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Age Adjustment Issues in Healthy People 2010. John Aberle-Grasse, MPH National Center for Health Statistics. Calculation of age-adjusted rate. Age-adjusted rate = S i (m i *w si ) m i = d i / p i * 100,000 w si = standard population weight in age group i
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Age Adjustment Issues in Healthy People 2010 John Aberle-Grasse, MPH National Center for Health Statistics
Calculation of age-adjusted rate • Age-adjusted rate = • Si (mi*wsi) • mi = di / pi * 100,000 • wsi = standard population weight in age group i • di = deaths in age group i • pi = population in age group i
Calculation of age-adjusted rate • Spreadsheet 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 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 adjustment
Standard population- a population based on some age distribution • NCHS 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 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, 1979-2000 2000 standard crude rate 1940 standard
Standard population- a population based on some age distribution • IMPORTANT REMINDER: Comparisons can only be made between rates calculated using the same standard population
Age-adjustment inHealthy People 2010 • Mortality data • Health outcomes, risk factors, and health services data
Diabetes prevalence by race/ethnicity (Obj. 5-3), 1999 Overall Hispanic/ Latino Asian/ Pacific Islander Not-Hispanic African American Not-Hispanic White American Indian/ Alaska Native Source: National Health Interview Survey (NHIS), CDC, NCHS.
Diabetes age specific rates, 1999 Source: National Health Interview Survey (NHIS), CDC, NCHS.
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.
Age-adjustment inHealthy People 2010 • Mortality data • Health outcomes, risk factors, and health services data • Main purposes: • Observe trends in populations over time • Monitor disparity between populations both at a point in time and over time
Standard population- age distributions • Several different age groupings are used to age-adjust data from different sources
Standard population- age distributions • Several 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)
Hispanics aged 2+ years with diabetes who have seen a dentist in the past year (Obj. 5-15) Age-adjusted Crude 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) < 45 separate < 45 combined Crude Source: National Health Interview Survey (NHIS), CDC, NCHS.
Some exceptions • Data that are not age-adjusted • Maternal/Infant mortality (live births as denominator) • National Household Survey on Drug Abuse • Occupational injury and death • Fatality Analysis Reporting System • Census of Fatal Occupational Injuries
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 1995 1995 1970 Source: National Vital Statistics System, CDC, NCHS.
Female cancer death rates, by age adjustment standard Crude rate 2000 standard population 1940 standard population Source: National Vital Statistics System, CDC, NCHS.