By Lucy Piper, Senior medwireNews Reporter
A Cochrane review of evidence to date has cast uncertainty over the magnitude of benefit children with attention deficit/hyperactivity (ADHD) gain by taking methylphenidate.
The comprehensive assessment of 185 trials involving 12,245 children or adolescents with ADHD showed that methylphenidate, versus placebo or no treatment, reduced teacher-reported ADHD symptoms and improved general behaviour and parent-reported quality of life.
However, the researchers found that all of the trials were at high risk of bias, largely due to side effects occurring in patients assigned to active treatment, and the quality of evidence was rated as “very low” for all outcomes. In addition, in some studies the reporting of results was incomplete and there was variation across trials.
“These considerations limit our confidence in the overall results of the review”, notes the team, led by Ole Jakob Storebø (Child and Adolescent Psychiatric Department, Roskilde, Denmark).
Methylphenidate’s beneficial effect on teacher-rated ADHD symptoms corresponded to an average 9.6-point decrease on the ADHD rating scale, meeting the clinically relevant 6.6-point difference. There was also evidence of improvement in general behaviour and quality of life, with standardised mean differences of 0.87 and 0.61, respectively.
But Storebø et al say that “the low quality of the underpinning evidence means that we cannot be certain of the magnitude of the effects.”
These also needed to be balanced against a 29% increased risk of non-serious adverse events among participants taking methylphenidate, most commonly sleeping problems and decreased appetite, at risk increases of 60% and 266%.
There was no increased risk of serious adverse events with methylphenidate over periods of up to 6 months, but the researchers point out that data were available for only nine of the 185 trials.
“If methylphenidate treatment is considered, clinicians might need to use it for short periods, with careful monitoring of both benefits and harms, and cease its use if no evidence of clear improvement of symptoms is noted, or if harmful effects appear”, they comment in The Cochrane Library.
The team also calls for better designed trials to assess the benefits of methylphenidate that report all outcomes and include adverse events. And they suggest the possible use of “nocebo tablet” controlled trials that cause adverse events in the control arm to improve bias, although for ethical reasons they recommend first conducting these in adults who can give informed consent.
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