• mortality
• population change

Modern societies are extremely mobile, yet the influence of population change in residential areas on mortality has rarely been investigated. Davey Smith et al showed that male and female mortality around the time of the 1991 census across 292 areas in Britain was inversely correlated with population growth in the previous two decades.^1,2 Molarius and Janson studied 16 municipalities in Sweden and found a similar correlation between population changes from 1975 to 1994 and male mortality in 1992–96, but no correlation with mortality in women.³ The authors of both studies pointed out that, if possible, people leave unfavourable social and physical environments to move to more attractive places, so that relative population shrinkage occurs in areas with high mortality.

A subject that has not been investigated is the possible relation between population changes and the magnitude of inequalities in mortality. That is, does population change lead to decreasing or increasing mortality inequalities within areas? As a person’s mobility is related with better health,⁴ inequalities in mortality are presumably smaller in growing areas than in those that are shrinking because people arriving in an area are healthy but their health is not dependent of their socioecenomic characteristics.^5,6