essential information on the availability of data for public reuse. These metadata offer important insights for public health statisticians and modelers to precisely monitor and track the geographic spread, event duration, and illness intensity of foodborne outbreaks.

Keywords: National Outbreak Reporting System (NORS); data completeness; electronic Foodborne Outbreak Reporting System (eFORS); foodborne outbreaks; precision public health; time series analyses.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
NORS foodborne outbreak data structure. CDCID is the unique identifier for each foodborne outbreak, characterized by 213 variables for 3 types of information and resulted in 103 variables after data cleaning and merging: general (n = 56 variables), etiological (n = 13 variables), and food-related (n = 34 variables). Variables were distributed over 13 sub-categories and data tables containing conditional (depicted in blue), combined (in purple), and unchanged variables (in gray). Numbers within the parentheses represent the original number of variables in each data table. Subcategories and data tables marked with an asterisk (*) indicate information only available for applicable outbreaks.
Figure 2
Figure 2
Average annual completeness across 103 variables by contaminant and contaminant type as reported by the National Outbreak Reporting System (NORS) in 1998–2019. The top panel provides a time series plot reporting the average annual completeness for all etiologies with the annualized mean indicated by the dashed red line. The bottom panel provides a heatmap with annual completeness estimates (left) and their average (right) for each of 41 contaminants. Blue color indicates outbreaks with no reported data for a given year while light grey and dark grey reflect low (~0%) and high (~100%) completeness, respectively. Contaminant group types are reported in descending order of outbreak counts.
Figure 3
Figure 3
Shared-axis, multi-panel, stacked time series plots for monthly counts and average monthly completeness of foodborne outbreaks for all pathogens and by five contaminant subgroups as reported by the National Outbreak Reporting System (NORS) in 1998–2019. Each panel provides monthly counts of outbreaks (grey bars, left vertical axis) with superimposed time-series line plots reporting average monthly completeness (right vertical axis). We calculated monthly completeness as the average completeness of all outbreaks per month (as defined by illness onset date) for each completeness category (represented by colored lines from yellow (least complete variables) to red (most complete variables)). We report study months from January 1998 (1) through December 2019 (264).
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