Introduction

In March 2018, the National Institute for Health and Care Excellence (NICE) updated its guideline (NG87) on diagnosing and managing attention-deficit hyperactivity disorder (ADHD),1 and its in-house systematic reviews on the efficacy and adverse events of pharmacological treatments for ADHD.2 3 The guideline recommends methylphenidate as the first-line pharmacological treatment for children over five, adolescents and adults with ADHD and lisdexamfetamine for adults only (recommendations under section 1.7).1 An appointed NICE committee formulated the recommendations based on clinical experience, drug licensing regulations and the systematic review evidence (developed in concert with the National Guideline Centre).4 The NICE committee conclude that methylphenidate and lisdexamfetamine provide clinically important benefits to patients with ADHD compared with placebo and other drugs (p. 47).1

ADHD is a neurodevelopmental disorder characterised by excessive hyperactivity, impulsivity and inattention.5 The condition is associated with increased risks of substance-use disorders, accidents, academic failure, diabetes, suicidal behaviour and other adverse health outcomes.6 There is some, but arguably not much, high-quality evidence that current behavioural and pharmacological interventions are effective, and the genetic and environmental causes of ADHD remain largely unknown.7 We previously authored four Cochrane systematic reviews on the clinical efficacy and adverse events of methylphenidate and amphetamines for children, adolescents and adults with ADHD.8–11 All published reviews concluded that the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) evidence quality (ie, the certainty in the treatment estimates)12 was low to very low, urging readers to cautiously interpret the results. The updated NICE systematic reviews and recommendations contrast markedly from the previous Cochrane findings.

As stated in the NICE manual,13 recommendations should be informed by the best available evidence. However, if confronted with unsubstantial or biased evidence, committee members often depend on subjective value judgements when developing recommendations.14 This …