# Presentation: 679264

## Representativeness of Emergency Department Data Reported to the BioSense System

-    Patrick Minor, M.S.P.H., Roseanne English, B.S., Jerome Tokars, M.D, M.P.H.*CDC, National Center for Public Health Informatics, Atlanta, GA*

- The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official positions of the Centers for Disease Control and Prevention.

**Notes:**
Introduce myself
Introduce Dr. Jerry Tokars and Roseanne English.   Jerry originated this question regarding the biosense data.  Roseanne kept us on pace and brought her expertise and knowledge of the data to the table.  

Since the Biosense data is a national program, it’s important to see how the Biosense data represents a national dataset that has been used for hundreds of publications over the years.  

## Overview

- Background
- Methods
- Results
- Conclusions
- Recommendations

## National Health Ambulatory Medical Care Survey (NHAMCS)

- National representative sample of visits to U.S. emergency departments (EDs)
- 2005 sample
- Survey done by National Center for Health Statistics
- Total visits estimated: 115.3 million
- Visits summarized by
- Major disease categories (e.g., ICD-9 codes 001-139, infectious diseases)
- Primary diagnosis groups (e.g., ICD-9 codes 920-924, contusions)

**Notes:**
Will be referred to as NHAMCS.

2005 is most recent national data available.  

Started in 1992 by the National Center for Health Statistics.

The NHAMCS public use data comprises 2 separate files.  One for Outpatient department visits and the other for Emergency Department visits.  This study focused on the ED visits. 

Average weight that each visit carried was 3,431. 

## Background--BioSense

- Emergency department data
- Chief complaints: 546 facilities (411 as of 2007)
- Diagnoses: 203 facilities (164 as of 2007)
- Most data sent from state/local health departments
- BioSense facilities are not necessarily representative of all U.S. facilities
- Data categorized by 11 syndromes

**Notes:**
Here we get a feel for the number of facilities that send ED data to Biosense as a Chief Complaint  or diagnosis.  You also get to see how many facilities have been added since 2007.  

411 to 546 facilities sending chief complaint
164 to 203 facilities sending diagnosis

## Hospital Emergency Department Data Sources—August 2008

| Type | No. of Facilities | 
Percent |
| --- | --- | --- |
| State/local health departments | 409 | 72 |
| Hospital systems | 152 | 27 |
| Individual hospitals | 8 | 1 |
| Total | 569 | 100 |

**Notes:**
Here we have the total number of facilities (irrespective of type of ED visits) that send data to Biosense as of August 2008.  And as mentioned before, most are state/local health departments. 

## BioSense Syndromes

- Botulism
- Fever
- Gastrointestinal
- Hemorrhagic Illness
- Localized Cutaneous Lesion
- Lymphadenitis
- Neurological
- Rash
- Respiratory
- Severe Illness or Death (Infectious Disease)
- Specific Infection

- Syndrome Definitions for Diseases Associated with Critical Bioterrorism-associated Agents, October 23, 2003
- http://www.bt.cdc.gov/surveillance/syndromedef/index.asp

**Notes:**
Beginning in 1999 to support several enhanced syndromic surveillance activities associated with high-profile community events (e.g., national political conventions), the Centers for Disease Control and Prevention (CDC) identified syndrome categories to be monitored that were indicative of the clinical presentations of several critical bioterrorism-associated conditions. 

These eleven syndromes were selected based on a systematic selection process.  

They can be captured by ICD-9 code or free text.  

## Purpose

- To assess the representativeness of BioSense emergency department data by comparing with the National Hospital Ambulatory Medical Care Survey (NHAMCS)

## Total Visits

- NHAMCS
- Visits sampled: 33,605
- 2005: 115.3 million visits, increase by 1.7 million per year
- 2007 estimate:  118.7 million visits
- BioSense (2007)
- 13.4 million visits
- 11.3% of total U.S. visits

**Notes:**
There were a total of 33,605  visits sampled in the NHAMCS data for 2005.  As mentioned before, on average, each visit carried a weight of a little over 3400.  With the weights, there is an estimate of 115.3 million visits for 2005.  

NCHS estimates an increase of 1.7 million ED visits each year on a national level.  That would give us a 2007 estimate of 118.7 Million visits for the NHAMCS data.  

For 2007, the Biosense data represents 11.3 % of all total US ED visits. 

## Percent of Visits by Age Group

**Notes:**
While focusing on total ED visits, we see that the Biosense data is very comparable with NHAMCS data, with almost half of all ED visits falling in the “15 to 44” age range.  

## Percent of Visits by Census Region

**Notes:**
Using the Census regions, we see that the Biosense data is not a representative of the NHAMCS data.  This will be portrayed on the next slide as well so that you get a feel for the location of the facilities that send data to the Biosense program.   Biosense gets most of its data feeds from the Midwest and the South.  NHAMES gets most of it ED visits from the South.  

## Slide 11

**Notes:**
Here we see the layout of facilities by census region.  As seen in the previous graph, most facilities are located in Midwest region.  The south has 2nd most facilities sending data to the Biosense program.  Please note that this is a total volunteer program and it explains the regional disparity that we see.  

## Analysis by NHAMCS Categories

- For NHAMCS
- Only the primary diagnosis is used
- Percent of visits with the primary diagnosis is presented
- For BioSense
- No primary diagnosis available
- All diagnoses used
- Percent of total diagnoses is presented

## * Used for our comparison study

| Major Disease Categories Used by NHAMCS | ICD-9 Range |
| --- | --- |
| *Infectious and parasitic diseases | 001-139 |
| Neoplasms | 140-239 |
| Endocrine, nutritional and metabolic diseases | 240-279 |
| Mental Disorders | 290-319 |
| Diseases of the nervous system  | 320-389 |
| Disease of the circulatory system | 390-459 |
| *Diseases of the respiratory system | 460-519 |
| *Diseases of the digestive system | 520-579 |
| Diseases of the genitourinary system | 580-629 |
| Diseases of the skin and subcutaneous tissue | 680-709 |
| Diseases of the musculoskeletal system  | 710-739 |
| *Symptoms, signs, and ill-defined Conditions | 780-799 |
| *Injury and poisoning | 800-999 |

## Percent of Visits by Major Disease Category

## Percent of Visits Among Most Common Primary Diagnosis Groups

## Analysis by BioSense Syndromes

- NHAMCS: up to 3 diagnoses per visits available
- BioSense: variable number of diagnoses per visit available
- If any diagnosis for the visit fits the definition, then the visit meets the definition
- Percent of total visits presented

## Percent of Visits by BioSense Syndrome

## Percent of Visits by BioSense Syndrome

## Mean Number of Diagnoses per Visit

## Discussion

- Because of differences in methods, comparisons between NHAMCS and BioSense are approximate
- In 2007, BioSense received >11% of U.S. emergency department visits
- Biosense data are representative by:
- Age
- Most major diagnosis categories and syndromes
- Differences may be due to sampling error or designation of primary diagnosis in NHAMCS
- Biosense data are not representative of geographic area

**Notes:**
In 2008, the number of facilities sending data is higher, so the % may be higher

## BioSense Strategic Plan

- Regional collaboratives*
- Federate data sources*
- Case detection technologies
- Health Information Exchanges (HIEs)*
- Open source software
- Incentives for clinicians to participate
- Research to develop surveillance technologies
- Add 8th one

- * Geared to improve geographic representation

## Acknowledgements

- Linda McCaig and Susan Schappert
- National Center for Health Statistics

## Contact

- _[PFM3@cdc.gov](mailto:PFM3@cdc.gov)_
- 404-498-6868
- _[www.cdc.gov/biosense](http://www.cdc.gov/biosense)_

## Thank You!!!