ECNP consensus meeting March 2003 guidelines for the investigation of efficacy in substance use disorders

Validating the clinical relevance of alternative stimulant use treatment outcome measures by examining their association with 3-month follow-up outcomes

The lack of a consensus on empirically supported and clinically meaningful outcome measures for stimulant use disorders (SUDs) continues to undermine the development and evaluation of effective behavioral and pharmacological treatment options. The aim of this study was to evaluate the clinical relevance of four stimulant use treatment outcome measures (longest duration of abstinence [LDA], percent of negative urinalysis submitted, abstinent in the last 2 weeks of treatment, and three or more weeks of continuous abstinence) by exploring their utility via association with stimulant and alcohol use, employment and legal problems, and severity of psychiatric symptomatology collected at follow-up. Data used in these secondary analyses came from a multisite randomized contingency management treatment trial for SUDs (n = 441) conducted through the NIDA Clinical Trials Network. Multiple regression analyses were conducted to explore the association of four stimulant use treatment outcome measures and eight 3-month follow-up outcomes. The percent of negative urinalysis outcomes showed the most consistent performance compared to alternative outcomes, being significantly associated with better responses in all eight 3-month follow-up outcomes (β range: -169 to -241, p < .01). Both dichotomous outcome measures showed similar performances being significantly associated with four follow-up outcomes (β range: -159 to -203, p < .01). All outcome measures were consistently associated with better outcome responses at the 3-month follow-up, adding support to their clinical relevance and their adoption in SUD treatment trials. The two dichotomous outcome measures are reliable candidates to be used as endpoint outcomes, as recommended by the U.S. Food and Drug Administration (FDA). (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The state of clinical outcome assessments for cannabis use disorder clinical trials: A review and research agenda

There is considerable variability in the use of outcome measures in clinical trials for cannabis use disorder (CUD), and a lack of consensus regarding optimal outcomes may have hindered development and approval of new pharmacotherapies. The goal of this paper is to summarize an evaluation of assessment measures and clinical endpoints for CUD clinical trials, and propose a research agenda and priorities to improve CUD clinical outcome assessments. The primary recommendation is that sustained abstinence from cannabis should not be considered the primary outcome for all CUD clinical trials as it has multiple limitations. However, there are multiple challenges to the development of a reliable and valid indicator of cannabis reduction, including the lack of a standard unit of measure for the various forms of cannabis and products and the limitations of currently available biological and self-report assessments. Development of a core toolkit of assessments is needed to both allow flexibility for study design, while facilitating interpretation of outcomes across trials. Four primary agenda items for future research are identified to expedite development of improved clinical outcome assessments for this toolkit: (1) determine whether minimally invasive biologic assays could identify an acute level of cannabis use associated with psychomotor impairment or other cannabis-related harms; (2) create an indicator of quantity of cannabis use that is consistent across product types; (3) examine the presence of cannabis-specific functional outcomes; and (4) identify an optimal duration to assess changes in CUD diagnostic criteria.

Within-treatment frequency of use versus abstinence as a predictor of longitudinal post-treatment follow-up assessments of drug use

BACKGROUND

Abstinence is a widely-used endpoint in clinical trials of stimulant use disorders. A quantitative measure of frequency of use may be a more sensitive endpoint; however, it is important to establish that it is associated with post-treatment drug use. We examine and compare how within-treatment abstinence and frequency of use are related to two post-treatment longitudinal measures of drug use.

METHODS

For each of three existing stimulant use disorder clinical trial datasets, we examined the association between within-treatment frequency of use (based on urine screens), within-treatment abstinence, and post-treatment follow-up assessments of drug use (urine screens and reported days of use). In joint analyses that simultaneously model the effects of within-treatment abstinence and frequency of use, it is possible to discern their relative importance as predictors of post-treatment drug use during the 12 months following the end of treatment.

RESULTS

Results indicate a quantitative measure of within-treatment frequency of use was associated with longitudinal post-treatment follow-up assessments of drug use. Results from joint analyses of post-treatment follow-up drug use assessed by urine screens suggest that within-treatment frequency of use, rather than abstinence per se, is predictive of post-treatment drug use. However, results from joint analyses of self-report of days of use are equivocal.

CONCLUSION

Results lend support to the use of a quantitative measure of within-treatment drug use as an alternative to complete abstinence. They suggest that some within-treatment use that fall short of complete abstinence may potentially represent clinically important improvements given their association with post-treatment drug use.

Statistical considerations in the choice of endpoint for drug use disorder trials

BACKGROUND

To date, the US Food and Drug Administration (FDA) requires drug use disorder trials developing new medications to use abstinence, a clinically meaningful endpoint, as the primary outcome. Although abstinence is the gold standard, only a relatively small percentage of participants in drug use disorder trials ever achieve this endpoint. This has prompted clinical trialists to consider quantitative measures of frequency of use, recognizing that some reductions in drug use that fall short of complete abstinence may potentially represent clinically important improvements. While much of the discussion concerning alternative outcomes to abstinence has focused on their clinical relevance, there are important statistical considerations that should also be taken into account.

PURPOSE

In this paper, we demonstrate and highlight the degree to which use of a quantitative measure of frequency of use, relative to a binary measure of abstinence, yields a very discernible increase in statistical power for assessing efficacy or effectiveness of treatments for drug use disorders.

CONCLUSION

While it is well established that dichotomizing a quantitative measure invariably results in loss of statistical power, what is less well recognized is the degree of loss in the context of drug use disorder trials. In some cases, the required sample size must be almost doubled to achieve the same level of power.

Medications development for substance-use disorders: contextual influences (dis)incentivizing pharmaceutical-industry positioning

INTRODUCTION

The significant contribution of substance-use disorders (SUDs) to the global-disease burden and associated unmet medical needs has not engendered a commensurate level of pharma-industry research and development (R&D) for novel SUD therapeutics invention. Analysis of contextual factors shaping this position suggests potential routes toward incentivizing R&D commitment for that purpose.

AREAS COVERED

This article considers multiple primary factors that have consorted to disincentivize pharma industry's operating in the SUD space: ill-understood pathology; variegated treatments and patient profiles; involved clinical trials; and - with particular reference to SUDs-negative cultural/business stigmas and shallow commercial precedent. Industry incentivization for SUD drug innovation requires progress on several fronts, including: translational experimental data and systems; personalized, holistic SUD treatment approaches; interactions among pharma, nonindustry constituencies, and the medical profession with vested interests in countering negative stereotypes and expanding SUD treatment options; and public-private alliances focused on improving SUD pharmacotherapy.

EXPERT OPINION

Given the well-entrenched business stance whereby the prospect of future profits in major markets largely determines drug-company R&D investment trajectory, strategic initiatives offering substantial reductions in the risks and opportunity (i.e., time and money) costs associated with SUD drug discovery are likely to be the most potent drivers for encouraging mainstream industry positioning in this therapeutic area. Such initiatives could originate from front-loaded R&D operational and back-loaded patent, regulatory, marketing and health-care policy reforms. These may be too involved and protracted for the turbulent pharmaceutical industry to entertain amid its recent retrenchment from psychiatric/CNS diseases and intense pressures to increase productivity and shareholder value.

Beyond drug use: a systematic consideration of other outcomes in evaluations of treatments for substance use disorders

Across the addictions field, the primary outcome in treatment research has been reduction in drug consumption. A comprehensive view of the impact of substance use disorders on human functioning suggests that effective treatments should address the many consequences and features of addiction beyond drug use, a recommendation forwarded by multiple expert panels and review papers. Despite recurring proposals, and a compelling general rationale for moving beyond drug use as the sole standard for evaluating addiction treatment, the field has yet to adopt any core set of 'other' measures that are routinely incorporated into treatment research. Among the many reasons for the limited impact of previous proposals has been the absence of a clear set of guidelines for selecting candidate outcomes. This paper is the result of the deliberations of a panel of substance abuse treatment and research experts convened by the National Institute on Drug Abuse to discuss appropriate outcome measures for clinical trials of substance abuse treatments. This paper provides an overview of previous recommendations and outlines specific guidelines for consideration of candidate outcomes. A list of outcomes meeting those guidelines is described and illustrated in detail with two outcomes: craving and quality of life. The paper concludes with specific recommendations for moving beyond the outcome listing offered in this paper to promote the programmatic incorporation of these outcomes into treatment research.

Primary outcome indices in illicit drug dependence treatment research: systematic approach to selection and measurement of drug use end-points in clinical trials

AIMS

Clinical trials test the safety and efficacy of behavioral and pharmacological interventions in drug-dependent individuals. However, there is no consensus about the most appropriate outcome(s) to consider in determining treatment efficacy or on the most appropriate methods for assessing selected outcome(s). We summarize the discussion and recommendations of treatment and research experts, convened by the US National Institute on Drug Abuse, to select appropriate primary outcomes for drug dependence treatment clinical trials, and in particular the feasibility of selecting a common outcome to be included in all or most trials.

METHODS

A brief history of outcomes employed in prior drug dependence treatment research, incorporating perspectives from tobacco and alcohol research, is included. The relative merits and limitations of focusing on drug-taking behavior, as measured by self-report and qualitative or quantitative biological markers, are evaluated.

RESULTS

Drug-taking behavior, measured ideally by a combination of self-report and biological indicators, is seen as the most appropriate proximal primary outcome in drug dependence treatment clinical trials.

CONCLUSIONS

We conclude that the most appropriate outcome will vary as a function of salient variables inherent in the clinical trial, such as the type of intervention, its target, treatment goals (e.g. abstinence or reduction of use) and the perspective being taken (e.g. researcher, clinical program, patient, society). It is recommended that a decision process, based on such trial variables, be developed to guide the selection of primary and secondary outcomes as well as the methods to assess them.

The clinical significance of drug craving

Although drug craving has received considerable research attention over the past several decades, to date there has been no systematic review of the general clinical significance of craving. This paper presents an overview of measurement issues of particular relevance to a consideration of use of craving in clinical settings. The paper then considers the relevance of craving across a broad array of clinical domains, including diagnosis, prognostic utility, craving as an outcome measure, and the potential value of craving as a direct target of intervention. The paper is both descriptive and prescriptive, informed by the current state of the science on craving with recommendations for the definition of craving, assessment practices, future research, and clinical applications. We conclude that craving has considerable utility for diagnosis and as a clinical outcome, and that findings from future research will likely expand the clinical potential of the craving construct in the domains of prognosis and craving as a treatment target.