[Zurück]

J. P. Caulkins, G. Tragler, D. Wallner:
"Optimal timing of use reduction vs. harm reduction in a drug epidemic model";
International Journal of Drug Policy (eingeladen), 20 (2009), 6; S. 480 - 487.

Background: Opponents of harm reduction fear that reducing harmfulness might increase use, and opponents
of use reduction fear that efforts to reduce use can increase harmfulness. We raise the possibility
that both strategies have a role but at different points in a drug "epidemic".
Methods: We present a stylized two-state, one-control policy simulation model of the use vs. harm
reduction choice when initiation stems from susceptible non-users interacting with current users.
Results: Within this model, whether harm reduction is a good strategy can depend on the particular drug
and/or country, the social cost structure, and the stage of the epidemic. The dynamic solutions also involve
indifference curves, consisting of points where the decision maker is indifferent between two transients
that will approach the same steady state in the long run. Depending on howoverall prevalence feeds back
to affect the likelihood a susceptible non-user will initiate after interacting with a current user, the model
can have tipping points where small shocks can haveamplified long-run effects. For most epidemic states,
harm reduction reduces the present value of future social costs, but not near such tipping points.
Conclusion: To the extent that drug use patterns involve feedback effects, any shock to initiation - from
harm reduction or any other source - can produce changes in use that are more than proportional, or
less than proportional, to the shock. Hence, advocates in the use vs. harm reduction debate may wish to
explain why their preferred policy is particularly appropriate at the current stage of a country´s drug use
trajectory, rather than arguing for universal applicability of their preferred programme.

Drug policy, Harm reduction, Optimal control, Epidemics

http://dx.doi.org/10.1016/j.drugpo.2009.02.010