The Strehler-Mildvan correlation as a valuable tool for monitoring the long-term health status of a population.

The increase in the logarithm of mortality with age from 40 years onward can be described by a Gompertz linear relationship with two parameters. The long-term relationship between these two parameters can itself be described by another linear relationship known as the Strehler-Mildvan (SM) correlation. Long-term data from three countries were evaluated in the context of the SM correlation. The earliest available periods were 1751-1754 for Sweden, 1816-1819 for France, and 1850-1854 for the Netherlands, while the most recent periods were 2020-2021 for France and the Netherlands, and 2020-2023 for Sweden. The best agreement with the SM model was observed in Sweden, and the weakest in France. While the SM correlation model generally describes long-term trends well, it can be significantly disrupted over shorter calendar periods. If we view the population as a dynamic system, then large short-term shocks-such as World War I-can temporarily break the SM correlation. Over time, however, the system tends to return to an equilibrium state in which the SM model becomes applicable again.