1. 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

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

3. 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?

4. 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?

5. 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)

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

7. 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

8. 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)

9. 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

10. 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

11. 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)

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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 standard

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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 = per Age-Adjusted Rate = 6.58 per 1000

25. 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,
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.

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