Ritalin may not help children with ADHD?

A few days ago, the media had a frenzy over a new study about the use of Ritalin (methylphenidate – a stimulant medication) for Attention Deficit Hyperactivity Disorder (ADHD) (http://goo.gl/Ht9GKF).

ADHD is always good for a headline grab because it is so polarizing. It’s like the new HIV – everyone’s got an opinion on ADHD, and most of them are facile or just plain ignorant. That doesn’t stop the armchair experts from sharing their opinions, and this new Cochrane review into the studies of Ritalin for ADHD just gives them another chance to vent their fatuous spleens.

Like a couple of the comments posted at the end of The Australian article. One suggested that ADHD was a disease invented so they could find another drug to treat it, and suggested that mobile phone games were the problem. Another thought he was rather humorous when he trotted out the tired old chestnut that it’s all the parents fault: “ADHD has been nicnamed {sic} ‘Absent Dad At Home’ syndrome!”  Sorry, but no one’s laughing. 

We need to take a step back from the uneducated and unwarranted opinion of the self-titled experts, and look at what the study actually said. To do that, lets have a look at what the study was, what it looked at, and what the results were. We’ll then compare the results with some of the other options available for treating ADHD, so we can make an informed decision about how to best manage ADHD.

First, what study are we talking about? The study in question is a Cochrane Review lead by Storebo, titled “Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD)” [1]. (You can read the official press release here: http://www.cochrane.org/news/researchers-urge-caution-prescribing-commonly-used-drug-treat-adhd or the abstract here: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD009885.pub2/abstract)

Cochrane reviews are scientific works that pool the best research on a particular topic and combine it into a mega-study, to get the best results available for a particular topic. First, all the papers written about the topic in question are found. The poorest quality studies are discarded, leaving studies that are suitable quality and are fairly uniform in how they did their research, so that the results from each study can be combined into one uniform result.

This process of meta-analysis increases the statistical power of the results enormously. The Cochrane Collaboration has been at the forefront of meta-analysis and has developed specific rules about the quality of evidence it accepts for its reviews, making a Cochrane review as trustworthy as medical research can be.

So what did the meta-analysis of methylphenidate for children with ADHD actually show? In short,

  • A strong improvement in the Teacher-Rated Symptoms score,
  • A strong improvement in the Teacher-Rated Behaviour score,
  • Small-to-moderate improvement in the ADHD rating scale,
  • Small increase in minor side effects such as poorer sleep and appetite, and
  • No increase in serious harm from methylphenidate.

So … that sounds pretty positive overall. Why the big hullabaloo? Why are these experts supposedly urging caution?

The concerns the researchers had was with the quality of the studies. Overall, the research that’s been done thus far has been deemed low quality by Cochrane’s standards. So they were cautious about suggesting that the results were reliable given the quality of the studies they had to work with. And that’s fair enough. Better quality studies are required to confirm the findings of the current Cochrane review, and this should be done as a matter of priority.

Unfortunately, the reviewer’s cautious approach to the research has been misinterpreted as a concern about the drug itself.

There are two important points here: 1. Accepting the limitations of the quality of the research it’s based on, the review still found a moderate effect of methylphenidate, and 2. Other “treatments” for ADHD have been proven in separate meta-analyses to be wholly ineffective.

There’s a little bit of statistical interpretation required here, but the Standardised Mean Difference (SMD, or sometimes called Cohens d) for the Teacher-Rated Symptoms score and Teacher-Rated Behaviour score was -0.77 and -0.87 respectively. The negative value here doesn’t mean that it’s bad; it’s just the arbitrary direction the reviewers chose to show improvement favouring Ritalin. Then there’s the SMD itself. The SMD takes into account the variability of the results overall, using a specific formula to take that into account.

The SMD used here doesn’t equate to the other value the reviewers used for the side effect statistics, which they expressed as a relative risk. So you can’t look at the numbers given and directly equate the power of the improvements with the chance of side effects of the medication.

However, it’s been said that an SMD of 0.2 is a small effect size, 0.5 is moderate, and 0.8 is large [2], so the effect of Ritalin given by the study was actually a strong effect. In comparison, the relative risk of minor adverse effects given by the review was 1.29, or a 29% increased risk, which is relatively small.

Then there’s the important consideration of the effects of other treatments for ADHD. The effect of Ritalin maybe backed by low quality evidence, but there’s no evidence of any effect for the other so-called ‘treatments’ for ADHD. As per the review by Sonuga-Barke (2013), there is a tiny amount of evidence for supplementation with omega-3 and 6 fatty acids, but none for:

  1. Elimination diets (including those for ‘antigenic’ foods, specific provoking foods, general elimination diets and ‘oligoantigenic’ diets)
  2. Food colouring (including certified food colours, Fein-gold diets and tartarazine)
  3. Cognitive training (including working memory specific, and attention specific training)
  4. Neurofeedback, and
  5. Behavioural intervention [3]

So no matter how inane or facile the arm-chair experts may be, there is no evidence that Ritalin for ADHD is harmful. There is a small risk of minor effects such as reduced appetite and sleep, but there is evidence (albeit low quality evidence) that it has a strong positive effect. In comparison, there’s no evidence of improvement from any other treatment that’s been adequately studied.

No drug is perfect, and that includes Ritalin. But it’s certainly not the devil in pill form either. It’s time to stop demonizing it, and ignorantly criticizing those children and their families who need it.

References

[1]       Storebo OJ, Ramstad E, Krogh HB, et al. Methylphenidate for children and adolescents with attention deficit hyperactivity disorder (ADHD). The Cochrane database of systematic reviews 2015 Nov 25;11:CD009885.
[2]       Faraone SV. Interpreting estimates of treatment effects: implications for managed care. P & T : a peer-reviewed journal for formulary management 2008 Dec;33(12):700-11.
[3]       Sonuga-Barke EJ, Brandeis D, Cortese S, et al. Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. The American journal of psychiatry 2013 Mar 1;170(3):275-89.

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