Indirect Age adjustment, cohort effect, interpreting observed changes in mortality

Indirect Age adjustmentLa Rosa, Gabrielle AnneMed- 2AIndirect age adjustmentused when numbers of deaths for each age-specific stratum are not availableused to study mortality in an occupationally exposed populationDo people who work in a certain industry, such as mining or construction, have a higher mortality than people of the same age in the general population?Is an additional risk associated with that occupation?

EXAMPLE OF INDIRECT AGE ADJUSTMENTIn a population of 534,533 white male miners, 436 died from tuberculosis (TBC) in 1950.How many deaths would we expect in these white miners if they had the same mortality experience as white men in the same age group in the general population?

Indirect age adjustmentChoose a reference or standard population. Calculate the observed number of deaths in the population (s) of interest. Multiply the number of people in each age group of the population(s) of interest by the age-specific mortality rate in the comparable age group of the reference population. Add the total number of expected deaths for the population of interest. Divide the total number of observed deaths of the population(s) of interest by the expected deaths (SMR).

Interpretation of Standardized mortality ratio (SMR)SMR=100 or 1observed number of deaths is the same as the expected number of deathsSMR>100 observed number of deaths exceeds the expected numberSMR