Carbon Monoxide Poisoning Kills Nearly 500 Annually In U.S., CDC Report Says

Carbon monoxide (CO) poisoning is a leading cause of unintentional poisoning deaths in the United States, with nearly 500 people succombing to the odorless, colorless gas each year, according to a report issued earlier this month by the Centers for Disease Control and Prevention (CDC).

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6030a2.htm?s_cid=mm6030a2_x

In a comprehensive 10-year report issued Aug. 5, the CDC basically has put together data on everything you would ever want to know about CO poisoning. 

The report stated that unintentional, non-fire-related CO poisoning is responsible for about 15,000 emergency department visits and nearly 500 deaths annually in the United States.

In the past, national estimates of CO exposures have been based on secondary data sources, such as hospital administrative records, and were limited to exposures treated within the health-care system, according to the CDC.

To describe more completely the national burden of CO exposure and risk factors associated with vulnerable populations, the CDC said that it used data from the National Poison Data System (NPDS) to characterize reported unintentional, non-fire-related CO exposures, including those that were managed at the site of exposure and were not treated at a health-care facility.

Among 68,316 CO exposures reported to poison centers during 2000 to 2009, a total of 30,798 (45.1 percent) were managed at the site of exposure with instructions from the poison center by telephone, 36,691 (53.7 percent) were treated at a health-care facility, and the management site for the remainder was unknown, the CDC report said.

Although symptoms varied slightly between persons managed on-site and those treated at a health-care facility, most CO exposures occurred at home and most often involved females; children aged 17 years and younger; and adults aged 18 to 44 years.

In its report, the CDC said, “Surveillance and analysis of data from NPDS and secondary sources might provide a more comprehensive description of the burden of CO exposure in the United States and assist in the development of interventions better targeted to high-risk populations.”

NPDS is a near real-time, comprehensive poisoning surveillance system that collects data on calls regarding poison exposure placed to any of the U.S. poison centers, according to the CDC. NPDS is owned and managed by the American Association of Poison Control Centers.

“CDC uses NPDS to receive, analyze, and display data from poison center calls,” the CDC report said. ” Calls to poison centers come from health-care professionals or persons voluntarily reporting a poison exposure. The information provided by the caller might pertain to themselves or others and is used by the poison center to create a record of the call with details such as the date, poison substance and symptoms.”

If the report concerns someone who was treated at a health-care facility, a poison center staff member will contact the health-care facility during the course of treatment to obtain pertinent clinical information, according to the CDC. Details from poison center records are uploaded to NPDS.

NPDS data from 2000 to 2009, in which CO was identified in the substance data field and the reason for exposure was recorded as “unintentional,” was extracted for the CDC report. If “fire” or “smoke” were in the substance data field, these exposures were excluded to restrict the analysis to unintentional, non-fire-related CO exposures.

“The data were then stratified according to management site (i.e., health-care facility or site of exposure) and a descriptive analysis was conducted,” the CDC said. “Rates were calculated using reports of CO exposures to the poison centers and 2000 to 2009 U.S. Census data.”

The characteristics of persons managed on-site were compared with those of persons managed at a health-care facility, as well.

The 68,316 CO exposures reported to poison centers during 2000 to 2009 represented 0.29 percent of all poison exposures reported in NPDS, according to the CDC report. Compared with all exposures reported to NPDS, the proportion of reported CO exposures steadily declined, from 0.31 percent in 2006 to 0.24 percent in 2009.

“On average, 23.2 CO exposures were reported per 1 million population per year (range: 19.7 to 25.3),” the CDC said. “The number of persons with reported CO exposures who were transported to a health-care facility ranged from 11.1 to 14.3  million each year and the number of persons with reported CO exposures who were managed on-site ranged from 8.6 to 14 million each year.”

Total reported CO exposures included 34,356 females (23 per million) and 30,257 males (20.9 per million). The most commonly exposed age groups were 17 years and younger (25.7 per million) and 18 to 44 years (19.4 per million), according to the CDC.

CO exposures most frequently occurred between November and February (53.5 percent) and among persons residing in the Midwest (31.2 million) or the Northeast (36.7 million), the report stated. A greater proportion of CO exposures managed on-site occurred in the Northeast (35.5 percent).

The exposure site was reported as “residence” (77.6 percent) or “workplace” (12 percent) in most cases, clinical symptoms were reported for 68.1 percent of the total exposures, with headache, nausea, and dizziness most commonly reported, according to the CDC.

However, 83 percent of reported exposures had a medical outcome of “no effect” or “minor effect.” During 2000 to 2009, a total of 235 CO exposure-related deaths were reported to NPDS. Of those persons who died, 65 percent were male and 30.5 percent were aged 18 to 44 years, the CDC said.

Most persons (68.2 percent) transported to a health-care facility were aged 45 and yonger and 18.6 percent experienced confusion, syncope, dyspnea or chest pain following CO exposure.

In contrast, among persons managed on-site, 6.2 percent experienced confusion, syncope, dyspnea, or chest pain, the CDC said. 

“NPDS provides national data regarding CO-exposed persons treated at a health-care facility and those who do not seek medical care at a health-care facilitym” the CDC report said. “This is the first analysis for which NPDS has been used to examine a 10-year period of reported CO exposures. During 2000 to 2009, based on reports to NPDS, 30,798 persons were exposed to CO but were not treated at a health-care facility.”

Those persons would not have been identified through CO exposure data sources that rely on health-care facility records and mortality data, according to the CDC. The characteristics of all CO exposures reported in NPDS, including those treated on-site and at a health-care facility, are consistent with previous knowledge of CO exposure.

Women and children are the most commonly exposed, but deaths from CO exposure more often occur among men, and exposures most often occur at home and during winter months.

CO exposures in the Northeast more frequently were managed on-site.

From 2006 to 2009, the rate of reported CO exposures steadily declined, and the call proportion declined from 0.31 percent to 0.24 percent, according to the CDC.

Similarly, the proportion of CO exposures among all reported unintentional poison exposures decreased by 0.8 percent during the period, which might be attributable to an overall reduction in calls to poison centers for any unintentional poisoning.

The decrease in CO exposure calls to poison centers also might be a result of factors such as increased use of home CO alarms and improved use and maintenance of portable generators and other CO-emitting devices, the CDC speculated.

Data available through NPDS are limited and insufficient to identify specific factors that might contribute to the observed decline in CO exposure calls. Poison center case notes could provide useful information to identify sources of exposure such as portable generators and furnaces, which are common in unintentional CO poisonings.