Current Drug Abuse Reviews, 2008, 1, 255-262 255 1874-4737/08 $55.00+.00 © 2008 Bentham Science Publishers Ltd. What Constitutes Prescription Drug Misuse? Problems and Pitfalls of Current Conceptualizations Sean P. Barrett *,1,2 , Jessica R. Meisner 1 and Sherry H. Stewart 1,2 Departments of 1 Psychology and 2 Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada Abstract: Many medications with sedative, anxiolytic, analgesic, or stimulant properties have the potential to be inappro- priately used. However, because these substances have beneficial effects, many issues pertinent to understanding prescrip- tion drug misuse may differ from those associated with other misused substances. There is currently a lack of consensus about what constitutes prescription misuse and a wide range of operational criteria have been proposed. Inappropriate medication use is frequently defined on the basis of user characteristics (i.e. any non-prescribed use), the reason for use (i.e. use for recreational purposes), the presence of clinically significant symptoms (i.e. meeting diagnostic criteria for abuse and dependence) or on the presence of any of these factors. In cases where multiple criteria are used to define mis- use there is often a lack of differentiation among them, while studies that use more specific criteria tend to exclude certain types of misuse from consideration altogether. In addition, in some cases there are a number of potential ways that a sin- gle operational criterion can be met and many of these may be associated with substantially different risks, harms, and predictors. Due to considerable variability in the classification of medication misuse both within and between studies, it is currently difficult to interpret the clinical significance of existing findings or to determine the true magnitude of problems associated with any particular form of misuse. In the present review many of the problems and challenges for adequately defining prescription drug misuse will be overviewed and recommendations will be made on how to better characterize this phenomenon. Keywords: Prescription drug misuse, drug dependence, addiction, drug abuse. INTRODUCTION AND OVERVIEW The inappropriate use of prescription medications is an issue of increasing concern [1-4]. Many psychiatric medica- tions with sedative, anxiolytic, analgesic, or stimulant prop- erties have the potential to be misused and the inappropriate use of such medications has been linked to a number of seri- ous adverse outcomes (e.g. [5-7]). While demand for, and availability of, such medications have been rising steadily in recent years, so too have documented cases of their non- sanctioned use (e.g. [8, 9]). Despite this, prescription medi- cation misuse remains poorly characterized and understood. Because these drugs have legitimate therapeutic benefits in addition to their potential problematic properties, many is- sues pertinent to defining and characterising their inappro- priate use may not be adequately addressed by frameworks that have been developed to describe the use and misuse of alcohol and illicit substances. Currently, there is no universally-accepted standard for what constitutes prescription medication misuse, and a wide range of operational criteria have been used throughout the literature. Prescription misuse has been variously defined in terms prescription status (e.g. any medication uses that occur without a prescription) [10-22], reasons for use (e.g. any intentional uses for intoxicating and/or euphoric effects) [8, 12, 16, 19, 23-26], the presence or absence of symptoms of abuse or dependence [27-31], or some combination of these factors [8-9, 32-45]. Often in cases where multiple criteria *Address correspondence to this author at the Department of Psychology, Dalhousie University, Halifax, Nova Scotia Canada, B3H 4J1; Tel: 902- 494-2956; Fax: 902-494-6585; E-mail: sean.barrett@dal.ca are used, there is a lack of differentiation among them (e.g., statistics are given for the broad category of prescription drug misuse while failing to report [or often to even meas- ure] how many individuals were so categorized according to each criterion employed). In contrast, studies that use more specific criteria tend to exclude certain types of misuse from consideration altogether. Matters are further complicated by the fact that often a single criterion will encompass several behaviours and/or patterns of use that may be associated with substantially different risks and harms and fail to dis- tinguish among them. For example, there are numerous po- tential ways that a medication can be used without a pre- scription (e.g. use for therapeutic benefits vs use for intoxi- cating properties), for its intoxicating effects (different pat- terns and routes of administration), or that an individual can become dependent on a medication (e.g. using medication as prescribed for extended periods vs substituting medication for an illicit substance with similar pharmacologic proper- ties). Due to the heterogeneity in individuals classified as ‘misusers’, both within and between studies, it is often diffi- cult to interpret the clinical significance of existing findings or to determine the true magnitude of problems associated with any particular form of inappropriate medication use. The primary purpose of this paper is to overview the problems and challenges for defining prescription drug mis- use. Emphasis is placed on difficulties posed by various con- ceptualizations commonly found in the scientific literature (i.e. any non-prescribed use; recreational use; meeting diag- nostic criteria for a substance use disorder; and the criteria used by the American National Survey on Drug Use and Health [A-NSDUH] [9]; a summary operational definitions used in the literature is presented in Table 1). Because there is often a lack of consistency and precision in the terminol-