About ZIP Code Asthma Hospital Discharge Rates by County and ZIP Code
Hospital discharge data from the Statewide Planning and Research Cooperative System (SPARCS) were used to create ZIP code level data for asthma hospital discharge rates organized by counties within New York State. Asthma hospital discharges were selected if the principal diagnosis was asthma (International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code of 493). Population estimates by ZIP code used for computing the hospital discharge rates were obtained by the New York State Department of Health (NYSDOH) from Claritas Corporation.
Data are available for the three-year period 2008-2010. ZIP code rates per 10,000 population were calculated by dividing the total number of asthma hospital discharges for the three-year period by three to get the average number of asthma hospital discharges per year. The average number of asthma hospital discharges was then divided by the average population of the three-year period and multiplied by 10,000. Data for a ZIP code that crosses county boundaries are allocated to one county only (the county that contains the largest geographic portion of that ZIP code).
Rates are available for the following groupings:
- 0-4 years of age
- 0-14 years of age
- 0-17 years of age
- 18-64 years of age
- 65 years of age and older
- Total population
ZIP codes are marked with a plus (+) when rates are based on less than or equal to ten visits (Relative Standard Error >30%) and are considered unstable (see Frequently Asked Questions About Asthma Hospital Discharge Data).
Each county table contains the total number of asthma hospital discharges for a three-year period, the average population of the three-year period, and the three-year average annual hospital discharge rate per 10,000 population by ZIP code. Data are not shown, due to confidentiality purposes, if the number of discharges is one or two and/or the population is 33 or less (i.e., equal to or less than an average of 33 per year or 100 over a three-year period). ZIP codes are marked with an asterisk when data is suppressed for this reason.
County maps display ZIP code level data geographically by quartile. Regional quartiles were calculated separately for the five boroughs (counties) of New York City and the remaining counties of the state. A ZIP code's color indicates the regional quartile it belongs to. Each map also contains the asthma hospital discharge rate for the county, New York State, and its region. A non shaded area indicates that part of that ZIP code predominantly lies in an adjacent county.
Why are small numbers of cases or events a concern when looking at health data?
Questions about diseases and conditions such as asthma often lead to looking at the disease in small geographic areas such as neighborhoods and ZIP codes. When the focus is on small areas, the number of health events is likely to be small. When dealing with small numbers of health events, privacy and confidentiality need to be maintained. In addition, people need to be aware that seemingly small changes in the number of events can dramatically change calculated rates.
No information should be presented in these tables that may identify a person or release confidential information about that person.
In the tables of asthma hospital discharges by ZIP code, the number of hospital discharges is not shown if the population is 33 or less (i.e., equal to or less than an average of 33 per year or 100 over a three-year period), or if the number of hospital discharges is one or two. A count of no hospital discharges is shown in the tables because a count of zero is not a threat to confidentiality.
In an area with a small number of hospital discharges per year, an increase or decrease of just one or two hospital discharges per year can cause the hospital discharge rate to change dramatically from year to year; such a rate is likely to be unstable.
In an area with a large number of hospital discharges each year, small increases or decreases in the number of hospital discharges have little effect on the hospital discharge rate (stable rate).(For additional information on this issue and the relative standard error [RSE], see Rates Based Small Numbers).
In the tables of asthma hospital discharges by ZIP code, rates based on ten or fewer ED visits (RSE 30%) are considered unstable and are marked with a plus (+). These rates should be interpreted with caution.