Next Article in Journal
Clinical Factors Associated with Longer Hospital Stay Following Ovarian Cancer Surgery
Next Article in Special Issue
Evaluating the Comparative Effectiveness of Two Diets in Pediatric Inflammatory Bowel Disease: A Study Protocol for a Series of N-of-1 Trials
Previous Article in Journal
End-of-Life Care Challenges from Staff Viewpoints in Emergency Departments: Systematic Review
Open AccessArticle

Power and Design Issues in Crossover-Based N-Of-1 Clinical Trials with Fixed Data Collection Periods

Model Risk Management, USAA, 9257 Delaney Creek Blv, Tampa, FL 33619, USA
Quantitative Medicine and Systems Biology, The Translational Genomics Research Institute (TGen), an affiliate of the City of Hope National Medical Center, 445 North Fifth Street, Phoenix, AZ 85004, USA
The Joint City of Hope/TGen IMPACT Center (NJS), Duarte, CA 91010, USA
Author to whom correspondence should be addressed.
Healthcare 2019, 7(3), 84;
Received: 6 May 2019 / Revised: 21 June 2019 / Accepted: 30 June 2019 / Published: 2 July 2019
(This article belongs to the Special Issue N-of-1 Trials in Healthcare)
“N-of-1,” or single subject, clinical trials seek to determine if an intervention strategy is more efficacious for an individual than an alternative based on an objective, empirical, and controlled study. The design of such trials is typically rooted in a simple crossover strategy with multiple intervention response evaluation periods. The effect of serial correlation between measurements, the number of evaluation periods, the use of washout periods, heteroscedasticity (i.e., unequal variances among responses to the interventions) and intervention-associated carry-over phenomena on the power of such studies is crucially important for putting the yield and feasibility of N-of-1 trial designs into context. We evaluated the effect of these phenomena on the power of different designs for N-of-1 trials using analytical theory based on standard likelihood principles assuming an autoregressive lag 1, i.e., AR(1), serial correlation structure among the measurements as well as simulation studies. By evaluating the power to detect effects in many different settings, we show that the influence of serial correlation and heteroscedasticity on power can be substantial, but can also be mitigated to some degree through the use of appropriate multiple evaluation periods. We also show that the detection of certain types of carry-over effects can be heavily influenced by design considerations as well. View Full-Text
Keywords: Efficacy; linear models; interventions; human clinical studies Efficacy; linear models; interventions; human clinical studies
Show Figures

Figure 1

MDPI and ACS Style

Wang, Y.; Schork, N.J. Power and Design Issues in Crossover-Based N-Of-1 Clinical Trials with Fixed Data Collection Periods. Healthcare 2019, 7, 84.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Search more from Scilit
Back to TopTop