epidemiology (schneider) compare outcomes using all the above specific categories, we could compare...

Epidemiology (Schneider)

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

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

15,420188,500,741Total

12,35631,078,76045-54

2,70942,467,71935-44

30340,873,13925-34

4135,946,63515-24

1138,134,4885-14

Lung Cancer DeathsPopulationAge (years)

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

15,420 xxx188,500,741Total

12,356

2,709

303

41

11

Lung Cancer Deaths

12,356 / 31,078,760 = 39.76

2,709 / 42,467,719 = 6.38

303 / 40,873,139 = 0.74

41 / 35,946,635 = 0.11

11 / 38,134,488 = 0.03

Age-Specific Lung Cancer Death Rate

31,078,76045-54

42,467,71935-44

40,873,13925-34

35,946,63515-24

38,134,4885-14

PopulationAge

(years)

What inferences can you make from these age-specific rates?

Cause Specific Rate = (15,420/188,500,741) x 100,000

= 8.18 / 100,000


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)


Creating a cause-specific, age-adjusted death rate using direct standardization

(3) x (4) = (5)(4)(1) / (2) = (3)(2)(1)

226,500,000xxx45,000115Total

25,700,00015,00010065+

140,300,00025,0001019-64

60,500,0005,00050-18

Expected 1980 U.S.

Standard Population

Age Specific Rate (per 1000)

Population at risk

Cancer Deaths

Age

Creating a cause-specific, age-adjusted death rate using direct standardization

(3) x (4) = (5)(4)(1) / (2) = (3)(2)(1)

288,039,000226,500,000xxx45,000115Total

171,419,00025,700,0006.6715,00010065+

56,120,000140,300,0000.4025,0001019-64

60,500,00060,500,0001.005,00050-18

Expected 1980 U.S.

Standard Population

ASR / 1000Population

at riskCancer Deaths

Age

Age-Adjusted Rate

(288,039,000 / 226,500,000) x 1000

1.27 per 1,000

>

Crude Rate

(115 / 45,000) x 1000

2.56 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


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


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



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



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


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



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


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



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



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)

0.07216,348,2540-4

1.000226,545,805Total

0.0102,240,06785+

0.0347,728,75575-84

0.06915,580,60565-74

0.09621,702,87555-64

0.10122,799,78745-54

0.11325,634,71035-44

0.16437,081,83925-34

0.18842,486,82815-24

0.15434,942,0855-14

Vector (%)PopulationAge

Create a STANDARDIZATION TABLE

and calculate rates

Crude Rate = 15.283 per 1000 Age-Adjusted Rate = 6.58 per 1000

5,726

2,259

1,901

829

320

124

47

26

30

30

160

Deaths

6.581

0.825

0.983

1.100

0.737

0.301

0.157

0.131

0.109

0.208

2.030

Expected

XXXXX

82.508

28.898

15.947

7.679

2.978

1.387

0.798

0.578

1.353

28.199

ASR per 1000

0.0725,6740-4

1.000374,665Total

0.01027,37985+

0.03465,78375-84

0.06951,98565-74

0.09641,67055-64

0.10141,63345-54

0.11333,87735-44

0.16432,56525-34

0.18851,93215-24

0.15422,1675-14

Std Vector (%)Population at

RiskAge

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

0-4 760 578 309 309 108 41

5-9 43 49 31 21 24 11

10-19 126 115 90 63 49 21

20-29 444 361 288 207 149 81

30-39 378 368 296 253 164 115

40-49 364 336 253 253 175 118

50-59 366 325 267 252 171 127

60-69 475 346 304 246 172 95

70+ 672 396 343 163 127 95

Data from Frost WH: The age selection of mortality from tuberculosis in successive decades. J Hyg 30:91-96, 1939.

epidemiology (schneider) compare outcomes using all the above specific categories, we could compare...

Documents

age specific rates

ageadjusted rates

ageadjusted rate slide

outcomes age

age group

age structure

ageadjusted death rate

population age years