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Introduction
Published in Wei Zhang, Fangrong Yan, Feng Chen, Shein-Chung Chow, Advanced Statistics in Regulatory Critical Clinical Initiatives, 2022
Wei Zhang, Fangrong Yan, Feng Chen, Shein-Chung Chow
An n-of-1 trial design is defined as a clinical trial design in which a single patient is the entire trial, a single case study. Thus, in an n-of-1 trial, n is the number of treatments and one is the single patient. An n-of-1 trial in which random allocation can be used to determine the order in which an experimental and a control are given to a patient. An n-of-1 trial is a multiple crossover study in a single participant.
Confidence Intervals
Published in Marcello Pagano, Kimberlee Gauvreau, Heather Mattie, Principles of Biostatistics, 2022
Marcello Pagano, Kimberlee Gauvreau, Heather Mattie
As a second example, methylphenidate is a drug widely used in the treatment of attention-deficit disorder. As part of a crossover study, 10 children between the ages of 7 and 12 who suffered from this disorder were assigned to receive the drug and 10 were given a placebo [183]. After a fixed period of time, treatment was withdrawn from all 20 children. Subsequently, patients were given the alternative treatment; children who had originally received methylphenidate were given the placebo, and those who had received the placebo now got the drug. (This is what is meant by a crossover study.) Measures of each child's attention and behavioral status, both while taking the drug and while taking placebo, were obtained using an instrument called the Parent Rating Scale. Distributions of these scores are approximately normal with unknown mean and standard deviation. In general, lower scores indicate an increase in attention. We wish to estimate the mean attention rating scores for children with attention-deficit disorder when taking methylphenidate, and when taking placebo.
Misconceptions, Experimental Design, and Behavioral Genetics
Published in Gail S. Anderson, Biological Influences on Criminal Behavior, 2019
An experiment can also be strengthened by conducting a crossover study. This involves swapping the treatment and control groups halfway through the experiment. In this way, half the chickens get the new diet and half get the old diet. The researchers record weights, then feed the diets to the opposite group, and weigh them. If all the variables are balanced, the weight increase should follow the diet type. This proves that the effect is not just in those chickens.
Effect of Short versus Long Duration Naps on Blood Pressure during Simulated Night Shift Work: A Randomized Crossover Trial
Published in Prehospital Emergency Care, 2023
P. Daniel Patterson, Tiffany S. Okerman, David G. L. Roach, Matthew D. Weaver, Charity G. Patterson, Sarah E. Martin, Nicholas Okwiya, Lily Nong, Chinemeh Eyiba, Jordan R. Huff, Anna Ruzicka, Julia Ruggieri, Quentin McIlvaine, Leonard S. Weiss
We used a laboratory-based experimental crossover study design with three conditions assigned at random. Data collection began March 2021 and ended October 2022. Each condition lasted 72 hrs, beginning with 36 hrs at home with fixed wake and sleep periods, followed by a 12-hr in-lab simulated night shift, a 12-hr in-lab recovery period, and ending with a 12-hr at-home recovery period. The three conditions were no nap (total sleep deprivation during the 12-hr in-lab simulated night shift), 30-min nap, and 2-hr nap, with each nap opportunity taken at 02:00 during the 12-hr in-lab simulated night shift. We based condition randomization on William’s square design (21), and included a required washout period of 1-week between conditions. The University of Pittsburgh institutional review board approved the study protocol and prior to first enrollment, we registered our study with clinicaltrials.gov (registration number: NCT04469803; public release date: 9 July 2020). The details of our protocol, including randomization procedures, are published elsewhere (20).
Reduced gut microbial diversity in familial hypercholesterolemia with no effect of omega-3 polyunsaturated fatty acids intervention – a pilot trial
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2022
Christopher Storm-Larsen, Liv Nesse Hande, Martin Kummen, Hilde Thunhaug, Beate Vestad, Simen Hyll Hansen, Anders Hovland, Marius Trøseid, Knut Tore Lappegård, Johannes R. Hov
We investigated a subgroup from a previously published interventional study. For a complete methodology, we refer to the original study [16]. In brief, individuals with genetically verified heterozygote FH aged 18–75 and using statins >12 months were recruited from Nordland Hospital’s lipid clinic (Bodø, Norway). All individuals had mutations in the gene for the LDL-receptor. The study was designed as a double-blind, placebo-controlled crossover study. In random order, all individuals were treated for 3 months with omega-3 PUFA supplement (2 g b.i.d) and 3 months placebo (olive oil, 2 g b.i.d), separated by a 3-month washout period (Figure 1). The marine omega-3 PUFA supplement was a 1000 mg capsule consisting of 460 mg of eicosapentaenoic acid (EPA) and 380 mg docosahexanoic acid (BASF, Lysaker, Norway). Blood and stool samples were collected at baseline and after each study period (3, 6 and 9 months). According to the returned medication in the original study, compliance was around 90% in both treatment groups.
Effect of probiotic supplementation on migraine prophylaxis: a systematic review and meta-analysis of randomized controlled trials
Published in Nutritional Neuroscience, 2022
Mohammad Parohan, Mahmoud Djalali, Payam Sarraf, Sajad Yaghoubi, Asal Seraj, Abbas Rahimi Foroushani, Sakineh Ranji-Burachaloo, Mohammad Hassan Javanbakht
This study also has several limitations: 1. The number of randomized clinical trials was low to show the potential effect of probiotics on migraine symptoms. 2. There were no data on dietary intake of probiotics. 3. Large variations in the number and type of bacterial species in probiotic products of different geographical regions have been found. 4. Small sample size and significant heterogeneity between studies. This heterogeneity could be explained by the use of different methodologies, using various dosages of probiotic and different trial durations. 5. One of the studies [12] includes patients co-morbid with Irritable Bowel Syndrome and migraine and there are 3 treatment groups: IgG elimination diet, probiotics and IgG elimination diet combined with probiotics; thus, there is no real control group in that study. In addition, the wash-out period was not defined in this cross-over study.