• The rates of all respiratory and cardiovascular hospitalizations emergency department (ED) visits in Minnesota, including asthma, chronic obstructive pulmonary disease (COPD), and heart disease.
• All cause and cardiopulmonary mortality rates.
• If rates vary geographically, by age, and other social determinants of health.
• The attributable rates from fine particle pollution and ozone. The attributable rates are defined as the proportion of health impact from the air pollutant that contributes to disease, and specifically for Life and Breath project—this is the hospitalization, ED or death rate that would be eliminated if exposure to particulate matter and ozone were eliminated.
• Death rates shown for ozone (underlying and attributable) only include deaths occurring in warm weather months (May-September) for all-ages cardiopulmonary deaths for ICD-10-CM codes: I00-I79, J10-J18, J69.
• Death rates for fine particle matter (underlying and attributable) are annual age-specific rates (25 and older population) for all-cause deaths.

• To inform the public about respiratory and cardiovascular hospitalizations and ED visits and mortality.
• For program planning and evaluation by state and local partners.

• What causes respiratory and cardiovascular disease.
• The total burden of respiratory and cardiovascular disease in a population.
• The number of people who are hospitalized or who visited the ED due to respiratory and cardiovascular disease. Because personal identifiers are removed from the hospital discharge data before analysis, individuals who have multiple hospitalizations or ED visits cannot be identified.

• All attributable rates for the health impacts of air pollution from the Life and Breath Report 2019, are estimated using Minnesota Hospital Discharge Data (MNHDD) and mortality data, in addition to Minnesota Pollution Control Agency (MPCA) annual air quality data and data from peer reviewed epidemiology studies. All of these data inputs are used with the US EPA’s Environmental Benefits Mapping and Analysis Program, mathematical modeling software.
• Hospitalization and ED data are extracted from Minnesota Hospital Discharge Data, which is maintained by the Minnesota Hospital Association (MHA).
  • MHA represents Minnesota's hospitals and health systems. Hospitals submit inpatient discharge data to MHA using a standardized billing form. In 2010, 99.3% of all hospitals in the state report hospital discharge data to the MHA, representing 99.4% of all licensed beds in the state.
  • MHA began data-sharing agreements with several states in 2005. Minnesota residents receiving care from hospitals from the participating border states of North Dakota, South Dakota and Iowa are also included in hospitalization measures beginning in 2005. Minnesota residents receiving care from emergency departments from North Dakota are also included in emergency department measures beginning in 2005.
• Mortality data are from the MDH Office of Vital Records.
• Rates are calculated using denominator counts from the US Census. Data from 2010 are from the Decennial Census. Data from 2011-2015 are from intercensal population estimates.

• Hospitalizations visits are defined as Minnesota residents who are discharged from a hospital in Minnesota or the bordering states of North Dakota, South Dakota, or Iowa. Emergency Department visits are defined as Minnesota residents who are treated and released or subsequently admitted to a facility in Minnesota or North Dakota.
• Respiratory and cardiovascular disease are defined as the International Classification of Disease 9th Revision, Clinical Modification (ICD-9-CM) codes 496, 786.06, 460-519, 410-414, 426-429,430-438,440-448 and (ICD-10-CM) codes J45, R062,J40-J45, J471, J479, J67, I20-I22, I24-I25, I44-I45, I47-I50, I60-I67, I69-I75, I77-I78, M30-M31, R001, G454.
• ED visits include both patients treated and released from the ED as well as those that enter the ED and are admitted to the hospital.
• Records with missing county are included in the state count but excluded from county counts.
• The Office of Vital records maintains death records for the state of Minnesota. ICD-10-CM codes include I00-I79, J10-J18, J40, J47 and J69.

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 or ED visits, but not the number of unique individuals hospitalized or who visited the ED.
• To protect an individual's privacy, counts from 1 to 5 are suppressed if the underlying population is less than or equal to 100,000.

Rate:

• If you want to understand the probability or what is the underlying risk in a population, then use a rate and confidence interval. A rate is a ratio between two measures with different units. In our analysis a rate is calculated using a numerator, the number of hospitalizations during a period of time, divided by a denominator, the number of people at risk in a population during the same period of time. This fraction is then multiplied by a constant (in this case 100,000) to make the number more legible.
• To protect an individual's privacy, counts from 1 to 5 and rates based on counts from 1 to 5 are suppressed if the underlying population is less than or equal to 100,000.
• Rates based on counts of 20 or less are flagged as unstable and should be interpreted with caution. These rates are unstable because they can change dramatically with the addition or subtraction of one case.
• 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 asthma hospitalizations in adults 35-44 years of age).

• Assessing the confidence interval for the percent or rate is one approach to determine whether there are differences over time or compared to another location. If they do not 'overlap' then they 'differ.' Although it is not a 'true' statistical test, it is a commonly accepted way to compare percents or rates and tends to be more conservative than statistical testing.
• A confidence interval for a rate is a measure of reliability. In this analysis, 95% confidence intervals were calculated. A 95% confidence intervals is the interval within which the true value of the rate would be expected to fall 95 times out of 100. When the number of events is fewer than 100, the 95% confidence interval is calculated based on the inverse gamma distribution in this analysis. When the number of events is 100 or greater, the 95% confidence interval is calculated based on normal approximation.

• Multiple hospitalizations or ED visits by the same patient cannot be identified, and are not excluded.
• These data are not appropriate for estimating the total burden of disease.
• Minnesota residents discharged from Wisconsin hospitals are not included, so hospitalization and ED visit rates for counties in which residents are likely to receive care from Wisconsin may be underestimated. Rates for counties in which residents are likely to visit hospitals that do not submit data to the Minnesota Hospital Association (e.g., Veteran's Administration or Indian Health Services hospitals) may also be artificially low.

To learn more about asthma, contact the MDH Asthma Program or the MDH Heart Disease Program. For more about the asthma hospitalization data and measures developed by the MN Tracking Program, contact us.