A retrospective cohort study is conducted of mortality from all causes of death among persons occupationally exposed
Question:
A retrospective cohort study is conducted of mortality from all causes of death among persons occupationally exposed to asbestos from 1970 to 2000. The standard population is the population of New York State, exclusive of New York City, for the same time period. To control for age and time period, indirect standardization is used. The person- years, observed deaths, and population rates are shown below for each stratum.
Person Years
Time Period
Age 1970-1979 1980-1989 1990-1999
20-29 1000 500 200
30-39 1000 1500 1000
40-49 1000 1700 1500
50-59 500 1000 1500
60+ 500 600 700
Observed Deaths
Time Period
Age 1970-1979 1980-1989 1990-1999
20-29 2 1 0
30-39 3 4 2
40-49 3 5 5
50-59 2 5 6
60+ 5 4 5
Standard Population Rates (per 1000 population/year)
Time Period
Age 1970-1979 1980-1989 1990-1999
20-29 1.8 1.8 1.6
30-39 2.2 2.2 1.9
40-49 3.1 2.8 2.7
50-59 4.3 4.0 3.9
60+ 6.5 6.1 5.8
1) Calculate the expected number of deaths for each stratum
Time Period
Age 1970-1979 1980-1989 1990-1999
20-29
30-39
40-49
50-59
60+
2) Summing across time period, calculate the SMR for each age stratum and for the entire study cohort.
3) Explain in a sentence the meaning of the SMR for the entire study cohort.
4) What are some of the advantages and disadvantages of using the general population of NYS, exclusive of NYC, as the comparison group for this study instead of another occupational group?
Elementary Statistics
ISBN: 978-0538733502
11th edition
Authors: Robert R. Johnson, Patricia J. Kuby