Evidence on methylphenidate in children and adolescents with ADHD is in fact of 'very low quality'

Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD)

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is one of the most commonly diagnosed and treated psychiatric disorders in childhood. Typically, children and adolescents with ADHD find it difficult to pay attention and they are hyperactive and impulsive. Methylphenidate is the psychostimulant most often prescribed, but the evidence on benefits and harms is uncertain. This is an update of our comprehensive systematic review on benefits and harms published in 2015.

OBJECTIVES

To assess the beneficial and harmful effects of methylphenidate for children and adolescents with ADHD.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, three other databases and two trials registers up to March 2022. In addition, we checked reference lists and requested published and unpublished data from manufacturers of methylphenidate.

SELECTION CRITERIA

We included all randomised clinical trials (RCTs) comparing methylphenidate versus placebo or no intervention in children and adolescents aged 18 years and younger with a diagnosis of ADHD. The search was not limited by publication year or language, but trial inclusion required that 75% or more of participants had a normal intellectual quotient (IQ > 70). We assessed two primary outcomes, ADHD symptoms and serious adverse events, and three secondary outcomes, adverse events considered non-serious, general behaviour, and quality of life.

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted data extraction and risk of bias assessment for each trial. Six review authors including two review authors from the original publication participated in the update in 2022. We used standard Cochrane methodological procedures. Data from parallel-group trials and first-period data from cross-over trials formed the basis of our primary analyses. We undertook separate analyses using end-of-last period data from cross-over trials. We used Trial Sequential Analyses (TSA) to control for type I (5%) and type II (20%) errors, and we assessed and downgraded evidence according to the GRADE approach.

MAIN RESULTS

We included 212 trials (16,302 participants randomised); 55 parallel-group trials (8104 participants randomised), and 156 cross-over trials (8033 participants randomised) as well as one trial with a parallel phase (114 participants randomised) and a cross-over phase (165 participants randomised). The mean age of participants was 9.8 years ranging from 3 to 18 years (two trials from 3 to 21 years). The male-female ratio was 3:1. Most trials were carried out in high-income countries, and 86/212 included trials (41%) were funded or partly funded by the pharmaceutical industry. Methylphenidate treatment duration ranged from 1 to 425 days, with a mean duration of 28.8 days. Trials compared methylphenidate with placebo (200 trials) and with no intervention (12 trials). Only 165/212 trials included usable data on one or more outcomes from 14,271 participants. Of the 212 trials, we assessed 191 at high risk of bias and 21 at low risk of bias. If, however, deblinding of methylphenidate due to typical adverse events is considered, then all 212 trials were at high risk of bias.

PRIMARY OUTCOMES

methylphenidate versus placebo or no intervention may improve teacher-rated ADHD symptoms (standardised mean difference (SMD) -0.74, 95% confidence interval (CI) -0.88 to -0.61; I² = 38%; 21 trials; 1728 participants; very low-certainty evidence). This corresponds to a mean difference (MD) of -10.58 (95% CI -12.58 to -8.72) on the ADHD Rating Scale (ADHD-RS; range 0 to 72 points). The minimal clinically relevant difference is considered to be a change of 6.6 points on the ADHD-RS. Methylphenidate may not affect serious adverse events (risk ratio (RR) 0.80, 95% CI 0.39 to 1.67; I² = 0%; 26 trials, 3673 participants; very low-certainty evidence). The TSA-adjusted intervention effect was RR 0.91 (CI 0.31 to 2.68).

SECONDARY OUTCOMES

methylphenidate may cause more adverse events considered non-serious versus placebo or no intervention (RR 1.23, 95% CI 1.11 to 1.37; I² = 72%; 35 trials 5342 participants; very low-certainty evidence). The TSA-adjusted intervention effect was RR 1.22 (CI 1.08 to 1.43). Methylphenidate may improve teacher-rated general behaviour versus placebo (SMD -0.62, 95% CI -0.91 to -0.33; I² = 68%; 7 trials 792 participants; very low-certainty evidence), but may not affect quality of life (SMD 0.40, 95% CI -0.03 to 0.83; I² = 81%; 4 trials, 608 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

The majority of our conclusions from the 2015 version of this review still apply. Our updated meta-analyses suggest that methylphenidate versus placebo or no-intervention may improve teacher-rated ADHD symptoms and general behaviour in children and adolescents with ADHD. There may be no effects on serious adverse events and quality of life. Methylphenidate may be associated with an increased risk of adverse events considered non-serious, such as sleep problems and decreased appetite. However, the certainty of the evidence for all outcomes is very low and therefore the true magnitude of effects remain unclear. Due to the frequency of non-serious adverse events associated with methylphenidate, the blinding of participants and outcome assessors is particularly challenging. To accommodate this challenge, an active placebo should be sought and utilised. It may be difficult to find such a drug, but identifying a substance that could mimic the easily recognised adverse effects of methylphenidate would avert the unblinding that detrimentally affects current randomised trials. Future systematic reviews should investigate the subgroups of patients with ADHD that may benefit most and least from methylphenidate. This could be done with individual participant data to investigate predictors and modifiers like age, comorbidity, and ADHD subtypes.

Fifteen-minute consultation: To prescribe or not to prescribe in ADHD, that is the question

Attention-deficit hyperactivity disorder (ADHD) is fraught with controversy. Some clinicians believe it is a biological neurodevelopmental disorder which should be treated with medication. Others are adamant that ADHD is a social construct in which children, who have suffered developmental trauma, are medicalised. Evolutionary science may help us find a solution to this dichotomy by seeing ADHD as an example of an evolutionary mismatch in which children with ADHD are caught in a school environment that does not suit their natures. By considering how to improve the 'goodness of fit' between the child and their environment, clinicians can be more flexible in finding solutions that are ethically sound.

Does Methylphenidate Work in Children and Adolescents with Attention Deficit Hyperactivity Disorder?

OBJECTIVE

Attention deficit hyperactivity disorder (ADHD) is a common psychiatric disorder diagnosed in increasing proportions of children and adolescents. The psychostimulant methylphenidate has been considered the first-line pharmacological treatment for children and adolescents with ADHD for more than 60 years. Considering recent publications on methylphenidate for ADHD, we here give an overview of its effects in children and adolescents with ADHD, elicited by a well-disputed Cochrane review and narratively synthesise the evidence in the field.

METHOD

We searched for systematic reviews and meta-analyses that investigated methylphenidate as an intervention for children and adolescence with ADHD compared with placebo or no treatment. We assessed the quality of the evidence using AMSTAR II.

RESULTS

We found 24 eligible systematic reviews and meta-analyses of which 11 were rated as high- quality evidence according to AMSTAR II. The evidence claiming that methylphenidate is beneficial in treating children and adolescents with ADHD was of very low certainty. The underreporting of adverse events in randomised clinical trials may impede an adequate depiction of the balance between benefits and harms.

CONCLUSIONS

It appears that there is uncertain evidence on group-level to support the claim that methylphenidate is beneficial in treating children and adolescents with ADHD. Future randomised clinical trials and systematic reviews should include individual participant data, which would allow us to assess intervention effects across modifiers, like age, sex, ADHD subtypes, comorbidities, and dose.

Risk of Bias and Quality of Evidence for Treatment of ADHD With Stimulant Medication

Storebø et al. provide a concise summary of two Cochrane reviews about benefits and harms of treatment of attention-deficit/hyperactivity disorder (ADHD) with methylphenidate: (1) a review of 185 randomized controlled trials that estimated benefits (e.g., moderate-to-large reduction in teacher-rated ADHD symptoms) and (2) a review of 260 nonrandomized trials that estimated harms (e.g., infrequent serious but frequent nonserious adverse events). They also mention (without providing much detail) additional information from the structured Cochrane method about the risk for bias in the trials reviewed (assessed as being high) and quality of evidence of the outcomes considered (rated as being very low). This led to the conclusion that "the jury is still out on benefits and harms." A similar conclusion of the first review generated an extensive debate in the literature. Some details will be summarized and discussed herein to provide context in case the recent review and the summary by Storebø et al. revive the debate.

The Cochrane Collaboration withdraws a review on methylphenidate for adults with attention deficit hyperactivity disorder

A Cochrane systematic review on immediate-release methylphenidate for adults with attention deficit hyperactivity disorder (ADHD) was withdrawn from the Cochrane Library on 26 May 2016 after substantial criticism of its methods and flawed conclusions. Retraction of scientific papers on this basis is unusual but can be necessary. We provide a summary of the criticism that led to the withdrawal. We detail the methodological flaws of the withdrawn Cochrane systematic review and general issues of bias and shortcomings of the included ADHD trials: cross-over designs compared with parallel-group designs, exclusion of participants with psychiatric comorbidity, absence of 'functional outcomes' and use of clinical outcomes with limited relevance, short trial duration and small trial populations, broken blinding caused by easily recognisable side effects, combining outcome assessments by trial investigators and participants, outcome reporting bias, poor evaluation of cardiovascular and psychiatric harms and conflicts of interest of trialists and systematic reviewers. The withdrawal of the Cochrane systematic review signals recognition of previous unreliable clinical ADHD research. We conclude that clinical trials of immediate-release methylphenidate in adults with ADHD are of very low quality. We urgently need well-conducted long-term trials free of bias to assess the benefits and harms of central stimulant treatment in adult ADHD.

Methylphenidate for ADHD in children and adolescents: throwing the baby out with the bathwater

A recent Cochrane review assessed the efficacy of methylphenidate for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. Notwithstanding the moderate-to-large effect sizes for ADHD symptom reduction found in the meta-analysis, the authors concluded that the quality of the evidence is low and therefore the true magnitude of these effects remains uncertain. We identified a number of major concerns with the review, in the domains of study inclusion, approaches to quality assessment and interpretation of data relating to serious adverse events as well as of the clinical implications of the reported effects. We also found errors in the extraction of data used to estimate the effect size of the primary outcome. Considering all the shortcomings, the conclusion in the Cochrane review that the status of the evidence is uncertain is misplaced. Professionals, parents and patients should refer to previous reviews and existing guidelines, which include methylphenidate as one of the safe and efficacious treatment strategies for ADHD.