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Are n-of-1 Trials Useful in ADHD Treatment?

n-of-1 stimulant trials offer information that parents and doctors can use to tailor treatment.

Children with attention-deficit/hyperactivity disorder (ADHD) have symptoms and behaviors that often improve with the use of stimulants. However, individual response is variable, making it difficult to predict an effective stimulant type and dose. In addition, parents and clinicians may ask whether a stimulant that has been taken on a long-term basis is still necessary or being given optimally. In this article, researchers describe an n-of-1 trial protocol they developed for children aged 5 to 16 years on a stable dose of stimulant medication for ADHD but with uncertainty about its effectiveness. They promoted the trial service to patients, family physicians, and pediatricians across Australia.

Each of the 86 completed trials used three treatment periods to compare stimulant with placebo, stimulant with another stimulant, or different doses of the same stimulant. A kit with the medications and rating scales for parents and teachers was mailed to each patient’s physician. The patient, physician, parents, teachers, and researchers were blinded to the sequence of medications until completion of the trial. Rating scales were mailed back to the researchers, and after unblinding, each patient was classified as a responder, possible responder, or nonresponder to the specific stimulant type or dose in question. The results were communicated to the patients’ physicians. Ten (12%) trials were not completed, primarily due to deterioration on placebo.

Of the 66 children who completed a stimulant versus placebo trial, 28 were responders; 68% of the responders reported staying on their stimulant medication. Of the 27 nonresponders, 44% reported stopping stimulant medication. The remaining 11 children were possible responders. Overall, 63% of post-trial management decisions reflected the n-of-1 trial results, and 44% of participants stopped or changed medication after the trial.

Comment: With mail and telephone communication, a centralized n-of-1 trial service for conditions with variable treatment responses, such as ADHD, seems feasible and convenient. Although n-of-1 trials are an improvement over trial-and-error because they control for the placebo effect, it remains to be seen whether physicians, parents, and patients would utilize a service like this on a large scale, and act on the information it delivers.

— Cornelius W. Van Niel, MD

Published in Journal Watch Pediatrics and Adolescent Medicine August 30, 2006

Citation(s):

Nikles CJ et al. An n-of-1 trial service in clinical practice: Testing the effectiveness of stimulants for attention-deficit/hyperactivity disorder. Pediatrics 2006 Jun; 117:2040-6.

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