Use of hierarchical cluster analysis to classify prisons in Ireland into mutually exclusive drug-use risk categories

AbstractAims: The aim of this paper is to propose a methodology for classifying prisons into distinct drug-use risk categories based on prisoners’ use of specified prescription and illegal drugs. The categories of prisons thus defined have particular relevance for the planning of drug-related interventions, education and services in Irish prisons. The methodology may be transferable to, and of value in, prison systems elsewhere. Methods: From the 14 prisons in Ireland, 824 randomly selected prisoners completed a self-administered questionnaire on lifetime, last year and last month use of specified prescription and non-prescription drugs. Questions were derived from the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and other sources. Oral fluid samples were collected for verification of recent drug use. The EMCDDA definition of “recent problematic drug use” was used in post hoc hierarchical cluster analysis to define categories of prisons with similar drug-use patterns. Findings: Four ca...