CO Poisoning surveillance data MMWR Surveillance Summaries article
DRAFT
1. Problem/Condition
Steve Macdonald with APRHB comments
Carbon monoxide (CO) is a colorless, odorless, nonirritating gas that is produced through the incomplete
combustion of hydrocarbons. Sources of CO include combustion devices (e.g., boilers and furnaces),
motor-vehicle exhaust, generators and other gasoline or diesel-powered engines, gas space heaters,
woodstoves, gas stoves, fireplaces, tobacco smoke, and various occupational exposures. CO poisoning is
CO poisoning is preventable; nonetheless it is a leading cause of unintentional poisoning deaths in the
United States. Unintentional, non-fire related CO poisoning is responsible for approximately 450 deaths
and 21,000 emergency department (ED) visits each year. (1-2) [ref: 1. Centers for Disease Control and Prevention
(CDC). Nonfatal, unintentional, non--fire-related carbon monoxide exposures--United States, 2004-2006. MMWR Morb Mortal
Wkly Rep. 2008 Aug 22;57(33):896-9. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5733a2.htm. 2. Centers for Disease
Control and Prevention (CDC). Carbon monoxide--related deaths--United States, 1999-2004. MMWR Morb Mortal Wkly Rep.
2007 Dec 21;56(50):1309-12. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5650a1.htm. ]
CO poisoning may be misdiagnosed due to its nonspecific symptoms, ranging from minor flu-like
symptoms (e.g., headache, dizziness, nausea, vomiting, fatigue, and confusion) to more severe effects
(e.g., impaired memory, collapse, cardiac irregularities, coma, and even death). (3-4) [ref: 3. Wright J.
Chronic and occult carbon monoxide poisoning: we don't know what we're missing. Emerg Med J. 2002 Sep;19(5):386-90.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1725950/ 4. Hampson NB, Piantadosi CA, Thom SR, Weaver LK. Practice
recommendations in the diagnosis, management, and prevention of carbon monoxide poisoning. Am J Respir Crit Care Med.
2012 Dec 1;186(11):1095-101. ] Diagnosis of carbon monoxide exposure can be confirmed by measuring
carboxyhemoglobin levels in the blood. CO can be removed from the body gradually by administering
oxygen therapy, or rapidly in hyperbaric treatment facilities for the most severe cases. Exposures to CO
may be prevented by not using fuel based products in poorly ventilated areas, the proper installation of
CO alarms and routine maintenance of home heating systems, together with adequately venting cooking
and fuel-burning appliances [cite CDC guidance for individuals: http://www.cdc.gov/co/guidelines.htm ]. Laws and
ordinances requiring installation and use of CO alarms, enforcement of workplace standards as well as
targeted public health messages aimed at susceptible populations, can reduce the number of CO
exposures. Ongoing surveillance of CO exposure will continue to aid public health practitioners in the
development of prevention measures and targeted interventions.
2. Reporting Period
NPDS: 2010-2012
State data: 2009-2011
3. Description of System
(3A) Surveillance data system methods for reporting and national notification
Steve Macdonald
The Council of State and Territorial Epidemiologists (CSTE) adopted the position statement “Public
Health Reporting and National Notification for Carbon Monoxide Poisoning” (13-EH-01) in June 2013, in
order to promote and standardize methods used for nationwide surveillance of carbon monoxide (CO)
poisoning. (5) [ref: 5. CSTE. Public Health Reporting and National Notification for Carbon Monoxide
Poisoning (13-EH-01). June 2013. http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/PS/13-EH-
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01.pdf. ] This position statement describes methods for inclusion of CO poisoning in standard public
health reporting, based on use of CO exposure and CO poisoning case data available from Poison Control
Centers (PCC) as the core case-ascertainment source, and case notification to CDC by means of the
American Association of Poison Control Centers (AAPCC) National Poison Data System (NPDS). (6) [ref: 6.
Centers for Disease Control and Prevention (CDC). Carbon monoxide exposures--United States, 20002009. MMWR Morb Mortal Wkly Rep. 2011 Aug 5;60(30):1014-7.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6030a2.htm. ]
The position statement describes four tiers of surveillance activities, which can vary depending upon the
resources available: PCC only; case-finding using multiple data sources, including PCC; case-finding using
multiple data sources with matching and record linkage; and, case-finding using multiple data sources
with individual case investigation. Data sources used for CO poisoning case ascertainment include:
reporting from clinicians, laboratories, hospitals and other entities; death certificates; and hospital
discharge, or outpatient records. The position statement standardizes:
•
Criteria for case identification, including both criteria to determine whether a case should be
reported to public health authorities, and criteria for case-finding from administrative data
•
Criteria for case classification for both reporting systems and administrative data, including
definitions for a confirmed case, a probable case, and a suspected case
•
Criteria to distinguish a new case of CO poisoning from reports or notifications which should not
be enumerated as a new case for surveillance
Add text here on AAPCC mechanisms to share data (include ref to AAPCC-CSTE 2012 survey results
http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/EnvironmentalHealth/PoisonAssessmentrepo
rt2012.pdf), update to include description of web services. [Steve, Jay]
(3B) Surveillance data system protocols in various states
Kathy, Prakash
Include: description of:
 how surveillance practices differ by hierarchical tier;
 mandatory vs. voluntary case reporting;
 criteria for case investigation;
 utility of case data beyond “unintentional, non-fire-related carbon monoxide”;
 definition of “cluster” variation by state [from conf call minutes: MI: >1 (death? Case?); MO: ≥2
Deaths?, ≥2 with 15% or higher carboxyhemoglobin; WI: >1 case? during one exposure event].
 how data system protocols describe data dissemination to agency program staff for use in
prevention policy development and program planning and implementation [this will bridge to
section 5].
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Consider inclusion of actual protocols in Appendix [which we may be able to include as “Supplemental
Online Material”]
(3C) “Active” vs. “passive” case-finding: contacting reporters to remind them
of reporting responsibility; assessments of completeness of reporting
(“passive surveillance system with followup”)
Kathy
(3D) Data sources: obtaining datasets retrospectively to confirm
completeness of reporting
Kathy
(3E) Obtaining datasets retrospectively to supplement case reports
Kathryn Lane
In addition to tracking hospital visits, deaths, and Poison Control Center data, health departments may
obtain other sources of data to supplement CO health surveillance and case investigation. For instance,
environmental data from fire departments or utility companies– which typically are the first responders
to CO incidents triggered by an alarm or an adverse health event – may be obtained retrospectively. In
New York City, data from the fire department is obtained on a yearly basis. Data are classified as
incidents where CO was not detected at the scene upon arrival, detected at low levels (1-99 ppm), or
detected at emergency levels (> 9 ppm). Data also include information on whether a CO alarm activated
or not. While this type of data may not include any information on numbers of people affected, health
symptoms, or health outcomes, it can allow for assessment of the burden of response to CO incidents
(including “false alarms” or those that do not result in contact with the healthcare system), tracking of
CO levels found in the environment, and measurement of changes in the detection of indoor CO
emission hazards over time. For instance, this data can be used to track the number of serious incidents
detected by a CO alarms and how this number may change over time.
(3F) “interstate reciprocal notification”: non-resident data exchange and/or
dual data display by location of residence and location of exposure; location of
diagnosis issues
Steve Macdonald
For the most part, state and municipal CO poisoning surveillance data systems do not use the methods
developed for use in infectious disease (ID) surveillance termed “interstate reciprocal notification” (IRN).
In ID surveillance, non-resident case information is sent to the jurisdiction of residence, because cases
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are assumed to have acquired their disease at their place of residence, and the jurisdiction of residence
is then used in official case counts for statistical purposes. Standard forms are used for this purpose [cite
CDC form http://www.cdph.ca.gov/pubsforms/forms/Documents/cdc42.1e.pdf and Florida form
http://www.doh.state.fl.us/disease_ctrl/epi/surv/Interstate_Reciprocal_CDC42.1.pdf ]. In chronic
disease surveillance and environmental disease surveillance, exposure pathways may be less certain,
and diagnosis may occur at some distance from the location of residence. In the absence of standardized
IRN, some jurisdictions have established informal means of non-resident data exchange, but most have
not. For this reason, the surveillance data may be best understood when there is dual data display by
location of residence and location of exposure, in separate tables. This practice is not yet widely used.
Prakash: please edit/expand as needed. Also, please confirm or correct the Florida IRN form URL.
(3G) NPDS scenario and substance-based fields
Prakash
The primary core functions of Poison Control Centers (PCCs) includes patient exposure assessment and
management, accurate data collection and coding through the use of an electronic medical record, and
response to the continuing need for poison-related public and professional education. Calls received at
US PCCs are managed by healthcare professionals who have received specialized training in toxicology
and the assessment, triage, management and monitoring of toxic exposure emergencies. Fifty-six
participating centers cover all states and territories of US and submit their data to the American
Association of Poison Control Centers’ (AAPCC) National Poison Data System (NPDS). NPDS is the data
repository for all poisoning and information calls received by all poison centers across the country. All
centers upload their call data near-real time through an automated upload process. The web-based
NPDS software has the capability for data analysis through enterprise reporting, volume and clinical
effects anomaly detection, and the recognition and reporting of NPDS surveillance anomalies. PCCs can
also elect to share NPDS surveillance technology with external organizations such as their state and local
health departments or other regulatory agencies. Few states in Tier 4 have direct access to all the
collected PCC data fields through an automated data transmission.
PCCs collect additional fields that are not uploaded to NPDS and are only available to their local or state
partners. These fields may include personal identifiers, full case note information, specific labs or other
non-NPDS fields. Likewise, some systems (e.g. Florida) have elected to also deploy “rule-based coding”
which allows for PCCs using this methodology to code additional field based on the substance and some
specifics of the exposure. This added information helps to collect additional information useful to
conduct surveillance and identify areas for prevention. Adoption of rule-based code by the AAPCC and
including additional substance specific fields would enhance NPDS ability to conduct CO surveillance.
(3H) use of trauma exclusion codes in code-based case finding
Jackie/Kanta
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(3I) Case definition for unintentional non-fire CO poisoning (APRHB, Tracking
Network)
Jackie/Kanta, Steve
Describe the differences between APRHB (which focuses on unintentional non-fire) and Tracking (which
also includes fire-related and unknown intent/mechanism). Describe differences (if any) between
unintentional non-fire case ascertainment and classification used by Tracking vs. APRHB.
(3J) Incomplete information = classify as Suspected case.
Steve Macdonald
Incomplete information is common in all public health surveillance data systems, and obtaining
complete information on exposure pathways is a special challenge in environmental disease
surveillance. For example, PCC notes may not give enough information about duration of exposure to
determine where a patient’s exposure falls on the curve relative to the threshold for poisoning. When
this occurs, the case cannot be classified with any greater certainty than as a Suspected Case, and is not
included in the final case count (based on Probable and Confirmed cases only). When resources are
available for a CO poisoning surveillance data system to expand from PCC only (Tier 1) to link a PCC
report with other data that may provide a more complete picture of exposure (Tier 3), cases can be
classified with greater certainty.
(3K) Non-specific ICD codes: exclusive vs. inclusive; ICD-9 vs. ICD-10
Steve Macdonald
Case-finding which utilizes coded administrative data, such as mortality or hospital data, depends upon
the definitions used for individual codes to identify cases. Non-specific underlying cause of death codes
in ICD-10 present a challenge. [ref: Ball LB, Macdonald SC, Mott JA, Etzel RA. Carbon monoxide-related
injury estimation using ICD-coded data: methodologic implications for public health surveillance. Arch
Environ Occup Health. 2005 May-Jun;60(3):119-27.] The 2013 CSTE position statement includes tables of
ICD-9-CM, ICD-10, and ICD-10-CM codes categorized as “Explicit” or “Inclusive”, determined by whether
CO poisoning is explicitly included or only implied. These tables indicate the case classification for each
code.
(3L) Exposure-only cases: PCC data, case investigations
Leslie
Maine reporting criteria for carbon monoxide poisoning require all health care providers, health care
facilities and medical laboratories to report “Clinical signs, symptoms or know exposure consistent with
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diagnosis of carbon monoxide poisoning and/or a carboxyhemoglobin (COHb) level >5%”. In addition,
the Maine Carbon Monoxide Poisoning Surveillance System receives all reports from the Northern New
England Poison Center (including call notes) for calls related to carbon monoxide exposure. Medical
records are requested for all cases where an unintentional, non-fire related poisoning is possible. Phone
surveys are performed for all cases where a poisoning is possible or clarification of the exposure is
needed.
Retrospectively, Maine has requested and reviewed medical records not previously received , which
were coded for CO poisoning in our hospital billing data.
Cases that do not meet criteria for confirmed, probable, or suspected cases are classified as “exposure”
cases if there is: exposure to a source of CO with evidence of environmental monitoring (eg., CO
detector), no lab results, but duration of exposure is too brief to result in CO poisoning; or, exposure to
a potential source of CO with no environmental monitoring or labs and no symptoms; or, exposure to a
source of CO with evidence of environmental monitoring, COHb not elevated and time between
cessation of exposure and blood draw is sufficiently known so that it is unlikely that COHb was in the
poisoning range at the time of cessation of exposure.
“Exposure” cases often represent cases that may have resulted in poisoning cases were circumstances
different. For those cases received in “real time”, phone surveys are important not only to clarify the
case designation, but also to assure (when it is uncertain from reviewed notes) that there is no ongoing
exposure and that the individual(s) have a functioning CO detector. In addition, the retrospective review
of hospital records revealed that may of the cases coded as carbon monoxide poisoning, did not meet
criteria for poisoning, but were actually “exposure” cases. Typically, a CO detector alarmed, the
individual immediately sought emergency evaluation, and the COHb was not elevated. It is important to
recognize that hospital coding may not distinguish between an exposure and a poisoning, thus not
distinguishing a case that is a public health success story (where a CO detector saved a life) from a case
which demonstrates a greater need for public health intervention (an actual poisoning).
(3M) Matching and de-duplication; matching when PCC data contains no
identifiers
Four states do matching and de-duplication of case reports from multiple data sources (FL, ME, MI, and
MO) based on available identifiers and other information. Matching is done based on patient name,
supplemented by other available information such as sex, birthdate/age, exposure date, event scenario,
address, hospital where treated, carboxyhemoglobin level. When name of patient is not available in
source data, a match is attempted based on exposure date and other available demographic data in
three (MO, MI, ME) of the four states [my impression is that Florida does not attempt a match when
name is missing]. Matching is done by a combination of state-specific electronic matching algorithms
and manual review of records.
4. Results and Interpretation
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(4A) NPDS data
APRHB staff
Text describing and discussing “Incidence and treatment of reported exposures to unintentional, nonfire-related carbon monoxide --- National Poison Data System, United States, 2010-2012” (Table 1)
(4B) State data
Text describing and discussing “State data, unintentional non-fire-related carbon monoxide cases,
2009-2011” (Table 2) and “State data, unintentional fire-related carbon monoxide cases, 2009-2011”
(Table 3). As needed, interpret findings (for example, storm-related events may be included in “clusters”
in some states but not all; data systems do not have consistent coding for “initiating event”).
Text describing and discussing “Source of data for case ascertainment, 2009-2011” (Table 4). As
needed, interpret findings; for example, case-finding variability by data source (add separate table or
graphic display?); case-finding completeness/sensitivity variability by data source (add separate table?);
false positives/PPV variability by data source (add separate table?); unique cases variability by data
source (add separate table?); unique case/exposure route information by data source (add separate
table?). Include discussion of potential for case-finding from administrative occupational health records,
such as workers compensation (retrospective data analysis). Include discussion of AAPCC-CSTE survey
results.
Text describing and discussing “Case definitions by jurisdiction, 2009-2011” (Table 5)
Text describing and discussing supplemental tables/graphics (Table 6?) [order of numbering of tables
may need to be modified…]. Example: graph of NPDS case counts by season (removed from Tables 2/3),
where winter = December, January, February; spring = March, April, May, etc. [consider use of individual
months for this]
5. Public Health Actions Taken
Prakash, Andy
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