ICD9 Codes in CDC BioSense Neurological Syndrome

1
ICD-9 Codes in CDC BioSense Neurological Syndrome

• Haobo Ma, Jerome Tokars, Roseanne English
• Centers for Disease Control and Prevention,
  Atlanta, GA

2
BioSense

• Electronic biosurveillance system to enhance
  national preparedness for
• Early event detection and health situational
  awareness
• Bioterrorism attacks
• Naturally-occurring diseases
• Safety net for public health

3
Current Data Sources

• Department of Defense (DoD) outpatient medical
  treatment facilities (n355)
• ICD-9 diagnosis codes
• CPT procedure codes
• Veterans Affairs (VA) outpatient medical centers
  and clinics (n849)
• ICD-9 diagnosis codes
• CPT procedure codes
• Laboratory Corporation of America
• Test orders
• BioWatch
• BioSense RT

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BioSense Syndromes

• ICD-9 codes binned to 11 syndromes
• Neurological syndrome
• Designed to detect acute neurological infection
  of central nervous system
• Classified as
• Category 1 (general symptoms and diseases of
  highest concern)
• Category 2 (high-volume codes might detract from
  the category 1 signal)
• Combined for analysis
• Possible neurological diseases in bioterrorism
  attack
• Western equine encephalitis, Eastern equine
  encephalitis Venezuelan equine fever, Taiga
  encephalitis, Central European encephalitis,
  Tick-borne encephalitis

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Methods

• Study period 01/01/2004 to 12/31/2005
• Demographics (age, gender)
• Data distribution among states
• Frequencies and seasonal patterns of ICD-9 codes
  composing neurological syndrome
• Differences in code use in Veterans Affairs (VA)
  vs. Department of Defense (DoD)

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Results

• 1,193,853 visits had ICD-9 codes for neurological
  syndrome
• 35 from Department of Defense (DoD)
• 65 from Veterans Affairs (VA)
• Median age
• DoD 29
• VA 56
• Gender
• DoD 40 male
• VA 90 male

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Neurological Syndrome Visits, by State, 2004 -
2005
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Neurological Group ICD-9 Codes, by Category
Category 1 ( 1.4 ) Category 2 ( 98.6 )
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Category 1 Code Frequencies, by Data Source
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047.9 Unspecified Viral Meningitis, DoD vs. VA
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322.9 Unspecified Meningitis, DoD vs. VA
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Category 2 Code Frequencies, by Data Source
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Neurological Syndrome - Summary

• VA and DoD outpatient visits differ
  demographically
• Most commonly used ICD-9 codes differ in VA vs.
  DoD
• Category 1 codes much less frequent than category
  2 codes
• Most frequent category 1 ICD-9 codes showed
  seasonal patterns in DoD

14
Meningitis-associated hospitalization by
etiologic category and month of discharge, NHDS,
United States, 1988-1999

• Khetsuriani N, Quiroz ES, Holman RC, Anderson LJ.
  Viral meningitis-associated hospitalizations in
  the United States, 1988-1999. Neuroepidemiology.
  2003 Nov-Dec22(6)345-52.

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Limitations

• Uncertain accuracy in ICD-9 code assignment
• Individual patients may contribute multiple visits

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BioSense RT

• Initiative within BioSense Project that
  emphasizes acquisition of clinically rich data in
  real time from hospitals in major US cities
• Neurological subsyndromes
• Alteration of consciousness, CNS inflammatory
  disease, convulsions, gait abnormality, headache,
  meningismus, photophobia
• Planned BioSense new interface will give users
  ability to create own ICD-9 code groups

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Conclusions

• Analyses of individual codes, or groups of codes,
  may be useful
• Category 2 codes may mask variations in category
  1 codes
• Split neurological syndrome into high vs. low
  frequent codes
• BioSense data may be a supplemental source for
  tracking diseases
• Unspecified viral meningitis ICD-9 code in DoD
• Influenza, injuries, and Respiratory Syncytial
  Virus

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Acknowledgements

• Stephen Kralovic, Gary Roselle, John F Quinn
• Nino Khetsuriani, Larry Anderson, Mark A
  Pallansch, Steve Oberste
• Laura R Hall, Paul McMurray