1. The hospital admission data displayed are provided by Virginia Health Information to the Virginia Department of Health. The data are analyzed by the Division of Population Health Data, Environmental Public Health Tracking Program, and displayed by the VDH Center for Public Health Informatics.   
2. Hospital admission records are selected using primary diagnosis codes only and are based on admission year rather than discharge year. This methodology may differ from other VDH hospitalization data dashboards.   
3. Admissions of residents to out-of-state hospitals are excluded. Admissions for border counties may be underestimated.   
4. Rates were calculated based on U.S. Census Bureau Single Race Population Estimates.   
5. Differences in counts and rates in 2015 compared with subsequent years could be a result of ICD coding changes. 
6. Non-zero counts of 1-4 are suppressed for display to protect privacy.  
7. Non-zero rates based on a numerator counts of 1-4 are suppressed for display due to rate instability.  
8. Other and unknown race/ethnicity categories have been excluded from display due to no matching population data for the denominator.  
9. Color legend for counts/rates shown in map was created from calculated cut-offs. Color legend does not change when choosing different filters.  

Virginia Department of Health. Division of Population Health Data. Environmental Public Health Tracking Program. Asthma Hospitalizations. 

This dataset can be used to assess the burden of more severe cases of asthma, monitor trends over time, identify high risk groups, and inform prevention, evaluation and program planning efforts.  

This dataset may also be used to further explore relationships with environmental variables or environmental events. If the data set is used to explore environmental relationships, see limitations.  

Numerator: Hospitalizations or “counts” for asthma, ICD-9-CM 493 or ICD-10-CM J45 as the primary diagnosis 
Denominator: Resident population (provided by U.S. Census Bureau) 

For rate display, rates are multiplied by a factor of 100,000 to allow for comparison across localities.

• Asthma hospitalizations will include some transfers between hospitals for the same individual for the same asthma event. Variations in the percentage of transfers or readmissions for the same asthma event may vary by geographic area. 
• Data are based on the date of admission rather than the date of discharge. Admission date is a better indicator of the time the patient first presented with severe enough symptoms to result in a hospital admission and may be more closely related to a potential environmental exposure or trigger. This methodology may differ from other VDH hospitalization data dashboards. 
• Counts are the number of inpatient hospitalizations. A patient could have stayed in the hospital more than once for asthma. These would count as separate hospitalizations. 
• Data on race and ethnicity are limited for several reasons. These data are not consistently recorded on medical records and when available are complicated further by non-standard definitions of race and ethnicity, the use of combined race/ethnicity, reporting of multiple race categories, and differences in self-report versus registrar reporting. Cases where race was classified as ‘other’ or ‘unknown’ have not been displayed due to the inability to calculate rates. These cases are included in the overall counts. 
• These data usually include only cases of state residents who were treated within the state. Measures for geographic areas (e.g., counties) bordering other states may be underestimated because of health care utilization patterns.  
• Excluded from the data are federal institutions such as Veterans Affairs, Indian Health Services, and prison facilities. 
• Practice patterns and payment mechanisms may affect diagnostic coding and decisions by health care providers to hospitalize patients. 
• Sometimes the mailing address of a patient is listed as the residence address of the patient. Patients may be exposed to environmental triggers in multiple locations, but geographic information is limited to residence. 
• On October 1, 2015, in the United States, the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) replaced the ninth revision (ICD-9-CM) for coding of medical terminology and disease classification. As a direct result of this change, there are nearly five times as many diagnosis codes in ICD-10-CM than in ICD-9-CM, allowing further expansion than was possible with ICD-9-CM. This coding change impacts information classifications for hospital discharge, emergency department, and outpatient records for administrative and financial transactions in all healthcare settings. Differences in counts and rates in years prior to 2015 (ICD-9-CM) compared with 2015 (ICD-9-CM and ICD-10-CM) and subsequent years (ICD-10-CM) could be a result of this coding change and not an actual difference in the number of events.  
• Hospitalization data, by definition, does not include asthma among individuals who do not receive medical care or who are not hospitalized, including those who die in emergency rooms, in nursing homes, or at home without being admitted to a hospital, and those treated in outpatient settings. 
• All-age locality rate is based on a crude, non-adjusted rate calculation. Comparing the all-age locality rate to the Virginia rate should be interpreted with caution due to variation in age distribution from locality to locality.  
• Rates may differ from those available from CDC’s National Environmental Public Health Data Explorer due to differences in the multiplier used to display rates (per 100,000 vs 10,000). Rates may also vary from CDC due to differences in population estimates used to calculate the rate.  
• Rates calculated with numerator counts between 5-20 are displayed but should be interpreted with caution.  
• Reporting rates at the state and/or county level will not show the true asthma burden at a more local level (i.e. neighborhood). 
• Differences in rates by area may be due to different socio-demographic characteristics and associated behaviors. 
• When comparing rates across geographic areas, a variety of non-environmental factors, such as access to medical care and diet, can impact the likelihood of persons being hospitalized for asthma. 

• Reporting rates at the state and/or county level may not be geographically resolved enough to be linked with many types of environmental data. 

The public use datasets are available on the Virginia Open Data Portal below: EPHT Hospitalizations Public Use Dataset EPHT Asthma Hospitalizations Public Use Dataset