Predictors of Placebo Response in Adults With Attention-Deficit/Hyperactivity Disorder: Data From 2 Randomized Trials of Osmotic-Release Oral System Methylphenidate
ABSTRACT To find potential correlates of placebo response in adults with attention-deficit/hyperactivity disorder (ADHD) and gain insights into why placebo response may be high in clinical trials.
Post hoc analysis of placebo data from 2 randomized controlled trials of osmotic-release oral system (OROS) methylphenidate in adults with ADHD defined according to the Diagnostic and Statistical Manual of Mental Diseases, Fourth Edition: the Long-Acting Methylphenidate in Adults with ADHD (LAMDA-I) study (2005-2006, 5 weeks, n = 95) and the LAMDA-II study (2008-2009, 13 weeks, n = 97). The primary efficacy measure was the Conners' Adult ADHD Rating Scale-observer rated, short version (CAARS:O-SV). Predictors of CAARS:O-SV change were assessed using a random-intercepts model with demographic and disease-related parameters as independent variables. Sensitivity analyses were conducted using the CAARS self-report (CAARS:S-S) and a categorical response criterion (improvement of > 30% in CAARS:O-SV), and in subjects who completed the study.
In LAMDA-I, mean ± SD change in CAARS:O-SV was -7.6 ± 9.9 with placebo and -11.9 ± 10.6 with OROS methylphenidate. Higher baseline CAARS score (P = .007) and lower educational achievement (P = .014) were significantly associated with greater improvement in placebo-treated subjects. In LAMDA-II, mean ± SD change in CAARS:O-SV was -10.4 ± 11.0 and -14.1 ± 10.7 in subjects receiving placebo and OROS methylphenidate, respectively. Variables significantly associated with greater placebo response were higher baseline CAARS:O-SV (P = .019), shorter time since ADHD diagnosis (P < .045), and younger age (P = .014). None of the sensitivity analyses challenged the outcomes.
Possible predictors of placebo response in adults with ADHD include higher severity of ADHD symptoms, younger age, shorter time since diagnosis, and lower educational level.
ClinicalTrials.gov identifier: NCT00246220 (LAMDA-I) and EudraCT number: 2007-002111-82 (LAMDA-II).
SourceAvailable from: Luana Colloca[Show abstract] [Hide abstract]
ABSTRACT: A strong placebo response in psychiatric disorders has been noted for the past 50 years and various attempts have been made to identify predictors of it, by use of meta-analyses of randomised controlled trials and laboratory studies. We reviewed 31 meta-analyses and systematic reviews of more than 500 randomised placebo-controlled trials across psychiatry (depression, schizophrenia, mania, attention-deficit hyperactivity disorder, autism, psychosis, binge-eating disorder, and addiction) for factors identified to be associated with increased placebo response. Of 20 factors discussed, only three were often linked to high placebo responses: low baseline severity of symptoms, more recent trials, and unbalanced randomisation (more patients randomly assigned to drug than placebo). Randomised controlled trials in non-drug therapy have not added further predictors, and laboratory studies with psychological, brain, and genetic approaches have not been successful in identifying predictors of placebo responses. This comprehensive Review suggests that predictors of the placebo response are still to be discovered, the response probably has more than one mediator, and that different and distinct moderators are probably what cause the placebo response within psychiatry and beyond.The Lancet Psychiatry 03/2015; 2(3):246-257. DOI:10.1016/S2215-0366(14)00092-3
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ABSTRACT: Although the identification of reliable predictors of methylphenidate response in adults with attention-deficit/hyperactivity disorder (ADHD) is necessary to guide treatment decisions, very few data exist on this issue. Here, we assessed the predictors of clinical response to immediate-release methylphenidate hydrochloride (IR-MPH) in a naturalistic setting by analyzing the influence of demographic factors, severity, and a wide range of comorbid psychiatric disorders. Two hundred fifty adult patients with ADHD were evaluated and completed a short-term treatment with IR-MPH. Mental health diagnoses were based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria through the use of standard structured interviews. The Swanson, Nolan, and Pelham Rating Scale, version 4, adapted to adults was used to assess the severity of ADHD. In the linear regression model, only higher severity of ADHD was associated to a better IR-MPH response (b = 0.770; P < 0.001). Treatment of comorbidities in a subsample (n = 62) did not modify this pattern. Our findings suggest that in clinical settings, patients with more severe ADHD symptoms have a good response to treatment independently from the presence of mild or stabilized comorbidities and their treatments. For adults with ADHD, differently from other common psychiatric disorders such as depression and anxiety, higher severity is associated with better treatment response.Journal of clinical psychopharmacology 04/2014; 34(2):212-7. DOI:10.1097/JCP.0000000000000091 · 3.76 Impact Factor