Age Adjustment Issues in Healthy People 2010 John Aberle-Grasse, MPH National Center for Health Statistics

Calculation of age-adjusted rate Age-adjusted rate =  i (m i *w si ) m i = d i / p i * 100,000 w si = standard population weight in age group i d i = deaths in age group i p i = population in age group i

Calculation of age-adjusted rate Spreadsheet vs. “manual” calculationSpreadsheet vs. “manual” calculation  NCHS continues to use “manual” method  Healthy People 2010 rate calculations are rounded/truncated to one decimal place  Weights are rounded/truncated to six places

Standard population- a population based on some age distribution NCHS in the pastNCHS in the past  mortality data used 1940 standard  survey data used mostly 1970 & 1980 standard NCHS now uses year 2000 US resident population as standard for all age adjustmentNCHS now uses year 2000 US resident population as standard for all age adjustment

Standard population- a population based on some age distribution NCHS in the pastNCHS in the past  mortality data used 1940 standard  survey data used mostly 1970 & 1980 standard NCHS now uses year 2000 US resident population as standard for all age adjustmentNCHS now uses year 2000 US resident population as standard for all age adjustment  2000-adjusted rates better reflect national demographics and current crude rates

Crude and age adjusted death rates based on year 1940 and 2000 standard populations: United States, standard 2000 standard crude rate

Standard population- a population based on some age distribution IMPORTANT REMINDER: Comparisons can only be made between rates calculated using the same standard populationIMPORTANT REMINDER: Comparisons can only be made between rates calculated using the same standard population

Mortality dataMortality data Health outcomes, risk factors, and health services dataHealth outcomes, risk factors, and health services data Age-adjustment in Healthy People 2010

Diabetes prevalence by race/ethnicity (Obj. 5-3), 1999 Source: National Health Interview Survey (NHIS), CDC, NCHS. Overall American Indian/ Alaska Native Asian/ Pacific Islander Hispanic/Latino Not-HispanicWhite Not-Hispanic African American

Diabetes age specific rates, 1999 Source: National Health Interview Survey (NHIS), CDC, NCHS.

2000 Census age distribution

Diabetes prevalence (Obj. 5-3), 1999 Source: National Health Interview Survey (NHIS), CDC, NCHS.

Diabetes prevalence (Obj. 5-3), 1999 Source: National Health Interview Survey (NHIS), CDC, NCHS.

Mortality dataMortality data Main purposes:Main purposes:  Observe trends in populations over time  Monitor disparity between populations both at a point in time and over time Health outcomes, risk factors, and health services dataHealth outcomes, risk factors, and health services data Age-adjustment in Healthy People 2010

Standard population- age distributions Several different age groupings are used to age-adjust data from different sourcesSeveral different age groupings are used to age-adjust data from different sources

Data systems Age distributions used

Standard population- age distributions Several different age groupings are used to age-adjust data from different sourcesSeveral different age groupings are used to age-adjust data from different sources Some data sources use fewer age groupings to stabilize the rates of less common events and smaller subpopulations (e.g. age groups for chronic disease)Some data sources use fewer age groupings to stabilize the rates of less common events and smaller subpopulations (e.g. age groups for chronic disease)

Hispanics aged 2+ years with diabetes who have seen a dentist in the past year (Obj. 5-15) Crude Age-adjusted Source: National Health Interview Survey (NHIS), CDC, NCHS.

Hispanics aged 2+ years with diabetes who have seen a dentist in the past year (Obj. 5-15) Source: National Health Interview Survey (NHIS), CDC, NCHS.

Hispanics aged 2+ years with diabetes who have seen a dentist in the past year (Obj. 5-15) Crude < 45 separate < 45 combined Source: National Health Interview Survey (NHIS), CDC, NCHS.

Some exceptions Data that are not age-adjustedData that are not age-adjusted  National Household Survey on Drug Abuse  Occupational injury and death  Fatality Analysis Reporting System  Census of Fatal Occupational Injuries  Maternal/Infant mortality (live births as denominator)

Some exceptions When to be careful in age-adjusting  Age specific rates for a measure vary differently between two population groups

Age specific cancer death rates among females, 1970 to Source: National Vital Statistics System, CDC, NCHS.

Female cancer death rates, by age adjustment standard 1940 standard population 2000 standard population Source: National Vital Statistics System, CDC, NCHS. Crude rate