Multiple Cause of Death Mortality (MCD) Data


Wide-ranging Online Data for Epidemiologic Research (WONDER) — is an easy-to-use internet system that makes the information resources of the Centers for Disease Control and Prevention (CDC) available to public health professionals and the public at large. It provides access to a wide array of public health information.

CDC WONDER furthers CDC’s mission of health promotion and disease prevention by speeding and simplifying access to public health information for state and local health departments, the Public Health Service, and the academic public health community. CDC WONDER is valuable in public health research, decision making, priority setting, program evaluation, and resource allocation.  To learn more about WONDER go to:

Uses for Asthma Surveillance

Several questions can be addressed statewide using CDC/WONDER underlying cause of death (MCD) mortality data:

Q  What is the mortality rate for deaths where asthma is the underlying cause of death (“probable” asthma cases”)?

Q  What is the mortality rate for deaths where asthma is a contributing cause of death (“possible” asthma cases)?

Q  Is the asthma mortality rate higher than the national average, or the Healthy People 2020 (HP2020) objective?

Q   Does asthma mortality vary by age, sex, race, season, and/or geography?

Q   What are the yearly trends in asthma mortality?

History of Multiple Cause of Death Data Collection

History:  Death certificates contain demographic and geographic information of the decedent, as well as ICD codes for up to 20 conditions that contributed to the death.  The U.S. standard certificate of death can be found at  All U.S. death certificate information is complied by the NCHS, Centers for Disease Control and Prevention, into the Multiple Cause of Death Mortality Data Tapes. Deaths of U.S. citizens and members of the Armed Forces occurring outside the United States are not included in this data.  A detailed data tape file is available for each year 1968 through 1999.  The multiple-cause files include one tape record for each death occurring during each data year except for 1972. In 1972, budgetary considerations allowed deaths to be obtained from only a 50% sample. Deaths from this year must therefore be weighted by a factor of two.

NCHS Data Management:  When the mortality data arrive at NCHS, the data are entered into a database unchanged. A computer program then processes the data, replacing words with synonyms, dropping unnecessary words, and arranging words in the proper order to achieve standardized data processing. A second computer program then takes this standardized death certificate data and applies coding rules to best determine the underlying cause of death (UCD).  This program is designed to select the underlying cause even if the conditions are not reported in an acceptable causal sequence.  In short, these cause of death codes are compiled in two forms; the entity axis, which contains conditions as stated on the death certificate, and the record axis, which is edited by a computer algorithm to revise some ICD codes to best describe the overall medical certification portion of the death certificate.  We recommend using the record-axis portion of the data for state-based asthma MCD mortality surveillance.  Additional information on the NCHS mortality data management process can be found at

The Difference between UCD and MCD Data:  Cause of death statistics can be based on the UCD, which is defined as “(a) the disease or injury which initiated the chain of events leading directly to death, or (b) the circumstances of the accident or violence which produced the fatal injury.”¹  However, the primary advantage of MCD data over the UCD data is that state asthma epidemiologists not only have access to those deaths where asthma was the UCD, but also to deaths where asthma was one of twenty possible conditions that contributed to the death (and may not have been the underlying cause).  When determining how many deaths include asthma as a contributing condition, each of the twenty fields of the death certificate should be searched for ICD codes applicable to asthma.  A complete description and list of variables available in the MCD mortality data can be found at

Asthma Case Definitions:  Deaths are coded based on the applicable revision of the ICD, which is published by the WHO.  Causes of death for 1968 – 1978 were coded according to the ICD-8 classification, adapted for use in the United States.  Causes of death for 1979 – 1998 were coded according to the ICD-9 classification.  Causes of death for 1999 and later are coded according to the ICD-10 classification.  The ICD-8 and ICD-9 codes for asthma are any 493 code.  Coding terminology for asthma, as well as for other illnesses, has changed with ICD-10, which began in 1999.  Asthma is coded in ICD-10 as codes J45 – J46.  NCHS reports a comparability ratio for persons over the age of 1 of 0.8938 for the coding of asthma mortality under ICD-10 as compared to ICD-9.  That is, about 11% fewer deaths will be coded under ICD-9.  For instructions for calculating comparability ratios for your state, go to and download “A Guide to State Implementation of ICD-10 for Mortality” parts I and II.  The Council for State and Territorial Epidemiologist (CSTE, has jointly developed a standardized case classification for asthma to identify probable and possible asthma cases in mortality data². There is no confirmed case classification for mortality data.  A “probable” case is a death with an ICD code for asthma as the UCD.  A “possible” case is a death with an ICD code for asthma as a contributing, but not an underlying, cause of death.

How to Access CDC/ WONDER Data

  • Use your Internet browser to go to
  • Under the heading “Mortality” click on “Multiple Cause of Death (Detailed Mortality)”
  • Click on either “Mortality for 1999 – 2015 with ICD 10 codes.”

The following page contains a tutorial designed to walk one through retrieving data from the CDC/WONDER site.  In this example, age-adjusted asthma death rates can be obtained by race for persons ≥ 5 years old for the period 1979 – 1998.  While CDC/ WONDER can be used to obtain crude and age-adjusted death rates by a variety of additional characteristics, this example is intended to provide enough familiarity to undertake additional analyses independently.

Direct your Internet browser to Make sure pop-ups are allowed.
o Use your Internet browser to go to
o Under the heading “Mortality” click on “Multiple Cause of Death (Detailed Mortality)”
o Under the heading “Mortality for 1999 – 2015 with ICD 10 codes” Click on “Data Request”
o Agree to the data use agreement.
o The Request screen will appear.

Use the following steps to complete each area of this screen.

  1. Organize table layout:
    • Select groupings:
      Select how you would like to summarize your data.  You may choose multiple groupings.
    • Select Measures:
      Select the measures you would like to have summarized in the output.  Default measures will automatically be checked: Deaths Population Crude Rate. Select age-adjusted rate.
    • Additional Rate Options:
    • Calculates rates per:
      Select 1,000,000
    • Select Standard Population:
      Highlight 2000 U.S. Standard Population
      Or, Non-Standard Population:
      Leave unchecked (following the recommendations of the NCHS
  2. Select location:
    • Select State, Census Region or HHS Region:
      Select the state to be queried from the list of states.
  3. Select demographics:
    • Select age, gender, Hispanic origin, and race:
      Select the desired demographics of interest.
    • Select age ranges:
      Age may be presented in Ten-Year Age Groups, Five-Year Age Groups, Single-Year Age and Infant Age Groups.
      To select 0-18 years, click on Single-Year Age and in the box, highlight “<1year” – “18 years.”
    • Select gender:
      Leave set at “All.”
    • Select Hispanic Origin:
      Leave set at “All.”
    • Select race:
      Leave set at “All.”
  4. Select year:
    • Select years:
      Highlight desired year(s).
  5. Select weekday, autopsy or place of death:
    • Select weekday:
      Leave set at “All weekdays.”
    • Select autopsy
      Leave set at “All values.”
    • Select place of death:
      Leave set at “All places.”
  6. Select Cause of Death
    • To search ICD code ranges:
      Click on “ICD-10 codes.” In the box below, select “search.” In the box, type “asthma.”  When the list appears, select J45 through J46 (highlight the codes).  Once all six are highlighted, they will appear in the box on the right.
    • To search the MCD ICD code ranges:
      Click on “ICD-10 codes.” In the box below, select “search.” In the box, type “category or code of interest.” When the list appears, highlight the codes. Once the codes are highlighted, they will appear in the box on the right.
  7. Other Options
    • Select “Show Suppressed Values”
    • Click “Send.”  The results of your query will appear in another window.

    More detailed instructions and background for those who wish to query the Compressed Mortality Data can be found at or by clicking the link “Compressed Mortality data description.”

    Analysis Standards

    Standard demographic breakdowns can be used when analyzing asthma surveillance data.  The applicability of these breakdowns to MCD mortality data are summarized below.  Analysis will need to be undertaken separately for death classified as “probable” (UCD) and “possible” (MCD) asthma deaths.

    • Age Categories: Rates can be calculated by age for single-year, 5-year 10-year, and infant age intervals.
    • Sex Categories: Rates can be calculated separately for “male” and “female” categories.
    • Race Categories: Rates can be calculated separately for “White,” “Black” and “Other” categories. If data on Hispanic ethnicity are available for your state (see the Q & A section) then rates can be calculated for “Hispanic,” “White, non-Hispanic,” “Black, non-Hispanic,” and “Other, non-Hispanic” race/ethnicity categories.
    • Time Trends: Rates can be calculated by year if possible. Rates also can be calculated by month and day of week.
    • Geographic Categories: Rates can be calculated at the state, county and city level if the cell sizes permit.  Age-standardized rates can be used to compare geographic units.

    NOTE:  Small sample size can result in release or inferred release of confidential or sensitive information and can also affect reliability of rates.  Please consider collapsing years or demographic groups, presenting confidence intervals, or suppressing rates and counts, or doing a combination of these three, if sample size of the numerator or denominator is inadequate.  In some cases, an aggregation of categories of data may be necessary to achieve the relative standard error of 23% that has been suggested to produce reliable rates (  For example, if the event count is <20 in any particular year, we recommend combining years to achieve numerators ≥20, or estimating trends based on 3-year rolling averages (e.g., calculate a single rate for 1978 – 1980, then 1979 – 1981, etc), or both.  To protect patient confidentiality, we recommend that counts <10 cases be suppressed.

    Anticipated Questions and Answers

    How should death rates be age adjusted when using MCD mortality data?
    Rates should be adjusted to the U.S. 2000 standard population.  For more information about age adjustment see  In addition, please refer to the NATC surveillance document for additional discussion about when to age-adjust rates.

    What denominator data should be used when creating death rates?
    We encourage states to make use of July 1 state resident population estimates for each year (not including armed forces overseas) as denominators to maintain comparability of rates across states.  These data can be downloaded from the U.S. Census Bureau web site at

    Can deaths of persons of Hispanic ethnicity be determined using MCD mortality data?
    Data on Hispanic ethnicity are available in the MCD mortality data for 1984 and later years.  Hispanic origin can be determined from categories 1 – 5 of the 26-category “Origin or Descent” variable for the years 1984 – 1988, and from categories 1 – 5 of the 7-category “Hispanic Origin” variable for the years after 1988.  Data on Hispanic ethnicity were available for the District of Columbia and 22 states during the years 1984 – 1987; 29 states in 1988; 44 states in 1989; 47 states during 1990 – 1991; 48 states in 1992; 49 states during 1993 – 1996; and 50 states and the District of Columbia starting in 1997.

    Federal and State Contacts and Resources for NHDS Data

    Centers for Disease Control and Prevention Contacts (CDC)
    National Center for Environmental Health
    Asthma and Community Health Branch
    General Number: (770) 488-3700

    General Contact Number: 1-800-496-8347

    National Center for Health Statistics
    Division of Vital Statistics
    General Number:  1-800-232-4636

    Current state asthma contacts:


    1. United States Public Health Service. Vital Statistics of the United States, 1990. Vol. II:  Mortality, Part A.  Technical Appendix. Washington, DC:  US Government Printing Office; 1994. DHHS publication no. (PHS) 95-1101.
    2. CSTE Environmental and Chronic Disease Committees. Asthma Surveillance and Case Definition – CSTE Position Statement 1998 – EH/CD 1. Available at: