Prevalence and Outcome Measures

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Current asthma prevalence

curent asthma pervalence
Data Standard Current asthma prevalence
Measure Annual estimates of:
  • Count: Estimated number of children ages 0-17 years with current asthma
  • At risk rate: N/A (equivalent to population-based rate given that all children are theoretically at risk of developing asthma)
  • Population-based rate: Percent of children ages 0-17 years with current asthma
Numerator definition Numerator: Number of children aged 0-17 years ever diagnosed with asthma by a health professional who still have asthmaSurvey questions (Source: NHIS):
YES response to both of two survey questions:
  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?”
    AND
  • “Does [child’s name] still have asthma?”

Benchmark data sources:
Denominator definition Denominator for population-based rate: Population of children 0-17 years of ageSource: Civilian noninstitutionalized population (CNIP): provided by US Census (https://www.census.gov/data/datasets/2017/demo/popest/nation-detail.htmlExternal). When using the NHIS, survey weights incorporate the estimated CNIP to produce nationally representative percentages. When using other data sources for the numerator that do not provide population-based survey weights, US Census resident population estimates can be used as the denominator for population-based rates.

Benchmark data sources:
Background Current asthma prevalence is an estimate of the percent of the population with current asthma at the time of the survey. This measure is available from NHIS beginning in 2001. The sampling methodology of the NHIS prevents seasonal bias that could arise from asking the survey questions during different times of the year. The NHIS is conducted throughout the year, and throughout each region of the US during all seasons.

The NHIS prevalence questions are based on case definition from the Council of State and Territorial Epidemiologists (CSTE) 1998 Position Statement(1). The NHIS was redesigned in 1997, and from 1997-2000, there was no established national point prevalence measure (see “asthma attack prevalence” definition). Prior to 1996, a period prevalence measure was used and was based on the question, “During the past year, did anyone in the family have asthma?” (2)
Significance to disparities Current asthma prevalence indicates the percentage of each population subgroup that is theoretically at risk for adverse asthma outcomes, such as asthma emergency room visits or hospitalizations. Generally, current asthma prevalence is higher among minority and low income populations of children(3). There are few primary prevention measures that can be used to prevent asthma from developing, or to address the disparity in asthma prevalence. Thus, the Federal Action Plan (4) includes increasing primary asthma prevention research as one of its four main strategies to address asthma disparities.
Data considerations
  • Current asthma prevalence based on survey data is a self-reported measure which is not confirmed by comparison to medical records.
  • Current asthma prevalence does not provide information about asthma severity or control that also affect disparities in adverse asthma outcomes.
  • The NHIS sampling methodology prevents seasonal bias (conducted throughout the year). Performing a similar survey during only a limited period or season could result in bias.
Data resources
Related data standards A related measure that was available from 1997-2000 (between the start of the redesigned NHIS and introduction of current asthma prevalence measure in 2001) is asthma attack prevalence (the number or percent of children with at least one asthma attack in the past 12 months):
References (1) Asthma Surveillance and Case Definition. Council of State and Territorial Epidemiologists Position Statement 1998-EH/CD-01. Environmental and Chronic Disease Committees.
(2) Akinbami LJ, Schoendorf KC, Parker J. US childhood prevalence estimates: the impact of the 1997 National Health Interview Survey redesign. Am J Epidemiology 2003:15:158(2):99-104.
(3) Moorman JE, Akinbami LJ, Bailey CM, et al. National Surveillance of Asthma: United States, 2001–2010. National Center for Health Statistics. Vital Health Stat 3(35). 2012.
(4) Coordinated Federal Action Plan to Reduce Racial and Ethnic Asthma Disparities: https://www.epa.gov/asthma/coordinated-federal-action-plan-reduce-racial-and-ethnic-asthma-disparitiesExternal
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Asthma attack prevalence

asthma attack prevalences
Data Standard Asthma attack prevalence
Measure Annual estimates of:
  • Count: Number of children ages 0-17 with current asthma who had an episode of asthma or an asthma attack in the past 12 months
  • At risk-rate: Number of children ages 0-17 years with current asthma who had an episode of asthma or an asthma attack in the past 12 months per 100 children aged 0-17 years with current asthma
  • Population-based rate: Number of children ages 0-17 years with current asthma who had an episode of asthma or an asthma attack in the past 12 months among all children aged 0-17 years
Numerator definition Numerator: Number of children ages 0-17 years who have had an episode of asthma or an asthma attack in the past 12 months.Survey question: (Source: National Health Interview Survey)
YES response to both of two questions:
  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?”
    AND
  • “During the past 12 months, has [child’s name] had an episode of asthma or an asthma attack?”

Benchmark data sources:
Denominator definition Denominator for population-based rate:
Population of children 0-17 years of ageSource: Civilian noninstitutionalized population
(CNIP): provided by US Census (https://www.census.gov/popest/data/index.html). When using the NHIS, survey weights incorporate the estimated CNIP to produce nationally representative percentages. When using other data sources for the numerator that do not provide population-based survey weights, US Census resident population estimates can be used as the denominator for population-based rates.Benchmark data sources:

Denominator for at-risk rate:
Number of children aged 0-17 years with current asthma

Survey questions used to determine current asthma prevalence:
YES response to both questions:

  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?”
    AND
  • “Does [child’s name] still have asthma?”

Exclude records with “don’t know,“ “not applicable,” and “refused” responses to above two questions.

Benchmark data sources:
Background In 2006-2010, 51.5% of persons with current asthma reported having had an asthma attack in the past year (1). Having an asthma attack in the past year can be a crude indicator of one’s management of asthma. Children with appropriate medical care and self-management should experience no or minimal asthma symptoms (2, 3).
Significance to disparities In 2010, black children had an asthma attack prevalence rate of 55.1 per 100 children and white children had a prevalence rate of 62.7 per 100 children (4). A recent analysis of asthma disparities between white and black children found that when using population based rates, disparities in asthma attack prevalence widened over time. However, when using at-risk rates, which account for differences in prevalence, there were no differences between white and black children in asthma attack prevalence (4). The authors concluded that even though there were no differences in asthma attack at-risk prevalence rates between white and black children, current asthma prevalence continues to increased among black children and racial disparities remained in asthma and ED visit and death rates (4).
Data considerations
  • Self-reported measure: not confirmed by comparison to medical records
  • Does not provide information about asthma severity or control which also affects disparities in adverse asthma outcomes.
Data resources
Related data standards Because children with severe asthma may be more likely to have had an asthma attack in the past 12 months, have visited the emergency department (ED), be hospitalized, or received urgent care, the following indicators may be similar measures for disease severity:
  • ED visit
  • Hospitalization
  • Urgent care visit
References (1) Moorman J, Person C, Zahran, H. Asthma attacks among persons with current asthma- United States, 2001-2010. Morbidity and Mortality Weekly Report (MMWR) 2013. Accessed on February 22, 2015: https://www.cdc.gov/mmwr/preview/mmwrhtml/su6203a16.htm.
(2) Sheffer AL, ed. Fatal asthma. New York, NY: Marcel Dekker; 1998.
(3) National Institutes of Health, National Asthma Education and Prevention Program. Expert panel report 3: guidelines for the diagnosis and management of asthma. Expert panel report 3. Bethesda, MD: National Institutes of Health, National Heart, Lung, and Blood Institute. 2007. Available at: http://www.nhlbi.nih.gov/guidelines/asthma/index.htmExternal. Accessed February 19, 2015.
(4) Akinbami LJ, Moorman JE, Simon AE, Schoendorf KC. Trends in racial disparities for asthma outcomes among children 0 to 17 years, 2001-2010. J Allergy Clin Immunol 2014, 134(3):547-553.
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Asthma emergency department (ED) visits

asthma emergenct department
Data Standard Asthma Emergency Department (ED) Visits
Measure Annual estimates of:
  • Count: Number of children ages 0-17 years with ED visits for asthma
  • At-risk rate: Number of children ages 0-17 years with an ED visits per 100 children aged 0-17 years with current asthma
  • Population-based rate: Number of children ages 0-17 years with an ED visit per 10,000 population aged 0-17 years
Numerator definition Numerator: ED visits with a principal diagnosis of asthma (ICD-9-CM code 493.XX; ICD-10-CM code J45 beginning 10/2015) for children ages 0-17 yearsBenchmark Source:
  • National Hospital Ambulatory Medical Care Survey (NHAMCS), annual nationally representative sample survey of visits to EDs and outpatient departments
Denominator definition Denominator for population-based rate:
US residential population for the same calendar year as the numerator for children ages 0-17 yearsBenchmark Source:

Denominator for at-risk rate:
Estimated Number of persons with asthma ages 0-17 years

Survey questions used to determine current asthma prevalence:
YES response to both questions:

  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?”
    AND
  • “Does [child’s name] still have asthma?”

Exclude records with “don’t know,“ “not applicable,” and “refused” responses to above two questions.

Benchmark Sources:
Background Asthma ED visits are an indicator of poorly controlled asthma and a risk factor for future exacerbations. (1) There are specific recommendations for patient education and disease management to prevent ED visits, including assessing inhaler technique, instructions for medication, steps to follow for worsening symptoms, and referral for follow-up asthma care(1). Each year, approximately 2 million ED visits related to asthma occur in the United States(2). The cost of ED care is substantially higher than the cost of outpatient and pharmaceutical services(1).

Healthy People 2020 Respiratory Disease Objective 3 (RD-3) is: Reduce emergency department (ED) visits for asthma. (https://www.healthypeople.gov/2020/topics-objectives/topic/respiratory-diseases/objectivesExternal)

CDC Chronic Disease Indicator: https://www.cdc.gov/cdi/definitions/asthma.html Emergency Department visit rate for asthma
Significance to disparities Among children 0-17 years of age, black children had an asthma ED visit rate nearly 5 times higher than white children in 2010. When only children with asthma are considered, black children with asthma had about a 2.5 times higher asthma ED than white children with asthma(3).
Data considerations
  • This indicator may be an overestimate of the burden of severe asthma exacerbations since people sometime use the ED inappropriately – i.e., using the ED for primary care. However, a study comparing asthma severity by race among children visiting the ED for asthma found similar levels of severity between black and white children(4).
  • Not all states have access to administrative billing ED data.
  • ED visit rates are an event rate, that is, a count of visits rather than a count per persons. In the NHAMCS data set, repeated visits for a given children cannot be detected.
Data resources
Related data standards Related indicators of asthma outcomes:
  • Asthma attack prevalence
  • Asthma hospitalization
  • Asthma deaths
  • Missed school/work days due to asthma
References (1) U.S. Department of Health and Human Services (HHS). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: HHS, National Heart, Lung and Blood Institute, National Institutes of Health. Publication No. 07–4051. 2007. (http://www.nhlbi.nih.gov/health-pro/guidelines/current/asthma-guidelinesExternal)
(2) Moorman JE, Akinbami LJ, Bailey CM, et al. National Surveillance of Asthma: United States, 2001–2010. National Center for Health Statistics. Vital Health Stat 3(35). 2012. Barnett SBL, Nurmagambetov TA. Costs of asthma in the United States: 2002-2007. J Allergy Clin Immunol 2011; 127:145-152.
(3) Akinbami LJ, Moorman JE, Simon AE, Schoendorf KC. Trends in racial disparities for asthma outcomes among children 0 to 17 years, 2001-2010. JACI 2014.
(4) Boudreaux ED, Emond SD, Clark S. Camargo CA Jr. Race/ethnicity and asthma among children presenting to the emergency department: differences in disease severity and management. Pediatrics 2003 May;115:e615-621.
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Asthma hospitalization rate

asthma hospialization rate
Data Standard Asthma Hospitalization Rate
Measure Annual estimates of:
  • Count: Annual number of hospitalizations for children ages 0-17 years for asthma.
  • At-risk Rate: Annual number hospitalizations for children ages 0-17 years per 100 children aged 0-17 years with asthma.
  • Population-based rate: Annual number of hospitalizations for children ages 0-17 years per 10,000 population aged 0-17 years.
Numerator definition Numerator: Inpatient hospitalizations with a principal discharge diagnosis of asthma (ICD-9-CM code 493, ICD-10-CM code J45 beginning 10/2015) for children 0-17 years of ageBenchmark Source:
Denominator definition Denominator for population-based rate:
US residential population for the same calendar year as the numerator for children ages 0-17 years.Benchmark Source:

Denominator for at-risk rate:
Estimated Number of persons with asthma ages 0-17 years.

Survey questions used to determine current asthma prevalence:
YES response to both questions:

  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?”
    AND
  • “Does [child’s name] still have asthma?”

Exclude records with “don’t know,“ “not applicable,” and “refused” responses to above two questions.

Benchmark Sources:
Background Asthma hospitalization represents a serious outcome that is theoretically preventable with high-quality health care, patient education, and optimal management of asthma. It also represent a risk factor for future asthma exacerbations(1). Each year, approximately 480,000 hospitalizations related to asthma occur in the United States.) Although inpatient hospitalization for asthma is less frequently used than outpatient and pharmaceutical services, its cost is substantially higher(4).

Healthy People 2020 Respiratory Disease Objective 2 (RD-2) is: Reduce hospitalizations for asthma. (https://www.healthypeople.gov/2020/topics- objectives/topic/respiratory-diseases/objectivesExternal)

CDC Chronic Disease Indicator: https://www.cdc.gov/cdi/definitions/asthma.html
Hospitalizations for asthma
Significance to disparities
  • Compared to white children, black children had an asthma hospitalization rate that was three times higher in 2010. If just children with asthma are considered, black children with asthma had a similar rate of asthma hospitalization rate compared to white children with asthma (about 1.5 times higher)(4).
  • Racial disparities in asthma hospitalization rates among children 0-17 years declined from 2001 to 2010 both for population-based rates and at-risk rates(4).
  • Hospitalizations due to asthma could be reduced if asthma is managed according to established guidelines. Effective management includes control of exposure to factors that trigger exacerbations, adequate pharmacological management, continual monitoring of the disease, and patient education in asthma care(1).
Data considerations
  • As one person can have multiple hospitalizations for asthma in a single calendar year, this indicator describes rate of events, not rate of persons hospitalized.
  • Hospital discharge data may not be available for all states. State hospitalization datasets may not include all facilities or populations.
  • Rates can be affected by changes in prevalence over time as well as practice patterns and payment mechanisms which can affect decisions by health-care providers to hospitalize patients.
Data resources
Related data standards Related indicators of asthma outcomes:
  • Asthma attack prevalence
  • Asthma emergency room visits
  • Asthma deaths
  • Missed school/work days due to asthma
References (1) U.S. Department of Health and Human Services (HHS). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: HHS, National Heart, Lung and Blood Institute, National Institutes of Health. Publication No. 07–4051. 2007. (http://www.nhlbi.nih.gov/health-pro/guidelines/current/asthma- guidelinesExternal)
(2) Number and rate of discharges from short-stay hospitals and of days of care, with average length of stay, and standard error, by selected first-listed diagnostic categories: United States, 2009. National Hospital Discharge Survey. Accessed 10/30/12 at https://www.cdc.gov/nchs/data/nhds/2average/2009ave2_firstlist.pdf Cdc-pdf[PDF – 58 KB]
(3) Moorman JE, Akinbami LJ, Bailey CM, et al. National Surveillance of Asthma: United States, 2001–2010. National Center for Health Statistics. Vital Health Stat 3(35). 2012.
(4) Akinbami LJ, Moorman JE, Simon AE, Schoendorf KC. Trends in racial disparities for asthma outcomes among children 0 to 17 years, 2001-2010. JACI 2014
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Asthma death rate

asthma death rate
Data Standard Asthma Death Rate
Measure Annual estimates of:
  • Count: Number of asthma deaths among children ages 0-17 years due to asthma
  • At-risk Rate: Number asthma deaths for children ages 0-17 years per 10,000 children aged 0-17 years with asthma
  • Population-based rate: Number of asthma deaths among children ages 0-17 years per 1,000,000 population aged 0-17 years
Numerator definition Numerator: Number of deaths with underlying cause of asthma (ICD-10 J45- J46)Benchmark Source:
Denominator definition Denominator for population-based rate:
US residential population for the same calendar year as the numerator for children ages 0-17 years.Benchmark Source:

Denominator for at-risk rate:
Estimated Number of persons with asthma ages 0-17 years.

Survey questions used to determine current asthma prevalence:
YES response to both questions:

  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?” AND
  • “Does [child’s name] still have asthma?”

Exclude records with “don’t know,“ “not applicable,” and “refused” responses to above two questions.

Benchmark Sources:
Background Asthma deaths are a rare, but preventable outcome among children. Predictors of asthma deaths include 3 or more asthma ED visits in the past year, an asthma hospitalization in the past month, overuse of short-acting beta agonist medication, an intensive care unit stay for asthma, lack of a written asthma plan, and low socioeconomic status(1). The number of deaths with asthma as the underlying cause declined steadily from 4,269 in 2001 to 3,388 in 2009, at a rate of 3.3% per year(1). Among children, the population-based rate of asthma deaths per million was 2.8 in 2009, and the at-risk based rate of asthma deaths per 10,000 children with asthma was 0.3(2).

Healthy People 2020 Respiratory Disease Objective 1 (RD-1) is: Reduce asthma deaths. (https://www.healthypeople.gov/2020/topics- objectives/topic/respiratory-diseases/objectivesExternal)

CDC Chronic Disease Indicator: https://www.cdc.gov/cdi/definitions/asthma.html Asthma mortality rate
Significance to disparities Although asthma deaths are rare among children, racial disparities in asthma death rates are the largest compared to other outcomes. In 2010, black children were 7 times more likely to die than white children. Among children with asthma, black children with asthma were 4 times more likely to die from asthma than white children with asthma(3). While there were improvements in racial disparities for asthma hospitalization rates from 2001 to 2010, there was no improvement in racial disparities for asthma death rates(3).
Data considerations
  • Cause of death is recorded by attending physicians, medical examiners, and coroners on death certificated filed in state vital statistics offices. Every death is attributed to one underlying condition, based on information reported on the death certificate, and using international rules for selecting the underlying cause of death (World Health Organization defines as “the disease or injury which initiated the train of events leading directly to death, or the circumstances of the accident or violence which produced the fatal injury”) from the conditions reported on the death certificate.
  • Race and ethnicity on death certificates are reported by the funeral director as provided by an informant, or in the absence of an informant, on the basis of observation.
Data resources
Related data standards Related indicators of asthma outcomes:
  • Asthma attack prevalence
  • Asthma emergency room visits
  • Asthma hospitalization rate
  • Missed school/work days due to asthma
References (1) U.S. Department of Health and Human Services (HHS). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Bethesda, MD: HHS, National Heart, Lung and Blood Institute, National Institutes of Health. Publication No. 07–4051. 2007. (http://www.nhlbi.nih.gov/health-pro/guidelines/current/asthma- guidelinesExternal)
(2)Moorman JE, Akinbami LJ, Bailey CM, et al. National Surveillance of Asthma: United States, 2001–2010. National Center for Health Statistics. Vital Health Stat 3(35). 2012.
(3) Akinbami LJ, Moorman JE, Simon AE, Schoendorf KC. Trends in racial disparities for asthma outcomes among children 0 to 17 years, 2001-2010. J Allergy Clin Immunol 2014, 134(3):547-553.
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Missed school/work days due to asthma

Missed school/work days due to asthma
Data Standard Missed Daycare/School/Work Days due to Asthma
Measure Annual estimates of:
  • Count: Number of children ages 0-17 years with current asthma who missed at least one day of daycare or preschool/school/work in the past 12 months due to asthma
  • At-risk rate: Number of children ages 0-17 years with current asthma who missed at least one day of daycare or preschool/school/work in the past 12 months due to asthma per 100 population (percent) children aged 0-17 years with current asthma
  • Population-based rate: Number of children ages 0-17 years with current asthma who missed at least one day of daycare or preschool/school/work in the past 12 months due to asthma per 100 population aged 0-17 years

Note: Rates may be calculated for children aged 5-17 years to include school-aged children only.
Numerator definition Numerator: Number of children ages 0-17 years with current asthma who missed at least one day of daycare or preschool/school/work in the past 12 months due to asthmaSurvey question (Source: National Health Interview Survey):
“During the past 12 months, how many days of daycare or preschool/ school or work did [child’s name] miss because of asthma?”

Benchmark data source:
Denominator definition Denominator for population-based rate:
US residential population for the same calendar year as the numerator for children ages 0-17 years.Benchmark Source:

Denominator for at-risk rate:
Estimated Number of persons with asthma ages 0-17 years.

Survey questions used to determine current asthma prevalence:
YES response to both questions:

  • “Has a doctor or other health professional EVER told you that [child’s name] had asthma?” AND
  • “Does [child’s name] still have asthma?”

Exclude records with “don’t know,“ “not applicable,” and “refused” responses to above two questions.

Benchmark Sources:
Background In 2008, nearly 60% of children with current asthma reported missing at least one day of school in the past 12 months (1). Children 5-17 years were reported to have missed 10.5 million school days in the past year due to asthma (1). Missed school days can be used as an asthma measure of morbidity because poor asthma control can lead to a loss of productivity resulting in missed school days. Children with appropriate medical care and self-management should not experience asthma symptoms or miss school because of their asthma (2). The National Asthma Education and Prevention Program (NAEPP) provides expert guidelines for diagnosis and management of asthma https://www.nhlbi.nih.gov/health-pro/resources/lung/naci/asthma-info/asthma- guidelines.htmExternal. Healthy People 2020 goals (RD-5.1) aim to reduce the proportion of children aged 5-17 years with asthma who miss school days http://www.healthypeople.gov/2020/topics- objectives/topic/respiratory-diseases/objectivesExternal.
Significance to disparities An analysis of asthma disparities among racial/ethnic groups in Passaic, New Jersey (1998-2001) revealed that black and Puerto Rican children had a higher percentage of missed school days due to asthma than white children or children in other Hispanic subgroups (Mexican and Dominican) (3). Black and Puerto Rican children also had the highest asthma prevalence.
Data considerations
  • Self-reported measure: subject to error due to recall bias.
  • Does not provide information about asthma severity or control which also affects disparities in adverse asthma outcomes.
Data resources
Related data standards Children who miss school due to asthma may also limit usual activities:
  • Limited usual activities
References (1) Akinbami, LJ, Moorman, JE, Liu, X. Asthma prevalence, healthcare use, and mortality: United States, 2005–2009. National health statistics report; no 32. Hyattsville, MD: National Center for Health Statistics. 2011.
(2) Sheffer AL, ed. Fatal asthma. New York, NY: Marcel Dekker; 1998.
(3) The Asthma and Allergy Foundation of America. Ethnic Disparities in the Burden and Treatment of Asthma. 2005. Accessed on February 22, 2015: http://www.aafa.org/page/burden-of-asthma-on-minorities.aspxExternal
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Page last reviewed: July 14, 2016
Content source: National Center for Environmental Health