Contagion models for the transmission of drug abuse among propinquity-of-rearing defined acquaintances : A Swedish national study
Background: Can we validate a contagion model for drug abuse (DA) in Propinquity-of-Rearing Defined Acquaintances (PRDAs)? Methods: PRDAs were defined as pairs of same-age males born 1975–1990 who grew up within 2 km of each other, one of whom (PRDA1) being first registered for DA in national registries. Using adult residential location, we predicted, using regression splines, proximity-dependent