Abstract:
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In 2014, the Agency for Healthcare Research and Quality released a user's guide for the design and implementation of N-of-1 trials to improve the general understanding of these designs and raise the level of evidence generated when such trials are conducted. However, N-of-1 trials remain relatively uncommon in areas where they may be most beneficial, such as for rare diseases. We examine the potential of N-of-1 trials in the setting of cystic fibrosis (CF), a life-shortening genetic disease affecting approximately 70,000 people worldwide, to identify when N-of-1 trials are more appropriate and/or more efficient than traditional study designs. Simulations comparing the sample size of N-of-1 designs to parallel and crossover studies are presented. Pulmonary function and sweat chloride endpoints from studies conducted by the Cystic Fibrosis Therapeutics Development Network are used to select simulation parameters. Sets of complementary N-of-1 trials require smaller sample sizes than AB/BA crossover designs for anticipated within-patient correlations. N-of-1 trials are a viable alternative to traditional designs and hold promise for evaluating new therapies in rare diseases such as CF.
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