Asthma Data Sources, Definitions and References

Contents

Data Sources

  1. Behavioral Risk Factor Surveillance System
  2. Vermont Hospital Discharge Data - “VT Uniform Discharge Data Set.” Vermont’s acute care hospitals participate in the state’s hospital data system by supplying discharge abstracts of comparable information to Health Care Investment Analysts, a subsidiary of AMBAC, under contract with the Vermont Association of Hospitals and Health Systems (VAHHS). VAHHS, using its EXPLOR data system, then provides data to the Department of Health, the hospital discharge data management designee of the Division of Health Care Administration. Records of Vermont resident discharges from hospitals in neighboring states are obtained by the Department of Health. Records from Massachusetts, New Hampshire and New York hospitals are obtained from the Massachusetts Health Data Consortium, the New Hampshire Divison of Public Health and the New York Department of Health respectively. The Veterans Administration provides discharge records from the VA hospital in White River Junction.(From 1995 VT Hospital Monograph Companion)
  3. Vital Records
  4. YTS : The Youth Tobacco Survey is a self-administered survey of all students in randomly selected schools statewide (grade 6-8).
  5. ATS : The Adult Tobacco Survey is a random-digit dialed telephone survey of the non-institutionalized state population aged 18 and older, with over-sampling of current smokers.
  6. Vermont Emergency Room Data VT Explor (emergency room data)—Vermont Association of Hospitals and Health Care Systems

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Definitions

  1. 95% Confidence Interval - A confidence interval is a range of values within which the true rate is expected to fall. If the confidence intervals of two groups (such as individual Vermont counties and Vermont as a whole) overlap, then any difference between the two rates is not statistically significant. All confidence intervals in this report are calculated at the 95 percent confidence level.
  2. Prevalence - The number of total cases who have an attribute or disease divided by the number in the population at risk. Prevalence may be age-adjusted.
  3. Risk Factor - An aspect of personal behavior or life-style, an environmental exposure or an inborn or inherited characteristic, which on the basis of epidemiologic evidence is known to be associated with health-related conditions(s) considered important to prevent. (Last, 3rd ed) A causal relationship was presumed to exist between an exposure and asthma, if the evidence met the standard epidemiologic criteria for causality (strength of association, biologic gradient or dose-response, consistency of association, biologic plausibility and coherence, and temporality). This report focuses on the risk factors related to indoor air quality, although there are many other possible risk factors for asthma development (here referred to as "risk factors") and exacerbation (here referred to as "risk factors for poor control"). For example, The Institute of Medicine "Clearing the Air" (see References below) found a causal relationship between environmental tobacco smoke (ETS) exposure and exacerbation of asthma in pre-school aged children (e.g. ETS exposure is a risk factor for poor control of asthma), and house dust mite allergen and development of asthma in susceptible children (e.g. house dust mite allergen is a risk factor for susceptible children).
  4. Comparisons & Statistical Significance - When comparing two groups (such as individual Vermont counties and Vermont as a whole), overlap of the two rates show that the two rates are not statistically significant.
  5. Three-year and Five-year Moving Average - A method of smoothing irregularities in trend data, such as long-term trends over time (incidence or mortality rates). Graphical display of 3 or 5-year moving averages makes it easier to discern long-term trends in rates that otherwise might be obscured by short-term fluctuations.(Last, 3rd ed, pg. 108) For example, asthma mortality rates were graphed as 5-year moving averages.
  6. Age-Adjustment - Age-adjusting is a statistical method used when comparing rates from populations that differ geographically (e.g. counties) or over time. All rates are age-adjusted to the 2000 U.S. standard population. This allows the comparison of rates among populations having different age distributions by standardizing the age-specific rates in each population to one standard population.
  7. Small Numbers - It is difficult to know if rare events, particularly from small populations, reflect real patterns or merely random variation. To provide a more stable estimate for rare events, multiple years of data have been used, for example with asthma mortality. The limited number of years of data in some data sets and the small population of the state require policies and procedures to prevent the unintentional identification of individuals. To protect patient privacy, data on rare outcomes for a particular age group, race group or group defined by other variables that could potentially identify individuals are not published.
  8. Income/Education Levels - Low-income/educational level is defined as having a high school education or less, and less than $15,000 annual income for one person (or less than $20,000 per household). High income/educational level is defined as having a college education or more and over $35,000 annual income. Middle income/educational level includes everyone else.
  9. Household vs. Individual - The Behavioral Risk Factor Surveillance System (BRFSS) provides estimates of adult asthma prevalence from a complex sample design which uses weighting factors to create population estimates based on a sample of adult non-institutionalized Vermonters. Estimates for the proportion of households, in which one or more children with asthma are living can be directly calculated, with the appropriate confidence intervals, from the BRFSS dataset. The proportion of children in Vermont with asthma may be higher than the proportion of households with at least one child with asthma.
  10. Discharges vs. Individual Records (AR) - Hospital discharges for asthma - an inpatient hospitalization in which the primary diagnosis code is for asthma. A count of hospital discharges measures how often care is sought. The same individual will be counted as more than one hospital discharge, if hospitalized more than once during the time studied.
  11. Costs vs. Charges - Hospital charges are defined as the amount that the hospital billed for its services, not the amount of payment it received. Payments are frequently less than charges as a result of contractual arrangements with payers.

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References

Written Management Plan References:

Asthma Surveillance System:

Risk Factors for Asthma and Asthma Control:

Other Regional and National Comparisons:

Depression:

Flu Shot Recommendations:

For more information about the Vermont asthma surveillance system, please contact:

Allison La Pointe, MPH
Asthma Epidemiologist
Vermont Department of Health
802-863-7654
alapoin@vdh.state.vt.us