Cold-related illness metadata: MN Public Health Data Access Portal - MN Dept. of Health

• The numbers and rates of hospitalizations, emergency department (ED) visits, or deaths attributed to cold-related illness by year, sex, or age group in Minnesota.
• If a measure is going up or down over time.
• If a segment of a population is at higher risk for hospitalization, a visit to the ED, or death resulting from cold exposure in Minnesota.
• Allow for a better understanding of spatial and temporal trends in cold-related illness.
• How average winter temperature relates to cold-related illness by year.

• The data can be used to document changes in cold-related illness over time and identify vulnerable populations.
• The data can be used to educate the public about the health effects from exposure to cold temperatures, winter weather conditions, or cold water.
• The general public can use this information to better understand their risk of cold-related illness.
• The maps can inform which Minnesota counties should be targeted for outreach and prevention efforts.
• State and local partners can use these data for program planning and evaluation.

• These data come from hospital records and death certificates and may not capture the full range of cold-related illness if exposure to excess cold is not explicitly documented.
• This analysis does not capture the full extent of cold-related health outcomes because only cases where cold exposure was recorded as an underlying or contributing cause of illness or death were included.

• The total burden of cold-related illness in a population.
• The number of people hospitalized or who visited the ED for cold-related illness. Personal identifiers are removed from the hospital discharge data before analysis, so we are unable to identify individuals who may receive care at more than one facility.

• Hospitalization and ED visit data are extracted from Minnesota Hospital Discharge Data (MNHDD), which is maintained by the Minnesota Hospital Association (MHA).
• MHA data are periodically revised by the MHA to reflect more complete and accurate discharge information.
• Mortality data are from the MN Center for Health Statistics at the Minnesota Department of Health.
• Temperature data was provided by the Minnesota Department of Natural Resources (DNR). Average winter temperature was calculated by averaging the mean temperature from each of the winter months (October-April).

Hospitalizations/ED visits:

• Minnesota residents who are hospitalized or visit the emergency department in the cold weather months (October-April) with a primary or other diagnosis of cold-related illness, defined as having any of the following ICD-9-CM codes: 991, E901.0, E901.8, E901.9, and E988.3 (excluding cases due to man-made cold exposure, ICD-9-CM code E901.1) and ICD-10-CM codes: X31, T68-69, or T33-34 (excluding cases due to man-made cold exposure, ICD-10-CM code W93).
• The data source for hospitalizations and ED visits is the Minnesota Hospital Discharge Data. The Minnesota Hospital Discharge Data collects hospital discharge information from acute care hospitals submitting data to the Minnesota Hospital Association (MHA).
• Hospitalizations include out-of-state hospitalizations of Minnesota residents in the nearby states of North Dakota, South Dakota, and Iowa. ED visits only include out-of-state hospitalizations of Minnesota residents after the year 2005.

Deaths:

• Minnesota residents deceased during the cold weather months (October-April) with ICD-10-CM codes X31, T68-69, or T33-34 (cold-related illness) listed as an underlying or contributing cause of death on the death certificate record (excluding intentional deaths and deaths due to man-made cold exposure, ICD-10-CM code W93).
• Demographic and cause of death data are collected from death certificates. Minnesota Mortality Data is maintained by the Center for Health Statistics at MDH.

• Learn more about the ICD-10-CM codes from the International Statistical Classification of Diseases 10th Revision

Number:

• The number indicates the total number of hospitalizations, ED visits, or deaths.
• To protect an individual's privacy, hospitalizations and ED visit counts from 1 to 5 are suppressed if the underlying population is less than or equal to 100,000.

Rate:

• A rate is a ratio between two measures with different units. In our analysis a rate is calculated using a numerator (the number of cold-related illness hospitalizations, ED visits, or deaths 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 100,000. Minnesota population estimates from the U.S. Census Bureau American Community Survey datasets are used to calculate a rate.
• To protect an individual's privacy, rates based on hospitalization or ED visits 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.
• An age-adjusted rate is an overall summary measure that helps to control for age differences between populations. A weighted average, called the "direct method," is used to adjust for age. The U.S. 2000 standard population is used as the basis for weight calculations.
• Age-adjusted rates are useful when comparing the rates of two population groups that have different age distributions.

• Only Minnesota resident data from Minnesota death certificate records are included in the analysis; this excludes out-of-state deaths. Before 2005, ED visits did not include out-of-state ED visits for Minnesota residents. Hospitalization and ED visit rates for counties in which residents are likely to cross state lines for care may be underestimated. Rates for counties whose 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.
• Multiple hospital or emergency department admissions by the same patient cannot be identified and are not excluded.
• Since only people with the most severe or acute symptoms of cold-related illness are hospitalized, treated at the ED, or die, these data are not appropriate for estimating the total burden of cold-related illness in a population. The actual number of Minnesotans who experience cold-related illness is unknown. Cold-related illness is not currently a reportable condition in Minnesota.

To learn more about cold-related illness data and measures, contact the MN Environmental Public Health Tracking Program at health.dataportal@state.mn.us.