NCHS Data Brief ■ No. 196 ■ April 2015

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Emergency Department Visits for Drug Poisoning:

United States, 2008–2011

Michael Albert, M.D., M.P.H.; Linda F. McCaig, M.P.H.; and Sayeedha Uddin, M.D., M.P.H.

Key findings 

Data from the National 

Hospital Ambulatory 

Medical Care Survey, 

2008–2011

● During 2008–2011, 

an average of 1.1 million 

emergency department (ED) 

visits were made each year for 

drug poisoning, with a visit rate 

of 35.4 per 10,000 persons.

● The ED visit rate for drug 

poisoning was highest among 

persons aged 20–34. The rate 

declined with age after 20–34, 

and rates for those aged 0–19 

were similar to those aged 50 

and over. 

● Drug-poisoning ED visit 

rates did not differ by sex and 

age, with the exception of 

persons aged 35–49, where 

females had a higher visit 

rate than males. The ED visit 

rate for unintentional drug 

poisoning was higher than selfinflicted drug poisoning overall 

and for males, but did not differ 

for females. 

● About one-quarter (24.5%) 

of drug-poisoning ED visits 

resulted in hospital admission.

Poisoning is the leading cause of injury-related mortality in the United 

States, with more than 40,000 deaths annually (1). Drugs account for 90% of 

poisoning deaths, and the number of deaths from drug poisoning has increased 

substantially in recent years (2). The emergency department (ED) plays an 

important role in the treatment of poisoning. This report describes nationally 

representative data on ED visits for drug poisoning during 2008–2011.

Keywords: health care utilization • injury • National Hospital Ambulatory 

Medical Care Survey (NHAMCS)

Did ED visit rates for drug poisoning vary by age? Did the 

rates change from 2004–2007 to 2008–2011?

● During 2008–2011, an estimated 1.1 million ED visits for drug poisoning 

were made each year, comprising 2.4% of total injury-related visits.

2

41.7 1

39.4

2,353.9

1

36.3

Figure 1. Emergency department visit rates for drug poisoning, by age: United States, 2004–2007 and 2008–2011

1

2004–2007 visit rates are significantly different (p < 0.05) for the following comparisons: 0–19 with 35–49; 20–34 with 50 and over; and 35–49 with 50 and over, 

based on a two-tailed t test. 2

2008–2011 visit rates are significantly different (p < 0.05) for all age group comparisons except 0–19 compared with 50 and over, based on a two-tailed t test. 3

Visit rate is significantly different (p < 0.05) for 2008–2011 compared with 2004–2007, based on a two-tailed t test.

NOTES: Figures are based on 4-year averages. In 2004–2007, a sample of 1,156 emergency department (ED) visits were made for drug poisoning, representing 

an annual average weighted total of 0.9 million visits. In 2008–2011, a sample of 1,081 ED visits were made for drug poisoning, representing an annual average 

weighted total of 1.1 million visits. Visit rates are based on estimates of the civilian noninstitutionalized population of the United States, as developed by the 

Population Division, U.S. Census Bureau.

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2004–2011. Visits per 10,000 persons

0

10

20

30

40

50

60 2004–2007 2008–2011

All 0–19 20–34 35–49 50 and over

30.7

35.4

1

28.3 2

28.8

22.4

Patient age (years)

2

25.2
NCHS Data Brief ■ No. 196 ■ April 2015

■  2  ■

The overall ED visit rate for drug poisoning was 35.4 per 10,000 persons (Figure 1). 

● In 2008–2011, the ED visit rate for drug poisoning was highest among persons aged 20–34. 

The rate increased from 28.8 per 10,000 persons among those aged 0–19 to peak at 53.9 per 

10,000 persons for those aged 20–34. The rate then declined with increasing age, reaching a 

rate of 25.2 per 10,000 persons for those aged 50 and over. 

● The ED visit rate for drug poisoning for persons aged 20–34 increased from 36.3 per 10,000 

persons in 2004–2007 to 53.9 per 10,000 persons in 2008–2011. Visit rates for other age 

groups and the overall visit rate did not differ between the two time periods.

Did ED visit rates for drug poisoning vary by sex and age in 2008–2011?

● Among persons aged 35–49, the ED visit rate for drug poisoning was higher among females 

(51.2 per 10,000 persons) compared with males (31.9 per 10,000 persons). The visit rate did 

not differ by sex for other age groups or overall (Figure 2). 

● The ED visit rate for males was higher for those in the 20–34 age group compared with 

other age groups.

● The ED visit rate for females was higher among those aged 20–34 and 35–49 compared 

with those aged 0–19 and 50 and over. 

Figure 2. Emergency department visit rates for drug poisoning, by age and sex: United States, 2008–2011

1

Visit rate is significantly different (p < 0.05) compared with males of other age groups, based on a two-tailed t test. 2

Visit rate is significantly different (p < 0.05) compared with females aged 0–19 and 50 and over, based on a two-tailed t test. 3

Visit rate is significantly different (p < 0.05) for males compared with females, based on a two-tailed t test.

NOTES: Figures are based on 4-year averages. Visit rates are based on the set of estimates of the U.S. civilian noninstitutionalized population, as developed

by the Population Division, U.S. Census Bureau. 

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2008–2011.

0

10

20

30

40

50

60 Female

All 0–19 20–34 35–49 50 and over

Visits per 10,000 persons

33.1

37.7

27.6

31.9

24.9 25.4

30.0

2 1 54.3 53.5 2,351.2

Patient age (years)

Male
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Did ED visit rates for drug poisoning vary by intent of injury and sex in 

2008–2011?

● The ED visit rate was highest for unintentional drug poisoning (17.0 per 10,000), followed 

by self-inflicted drug poisoning (13.4 per 10,000) and drug poisoning of undetermined intent 

(5.0 per 10,000) (Figure 3). 

● The ED visit rate for unintentional drug poisoning (18.0 per 10,000 persons) was higher 

than the rate for self-inflicted drug poisoning (10.2 per 10,000) among males, but these rates 

did not differ in females (16.0 per 10,000 and 16.4 per 10,000, respectively). 

● Females had a higher ED visit rate for drug poisoning that were self-inflicted compared with 

males. The ED visit rate for unintentional drug poisoning was not significantly different 

between males and females.

Figure 3. Emergency department visit rates for drug poisoning, by intent and sex: United States, 2008–2011

1

Visit rate is significantly different (p < 0.05) for unintentional compared with self-inflicted poisoning, based on a two-tailed t test. 2

Visit rate is significantly different (p < 0.05) for males compared with females, based on a two-tailed t test.

NOTES: Figures are based on 4-year averages. Visit rates are based on the set of estimates of the U.S. civilian noninstitutionalized population, as developed

by the Population Division, U.S. Census Bureau.

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2008–2011. Visits per 10,000 persons

0

5

10

15

20 Overall Male Female

Unintentional Self-inflicted Undetermined intent

1

18.0

1

17.0

2

10.2

5.0

16.0

13.4

16.4

4.8 5.2
NCHS Data Brief ■ No. 196 ■ April 2015

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Which drugs were associated with ED visits for drug poisoning in

2008–2011?

● For both unintentional and self-inflicted drug-poisoning ED visits, about one-half of 

visits resulted from poisoning by drugs in the categories of analgesics, antipyretics, and 

antirheumatics or sedatives, hypnotics, tranquilizers, and other psychotropic agents

(Figure 4).

● Analgesics that were specifically opiates or related narcotics, including heroin and 

methadone, accounted for 14.0% of ED visits for unintentional drug poisoning.

Other drug

categories

Sedatives, hypnotics, tranquilizers,

and other psychotropic agents

Figure 4. Percentage of emergency department visits for drug poisoning, by intent and drug category: United States, 

2008–2011

1

Specified analgesics, antipyretics, and antirheumatics for self-inflicted poisoning are not contained in the “Supplementary Classification of External Causes of 

Injury and Poisoning,” in the International Classification of Diseases, Ninth Revision, Clinical Modification.

NOTE: Figures are based on 4-year averages. 

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2008–2011.

Other analgesics, antipyretics, and antirheumatics

Other opiates and related narcotics

Heroin and methadone

Unintentional Self-inflicted

5.7

10.4

8.3

27.3

48.3

24.4

46.7

1

21.6

31.7

Analgesics, antipyretics, and antirheumatics
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What percentage of ED visits for drug poisoning led to hospitalization? Did 

this differ from other ED visits in 2008–2011?

● About one-quarter (24.5%) of drug-poisoning ED visits resulted in hospital admission, 

which was higher compared with other ED visits (12.7%) (Figure 5). 

● The percentage of ED visits for drug poisoning that resulted in hospital admission was 

higher than the percentage for other ED visits for all age groups except persons aged 50 and 

over.

● The percentage of ED visits for drug poisoning resulting in hospitalization increased with 

age for both ED visits for drug poisoning and other ED visits.

Figure 5. Percentage of emergency department visits admitted to the hospital, by age and cause of visit: United States, 

2008–2011

1

Percentages are significantly different (p < 0.05) for drug-poisoning visits compared with other visits, based on a two-tailed t test. 2

Linear trend for age is significant (p < 0.05) based on a weighted least-squares regression test.

NOTE: Percentages are based on 4-year annual averages. 

SOURCE: CDC/NCHS, National Hospital Ambulatory Medical Care Survey, 2008–2011. Percent of visits

0

10

20

30

40 Drug-poisoning visits Other visits

All 0–19 20–34 35–49 50 and over

1

24.5

12.7

2

3.5

1

22.7

1

29.0

1,211.1

5.4

10.6

35.6

28.0

Patient age (years)

Summary

This analysis of National Hospital Ambulatory Medical Care Survey (NHAMCS) data indicates 

that in 2008–2011, an annual average of 1.1 million ED visits were made for drug poisoning, 

corresponding to an overall visit rate of 35.4 per 10,000 persons. The highest visit rate was 

observed for persons aged 20–34, and this age group showed a statistically significant increase 

from 2004–2007 to 2008–2011. For persons aged 35–49, the visit rate was higher for females 

than males. Females had a higher visit rate for self-inflicted drug poisoning than males. Drugs 

classified as analgesics, antipyretics, and antirheumatics; or sedatives, hypnotics, tranquilizers, 

and other psychotropic agents were involved in a substantial portion of drug-poisoning visits. 
NCHS Data Brief ■ No. 196 ■ April 2015

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Although visits for drug poisoning made up a small percentage of overall ED visits, they tended 

to be more serious, resulting in more frequent hospitalization. 

Preventing increases in both poisoning deaths and nonfatal poisonings are Healthy People 2020 

objectives (3). This report examining national data on ED visits for drug poisoning can help 

inform injury-prevention efforts to meet these objectives.

Definitions

Injury-related visit: A visit that met one of the following three conditions: a “yes” was marked in 

response to the question, “Is this visit related to an injury, poisoning, or adverse effect of medical 

treatment?”; a cause of injury or a nature of injury diagnosis was provided; or an injury-related 

reason for the visit was reported.

Visit for drug poisoning: An injury-related visit with a first-listed external cause-of-injury code 

of E850–E858, E950.0–E950.5, or E980.0–E980.5 based on the International Classification of 

Diseases, Ninth Revision, Clinical Modification (4). Codes for unintentional drug poisoning were: 

E850 analgesics, antipyretics, antirheumatics; E851–E854 sedatives, hypnotics, tranquilizers, and 

other psychotropic agents; and E855–E858 other and unspecified drug categories. Subcategories 

of unintentional drug poisoning by analgesics, antipyretics, antirheumatics were: E850.0–E850.1 

heroin and methadone; E850.2 other opiates and related narcotics; and E850.3–E850.9 other and 

unspecified drugs. Codes for self-inflicted drug poisoning were: E950.0 analgesics, antipyretics, 

antirheumatics; E950.1–E950.3 sedatives, hypnotics, tranquilizers, and other psychotropic agents; 

and E950.4–E950.5 other and unspecified drugs. Codes for drug poisoning of undetermined intent 

were E980.0–E980.5. Injury visits resulting from assault by drug poisoning (E962.0) were not 

included in this analysis due to the small number of visits.

Data source and methods

Data are from the 2004–2011 NHAMCS, an annual nationally representative survey of 

nonfederal, general, and short-stay hospitals that is conducted by the Centers for Disease Control 

and Prevention’s (CDC) National Center for Health Statistics. NHAMCS uses a multistage 

probability design with samples of geographic primary sampling units (PSUs), hospitals within 

PSUs, and patient visits within EDs. Each year, approximately 480 hospitals are selected for 

inclusion in NHAMCS, and data are collected on approximately 35,000 ED visits. Additional 

information on the methodology of NHAMCS is available online (5). 

Data were imputed for patient birth year and sex. Less than 1% of drug-poisoning visit records 

had missing data for either of these variables. Data analyses were performed using the statistical 

packages SAS version 9.3 (SAS Institute, Cary, N.C.) and SAS-callable SUDAAN version 11.0 

(RTI International, Research Triangle Park, N.C.). Differences among subgroups were evaluated 

using a two-tailed t test. A weighted least-squares regression analysis was used to test the 

significance of linear trends by age in Figure 5. Comparisons reported in the text are statistically 

significant (p < 0.05) unless otherwise indicated.
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About the authors

Michael Albert, Linda F. McCaig, and Sayeedha Uddin are with CDC’s National Center for 

Health Statistics, Division of Health Care Statistics. 

References

1. Warner M, Chen LH, Makuc DM, et al. Drug poisoning deaths in the United States, 1980–

2008. NCHS data brief, no 81. Hyattsville, MD: National Center for Health Statistics. 2011.

2. Chen LH, Hedegaard H, Warner M. Drug-poisoning deaths involving opioid analgesics: 

United States, 1999–2011. NCHS data brief, no 166. Hyattsville, MD: National Center for Health 

Statistics. 2014.

3. HHS. Office of Disease Prevention and Health Promotion. Healthy People 2020 topics and 

objectives: Injury and violence prevention. Available from: https://www.healthypeople.gov/2020/

topics-objectives/topic/injury-and-violence-prevention/objectives.

4. Centers for Medicare & Medicaid Services. International classification of diseases, ninth 

revision, clinical modification, 6th ed. DHHS Pub No. (PHS) 06–1260. 2006. Available from: 

http://www.cdc.gov/nchs/icd/icd9cm.htm.

5. NCHS. 2010 NHAMCS micro-data file documentation. 2010. Available from: ftp://ftp.cdc.

gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHAMCS/doc2010.pdf.
NCHS Data Brief ■ No. 196 ■ April 2015

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Suggested citation

Albert M, McCaig LF, Uddin S. Emergency 

department visits for drug poisoning: United 

States, 2008–2011. NCHS data brief, no 

196. Hyattsville, MD: National Center for 

Health Statistics. 2015.

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