Compare Outcomes Using all the above specific categories, we could compare 0-4 year-old male Asian mortality rates for asthma with 0-4 Asian female rates for asthma 0-4 other than Asian male rates for asthma 0-4 Asian male rates for diseases other than asthma Data Sets and Outcome Measures - Part 3

What information will you need? Calculation Practice Calculate cause-specific and age-specific lung cancer death rates What information will you need?

Lung Cancer Deaths by Age Group, United States, 1995 Age (years) Population 5-14 38,134,488 11 15-24 35,946,635 41 25-34 40,873,139 303 35-44 42,467,719 2,709 45-54 31,078,760 12,356 Total 188,500,741 15,420 How would you calculate the cause-specific lung cancer death rate? How would you calculate age-specific lung cancer death rates?

Lung Cancer Deaths by Age Group, United States, 1995 Age (years) Population Lung Cancer Deaths Age-Specific Lung Cancer Death Rate 5-14 38,134,488 11 11 / 38,134,488 = 0.03 15-24 35,946,635 41 41 / 35,946,635 = 0.11 25-34 40,873,139 303 303 / 40,873,139 = 0.74 35-44 42,467,719 2,709 2,709 / 42,467,719 = 6.38 45-54 31,078,760 12,356 12,356 / 31,078,760 = 39.76 Total 188,500,741 15,420 xxx Cause Specific Rate = (15,420/188,500,741) x 100,000 = 8.18 / 100,000 What inferences can you make from these age-specific rates?

Mortality Outcomes (cont.) Adjusted rate: Used to compare rates for entire populations, taking into account differences in variables we consider as influencing outcomes (age, gender, race)

Two methods to adjust rates: Direct Method: AAR (age-adjusted rate) Indirect Method: SMR (standardized mortality ratio)

Standardization for Age (Age Adjustment) Direct method Requires Age-specific rates for the sample Age-structure of a standard population Yields a summary figure: AGE-ADJUSTED RATE

Standardization: Age Adjustment (cont.) Indirect method Requires Age structure of the sample population at risk Total cases in the sample population (not ages of cases) Age-specific rates for a standard population Yields a summary figure: STANDARDIZED MORTALITY RATIO (SMR)

Age Specific Rate (per 1000) Creating a cause-specific, age-adjusted death rate using direct standardization Age Cancer Deaths Population at risk Age Specific Rate (per 1000) Expected 1980 U.S. Standard Population (1) (2) (1) / (2) = (3) (4) (3) x (4) = (5) 0-18 5 5,000 60,500,000 19-64 10 25,000 140,300,000 65+ 100 15,000 25,700,000 Total 115 45,000 xxx 226,500,000

Creating a cause-specific, age-adjusted death rate using direct standardization Standard Population Age Cancer Deaths Population at risk ASR / 1000 Expected (1) (2) (1) / (2) = (3) (4) (3) x (4) = (5) 0-18 5 5,000 1.00 60,500,000 60,500,000 19-64 10 25,000 0.40 140,300,000 56,120,000 65+ 100 15,000 6.67 25,700,000 171,419,000 Total 115 45,000 xxx 226,500,000 288,039,000 Crude Rate (115 / 45,000) x 1000 2.56 per 1,000 > Age-Adjusted Rate (288,039,000 / 226,500,000) x 1000 1.27 per 1,000

Comparing crude and age-adjusted rates If crude rate decreases after adjustment, the study population is older than the standard population (Crude rate > age-adjusted rate  study population is older) If crude rate increases after adjustment, the study population is younger than the standard population (Crude rate < age-adjusted rate  study population is younger)

The adjusted rate tells you what the rate would be if the sample population had a similar age structure to that of the United States in 1980

Comparing Crude and Age-Adjusted Rates Crude Death Rate per 100,000 Age-Adjusted Death Rate per 100,000 San Fran Males 1,245 1,120 San Jose Males 650 1,176 San Fran Females 1,074 652 San Jose Females 536 697

Comparing Crude and Age-Adjusted Rates (cont.) San Francisco males and females had crude rates double those for their counterparts in San Jose San Francisco may have had an older population than San Jose and therefore higher crude rates NEVER assume from crude rates that one place is less healthy than another

Comparing Crude and Age-Adjusted Rates (cont.) When age structure was controlled through age-adjustment, San Francisco no longer stood out as having higher rates San Jose’s age-adjusted rates were slightly higher than those for San Francisco Public health as measured by age-adjusted rates is not significantly different between the two cities Note: Failure to take differences in population structures into account may lead to inappropriate conclusions Adjustment aids in preventing CONFOUNDING

Comparing Crude and Age-Adjusted Rates (cont.) One type of rate is not necessarily more important than another Which you choose depends on the information sought To estimate the economic burden of high rates on a community, it is usual to start with crude rates Crude rates are often used for health services planning

Comparing Crude and Age-Adjusted Rates (cont.) To compare rates among subpopulations or for various causes, specific rates are preferred infant mortality maternal mortality rates To compare the health of entire populations, adjusted rates are preferred as they allow for comparison of populations with different demographic structures

New 2000 Standard for Age-Adjustment Historically, a 1940 base-year has been used for age-adjustment Also, other standards have been used which created confusion among data users Starting September 1, 1998, HHS agencies and programs were required to use the year 2000 standard

New 2000 Standard for Age-Adjustment (cont.) What are the implications? When describing disparities in mortality between racial and ethnic groups, the size of the disparity between Blacks and Whites and between Hispanics and Non-Hispanics will be affected

New 2000 Standard for Age-Adjustment (cont.) Example: The mortality ratio for Black and White total populations in 1995 is reduced from 1.6 (1940 standard) to 1.4 (2000 standard) The Blacks population tends to be younger than the White population

New 2000 Standard for Age-Adjustment (cont.) NCHS recommends that researchers present age-specific rates, not just AARs If an AAR is used to describe racial and ethnic disparities, explain the impact of the change in the standard and provide age- specific rates When comparing AARs over time, make sure the same standard is used throughout

Alternate Method of Direct Adjustment Some calculators cannot handle large numbers To overcome this limitation, you can convert your standard population into a standard vector

Calculate a STANDARD VECTOR (1980 US Census) Age Population Vector (%) 0-4 16,348,254 0.072 5-14 34,942,085 0.154 15-24 42,486,828 0.188 25-34 37,081,839 0.164 35-44 25,634,710 0.113 45-54 22,799,787 0.101 55-64 21,702,875 0.096 65-74 15,580,605 0.069 75-84 7,728,755 0.034 85+ 2,240,067 0.010 Total 226,545,805 1.000

Create a STANDARDIZATION TABLE and calculate rates Age Deaths Population at Risk ASR per 1000 Std Vector (%) Expected 0-4 160 5,674 28.199 0.072 2.030 5-14 30 22,167 1.353 0.154 0.208 15-24 30 51,932 0.578 0.188 0.109 25-34 26 32,565 0.798 0.164 0.131 35-44 47 33,877 1.387 0.113 0.157 124 41,633 2.978 0.101 0.301 45-54 320 41,670 7.679 0.096 0.737 55-64 65-74 829 51,985 15.947 0.069 1.100 75-84 1,901 65,783 28.898 0.034 0.983 85+ 2,259 27,379 82.508 0.010 0.825 Total 5,726 374,665 XXXXX 1.000 6.581 Crude Rate = 15.283 per 1000 Age-Adjusted Rate = 6.58 per 1000

Sometimes there are COHORT EFFECTS that need to be considered as specific groups may vary in exposures or treatments as they move together through time. Age-Specific Death Rates per 100,000 From Tuberculosis (All Forms), Males, Massachusetts, 1880-1930 Year Age (yr) 1880 1890 1900 1910 1920 1930 0-4 760 578 309 108 41 5-9 43 49 31 21 24 11 10-19 126 115 90 63 20-29 444 361 288 207 149 81 30-39 378 368 296 253 164 40-49 364 336 175 118 50-59 366 325 267 252 171 127 60-69 475 346 304 246 172 95 70+ 672 396 343 163 Data from Frost WH: The age selection of mortality from tuberculosis in successive decades. J Hyg 30:91-96, 1939.

Age-specific death rates from tuberculosis (all forms) among males in successive ten-year birth cohorts, Massachusetts