Generalizability of clinical trials for cannabis dependence to community samples

Estimating the impact of stimulant use on initiation of buprenorphine and extended-release naltrexone in two clinical trials and real-world populations

BACKGROUND

Co-use of stimulants and opioids is rapidly increasing. Randomized clinical trials (RCTs) have established the efficacy of medications for opioid use disorder (MOUD), but stimulant use may decrease the likelihood of initiating MOUD treatment. Furthermore, trial participants may not represent "real-world" populations who would benefit from treatment.

METHODS

We conducted a two-stage analysis. First, associations between stimulant use (time-varying urine drug screens for cocaine, methamphetamine, or amphetamines) and initiation of buprenorphine or extended-release naltrexone (XR-NTX) were estimated across two RCTs (CTN-0051 X:BOT and CTN-0067 CHOICES) using adjusted Cox regression models. Second, results were generalized to three target populations who would benefit from MOUD: Housed adults identifying the need for OUD treatment, as characterized by the National Survey on Drug Use and Health (NSDUH); adults entering OUD treatment, as characterized by Treatment Episodes Dataset (TEDS); and adults living in rural regions of the U.S. with high rates of injection drug use, as characterized by the Rural Opioids Initiative (ROI). Generalizability analyses adjusted for differences in demographic characteristics, substance use, housing status, and depression between RCT and target populations using inverse probability of selection weighting.

RESULTS

Analyses included 673 clinical trial participants, 139 NSDUH respondents (weighted to represent 661,650 people), 71,751 TEDS treatment episodes, and 1,933 ROI participants. The majority were aged 30-49 years, male, and non-Hispanic White. In RCTs, stimulant use reduced the likelihood of MOUD initiation by 32% (adjusted HR [aHR] = 0.68, 95% CI 0.49-0.94, p = 0.019). Stimulant use associations were slightly attenuated and non-significant among housed adults needing treatment (25% reduction, aHR = 0.75, 0.48-1.18, p = 0.215) and adults entering OUD treatment (28% reduction, aHR = 0.72, 0.51-1.01, p = 0.061). The association was more pronounced, but still non-significant among rural people injecting drugs (39% reduction, aHR = 0.61, 0.35-1.06, p = 0.081). Stimulant use had a larger negative impact on XR-NTX initiation compared to buprenorphine, especially in the rural population (76% reduction, aHR = 0.24, 0.08-0.69, p = 0.008).

CONCLUSIONS

Stimulant use is a barrier to buprenorphine or XR-NTX initiation in clinical trials and real-world populations that would benefit from OUD treatment. Interventions to address stimulant use among patients with OUD are urgently needed, especially among rural people injecting drugs, who already suffer from limited access to MOUD.

Threats to external validity in the neuroprediction of substance use treatment outcomes

Background: Tools predicting individual relapse risk would invaluably inform clinical decision-making (e.g. level-of-care) in substance use treatment. Studies of neuroprediction - use of neuromarkers to predict individual outcomes - have the dual potential to create such tools and inform etiological models leading to new treatments. However, financial limitations, statistical power demands, and related factors encourage restrictive selection criteria, yielding samples that do not fully represent the target population. This problem may be further compounded by a lack of statistical optimism correction in neuroprediction research, resulting in predictive models that are overfit to already-restricted samples.Objectives: This systematic review aims to identify potential threats to external validity related to restrictive selection criteria and underutilization of optimism correction in the existing neuroprediction literature targeting substance use treatment outcomes.Methods: Sixty-seven studies of neuroprediction in substance use treatment were identified and details of sample selection criteria and statistical optimism correction were extracted.Results: Most publications were found to report restrictive selection criteria (e.g. excluding psychiatric (94% of publications) and substance use comorbidities (69% of publications)) that would rule-out a considerable portion of the treatment population. Furthermore, only 21% of publications reported optimism correction.Conclusion: Restrictive selection criteria and underutilization of optimism correction are common in the existing literature and may limit the generalizability of identified neural predictors to the target population whose treatment they would ultimately inform. Greater attention to the inclusivity and generalizability of addiction neuroprediction research, as well as new opportunities provided through open science initiatives, have the potential to address this issue.

Peer support and online cognitive behavioural therapy for substance use concerns: protocol for a randomised controlled trial

INTRODUCTION

Hazardous alcohol and drug use is associated with substantial morbidity, mortality and societal cost worldwide. Yet, only a minority of those struggling with substance use concerns receive specialised services. Numerous barriers to care exist, highlighting the need for scalable and engaging treatment alternatives. Online interventions have exhibited promise in the reduction of substance use, although studies to date highlight the key importance of patient engagement to optimise clinical outcomes. Peer support may provide a way to engage patients using online interventions. The goal of this study is to evaluate the efficacy and cost-effectiveness of Breaking Free Online (BFO), an online cognitive-behavioural intervention for substance use, delivered with and without peer support.

METHODS AND ANALYSIS

A total of 225 outpatients receiving standard care will be randomised to receive clinical monitoring with group peer support, with BFO alone, or with BFO with individual peer support, in an 8-week trial with a 6-month follow-up. The primary outcome is substance use frequency; secondary outcomes include substance use problems, depression, anxiety, quality of life, treatment engagement and cost-effectiveness. Mixed effects models will be used to test hypotheses, and thematic analysis of qualitative data will be undertaken.

ETHICS AND DISSEMINATION

The protocol has received approval by the Centre for Addiction and Mental Health Research Ethics Board. Results will help to optimise the effectiveness of structured online substance use interventions provided as an adjunct to standard care in hospital-based treatment programmes. Findings will be disseminated through presentations and publications to scholarly and knowledge user audiences.

TRIAL REGISTRATION NUMBER

NCT05127733.

Under-representation of key demographic groups in opioid use disorder trials

Background

The extent to which clinical trials of medications for opioid use disorder (MOUD) are representative or not is unknown. Some patient characteristics modify MOUD effectiveness; if these same characteristics differ in distribution between the trial population and usual-care population, this could contribute to lack of generalizability-a discrepancy between trial and usual-care effectiveness. Our objective was to identify interpretable, multidimensional subgroups who were prescribed MOUD in substance use treatment programs in the US but who were not represented or under-represented by clinical trial participants.

Methods

This was a secondary descriptive analysis of trial and real-world data. The trial data included twenty-seven US opioid treatment programs in the National Drug Abuse Treatment Clinical Trials Network, N = 2,199 patients. The real-world data included US substance use treatment programs that receive public funding, N = 740,015 patients. We characterized real-world patient populations who were non-represented and under-represented in the trial data in terms of sociodemographic and clinical characteristics that could modify MOUD effectiveness.

Results

We found that 10.7% of MOUD patients in TEDS-A were not represented in the three clinical trials. As expected, pregnant MOUD patients (n = 19,490) were not represented. Excluding pregnancy, education and marital status from the characteristics, 2.6% of MOUD patients were not represented. Patients aged 65 years and older (n = 11,204), and those 50-64 years who identified as other (non-White, non-Black, and non-Hispanic) race/ethnicity or multi-racial (n = 7,281) were under-represented.

Conclusions

Quantifying and characterizing non- or under-represented subgroups in trials can provide the data necessary to improve representation in future trials and address research-to-practice gaps.

Examination of exclusion criteria in total knee arthroplasty rehabilitation trials: influence on the application of evidence in day-to-day practice

OBJECTIVE

Total knee arthroplasty (TKA) rehabilitation trials use exclusion criteria, which may limit their generalizability in practice. We investigated whether patients seen in routine practice who meet common exclusion criteria recover differently from TKA compared to research-eligible patients. We hypothesized that research-ineligible patients would demonstrate poorer average postoperative function and slower rate of functional recovery compared to research-eligible patients.

METHODS

Patient characteristics and exclusion criteria were extracted and summarized from trials included in the three most recent systematic reviews of TKA rehabilitation. Trial participant characteristics were compared to a clinical dataset of patient outcomes collected in routine TKA rehabilitation. Where possible, individual exclusion criterion from the trials were applied to the clinical dataset to determine "eligible" and "ineligible" groups for research participation. Postoperative functional outcomes including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Timed Up and Go (TUG) were compared between "eligible" and "ineligible" groups using mixed effects models.

RESULTS

2,528 participants from 27 trials were compared to 474 patients from the clinical dataset. Research participants were older, with lower Body Mass Index than patients in the clinical dataset. Many patients in the clinical dataset would be "ineligible" for research participation based upon common exclusion criteria from the trials. Differences were observed in average postoperative functioning between some "eligible" and "ineligible" groups in the clinical dataset. However, no differences were observed in functional recovery rate between groups, except for patients with diabetes whose TUG recovered more slowly than their "eligible" counterparts.

CONCLUSIONS

Many patients in the clinical dataset were "ineligible" for research participation based upon common TKA rehabilitation trial exclusion criteria. However, the postoperative recovery rate did not differ between "eligible" and "ineligible" groups based on individual exclusion criterion-except for individuals with diabetes. This suggests that both clinical and research populations may recover similarly from TKA.

Generalizability of pharmacologic and psychotherapy trial results for late-life unipolar depression

OBJECTIVES

Despite evidence of low representativeness of clinical trial results for depression in adults, the generalizability of clinical trial results for late-life depression is unknown. This study sought to quantify the representativeness of pharmacologic and psychotherapy clinical trial results for late-life unipolar depression.

METHOD

Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a nationally representative sample of 34,653 adults from the United States population. To assess the generalizability of clinical trial results for late-life depression, we applied a standard set of eligibility criteria representative of pharmacologic and psychotherapy clinical trials to all individuals aged 65 years and older in NESARC with a DSM-IV diagnosis of MDE and no lifetime history of mania/hypomania (n = 273) and in a subsample of individuals seeking help for depression (n = 78).

RESULTS

More than four of ten respondents and about two of ten respondents would have been excluded by at least one exclusion criterion in a typical pharmacologic and psychotherapy efficacy trial, respectively. Similar results (i.e.41.1% and 25.9%, respectively) were found in the subsample of individuals seeking help for depression. Excess percentage of exclusion in typical pharmacologic studies was accounted for by the criterion "significant medical condition". We also found that populations typically included in pharmacologic and psychotherapy clinical trials for late-life unipolar depression may substantially differ.

CONCLUSION

Psychotherapy trial results may be representative of most patients with late-life unipolar depression in routine clinical practice. By contrast, pharmacologic clinical trials may not be readily generalizable to community samples.

Inclusion of Cannabis Users in Alcohol Research Samples: Screening In, Screening Out, and Implications

BACKGROUND

Alcohol and cannabis are frequently co-used, as 20-50% of those who drink alcohol report co-using cannabis. This study is based on the argument that alcohol researchers should enroll cannabis users in human laboratory studies of alcohol use disorder (AUD) to strengthen generalizability. This study examines how heavy drinking cannabis users differ from non-cannabis using heavy drinkers.

METHODS

In a community sample of non-treatment-seeking heavy drinkers (n = 551, 35% female), cannabis users were identified through: (a) self-reported cannabis use in the past 6 months and (b) positive urine toxicology test for tetrahydrocannabinol (THC). Cannabis users, identified as described previously, were compared with non-cannabis users on demographic and clinical characteristics.

RESULTS

Those who endorsed cannabis use in the past 6 months reported more binge drinking days. Participants who tested positive for THC had higher Alcohol Use Disorder Identification Test scores and more binge drinking days. Younger age and being a tobacco smoker were associated with an increased likelihood of cannabis use in the past 6 months, whereas male gender and being a tobacco use were associated with a greater likelihood of testing positive for THC. Individuals with cannabis use disorder (CUD) endorsed more depression and anxiety and had higher AUD symptom counts than cannabis users without CUD.

CONCLUSIONS

The inclusion of cannabis users in AUD samples allows for increased clinical severity. Excluding cannabis users from AUD studies may limit representativeness and expend unnecessary study resources. Lastly, tobacco use may explain a large portion of the effects of cannabis use on sample characteristics.

SHORT SUMMARY

Alcohol and cannabis are frequently co-used substances. In a sample of non-treatment-seeking heavy drinkers (n = 551, 35% female), cannabis users reported higher alcohol use and higher likelihood of tobacco use than non-cannabis users. Including cannabis users in alcohol research studies will improve representativeness and likely increase clinical severity.

The influence of substance use on the effectiveness of antipsychotic medication: a prospective, pragmatic study

Background: Psychosis is associated with a high prevalence of substance use, leading to worsened prognosis. Less is known about how comorbid substance abuse may influence the effectiveness of antipsychotic medications. The aim of this study was to compare the effectiveness of second generation antipsychotics in patients with psychosis with and without substance use. Methods: All patients (n = 226) were aged >18 years old had symptom level scores of ≥4 on selected psychosis items on the Positive and Negative Syndrome Scale and met ICD-10 diagnostic criteria for psychosis. Information on substance use was collected based on the Clinician Drug Use Scale. Patients were grouped at baseline according to the presence of substance use, medication history and diagnosis group. Clinical symptoms at baseline and changes at follow-up were assessed with the PANSS. Results: At baseline about 30% of the patients used substances, most frequently cannabis followed by methamphetamine. About half (47%) of the patients had no prior exposure to antipsychotic medication at inclusion. Patients who had consumed substances showed no substantial differences in the PANSS score reduction as a result of antipsychotic medication compared to patients without substance. There were, however, some group differences in relation to pattern of change that were influenced by medication history. Substance use was found to be related to stronger reduction of positive symptoms from week 4 to week 27. Conclusion: Substance use alone did not influence antipsychotic effectiveness in this sample of patients with psychosis.

Comparing pharmacological treatments for cocaine dependence: Incorporation of methods for enhancing generalizability in meta-analytic studies

OBJECTIVES

Few head-to-head comparisons of cocaine dependence medications exist, and combining data from different randomized controlled trials (RCTs) is fraught with methodological challenges including limited generalizability of the RCT findings. This study applied a novel meta-analytic approach to data of cocaine dependence medications.

METHODS

Data from 4 placebo-controlled RCTs (Reserpine, Modafinil, Buspirone, and Ondansetron) were obtained from the National Institute of Drug Abuse Clinical Trials Network (n = 456). The RCT samples were weighted to resemble treatment-seeking patients (Treatment Episodes Data Set-Admissions) and individuals with cocaine dependence in general population (National Survey on Drug Use and Health). We synthesized the generalized outcomes with pairwise meta-analysis using individual-level data and compared the generalized outcomes across the 4 RCTs with network meta-analysis using study-level data.

RESULTS

Weighting the data by the National Survey on Drug Use and Health generalizability weight made the overall population effect on retention significantly larger than the RCT sample effect. However, there was no significant difference between the population effect and the RCT sample effect on abstinence. Weighting changed the ranking of the effectiveness across treatments.

CONCLUSIONS

Applying generalizability weights to meta-analytic studies is feasible and potentially provides a useful tool in assessing comparative effectiveness of treatments for substance use disorders in target populations.

Comparing adult cannabis treatment-seekers enrolled in a clinical trial with national samples of cannabis users in the United States

BACKGROUND

Cannabis use rates are increasing among adults in the United States (US) while the perception of harm is declining. This may result in an increased prevalence of cannabis use disorder and the need for more clinical trials to evaluate efficacious treatment strategies. Clinical trials are the gold standard for evaluating treatment, yet study samples are rarely representative of the target population. This finding has not yet been established for cannabis treatment trials. This study compared demographic and cannabis use characteristics of a cannabis cessation clinical trial sample (run through National Drug Abuse Treatment Clinical Trials Network) with three nationally representative datasets from the US; 1) National Survey on Drug Use and Health, 2) National Epidemiologic Survey on Alcohol and Related Conditions-III, and 3) Treatment: Episodes Data Set - Admissions.

METHODS

Comparisons were made between the clinical trial sample and appropriate cannabis using sub-samples from the national datasets, and propensity scores were calculated to determine the degree of similarity between samples.

RESULTS

showed that the clinical trial sample was significantly different from all three national datasets, with the clinical trial sample having greater representation among older adults, African Americans, Hispanic/Latinos, adults with more education, non-tobacco users, and daily and almost daily cannabis users.

CONCLUSIONS

These results are consistent with previous studies of other substance use disorder populations and extend sample representation issues to a cannabis use disorder population. This illustrates the need to ensure representative samples within cannabis treatment clinical trials to improve the generalizability of promising findings.

Generalizability of findings from randomized controlled trials: application to the National Institute of Drug Abuse Clinical Trials Network

AIMS

To compare randomized controlled trial (RCT) sample treatment effects with the population effects of substance use disorder (SUD) treatment.

DESIGN

Statistical weighting was used to re-compute the effects from 10 RCTs such that the participants in the trials had characteristics that resembled those of patients in the target populations.

SETTINGS

Multi-site RCTs and usual SUD treatment settings in the United States.

PARTICIPANTS

A total of 3592 patients in 10 RCTs and 1 602 226 patients from usual SUD treatment settings between 2001 and 2009.

MEASUREMENTS

Three outcomes of SUD treatment were examined: retention, urine toxicology and abstinence. We weighted the RCT sample treatment effects using propensity scores representing the conditional probability of participating in RCTs.

FINDINGS

Weighting the samples changed the significance of estimated sample treatment effects. Most commonly, positive effects of trials became statistically non-significant after weighting (three trials for retention and urine toxicology and one trial for abstinence); also, non-significant effects became significantly positive (one trial for abstinence) and significantly negative effects became non-significant (two trials for abstinence). There was suggestive evidence of treatment effect heterogeneity in subgroups that are under- or over-represented in the trials, some of which were consistent with the differences in average treatment effects between weighted and unweighted results.

CONCLUSIONS

The findings of randomized controlled trials (RCTs) for substance use disorder treatment do not appear to be directly generalizable to target populations when the RCT samples do not reflect adequately the target populations and there is treatment effect heterogeneity across patient subgroups.

Pragmatic trial of a Study Navigator Model (NAU) vs. Ambassador Model (N+) to increase enrollment to health research among community members who use illicit drugs

BACKGROUND

Although drug use is common in the population, drug users are sometimes excluded from research without justification. Two models of individualized study matching were compared for effectiveness in enrolling people who "endorsed current drug use" and those who "did not" into appropriate research.

METHODS

Participants in the NIDA-funded Transformative Approach to Reduce Research Disparities Towards Drug Users study (Navigation Study) were recruited through a Clinical and Translational Science Award (CTSA) community engagement model. Of the 614 community-recruited adults, 326 endorsed current drug use (cases); 288 did not (controls). Participants were randomized to one of two intervention groups: Navigation as Usual (NAU) [individualized study matching through a Study Navigator] or Enhanced Navigation (N+) [individualized study matching plus transportation and other assistance through an Ambassador]. Rates of enrollment into research studies were compared.

RESULTS

At 90 days, N+ vs. the NAU intervention was associated with higher enrollment among both drug users (36.0% N+ vs. 24.9% NAU) and non-drug users (45.5% N+ vs. 25.2% NAU). NAU attained the same rate of enrollment for users of drugs (24.9%) and non-users (25.2%); N+ had similar rates as well (36.0% drug users vs. 45.5% non-drug users). In addition, high rates of enrollment were achieved among all groups of participants, from 24.9% (drug users in NAU) to 45.5% (non-drug users in N+).

CONCLUSIONS

Both the NAU and N+ methods can reduce barriers and help users and non-users become part of the population that participates in research. Working with the local CTSA adds significant value to the research enterprise.

Toward National Estimates of Effectiveness of Treatment for Substance Use

OBJECTIVE

To estimate how results would have varied if a substance abuse clinical trial had been conducted with nationally representative adults with substance use and with representative adults receiving substance use treatment.

METHODS

Results were analyzed from a multisite clinical trial comparing the effectiveness of the Therapeutic Education System to treatment as usual for outpatient addiction treatment (n = 507). Patients were recruited between June 2010 and August 2011. Abstinence was the primary outcome. The general population sample and general population-treated samples were derived from Wave 1 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) (n = 43,093). Propensity scores provided a standardized measure of the difference between clinical trial participants and the 2 NESARC samples. The clinical trial was reanalyzed by reweighting the sample with propensity scores derived from the 2 samples to obtain generalizable estimates of treatment effects.

RESULTS

Before the clinical trial sample was reweighted, the odds ratio (OR) of response to Therapeutic Education System versus treatment as usual in the trial was 1.62 (95% CI, 1.12-2.35). After the sample was reweighted to be representative of the 2 NESARC groups, ORs were 1.33 (95% CI, 0.34-5.26) for the representative sample with any substance use and 1.64 (95% CI, 0.82-3.27) for the representative treated sample.

CONCLUSIONS

Applying propensity score weighting to clinical trial results provides a method for estimating the population generalizability of clinical trial findings that relies on effect moderators observed in the study sample and population. Broader confidence intervals in the reweighted samples do not necessarily indicate lack of efficacy of the Therapeutic Education System but rather greater uncertainty concerning effectiveness in general population samples.

Selection criteria limit generalizability of smoking pharmacotherapy studies differentially across clinical trials and laboratory studies: A systematic review on varenicline

BACKGROUND

The selection criteria used in clinical trials for smoking cessation and in laboratory studies that seek to understand mechanisms responsible for treatment outcomes may limit their generalizability to one another and to the general population.

METHODS

We reviewed studies on varenicline versus placebo and compared eligibility criteria and participant characteristics of clinical trials (N=23) and laboratory studies (N=22) across study type and to nationally representative survey data on adult, daily USA smokers (2014 National Health Interview Survey; 2014 National Survey on Drug Use and Health).

RESULTS

Relative to laboratory studies, clinical trials more commonly reported excluding smokers who were unmotivated to quit and for specific medical conditions (e.g., cardiovascular disease, COPD), although both study types frequently reported excluding for general medical or psychiatric reasons. Laboratory versus clinical samples smoked less, had lower nicotine dependence, were younger, and more homogeneous with respect to smoking level and nicotine dependence. Application of common eligibility criteria to national survey data resulted in considerable elimination of the daily-smoking population for both clinical trials (≥47%) and laboratory studies (≥39%). Relative to the target population, studies in this review recruited participants who smoked considerably more and had a later smoking onset age, and were under-representative of Caucasians.

CONCLUSIONS

Results suggest that selection criteria of varenicline studies limit generalizability in meaningful ways, and differences in criteria across study type may undermine efforts at translational research. Recommendations for improvements in participant selection and reporting standards are discussed.

Representativeness of the participants in the smoking Cessation in Pregnancy Incentives Trial (CPIT): a cross-sectional study

Background

The limited representativeness of trial samples may restrict external validity. The aim of this study was to ascertain the representativeness of the population enrolled in the Cessation in Pregnancy Incentives Trial (CPIT), a therapeutic exploratory study to examine the effectiveness of financial incentives for smoking cessation during pregnancy.

Methods

CPIT participants (n = 492) were compared with all self-reported smokers at maternity booking who did not participate in the trial (n = 1982). Both groups were drawn from the National Health Service (NHS) Greater Glasgow and Clyde area over a 1-year trial enrolment period. Variables used for comparison were age, area-based deprivation index, body mass index, gestation, and carbon monoxide (CO) breath test level. Chi-square and Mann-Whitney U tests were used to compare groups.

Results

From January to December 2012, 2474/13,945 (17.7 %) women, who booked for maternity care, self-reported as current smokers (at least one cigarette in the last week). Seven hundred and fifty-two were ineligible for trial participation because of a CO breath test level of less than 7 parts per million (ppm) used as a biochemical cut-off to corroborate self-report of current smoking. At telephone consent 301 could not be contacted, 11 had miscarried, 16 did not give consent and 3 opted out after randomisation, leaving 492 participants for analysis. There were no differences in demographic or clinical characteristics between trial participants, and self-reported smokers not enrolled in the trial in terms of CO breath test (as a measure of smoking level for those with a CO level of 7 ppm or higher), material deprivation (using an area-based measure), maternal age and maternal body mass index. Gestation at booking was statistically significantly lower for participants.

Conclusions

To ensure that all trial participants were smokers, biochemical validation excluded self-reported smokers with a CO level of less than 7 ppm from taking part in the trial, which excluded 30 % of self-reported smokers who were ‘lighter’ smokers. The efficacy of financial incentives would not have been likely to decrease if ‘lighter’ smokers had been included in the trial population. Trial participants were slightly earlier in their pregnancy at maternity booking, but this difference would not clinically affect the provision of financial incentives if provided routinely. Overall, the trial population was representative of all self-reported smokers with regard to available routinely collected data. Appropriate comparison of trial and target populations, with detailed reporting of exclusion criteria would contribute to the understanding of the wider applicability of trial results.

Trial registration

Current Controlled Trials ISRCTN87508788. Registered/Assigned on 1 September 2011.

Assessing sample representativeness in randomized controlled trials: application to the National Institute of Drug Abuse Clinical Trials Network

AIMS

To compare the characteristics of individuals participating in randomized controlled trials (RCTs) of treatments of substance use disorder (SUD) with individuals receiving treatment in usual care settings, and to provide a summary quantitative measure of differences between characteristics of these two groups of individuals using propensity score methods. Design Analyses using data from RCT samples from the National Institute of Drug Abuse Clinical Trials Network (CTN) and target populations of patients drawn from the Treatment Episodes Data Set-Admissions (TEDS-A). Settings Multiple clinical trial sites and nation-wide usual SUD treatment settings in the United States.

PARTICIPANTS

A total of 3592 individuals from 10 CTN samples and 1 602 226 individuals selected from TEDS-A between 2001 and 2009. Measurements The propensity scores for enrolling in the RCTs were computed based on the following nine observable characteristics: sex, race/ethnicity, age, education, employment status, marital status, admission to treatment through criminal justice, intravenous drug use and the number of prior treatments. Findings The proportion of those with ≥ 12 years of education and the proportion of those who had full-time jobs were significantly higher among RCT samples than among target populations (in seven and nine trials, respectively, at P < 0.001). The pooled difference in the mean propensity scores between the RCTs and the target population was 1.54 standard deviations and was statistically significant at P < 0.001.

CONCLUSIONS

In the United States, individuals recruited into randomized controlled trials of substance use disorder treatments appear to be very different from individuals receiving treatment in usual care settings. Notably, RCT participants tend to have more years of education and a greater likelihood of full-time work compared with people receiving care in usual care settings.

Exclusion criteria in treatment research on alcohol, tobacco and illicit drug use disorders: A review and critical analysis

ISSUES

High rates of exclusion in substance use disorder treatment studies reduce the external validity and clinical utility of research findings to an unknown extent. Accordingly, the current review examined commonly used exclusion criteria and their effect on study samples and outcomes.

APPROACH

English-language literature was identified by PubMed searches and review of identified articles' reference lists. Studies were included if they analysed data on: (i) the prevalence and nature of exclusion criteria in the substance use disorder treatment field; and/or (ii) the impact of exclusion criteria on sample representativeness or study results.

KEY FINDINGS

The search yielded 22 studies examining different aspects of exclusion criteria, including 15 empirical examinations of the impact of study exclusion criteria across different substance use disorder treatments on enrolment and outcome results. Aggregating across these 15 studies, we estimated that between 64 and 96% of potential study participants are excluded from substance use disorder treatment studies.

IMPLICATIONS

The widespread exclusion of large proportions of people with substance use disorders limits the external validity of the substance use disorder treatment research literature.

CONCLUSION

Although some eligibility criteria are necessary to protect participant safety and ensure internal validity, researchers conducting studies on substance use disorder treatments should thoughtfully consider the justification for and specific operationalisation of the extensive exclusion criteria they often utilise. [Moberg C, Humphreys K. Exclusion criteria in treatment research on alcohol, tobacco and illicit drug use disorders: A review and critical analysis. Drug Alcohol Rev 2017;36:378-388].

Generalizability of pharmacological and psychotherapy clinical trial results for borderline personality disorder to community samples

The present study sought to quantify the generalizability of clinical trial results in individuals with a Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) diagnosis of borderline personality disorder (BPD) to a large representative community sample. Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a large nationally representative sample of 34,653 adults from the United States population. We applied a standard set of exclusion criteria representative of pharmacological and psychotherapy clinical trials to all adults with a DSM-IV diagnosis of BPD (n = 2,231). Our aim was to assess how many participants with BPD would not fulfill typical eligibility criteria. We found that more than 7 of 10 respondents in a typical pharmacological efficacy trial and more than 5 of 10 participants in a typical psychotherapy efficacy trial would have been excluded by at least 1 criterion. Having a current history of alcohol or drug use disorder and a lifetime history of bipolar disorder explained a large proportion of ineligibility in both pharmacological and psychotherapy efficacy trials. Clinical trials should carefully consider the impact of exclusion criteria on the generalizability of their results. As required by CONSORT guidelines, reporting exclusion rate estimate and reasons of eligibility should be mandatory in both clinical trials and meta-analyses. As treatment trials of borderline personality disorder move from efficacy to effectiveness to better inform clinical practice, the eligibility rate must be increased by imposing less stringent eligibility criteria to allow for more generalizable results.

The National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) Waves 1 and 2: review and summary of findings

PURPOSE

The NESARC, a "third-generation" psychiatric epidemiologic survey that integrated detailed measures of alcohol and drug use and problems has been the data source for over >850 publications. A comprehensive review of NESARC findings and their implications is lacking.

METHOD

NESARC was a survey of 43,093 participants that covered alcohol, drug and psychiatric disorders, risk factors, and consequences. Wave 1 of the NESARC was conducted in 2001-2002. Three years later, Wave 2 follow-up re-interviews were conducted with 34,653 of the original participants. Scopus and Pubmed were used to search for NESARC papers, which were sorted into topic areas and summarized.

RESULT

The most common disorders were alcohol and posttraumatic stress disorders, and major depression. Females had more internalizing disorders and males had more externalizing disorders, although the preponderance of males with alcohol disorders (the "gender gap") was less pronounced than it was in previous decades. A race/ethnic "paradox" (lower risk among disadvantaged minorities than whites) remains unexplained. Younger participants had higher risk for substance and personality disorders, but not unipolar depressive or anxiety disorders. Psychiatric comorbidity was extensive and often formed latent trans-diagnostic domains. Since 1991-1992, risk for marijuana and prescription drug disorders increased, while smoking decreased, although smoking decreases were less pronounced among those with comorbidity. A nexus of comorbidity, social support, and stress predicted transitions in diagnostic status between Waves 1 and 2. Childhood maltreatment predicted psychopathology. Alcohol and drug use disorders were seldom treated; attitudinal barriers (little perceived need, perceived alcoholism stigma, pessimism about efficacy) were more important in predicting non-treatment than financial barriers.

CONCLUSIONS

Understanding comorbidity and the effects of early stressors will require research incorporating biologic components, e.g., genetic variants and brain imaging. The lack of treatment for alcohol and drug disorders, predicted by attitudinal rather than financial variables, suggests an urgent need for public and professional education to reduce the stigma associated with these disorders and increase knowledge of treatment options.

Opioid substitution and antagonist therapy trials exclude the common addiction patient: a systematic review and analysis of eligibility criteria

BACKGROUND

Eligibility criteria that result in the exclusion of a substantial number of patients from randomized trials jeopardize the generalizability of treatment effect to much of the clinical population. This is important when evaluating opioid substitution and antagonist therapies (OSATs), especially given the challenges associated with treating the opioid-dependent population. We aimed to identify OSAT trials' eligibility criteria, quantify the percentage of the clinical population excluded by these criteria, and determine how OSAT guidelines incorporate evidence from these trials.

METHODS

We performed a systematic review to identify the eligibility criteria used across trials. We searched Medline, EMBASE, PsycINFO, Web of Science, Cochrane Library, Cochrane Clinical Trials Registry (CTR), World Health Organization International CTR Platform Search Portal, and the National Institutes of Health CTR databases from inception to January 1, 2014. To quantify the effect of trials' eligibility criteria on generalizability, we applied these criteria to data from an observational study of opioid-dependent patients (n = 394). We then accessed the Canadian, American, British, and World Health Organization (WHO) OSAT guidelines to evaluate how evidence is used in the recommendations.

RESULTS

Among the 60 trials identified the majority (≥50 % of trials) exclude patients with psychiatric (60 %) and physical comorbidity (51.7 %). Additionally, we found 19 trials exclude patients with current alcohol/substance-use problems (31.7 %), and 29 (48.3 %) exclude patients taking psychotropic medications. These criteria were restrictive and in some cases rendered 70 % of the observational sample ineligible. North American OSAT guidelines made strong recommendations supported by evidence with poor generalizability. National Institute of Health and Care Excellence (NICE) and WHO guidelines for opioid misuse provide a critical assessment of the literature used to inform their recommendations.

CONCLUSIONS

Trials assessing OSATs often exclude patients with concurrent disorders. If the excluded patients respond differently to treatment, results from these trials are likely to overestimate the true effectiveness of OSATs. North American guidelines should consider these limitations when drafting clinical recommendations.

Alcohol Dependence, Co-occurring Conditions and Attributable Burden

AIMS

Alcohol dependence is associated with high rates of co-occurring disorders which impact health-related quality of life (HRQoL) and add to the cost-of-illness. This study investigated the burden of alcohol dependence and associated co-occurring conditions on health and productivity.

METHODS

A cross-sectional survey was conducted in eight European countries. Physicians (Psychiatrists and General Practitioners) completed patient record forms, which included assessment of co-occurring conditions, and patients completed matching self-completion forms. Drinking risk level (DRL) was calculated and the relationship between DRL, co-occurring conditions, work productivity, hospitalisations and rehabilitation stays was explored.

RESULTS

Data were collected for 2979 alcohol-dependent patients (mean age 48.8 ± 13.6 years; 70% male). In total, 77% of patients suffered from moderate-to-severe co-occurring psychiatric and/or somatic conditions. High DRL was significantly associated with depression, greater work productivity losses, increased hospitalisations and rehabilitation stays. Co-occurring conditions were significantly associated with poorer HRQoL and decreased work productivity, with a statistical trend towards an increased frequency of rehabilitation stays.

CONCLUSIONS

Alcohol-dependent patients manifest high rates of co-occurring psychiatric and somatic conditions, which are associated with impaired work productivity and HRQoL. The continued burden of illness observed in these already-diagnosed patients suggests an unmet need in both primary and secondary care.

Predicting Participation in Psychiatric Randomized Controlled Trials: Insights From the STEP-BD

OBJECTIVE

Differences between patients who do and do not participate in randomized controlled trials (RCTs) could diminish the generalizability of results. This study examined whether RCT participants differ from non-RCT participants who are recruited from the same patient and provider population.

METHODS

The Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) was an observational study in which participants also could enroll in an RCT during exacerbations of acute depression. The odds that a patient was enrolled in the STEP-BD acute depression RCTs (pharmacotherapy or psychotherapy) were estimated by fitting logistic regression models to STEP-BD participants with acute bipolar depression (total N=2,222; RCT, N=413; observational arm, N=1,809). Predictor variables included demographic characteristics, clinical information (including severity scales and comorbidities), and study site. The extent to which site determined RCT participation was estimated by using the area under the receiver operating characteristic curve (AUC).

RESULTS

RCT participation was associated with having no insurance (odds ratio [OR]=1.58, 95% confidence interval [CI]=1.16-2.15), a Clinical Global Impression score indicating greater severity (severe versus mild: OR=1.52, CI=1.08-2.15), and site (predicted probability range 8%-31%). Site was the most significant predictor of RCT enrollment (model excluding site, AUC=.61, CI=.58-.64; full model, AUC=.70, CI=.67-.73).

CONCLUSIONS

STEP-BD RCT participants differed from those in the observational arm in few clinical or demographic characteristics. Site was the strongest predictor of RCT participation. Future study is needed to understand site characteristics associated with RCT participation and whether these characteristics are associated with patient outcomes and to test these findings in usual-care settings.

Visual aggregate analysis of eligibility features of clinical trials

OBJECTIVE

To develop a method for profiling the collective populations targeted for recruitment by multiple clinical studies addressing the same medical condition using one eligibility feature each time.

METHODS

Using a previously published database COMPACT as the backend, we designed a scalable method for visual aggregate analysis of clinical trial eligibility features. This method consists of four modules for eligibility feature frequency analysis, query builder, distribution analysis, and visualization, respectively. This method is capable of analyzing (1) frequently used qualitative and quantitative features for recruiting subjects for a selected medical condition, (2) distribution of study enrollment on consecutive value points or value intervals of each quantitative feature, and (3) distribution of studies on the boundary values, permissible value ranges, and value range widths of each feature. All analysis results were visualized using Google Charts API. Five recruited potential users assessed the usefulness of this method for identifying common patterns in any selected eligibility feature for clinical trial participant selection.

RESULTS

We implemented this method as a Web-based analytical system called VITTA (Visual Analysis Tool of Clinical Study Target Populations). We illustrated the functionality of VITTA using two sample queries involving quantitative features BMI and HbA1c for conditions "hypertension" and "Type 2 diabetes", respectively. The recruited potential users rated the user-perceived usefulness of VITTA with an average score of 86.4/100.

CONCLUSIONS

We contributed a novel aggregate analysis method to enable the interrogation of common patterns in quantitative eligibility criteria and the collective target populations of multiple related clinical studies. A larger-scale study is warranted to formally assess the usefulness of VITTA among clinical investigators and sponsors in various therapeutic areas.

Association of race and age with treatment attendance and completion among adult marijuana users in community-based substance abuse treatment

OBJECTIVES

African American youth who use marijuana are less likely to attend and complete treatment than white youth. Limited information is available on racial and age variation in treatment attendance and completion among adults who use marijuana.

METHODS

The current research examined differences in community-based substance abuse treatment attendance and completion between adult African American and white marijuana users in 2 independent samples from the US southeastern (N = 160; 70.6% African American) and mid-Atlantic (N = 450; 34.7% African American) regions.

OUTCOMES

Attended at least 3 treatment sessions, successful treatment completion, number of days in treatment, and percentage of positive urine drug screens. Adjusted regression models examined the association of race, age, and the interaction of race and age with treatment attendance and completion.

RESULTS

In the southeastern sample, successful treatment completion was significantly associated with the interaction of race and age (adjusted odds ratio = 1.35, 95% confidence interval = 1.08-1.69); whereas younger African Americans were less likely to complete treatment than older African Americans, age was unrelated to treatment completion among whites. In the mid-Atlantic sample, African Americans were significantly less likely to attend at least 3 treatment sessions (adjusted odds ratio = 0.37, 95% confidence interval = 0.23-0.58), and younger adult marijuana users were retained for fewer days in treatment (adjusted β = 0.13, 95% confidence interval = 0.27-2.48). Among African Americans, 37.9% (SD = 38.0) of urine drug screens tested positive for at least 1 illicit drug, and among whites, 34.2% (SD = 37.8%) tested positive; the percentage of positive urine drug screens was not associated with race or age.

CONCLUSIONS

Among marijuana-using adults, treatment attendance and completion differ by race and age, and improvements in treatment completion may occur as some African Americans mature out of young adulthood.

Are participants in pharmacological and psychotherapy treatment trials for social anxiety disorder representative of patients in real-life settings?

BACKGROUND

The present study sought to quantify the generalizability of clinical trial results in individuals with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis of social anxiety disorder (SAD) to a large representative community sample.

METHODS

Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions, a large nationally representative sample of 34,653 adults from the US population. We applied a standard set of exclusion criteria representative of pharmacological and psychotherapy clinical trials to all adults with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis of SAD (n = 965) in the past 12 months and then to a subsample of participants seeking treatment (n = 363). Our aim was to assess how many participants with SAD would fulfill typical eligibility criteria.

RESULTS

We found that more than 7 of 10 respondents from the overall SAD sample in a typical pharmacological efficacy trial and more than 6 of 10 participants in a typical psychotherapy efficacy trial would have been excluded by at least 1 criterion. In addition, more than 8 of 10 respondents seeking treatment for SAD would have been excluded from participation in a typical pharmacological or psychotherapy efficacy trial. Having a current major depression explained a large proportion of ineligibility.

CONCLUSIONS

Clinical trials should carefully consider the impact of exclusion criteria on the generalizability of their results and explain the rationale for their use. For SAD treatment trials to adequately inform clinical practice, the eligibility rate must be increased through a general relaxation of overly stringent eligibility criteria.

Predictors of quit attempts and successful quit attempts among individuals with alcohol use disorders in a nationally representative sample

BACKGROUND

This study sought to identify predictors of attempting to quit and of successfully quitting alcohol abuse or dependence in the general population.

METHODS

Data were drawn from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

RESULTS

Approximately 10% of individuals with alcohol abuse and 18% of those with dependence attempted to quit over the three year follow-up period. Of those who tried, 38% of individuals with abuse and 30% of those with dependence successfully quit. Among individuals with alcohol abuse or dependence, being single, younger than 40 years old, having low income, a co-occurring psychiatric disorder and greater number of dependence symptoms increased the likelihood of attempting to quit. Among individuals with alcohol abuse, male gender and low educational attainment further increased the odds of quit attempts. However, greater severity of alcohol use disorder, having a co-occurring drug use disorder and greater number of psychiatric disorders decreased the odds of success among individuals with alcohol abuse, while female gender, being married and older than 40 years old increased the odds of success. Among individuals with alcohol dependence, having nicotine dependence, greater number of psychiatric disorders and personality disorders decreased the odds of success.

CONCLUSIONS

Predictors of attempts to quit are different and sometimes opposite from those leading to successful quitting probably indicating that some factors that increase motivation may decrease ability to quit. These findings may help in the development of more targeted and effective interventions for alcohol use disorders.

Representativeness of obstetric patients who participate in perinatal depression research: findings from the Women's Mental Health and Infants Program (WMHIP) integrated dataset

The aims of this study were to evaluate the feasibility of integrating archival datasets from depression projects involving pregnant women recruited from obstetric clinics and then assess the representativeness of the integrated dataset. Datasets from six studies were standardized and integrated. Chi-square, t-, and Wilcoxon rank-sum tests were used to compare characteristics between women who completed a depression screening questionnaire (DSQ) and were (1) eligible and ineligible for research participation and (2) eligible women who accepted and declined participation. The integrated dataset comprises 9,112 pregnant women, of whom 71.0 % (n = 6,472) were ineligible for participation because their DSQ scores indicated no-to-minimal depressive symptoms (NDS). Among the 23.9 % (2,176) of women identified as eligible, in part, because their DSQ scores indicated elevated levels of depressive symptoms (EDS), 29.6 % (644) of women participated (P-EDS) and 47.6 % (1,036) of women did not participate (D-EDS). While the NDS and EDS groups were significantly different on almost all variables, the P-EDS and D-EDS groups were significantly different on only a few variables. Compared to the D-EDS group, the P-EDS group was earlier in pregnancy and, on the Edinburgh Postnatal Depression Screen, was more likely to endorse impaired "ability to laugh" and "enjoy oneself", and endorse at greater severity "ability to laugh." It is a reasonable and feasible strategy to integrate thematically similar datasets to increase statistical power. Additionally, typical recruitment strategies for minimal risk perinatal depression research at obstetric clinics, during routine prenatal care visits, appear to produce an externally valid study cohort.

Excluding the typical patient: thirty years of pharmacotherapy efficacy trials for obsessive-compulsive disorder

BACKGROUND

Over the past 30 years, clinical trials have resulted in several successful pharmacotherapies for obsessive-compulsive disorder (OCD), yet patients in clinical settings often report inadequate response. This study compares clinical characteristics of treatment-seeking OCD patients to the inclusion/exclusion criteria used in pharmacotherapy trials.

METHODS

The sample consisted of 325 community members with a DSM-IV diagnosis of OCD who underwent systematic interviews with clinicians knowledgeable in the diagnosis and treatment of OCD. We compiled pharmacotherapy studies for OCD published between 1980 and 2010 using Medline, PubMed, and library resources, and estimated the proportion of patients in each decade satisfying the most common inclusion/exclusion criteria.

RESULTS

We included 39 clinical trials and found 72% of the 325 patients would have been excluded from trials conducted between 1980 and 2010. Exclusion was projected as dramatically lower for trials conducted between 1980 and 1989 (19.7%) compared with 74.8% for trials conducted between 1990 and 1999 and 76.9% for trials between 2000 and 2010.

CONCLUSIONS

The majority of treatment-seeking individuals with OCD would not qualify for OCD treatment studies due to comorbid psychiatric disorders, and failure to meet OCD severity threshold criteria. This illustrates the need to include a more community-representative sample of OCD patients in clinical trials examining pharmacotherapy efficacy.

Probability and predictors of cannabis use disorders relapse: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC)

BACKGROUND

This study aims to estimate the odds and predictors of Cannabis Use Disorders (CUD) relapse among individuals in remission.

METHODS

Analyses were done on the subsample of individuals with lifetime history of a CUD (abuse or dependence) who were in full remission at baseline (Wave 1) of the National Epidemiological Survey of Alcohol and Related Conditions (NESARC) (n=2350). Univariate logistic regression models and hierarchical logistic regression model were implemented to estimate odds of relapse and identify predictors of relapse at 3 years follow up (Wave 2).

RESULTS

The relapse rate of CUD was 6.63% over an average of 3.6 year follow-up period. In the multivariable model, the odds of relapse were inversely related to time in remission, whereas having a history of conduct disorder or a major depressive disorder after Wave 1 increased the risk of relapse.

CONCLUSIONS

Our findings suggest that maintenance of remission is the most common outcome for individuals in remission from a CUD. Treatment approaches may improve rates of sustained remission of individuals with CUD and conduct disorder or major depressive disorder.

Are subjects in treatment trials of panic disorder representative of patients in routine clinical practice? Results from a national sample

BACKGROUND

Research on the generalizability of clinical trials in panic disorder is limited. The present study sought to quantify the generalizability of clinical trials' results of individuals with DSM-IV panic disorder (PD) to a large community sample.

METHODS

Data were derived from the National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a large national representative sample of 43,093 adults of the United States population. We applied a standard set of eligibility criteria representative of PD clinical trials to all adults with past 12 months PD (n=907), and then to a subgroup of participants seeking treatment (n=105). Our aim was to determine the proportion of participants with PD who would have been excluded by typical eligibility criteria.

RESULTS

We found that more than 8 out of ten participants (80.52%; 95% CI=77.13-83.52%) with PD were excluded by at least one criterion. In the subgroup of participants who sought treatment, the exclusion rate by at least one criterion was higher (92.40%; 95% CI=84.60-96.42%). For the full sample and the treatment-seeking subsample, having currently a depression and a diagnosis of alcohol or drug abuse/dependence were the criteria excluding the highest percentage of participants. Having a lifetime history of bipolar disorder and a current significant medical condition also excluded a substantial proportion of individuals in both samples. Exclusion rates were similar when considering panic disorder with and without agoraphobia.

CONCLUSIONS

Clinical trials, that exclude a majority of adults with panic disorder, should carefully consider the impact of eligibility criteria on the generalizability of their results. As required by CONSORT guidelines, reporting exclusion rate estimate and reasons of eligibility should be mandatory in both clinical trials and meta-analyses.

Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings

Background

The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents.

Methods

Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered.

Results

One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure.

Limitations

However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings.

Conclusion

Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives.

Generalizability of clinical trial results for generalized anxiety disorder to community samples

BACKGROUND

There has been little research on the generalizability of clinical trials for generalized anxiety disorder (GAD). The present study examines the generalizability of pharmacological and psychotherapy clinical trials' results of individuals with DSM-IV GAD to a large community sample.

METHODS

Data were drawn from the National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a large national representative face-to-face sample of 43,093 adults of the United States population. We applied a standard set of eligibility criteria representative of GAD pharmacological and psychotherapy clinical trials to all adults with past 12 months GAD (n = 894), and to a subgroup of participants seeking treatment (n = 329). Our aim was to assess how many participants with GAD would fulfil typical eligibility criteria.

RESULTS

We found that more than seven out of 10 participants with GAD were excluded by at least one criterion. In the subgroup of GAD participants who sought treatment, the exclusion rate by at least one criterion raised to more than eight out of 10 participants with GAD. For the overall sample and the treatment-seeking subsample, having a current depression was the criterion excluding the highest percentage of individuals. Having a lifetime history of bipolar disorder, a current significant medical condition, a current diagnosis of alcohol abuse or dependence, and a social or specific phobia also excluded a substantial proportion of individuals in both samples.

CONCLUSIONS

Clinical trials exclude a majority of adults with GAD. Clinical trials should carefully consider the impact of eligibility criteria on the generalizability of their results.

Assessing the Sensitivity of Treatment Effect Estimates to Differential Follow-Up Rates: Implications for Translational Research

We develop a new tool for assessing the sensitivity of findings on treatment effectiveness to differential follow-up rates in the two treatment conditions being compared. The method censors the group with the higher response rate to create a synthetic respondent group that is then compared with the observed cases in the other condition to estimate a treatment effect. Censoring is done under various assumptions about the strength of the relationship between follow-up and outcomes to determine how informative differential dropout can alter inferences relative to estimates from models that assume the data are missing at random. The method provides an intuitive measure for understanding the strength of the association between outcomes and dropout that would be required to alter inferences about treatment effects. Our approach is motivated by translational research in which treatments found to be effective under experimental conditions are tested in standard treatment conditions. In such applications, follow-up rates in the experimental setting are likely to be substantially higher than in the standard setting, especially when observational data are used in the evaluation. We test the method on a case study evaluation of the effectiveness of an evidence-supported adolescent substance abuse treatment program (Motivational Enhancement Therapy/Cognitive Behavioral Therapy-5 [MET/CBT-5]) delivered by community-based treatment providers relative to its performance in a controlled research trial. In this case study, follow-up rates in the community based settings were extremely low (54%) compared to the experimental setting (95%) giving raise to concerns about non-ignorable drop-out.