Predictors of pharmacological treatment outcomes with atomoxetine or methylphenidate in patients with attention-deficit/hyperactivity disorder from China, Egypt, Lebanon, Russian Federation, Taiwan, and United Arab Emirates

Predicting the Response of Children and Adolescents With ADHD to Methylphenidate: A Systematic Review

OBJECTIVE

To report the characteristics associated with response to methylphenidate (MPH) in children and adolescents with ADHD.

METHODS

Studies reporting potentials predictors of response to MPH were searched in Medline and Embase from January 1998 to March 2022. Narrative synthesis was performed.

RESULTS

Fifty-seven reports of 46 studies totaling 6,656 ADHD patients were included. No association appears between response to MPH and age, gender, MPH dosage, ADHD subtype, comorbidities nor socioeconomic status when considering a specific patient. No conclusion could be drawn about body weight, ADHD severity, intelligence quotient, and parental symptoms of depression or ADHD.

CONCLUSIONS

None of these potential predictors have proven their usefulness to predict response to MPH on an individual basis in clinical practice. In research, potential predictors should be measured, their association with response to MPH assessed, in order to control for confounding variables when modeling response to MPH.

Treatments for child and adolescent attention deficit hyperactivity disorder in low and middle-income countries: A narrative review

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that affects approximately 2-7 % of children globally and is associated with a myriad of difficulties that have long-term consequences. Most children and adolescents live in low- and middle-income countries (LMICs), but there are few reports and no consolidation of findings on ADHD treatment outcomes in this population. We conducted a review of ADHD treatment literature for children and adolescents living in LMICs.

METHODS

Studies were identified using databases (PsychoINFO, Pubmed, MEDLINER, EMBASE, Global Health, Academic Search Complete, Google Scholar). The initial search produced 139 articles. These were filtered for language, title, abstract, and full-text keyword identification to yield a final 20 articles to be included in this review.

RESULTS

Reports on outcomes of both psychological and pharmacological treatment were relatively sparse, particularly the former, which mostly referred to parent training and multimodal programs in pre-school children. Most evidence exists for the benefit of methylphenidate-IR with a few reports on other agents, including clonidine, atomoxetine, and lisdexamfetamine. Methylphenidate is the most common agent to treat ADHD in youth in LMICs. Younger age, combined subtype, and comorbid oppositional defiant disorder were associated with poorer treatment outcome.

CONCLUSION

Access to treatment for ADHD is overall limited in LMICs and varied among individual countries. Pharmacological treatments were generally more available than psychological interventions. Several barriers including stigma, cost, and lack of resources were reported to impact treatment acceptance. More research in LMICs is needed to improve and expand mental health services in these regions.

Identification of factors associated with the efficacy of atomoxetine in adult attention-deficit/hyperactivity disorder

Aim

Atomoxetine (ATX) is a non‐central stimulant and a standard treatment for adult attention‐deficit/hyperactivity disorder (ADHD). The long‐term efficacy of Atomoxetine is about 40% at 6 months. The variability in efficacy between individuals is thought to be related to patient‐specific factors, but no detailed research has been conducted. In this retrospective cohort study, we aimed to identify the factors associated with Atomoxetine efficacy.

Methods

A total of 147 patients with attention‐deficit/hyperactivity disorder aged ≥18 years who were using Atomoxetine for the first time were included in this study. The outcome was treatment success (treatment maintained for at least 6 months and improvement in symptoms). Symptom assessment was based on the overall improvement in symptoms judged by an expert physician.

Results

Of the patient sample, 103 (70.1%) achieved the outcome. Logistic regression analysis identified “the maximum dose of ATX” and “gambling habit” as factors associated with efficacy ( P  < 0.05). In the process of Atomoxetine titration, the larger the maximum dose, the higher the efficacy was shown to be. Gambling habits may be indicative of impulsivity, which is among the core symptoms of attention‐deficit/hyperactivity disorder. Thus, a gambling habit may be considered a surrogate marker for impulsivity.

Conclusions

Knowledge of these factors will help healthcare professionals to predict the likely efficacy of Atomoxetine in a given patient before subscribing it, facilitating individualized pharmacotherapy for adult attention‐deficit/hyperactivity disorder.

We retrospectively examined factors associated with the efficacy of atomoxetine for adult ADHD. The maximum dose of atomoxetine and gambling habit were identified as significant factors related to the efficacy.

Individual Variability in Reaction Time and Prediction of Clinical Response to Methylphenidate in Adult ADHD: A Prospective Open Label Study Using Conners' Continuous Performance Test II

Objective: The aim of this study was to examine whether reaction time parameters in adult patients with ADHD could predict their response to methylphenidate (MPH). Method: Previously unmedicated patients (N = 123) were administered the Conners' Continuous Performance Test II (CPT II) at baseline and after 6 weeks of treatment with immediate-release MPH. In addition to traditional CPT measures, we extracted intraindividual raw data and analyzed time series using linear and nonlinear mathematical models. Results: Clinical responders, assessed with the Clinical Global Impression-Improvement scale, showed significant normalization of target failures, reduced variability and skewness, and increased complexity of reaction time series after 6 weeks of treatment, while nonresponders showed no significant changes. Prior to treatment, responders had significantly higher variability and skewness, combined with lower complexity, compared with nonresponders. Conclusion: These results show that the CPT test is useful in the evaluation of treatment response to MPH.

The Association with Quantitative Response to Attention-Deficit/Hyperactivity Disorder Medication of the Previously Identified Neurodevelopmental Network Genes

Objective: A recent pharmacoimaging study suggested that methylphenidate (MPH) and atomoxetine (ATX) might have common mechanisms for the treatment of attention-deficit/hyperactivity disorder (ADHD). Previous pharmacogenetic studies have by and large only involved genes in neurotransmitter systems, which accounted for very small variances. Therefore, this study aimed to investigate whether the neurodevelopmental genes identified in a prior ADHD etiology Genome-Wide Association Study (GWAS) could predict patients' responses to MPH and ATX, given the aforementioned mechanisms of action. Methods: For our sample of 241 patients with ADHD, we assessed the change in the ADHD rating scale (ADHD-RS) total symptom scores from baseline to the end of the 12th week of treatment with either MPH or ATX. We performed association analyses at the genetic single-marker, gene-based, set-based, and GWAS-based polygenic levels. Results: In our analyses, neither single nucleotide polymorphism (SNP) nor gene-level analyses yielded significant markers associated with the change in the ADHD-RS score after multiple comparison correction. The polygenic risk score model, which was based on SNPs associated with ADHD etiology at a threshold of p ≤ 0.0001 in a recent Han Chinese GWAS, predicted symptomatic improvement with ADHD medication (p = 0.018, R² = 0.023). Conclusion: Our results provide new evidence for a small influence of neurodevelopmental genes on the efficacy of medications for ADHD.

A Review of Factors Influencing the Three Phases of Medication Adherence in People with Attention-Deficit/Hyperactivity Disorder

Objectives: Factors affecting adherence to medications in people with attention-deficit/hyperactivity disorder (ADHD) are not well understood in the context of their influence on the different phases of adherence, that is, initiation, implementation, and discontinuation. This review aimed to identify the factors affecting the three phases of medication adherence in people with ADHD. Methods: Six electronic databases, including Medline, PubMed, IPA, CINAHL, Embase, and PsycINFO, were systematically searched from inception through October 2018 with the limitations of English language and human studies. The search strategy was based on three concepts (adherence, ADHD, and factors) and their relevant terminologies. Results: Considerable variability was observed with regards to the criteria used to define adherence in identified studies (n = 48). Most studies focused on the implementation phase of adherence (n = 27), while only a handful focused on the initiation (n = 6) and discontinuation (n = 5) phase of adherence. The remaining studies (n = 10) examined multiple phases of adherence. Conflicting information received about medication, medication frequency, and fears of medication's effect on growth were the unique factors impacting initiation, implementation, and discontinuation, respectively. Moreover, factors within each phase of adherence also differed with different populations such as parents, children, adolescents, and adults. Fear of addiction, medication effectiveness, psychiatric comorbidity, and medication side effects were the most common factors identified in all three phases of adherence. Conclusions: This review found some unique factors in each phase of adherence while some overlap was also noted. Future interventions to improve adherence should be phase- and group specific rather than consider adherence as a single variable.

Clinical and Neuropsychological Factors Associated with Treatment Response and Adverse Events of Atomoxetine in Children with Attention-Deficit/Hyperactivity Disorder

Objectives:

The objective of this study was to investigate clinical and neuropsychological factors associated with treatment response and adverse events of atomoxetine in children with attention-deficit/hyperactivity disorder (ADHD) in Korea.

Methods:

Children with ADHD were recruited at the Department of Psychiatry of Asan Medical Center from April 2015 to April 2018. Diagnoses of ADHD and comorbid psychiatric disorders were confirmed with the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version. The subjects were subsequently treated with atomoxetine for 12 weeks and illness severity was scored using the ADHD Rating Scale, Clinical Global Impression-Severity scale (CGI-S) and/or Improvement scale (CGI-I), at pre- and post-treatment. They also completed the Advanced Test of Attention (ATA), while their caregivers completed the Korean Personality Rating Scale for Children (KPRC) at pre- and post-treatment. Independent t-test, Fisher’s exact test, χ² test, mixed between-within analysis of variance and correlation analysis were used for statistical analysis.

Results:

Sixty-five children with ADHD (mean age: 7.9±1.4 years, 57 boys) were enrolled, of which, 33 (50.8%) were treatment responders. Scores on the social dysfunction subscale of the KPRC (p=0.021) and commission errors on the visual ATA (p=0.036) at baseline were higher in treatment non-responders than in responders; however, the statistical significances disappeared after adjusting for multiple comparisons. Mood changes were also observed in 13 subjects (20.0%), and three of them discontinued atomoxetine due to this. Additionally, atomoxetine-emergent mood change was observed more frequently in girls (p=0.006), while the intelligence quotient (p=0.040) was higher in those subjects with mood changes than in those without.

Conclusion:

The results of our study suggest that clinical and neuropsychological factors could be associated with treatment response or adverse events of atomoxetine in children with ADHD. Further long-term studies with larger samples are needed.

On the question of non-medical cognitive enhancers among in-school adolescents: prevalence, predictors and potential health-related harms

Little is known about the use of non-medical cognitive enhancers (NCEs) in the general population, and even less among youth. The study utilises a nationally representative, cross-sectional survey of adolescents attending high schools to provide a comprehensive overview of NCEs and to assess risk factors such as socio-demographics, schooling, mental health and related substance use among French adolescents. A total of 6692 students attending high school (secondary schools) answered an anonymous questionnaire collecting information on demographics, health, psychoactive substance uses (neuroleptics, tobacco, alcohol, cannabis, illicit substances) and patterns of sociability. The use of cognitive enhancers appears to be an underestimated phenomenon among youth. Prevalence of use is heavily gender-influenced, with females twice as likely to use NCEs than males. More than daily school commitments, the use of cognitive enhancers is related to the proximity of the national secondary education examination. Moreover, mental health, use of prescribed anxiolytics and other psychoactive substances are significantly independently associated with the use of cognitive enhancers, particularly among females. The unregulated use of cognitive enhancers is a predictor of potential mental frailty and a substance-based response to stressful events, a behaviour likely to persist during adulthood. The study underpins the lack of contextual and comparable data. Systematic monitoring of younger students in neighbouring countries is required to develop reliable prevention programmes.

Methylphenidate for attention deficit hyperactivity disorder (ADHD) in children and adolescents - assessment of adverse events in non-randomised studies

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in childhood. The psychostimulant methylphenidate is the most frequently used medication to treat it. Several studies have investigated the benefits of methylphenidate, showing possible favourable effects on ADHD symptoms, but the true magnitude of the effect is unknown. Concerning adverse events associated with the treatment, our systematic review of randomised clinical trials (RCTs) demonstrated no increase in serious adverse events, but a high proportion of participants suffered a range of non-serious adverse events.

OBJECTIVES

To assess the adverse events associated with methylphenidate treatment for children and adolescents with ADHD in non-randomised studies.

SEARCH METHODS

In January 2016, we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, 12 other databases and two trials registers. We also checked reference lists and contacted authors and pharmaceutical companies to identify additional studies.

SELECTION CRITERIA

We included non-randomised study designs. These comprised comparative and non-comparative cohort studies, patient-control studies, patient reports/series and cross-sectional studies of methylphenidate administered at any dosage or formulation. We also included methylphenidate groups from RCTs assessing methylphenidate versus other interventions for ADHD as well as data from follow-up periods in RCTs. Participants had to have an ADHD diagnosis (from the 3rd to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders or the 9th or 10th edition of theInternational Classification of Diseases, with or without comorbid diagnoses. We required that at least 75% of participants had a normal intellectual capacity (intelligence quotient of more than 70 points) and were aged below 20 years. We excluded studies that used another ADHD drug as a co-intervention.

DATA COLLECTION AND ANALYSIS

Fourteen review authors selected studies independently. Two review authors assessed risk of bias independently using the ROBINS-I tool for assessing risk of bias in non-randomised studies of interventions. All review authors extracted data. We defined serious adverse events according to the International Committee of Harmonization as any lethal, life-threatening or life-changing event. We considered all other adverse events to be non-serious adverse events and conducted meta-analyses of data from comparative studies. We calculated meta-analytic estimates of prevalence from non-comparative cohorts studies and synthesised data from patient reports/series qualitatively. We investigated heterogeneity by conducting subgroup analyses, and we also conducted sensitivity analyses.

MAIN RESULTS

We included a total of 260 studies: 7 comparative cohort studies, 6 of which compared 968 patients who were exposed to methylphenidate to 166 controls, and 1 which assessed 1224 patients that were exposed or not exposed to methylphenidate during different time periods; 4 patient-control studies (53,192 exposed to methylphenidate and 19,906 controls); 177 non-comparative cohort studies (2,207,751 participants); 2 cross-sectional studies (96 participants) and 70 patient reports/series (206 participants). Participants' ages ranged from 3 years to 20 years. Risk of bias in the included comparative studies ranged from moderate to critical, with most studies showing critical risk of bias. We evaluated all non-comparative studies at critical risk of bias. The GRADE quality rating of the evidence was very low.Primary outcomesIn the comparative studies, methylphenidate increased the risk ratio (RR) of serious adverse events (RR 1.36, 95% confidence interval (CI) 1.17 to 1.57; 2 studies, 72,005 participants); any psychotic disorder (RR 1.36, 95% CI 1.17 to 1.57; 1 study, 71,771 participants); and arrhythmia (RR 1.61, 95% CI 1.48 to 1.74; 1 study, 1224 participants) compared to no intervention.In the non-comparative cohort studies, the proportion of participants on methylphenidate experiencing any serious adverse event was 1.20% (95% CI 0.70% to 2.00%; 50 studies, 162,422 participants). Withdrawal from methylphenidate due to any serious adverse events occurred in 1.20% (95% CI 0.60% to 2.30%; 7 studies, 1173 participants) and adverse events of unknown severity led to withdrawal in 7.30% of participants (95% CI 5.30% to 10.0%; 22 studies, 3708 participants).Secondary outcomesIn the comparative studies, methylphenidate, compared to no intervention, increased the RR of insomnia and sleep problems (RR 2.58, 95% CI 1.24 to 5.34; 3 studies, 425 participants) and decreased appetite (RR 15.06, 95% CI 2.12 to 106.83; 1 study, 335 participants).With non-comparative cohort studies, the proportion of participants on methylphenidate with any non-serious adverse events was 51.2% (95% CI 41.2% to 61.1%; 49 studies, 13,978 participants). These included difficulty falling asleep, 17.9% (95% CI 14.7% to 21.6%; 82 studies, 11,507 participants); headache, 14.4% (95% CI 11.3% to 18.3%; 90 studies, 13,469 participants); abdominal pain, 10.7% (95% CI 8.60% to 13.3%; 79 studies, 11,750 participants); and decreased appetite, 31.1% (95% CI 26.5% to 36.2%; 84 studies, 11,594 participants). Withdrawal of methylphenidate due to non-serious adverse events occurred in 6.20% (95% CI 4.80% to 7.90%; 37 studies, 7142 participants), and 16.2% were withdrawn for unknown reasons (95% CI 13.0% to 19.9%; 57 studies, 8340 participants).

AUTHORS' CONCLUSIONS

Our findings suggest that methylphenidate may be associated with a number of serious adverse events as well as a large number of non-serious adverse events in children and adolescents, which often lead to withdrawal of methylphenidate. Our certainty in the evidence is very low, and accordingly, it is not possible to accurately estimate the actual risk of adverse events. It might be higher than reported here.Given the possible association between methylphenidate and the adverse events identified, it may be important to identify people who are most susceptible to adverse events. To do this we must undertake large-scale, high-quality RCTs, along with studies aimed at identifying responders and non-responders.

Lost in transition: A review of the unmet need of patients with attention deficit/hyperactivity disorder transitioning to adulthood

This review discusses the unmet needs of patients with attention deficit/hyperactivity disorder (ADHD) who are transitioning into adulthood. Although awareness and recognition of ADHD in children, adolescents, and adults have improved in recent years, there is often an interruption in management of the disorder when adolescent patients transition to adult health care services. This review has the following objectives: (1) to identify key issues patients with ADHD (with or without an early diagnosis) face during transition into adulthood; (2) to review the current clinical practice and country-specific approaches to the management of the transition into adulthood for patients with ADHD; (3) to discuss challenges facing clinicians and their patients when drug treatment for ADHD is initiated; (4) to review current ADHD guidelines on transition management in Hong Kong, Singapore, South Korea, Turkey, and Africa; and (5) to examine economic consequences associated with ADHD. The review suggests that the transition period to adult ADHD may be an underresearched and underserved area. The transition period plays an important role regarding how ADHD symptoms may be perceived and acted upon by adult psychiatrists. Further studies are needed to explore the characteristics of the transition period. If only a fraction of adolescents go on to have mental disorders during adulthood, especially ADHD, it is crucial to identify their characteristics to target appropriate interventions at the beginning of the course of illness. There continues to be low recognition of adult ADHD and a severe lack of medical services equipped to diagnose and care for patients with ADHD transitioning from child to adult services.

Predictors of relapse or maintenance of response in pediatric and adult patients with attention-deficit/hyperactivity disorder following discontinuation of long-term treatment with atomoxetine

We identified relapse/maintenance-of-response (MOR) predictors following discontinuation of long-term atomoxetine treatment in pediatric and adult patients with attention-deficit/hyperactivity disorder (ADHD) and assessed correlations between ADHD symptoms and quality of life (QoL). Post hoc analyses of data from two randomized, double-blind, placebo-controlled, phase 3 withdrawal studies in patients with ADHD meeting predefined response criteria before randomization. Study 1: patients (N = 163; 6-15 years) received atomoxetine (1.2-1.8 mg/kg/day) for 1 year, followed by randomization to atomoxetine (n = 81) or placebo (n = 82) for 6 months. Study 2: patients (N = 524; 18-50 years) received atomoxetine (80-100 mg/day) for ~6 months, followed by randomization to atomoxetine (n = 266) or placebo (n = 258) for ~6 months. Placebo patients were used for the analyses. Relapse: ≥50% worsening of prerandomization improvement in ADHD symptoms and ≥2 level severity increase on the Clinical Global Impression-Severity (CGI-S) scale at 2 consecutive visits; MOR: retaining ≥75% of prerandomization symptom improvement and CGI-S ≤ 2 at all visits (study 1); retaining ≥70% of prerandomization symptom improvement and CGI-S ≤ 3 at all visits (study 2). In adults, statistically significantly (P ≤ .05) increased likelihood of relapse was associated with prerandomization presence of Conners' Adult Attention-Deficit/Hyperactivity Disorder Rating Scale-Investigator-Rated:Screening Version (CAARS-Inv:SV) items "difficulty awaiting turn" and "careless mistakes." In pediatric patients, less MOR was associated with prerandomization presence of ADHD Rating Scale-IV-Parent Version Investigator-Rated item "does not listen"; in adults, less MOR was associated with prerandomization presence of CAARS-Inv:SV items "loses things" and "difficulty awaiting turn." Changes in patients' QoL after withdrawal from atomoxetine moderately correlated with changes in ADHD symptoms in pediatric patients and mildly in adults.

Exploratory analysis of early treatment discontinuation and clinical outcomes of patients with attention-deficit/hyperactivity disorder

INTRODUCTION

This post-hoc analysis was to investigate the impact of treatment discontinuation on clinical outcomes in patients with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Data are from a 12-month, observational, multinational study that included outpatients aged 6-17 years who were diagnosed with ADHD and treated with atomoxetine, methylphenidate, or nootropic agents. Treatment effectiveness and proportions of patients who discontinued treatment were compared between China and the other non-Western countries/regions combined. Propensity score matching was used to further estimate the association between treatment discontinuation and effectiveness.

RESULTS

Of the 546 patients who entered the study, 337 patients had complete data and were included in the analyses. Compared with the other countries/regions, China subgroup had a higher treatment discontinuation rate (odds ratio = 25.80; P < 0.0001) and poorer treatment effectiveness: least-squares (LS) mean changes were 5.74 versus 8.56 (P = 0.0225) for the Child Health and Illness Profile-Child Edition (CHIP-CE) Achievement domain and -1.87 versus -2.13 (P = 0.0401) for Clinical Global Impressions-ADHD-Severity (CGI-ADHD-S). Further analyses of matched discontinuer-maintainer pairs showed that discontinuers demonstrated poorer effectiveness: LS mean changes for the CHIP-CE Achievement domain and CGI-ADHD-S (discontinuer versus maintainer) were 5.36 versus 9.10 (P = 0.0255) and -1.32 versus -1.96 (P = 0.0179) for overall population, respectively, and 4.40 versus 10.17 (P = 0.0065) and -1.48 versus -2.45 (P = 0.0089), respectively, for China subgroup.

DISCUSSION

This analysis found that early treatment discontinuation was associated with worse clinical outcomes for patients with ADHD. China subgroup had substantially higher discontinuation rates and poorer effectiveness outcomes. Strategies to improve medication persistence have the potential to improve outcomes for ADHD patients in China.

Clinical Impact of Not Achieving Recommended Dose on Duration of Atomoxetine Treatment in Adults with Attention-Deficit/Hyperactivity Disorder

Aim

To compare atomoxetine (ATX) length of therapy (LoT) among adults with ADHD who reached the recommended dose of 80 mg/day (ATX ≥ 80) versus those who did not (ATX < 80) analyzed separately in patients prescribed ATX as monotherapy (mono) and in combination with other ADHD medications (combo).

Methods

This was a retrospective observational cohort study of the Truven Health Marketscan Commercial Claims Database from January 1, 2006–September 30, 2013, with a 6‐month preindex period free of ATX (1st ATX claim as index event) and a 1‐year follow‐up. LoT during follow‐up was calculated using prescription claim fill dates and included all days with medication on hand regardless of treatment gaps.

Results

Only 45.0% of the 36,076 mono and 77.9% of the 1548 combo patients reached an ATX dose of ≥80 mg/day in 1‐year follow‐up. When patients filled at least one 80 mg prescription, their total days of therapy over the course of a year were significantly greater than if they did not (mono: 159.3 vs. 65.6 days; combo: 237.4 vs. 172.0; P < 0.0001). Across all timepoints examined (Day 14, 30, 60, 90, 210) for mono and combo, ATX ≥ 80 versus ATX < 80 patients had greater mean doses (P < 0.0001). Combo patients had longer ATX LoT than mono patients regardless if they reached 80 mg or not (P < 0.0001), but mono patients LoT was 93.8 days longer for ATX ≥ 80 versus ATX < 80 patients compared to 65.5 days for combo patients. Of patients reaching 80 mg/day, 71.7% of mono and 62.8% of combo patients did so by Day 30. For mono ATX ≥ 80 and ATX < 80 patients, LoT was significantly (P < 0.0001) less in previously treated patients compared to naive patients.

Conclusion

Ensuring adult ADHD patients are treated with ATX at a target dose of 80 mg/day is an important clinical consideration for maximizing patient days on therapy, which can be important for treatment optimization.

Post Hoc Analysis of Potential Predictors of Response to Atomoxetine for the Treatment of Adults with Attention-Deficit/Hyperactivity Disorder using an Integrated Database

BACKGROUND

Responses to atomoxetine vary for individual patients with attention-deficit/hyperactivity disorder (ADHD). However, we do not know whether any factors can be used to reliably predict how individuals with ADHD will respond to treatment.

OBJECTIVE

Our objective was to evaluate background variables that facilitate early identification of those adults with ADHD who are likely to respond to treatment with atomoxetine.

METHODS

We pooled data for atomoxetine-treated adults with ADHD from 12 clinical trials for a short-term (10-week) analysis, and from 11 clinical trials for a long-term (24-week) analysis. Patients not meeting a response definition [≥30 % reduction in Conners' Adult ADHD Rating Scales-Investigator Rated: Screening Version (CAARS-Inv:SV) total score and Clinical Global Impressions of ADHD Severity Scale (CGI-S) score ≤3 at endpoint], or who discontinued, were defined as non-responders. Another definition of response (≥30 % reduction in CAARS-Inv:SV total score at endpoint) was also used in these analyses; only the results with the former definition are shown in this abstract, as the same conclusions were gained with both definitions. A treatment-specified subgroup detection tool (a resampling-based ensemble tree method) was used to identify predictors of response.

RESULTS

Of 1945 adults in the long-term analysis, 548 (28.2 %) were responders to atomoxetine at week 24; 65.2 % of 1397 non-responders had discontinued. Of 4524 adults in the short-term analysis, 1490 (32.9 %) were responders at week 10; 33.2 % of 1006 non-responders had discontinued. No analyzed baseline parameters (age, sex, prior stimulant use, ADHD subtype, CAARS-Inv:SV, CGI-S) were statistically significant predictors of response. Reductions in CAARS-Inv:SV total, CAARS-Inv:SV subscores, and CGI-S at week 4 in the short-term analysis, and at weeks 4 or 10 in the long-term analysis, were statistically significant predictors of response, i.e., patients with versus without these reductions early in treatment were more likely to be clinical responders at later time points. Sensitivity ranged from 28.6 to 85.9 %, and specificity ranged from 23.8 to 86.7 %. Predictors with higher sensitivity had lower specificity, and vice versa.

CONCLUSIONS

Reductions in CAARS-Inv:SV and CGI-S scores at weeks 4 and 10 are statistically significant predictors of response to atomoxetine at later time points in adults with ADHD. However, the predictors identified by these analyses are not reliable enough for use in clinical practice. The only currently available method to judge whether individuals with ADHD will respond to atomoxetine is to start treatment and assess the response over an extended period, sometimes longer than 10 weeks.

Factors affecting treatment adherence to atomoxetine in ADHD: a systematic review

The purpose of this paper was to systematically review the literature related to research about the factors affecting treatment adherence and discontinuation of atomoxetine in pediatric, adolescent, and adult patients with attention-deficit/hyperactivity disorder (ADHD). Medline was systematically searched using the following prespecified terms: "ADHD", "Adherence", "Compliance", "Discontinuation", and "Atomoxetine". We identified 31 articles that met all inclusion and exclusion criteria. The findings from this review indicate that persistence and adherence to atomoxetine treatment were generally high. Factors found to influence adherence and nonadherence to atomoxetine treatment in ADHD in this review include age, sex, the definition of response used, length of treatment, initial dose of treatment, comorbid conditions, and reimbursement. Tolerability was cited as an important reason for treatment discontinuation. More research is needed to understand those factors that can help to identify patients at risk for poor adherence and interventions that could improve treatment adherence early in the stage of this illness to secure a better long-term prognosis.

Atomoxetine in patients with ADHD: A clinical and pharmacological review of the onset, trajectory, duration of response and implications for patients

This article reviews data providing new insight into the trajectory of response and maintenance of response of atomoxetine in the treatment of child and adult attention-deficit hyperactivity disorder (ADHD). This nonsystematic review includes: onset of action and duration of effect, response rate, effect size, time to optimal response and norepinephrine transporter blockade biomarker data. Atomoxetine can have an onset of action within 1-2 weeks of starting treatment, but there is an incrementally increasing response for up to 24 weeks or longer. Responder rates and effect sizes are similar to methylphenidate. Upon treatment discontinuation, relapse rates are lower than expected. In adults, 50% maintain their response for at least 6 months after stopping atomoxetine, following 6 months of treatment. Single-dose atomoxetine can provide 24-hour efficacy, despite a 5-hour plasma half-life. Hypotheses can be generated relating to neuroadaptive changes, to explain these findings. Atomoxetine has a trajectory of response that is incremental over a long period of time, with a greater than expected maintenance of response. This has implications for physician atomoxetine dosing and efficacy assessment, patient education and outcomes, and for clinical trial design and assessment of comparative efficacy with stimulant medications.