ageadjusted

Ageadjusted refers to the adjustment of a rate to account for differences in age distribution between populations or over time. It is a standard technique in epidemiology and public health used to enable fair comparisons of disease incidence, prevalence, or mortality when age structures differ.

The core idea is to remove the confounding effect of age by applying a common age distribution, called a standard population, to the observed data. There are two main methods: direct standardization and indirect standardization. In direct standardization, the age-specific rates from the study population are applied to the age distribution of a standard population. The resulting sum, typically expressed per 100,000 people, is the age-adjusted rate for that population. In indirect standardization, the standard population’s age-specific rates are applied to the study population’s age distribution to estimate expected cases; comparisons often use measures like the standardized mortality ratio (SMR).

Age-adjusted rates are widely used to compare regions, countries, or time periods where age profiles differ, such as evaluating cancer mortality or cardiovascular disease rates across populations. They are also used in trend analysis to assess whether changes reflect real shifts in risk rather than changes in age structure. Limitations include dependence on the choice of standard population and potential masking of risk in specific age groups. Consequently, age-adjusted rates should be interpreted in context and alongside unadjusted figures when possible.