An exploration of site effects in a multisite trial of OROS-methylphenidate for smokers with attention deficit/hyperactivity disorder

Extended-release methylphenidate for attention deficit hyperactivity disorder (ADHD) in adults

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a psychiatric diagnosis increasingly used in adults. The recommended first-line pharmacological treatment is central nervous system (CNS) stimulants, such as methylphenidate, but uncertainty remains about its benefits and harms.

OBJECTIVES

To assess the beneficial and harmful effects of extended-release formulations of methylphenidate in adults diagnosed with ADHD.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, nine other databases and four clinical trial registries up to February 2021. We searched 12 drug regulatory databases for clinical trial data up to 13 May 2020. In addition, we cross-referenced all available trial identifiers, handsearched reference lists, searched pharmaceutical company databases, and contacted trial authors.

SELECTION CRITERIA

Randomised, double-blind, parallel-group trials comparing extended-release methylphenidate formulations at any dose versus placebo and other ADHD medications in adults diagnosed with ADHD.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data. We assessed dichotomous outcomes as risk ratios (RRs), and rating scales and continuous outcomes as mean differences (MDs) or standardised mean differences (SMDs). We used the Cochrane risk of bias tool to assess risks of bias, and GRADE to assess the certainty of the evidence. We meta-analysed the data using a random-effects model. We assessed three design characteristics that may impair the trial results' 'generalisability'; exclusion of participants with psychiatric comorbidity; responder selection based on previous experience with CNS stimulants; and risk of withdrawal effects. Our prespecified primary outcomes were functional outcomes, self-rated ADHD symptoms, and serious adverse events. Our secondary outcomes included quality of life, ADHD symptoms rated by investigators and by peers such as family members, cardiovascular variables, severe psychiatric adverse events, and other adverse events.

MAIN RESULTS

We included 24 trials (5066 participants), of which 21 reported outcome data for this review. We also identified one ongoing study. We included documents from six drug regulatory agencies covering eight trials. Twenty-one trials had an outpatient setting and three were conducted in prisons. They were primarily conducted in North America and Europe. The median participant age was 36 years. Twelve trials (76% of participants) were industry-sponsored, four (14% of participants) were publicly funded with industry involvement, seven (10% of participants) were publicly funded, and one had unclear funding. The median trial duration was eight weeks. One trial was rated at overall unclear risk of bias and 20 trials were rated at overall high risk of bias, primarily due to unclear blinding of participants and investigators, attrition bias, and selective outcome reporting. All trials were impaired in at least one of the three design characteristics related to 'generalisability'; for example, they excluded participants with psychiatric comorbidity such as depression or anxiety, or included participants only with a previous positive response to methylphenidate, or similar drugs. This may limit the trials' usefulness for clinical practice, as they may overestimate the benefits and underestimate the harms. Extended-release methylphenidate versus placebo (up to 26 weeks) For the primary outcomes, we found very low-certainty evidence that methylphenidate had no effect on 'days missed at work' at 13-week follow-up (mean difference (MD) -0.15 days, 95% confidence interval (CI) -2.11 to 1.81; 1 trial, 409 participants) or serious adverse events (risk ratio (RR) 1.43, CI 95% CI 0.85 to 2.43; 14 trials, 4078 participants), whereas methylphenidate improved self-rated ADHD symptoms (small-to-moderate effect; SMD -0.37, 95% CI -0.43 to -0.30; 16 trials, 3799 participants). For secondary outcomes, we found very low-certainty evidence that methylphenidate improved self-rated quality of life (small effect; SMD -0.15, 95% CI -0.25 to -0.05; 6 trials, 1888 participants), investigator-rated ADHD symptoms (small-to-moderate effect; SMD -0.42, 95% CI -0.49 to -0.36; 18 trials, 4183 participants), ADHD symptoms rated by peers such as family members (small-to-moderate effect; SMD -0.31, 95% CI -0.48 to -0.14; 3 trials, 1005 participants), and increased the risk of experiencing any adverse event (RR 1.27, 95% CI 1.19 to 1.37; 14 trials, 4214 participants). We rated the certainty of the evidence as 'very low' for all outcomes, primarily due to high risk of bias and 'indirectness of the evidence'. One trial (419 participants) had follow-up at 52 weeks and two trials (314 participants) included active comparators, hence long-term and comparative evidence is limited.

AUTHORS' CONCLUSIONS

We found very low-certainty evidence that extended-release methylphenidate compared to placebo improved ADHD symptoms (small-to-moderate effects) measured on rating scales reported by participants, investigators, and peers such as family members. Methylphenidate had no effect on 'days missed at work' or serious adverse events, the effect on quality of life was small, and it increased the risk of several adverse effects. We rated the certainty of the evidence as 'very low' for all outcomes, due to high risk of bias, short trial durations, and limitations to the generalisability of the results. The benefits and harms of extended-release methylphenidate therefore remain uncertain.

The neurobiology of impulsivity and substance use disorders: implications for treatment

Impulsivity is strongly associated with substance use disorders (SUDs). Our review discusses impulsivity as an underlying vulnerability marker for SUDs, and treatment of co-occurring impulsivity in SUDs. Three factors should be considered for the complex relationship between impulsivity and a SUD: (1) the trait effect of impulsivity, centering on decreased cognitive and response inhibition, (2) the state effect resulting from either acute or chronic substance use on brain structure and function, and (3) the genetic and environmental factors (e.g., age and sex) may influence impulsive behavior associated with SUDs. Both subjective and objective measures are used to assess impulsivity. Together, treatment developments (pharmacological, behavioral, and neurophysiological) should consider these clinically relevant dimensions assessed by a variety of measures, which have implications for treatment matching in individuals with SUD. Despite its heterogeneity, impulsivity is a marker associated with SUDs and may be understood as an imbalance of bottom-up and top-down neural systems. Further investigation of these relationships may lead to more effective SUD treatments.

A systematic approach to subgroup analyses in a smoking cessation trial

BACKGROUND

Traditional approaches to subgroup analyses that test each moderating factor as a separate hypothesis can lead to erroneous conclusions due to the problems of multiple comparisons, model misspecification, and multicollinearity.

OBJECTIVE

To demonstrate a novel, systematic approach to subgroup analyses that avoids these pitfalls.

METHODS

A Best Approximating Model (BAM) approach that identifies multiple moderators and estimates their simultaneous impact on treatment effect sizes was applied to a randomized, controlled, 11-week, double-blind efficacy trial on smoking cessation of adult smokers with attention-deficit/hyperactivity disorder (ADHD), randomized to either OROS-methylphenidate (n = 127) or placebo (n = 128), and treated with nicotine patch. Binary outcomes measures were prolonged smoking abstinence and point prevalence smoking abstinence.

RESULTS

Although the original clinical trial data analysis showed no treatment effect on smoking cessation, the BAM analysis showed significant subgroup effects for the primary outcome of prolonged smoking abstinence: (1) lifetime history of substance use disorders (adjusted odds ratio [AOR] 0.27; 95% confidence interval [CI] 0.10-0.74), and (2) more severe ADHD symptoms (baseline score >36; AOR 2.64; 95% CI 1.17-5.96). A significant subgroup effect was also shown for the secondary outcome of point prevalence smoking abstinence--age 18 to 29 years (AOR 0.23; 95% CI 0.07-0.76).

CONCLUSIONS

The BAM analysis resulted in different conclusions about subgroup effects compared to a hypothesis-driven approach. By examining moderator independence and avoiding multiple testing, BAMs have the potential to better identify and explain how treatment effects vary across subgroups in heterogeneous patient populations, thus providing better guidance to more effectively match individual patients with specific treatments.

Prevalence and smoking behavior characteristics of nonselected smokers with childhood and/or adult self-reported ADHD symptoms in a smoking-cessation program: a cross-sectional study

BACKGROUND

ADHD involves impairing core symptoms of inattention and hyperactivity/impulsivity in children (childhood ADHD = CH) that may persist in adulthood (adult ADHD = AD). Conflicting findings have been found regarding AD prevalences among adult smokers, and it is unclear whether AD is associated with a more severe smoking behavior in adulthood.

OBJECTIVE

The aim of this article is (a) to determine CH and AD prevalences in a nonselected sample of adult smokers, (b) to describe the characteristics of smokers with ADHD symptoms versus those without, and (c) to determine whether CH and/or AD symptoms are risk factors for more severe smoking in adulthood.

METHOD

Three hundred and seventy-three participants aged 18 years and over were prospectively recruited in a smoking-cessation unit. Participants were classified as "no ADHD symptoms," "CH symptoms," or "AD symptoms" according to their baseline score on the Wender Utah Rating Scale (WURS) alone (for CH symptoms) and WURS combined to the Adult Self Report Scale (ASRS) for AD symptoms. Other clinical variables were reported at first consultation.

RESULTS

(a) CH symptoms were reported in 15.3% (57/373) of the total sample, 42.1% (24/57) of whom also had persistent ADHD symptoms in adulthood (prevalence of AD was 24/373 = 6.4%). (b) In comparison with participants without ADHD symptoms, smokers with ADHD symptoms consume significantly more tobacco, but ADHD symptoms were no longer significantly associated with the daily number of smoked cigarettes after adjustment for sociodemographic variables. No significant association was found between the two groups and age at the first cigarette, age at onset daily smoking, and nicotine dependence. (c) Participants were categorized into three groups: Group 1 without ADHD symptoms lifetime (NH; n = 316), Group 2 with childhood history of ADHD symptoms (CH; n = 33), and Group 3 with Adult ADHD symptoms (AD; n = 24). The association with tobacco consumption (>20 cigarettes/day) was significant for CH only (p = .02). After adjustment for gender, age, professional status, and educational level, this association was not longer significant.

CONCLUSION

Childhood and adult ADHD symptoms are both highly prevalent among nonselected smokers but our study failed to show more severe smoking characteristics among these participants after adjustment with sociodemographic variables.

Toward personalized smoking-cessation treatment: Using a predictive modeling approach to guide decisions regarding stimulant medication treatment of attention-deficit/hyperactivity disorder (ADHD) in smokers

BACKGROUND AND OBJECTIVES

Osmotic-release oral system methylphenidate (OROS-MPH) did not show overall benefit as an adjunct smoking cessation treatment for adult smokers with ADHD in a randomized, placebo-controlled, multicenter clinical trial. A secondary analysis revealed a significant interaction between ADHD symptom severity and treatment-response to OROS-MPH, but did not account for other baseline covariates or estimate the magnitude of improvement in outcome if treatment were optimized. This present study addressed the gaps in how this relationship should inform clinical practice.

METHODS

Using data from the Adult Smokers with ADHD Trial (N = 255, six sites in five US States), we build predictive models to calculate the probability of achieving prolonged abstinence, verified by self-report, and expired carbon monoxide measurement. We evaluate the potential improvement in achieving prolonged abstinence with and without stratification on baseline ADHD severity.

RESULTS

Predictive modeling demonstrates that the interaction between baseline ADHD severity and treatment group is not affected by adjusting for other baseline covariates. A clinical trial simulation shows that giving OROS-MPH to patients with baseline Adult ADHD Symptom Rating Scale (ADHD-RS) >35 and placebo to those with ADHD-RS ≤35 would significantly improve the prolonged abstinence rate (52 ± 8% vs. 42 ± 5%, p < .001).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

In smokers with ADHD, utilization of a simple decision rule that stratifies patients based on baseline ADHD severity can enhance overall achievement of prolonged smoking abstinence. Similar analysis methods should be considered for future clinical trials for other substance use disorders.

Convergent pharmacological mechanisms in impulsivity and addiction: insights from rodent models

Research over the last two decades has widely demonstrated that impulsivity, in its various forms, is antecedent to the development of drug addiction and an important behavioural trait underlying the inability of addicts to refrain from continued drug use. Impulsivity describes a variety of rapidly and prematurely expressed behaviours that span several domains from impaired response inhibition to an intolerance of delayed rewards, and is a core symptom of attention deficit hyperactivity disorder (ADHD) and other brain disorders. Various theories have been advanced to explain how impulsivity interacts with addiction both causally and as a consequence of chronic drug abuse; these acknowledge the strong overlaps in neural circuitry and mechanisms between impulsivity and addiction and the seemingly paradoxical treatment of ADHD with stimulant drugs with high abuse potential. Recent years have witnessed unprecedented progress in the elucidation of pharmacological mechanisms underpinning impulsivity. Collectively, this work has significantly improved the prospect for new therapies in ADHD as well as our understanding of the neural mechanisms underlying the shift from recreational drug use to addiction. In this review, we consider the extent to which pharmacological interventions that target impulsive behaviour are also effective in animal models of addiction. We highlight several promising examples of convergence based on empirical findings in rodent-based studies.

Attention-deficit/hyperactivity disorder (ADHD) symptoms, craving to smoke, and tobacco withdrawal symptoms in adult smokers with ADHD

BACKGROUND

Tobacco withdrawal symptoms may be confounded with attention-deficit/hyperactivity disorder (ADHD) symptoms among smokers with ADHD.

OBJECTIVE

(1) To assess overlap between ADHD symptoms and tobacco/nicotine withdrawal symptoms and craving; (2) to assess the relationship between craving or withdrawal symptoms and the effect of osmotic-release oral system methylphenidate (OROS-MPH) on ADHD symptoms; (3) to assess the association of ADHD symptoms, craving, and withdrawal symptoms with abstinence.

METHODS

Secondary analysis of a randomized, placebo controlled smoking cessation trial assessing the efficacy of OROS-MPH taken in addition to nicotine patch among individuals with ADHD. ADHD symptoms, withdrawal symptoms, and craving were assessed at baseline and 2, 4 and 6 weeks after a target quit day.

RESULTS

Withdrawal symptoms and craving showed limited and modest overlap with ADHD symptoms prior to abstinence but more extensive and stronger correlation after quit day. Compared to placebo, OROS-MPH reduced ADHD symptoms; this effect was attenuated by controlling for withdrawal symptoms, but not by craving. Craving, but not ADHD symptoms and withdrawal symptoms, was associated with abstinence during the trial.

CONCLUSION

When treating smokers with ADHD (1) craving, rather than tobacco withdrawal symptoms or ADHD symptoms may be the more effective therapeutic smoking cessation targets; (2) careful distinction of craving, withdrawal symptoms, and ADHD symptoms when assessing withdrawal phenomena is needed.

Tobacco dependence counseling in a randomized multisite clinical trial

Pharmacotherapy trials for treating tobacco dependence would benefit from behavioral interventions providing treatment consistent with clinical practice guidelines but not directing participants to treatments not evaluated in the trial. The Smoke Free and Living It© behavioral intervention manual includes participant and interventionist guides and is designed to provide both practical counseling and intra-treatment support. We utilized this intervention manual in a multicenter, randomized clinical trial of smokers with attention deficit hyperactivity disorder. In this study, we evaluated how the interventional manual performed in a "train-the-trainer" model requiring uniform counseling across 6 sites and 15 interventionists. We analyzed the skill-adherence of the interventionists and the intervention-adherence of the participants. The 255 randomized participants completed 9.3±2.8 sessions (mean±SD), with 157 participants (61.6%) completing all 11 of the sessions and 221 (86.7%) completing at least 6 of the 11 sessions. Of the 163 sessions for which the study interventionists were evaluated, 156 (95.7%) were rated as adherent to protocol and "meeting expectations" on at least 6 of 7 established criteria, illustrating that fidelity can be maintained with minimal supervision. The self-help and interventionists guides of the Smoke Free and Living It manual can thus be used to provide behavioral intervention with a high rate of adherence by both the interventionists and the participants. This manual meets the requirements of the United States Public Health Service Clinical Practice Guideline, can be adapted to specific research protocols, and provides a useful option for behavioral intervention during clinical trials for smoking cessation.