About Heart Attacks Data
Tracking heart attacks involves collecting data about the number of hospital admissions due to a heart attack.
This page provides general information about heart attack data and measures developed by the Iowa Public Health Tracking program. Contact Us for more information about these data.
Information on this page:
What do these data tell us?
- The numbers and rates of heart attack hospitalizations in Iowa by year, age group and gender.
- If heart attack hospitalizations are going up or down over time.
- If a segment of a population is at higher risk for hospitalization due to heart attack.
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How we can use these data?
- To inform the public about heart attack hospitalizations.
- For program planning and evaluation by state and local partners.
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What these data cannot tell us?
- What causes heart attack, or what leads to heart attack hospitalizations.
- The total burden of heart attack in a population.
- The number of people who are hospitalized due to heart attack. Because personal identifiers are removed from the hospital before analysis, individuals who have multiple hospitalizations cannot be identified.
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What is the source of the data?
- Hospitalization data are collected by the Iowa Hospital Association on behalf of in accordance with Iowa Code section 135.166.
- population estimates from the National Center for Health Statistics and US Census. Data from 2000 to 2009 are based on intercensal population estimates and 2010-most current year are based on the postcensal population estimates.
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What time period of data is available?
- The Iowa Public Health Tracking portal displays hospitalization data from the year 2000 through the most recent year of data available.
- There is usually a two-year lag period before hospitalization data are available.
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How are heart attack hospitalizations identified?
- Hospitalizations are defined as Iowa residents who are discharged from a hospital in Iowa.
- Heart attack hospitalizations have a primary discharge diagnosis of heart attack.
- Heart attack is defined as the International Classification of Disease 9th Revision, Clinical Modification () codes that begin with 410.
- Heart attack is defined as the International Classification of Disease 10th Revision, Clinical Modification () codes that begin with I21 or I22.
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What is the difference between a number, rate, age-adjusted rate, and age-specific rate? How would I use them?
Number:
- If you want to understand the magnitude or how big the overall burden is, then use the number.
- The number indicates the total number of hospitalizations due to heart attack, but not the number of unique individuals hospitalized.
- To protect an individual's privacy, counts of 5 or less are suppressed.
:
- If you want to understand the probability or what is the underlying risk in a population, then use a rate.
- In our analysis a rate is calculated using a numerator, the number of heart attack hospitalizations during a period of time, divided by a denominator, the number of people in a population during the same period of time. This fraction is then multiplied by 10,000 to provide a more recognizable value.
- To protect an individual's privacy, rates based on counts of 5 or less are suppressed.
Age-adjusted rate:
- Age-adjusted rates are useful when comparing the rates of two population groups that have different age distributions.
- For Heart Attacks we use the age-adjusted rate among persons 35 years of age or older. This allows a more accurate comparison because very few persons under 35 have heart attacks.
- A weighted average, called the direct method, is used to adjust for age in this analysis. Age specific rates in a given population are adjusted to the age distribution in a standard population by applying a weight. The U.S. 2000 Standard population is used as the basis for weight calculations.
- To protect an individual's privacy, rates based on counts of 5 or less are suppressed.
Age-specific rate:
- A rate of an event (such as disease or death) measured within a particular age group. It is similar to a crude rate but is calculated within an age group (e.g. an age-specific rate of heart attack hospitalizations in adults 35-44 years of age).
- To protect an individual's privacy, rates based on counts of 5 or less are suppressed.
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What are the limitations of the data?
- Multiple hospitalizations by the same patient cannot be identified, and are not excluded.
- These data are not appropriate for estimating the total burden of heart attack.
- These measures use hospital admission dates while other public health programs use the hospital discharge dates to count heart attack cases. This may cause a difference in heart attack rates between the Tracking Network and other public health websites.
- Iowa residents discharged from hospitals in surrounding states are not included, so hospitalization and emergency department visit rates for counties in which residents are likely to receive care in a surrounding state may be underestimated. Rates for counties in which residents are likely to visit hospitals that do not submit data to the Iowa Hospital Association (e.g., Veteran's Administration, Indian Health Services hospitals, and institutionalized populations) may also be artificially low.
- There is usually a two-year lag period before hospitalization data are available.
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Where can I find more technical information about the data?
More detailed documentation of the heart attack hospitalization data can be found in the following documents:
Indicator Profiles
Hospitalizations for Heart Attack 
Descriptive Metadata
Hospitalizations for Heart Attack
Contact Us to learn more about heart attack, hospitalization data, or any of the measures displayed on the Iowa Public Health Tracking Portal.
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