N of 1 Trials

Environmental & Science Education

STEM

Health

Medicine

Edward Hessler

When we think of health studies we generally assume the involvement of large numbers of patients (and are suspicious when numbers are small, often with justification. and especially when authors don't discuss this). I learned recently of really small trials. These are are known as N of 1 trials, the study of one person. Such studies are also referred to as SCEDs, single-case experimental studies. 

Writing for Undark, Chris Woolston describes what can be learned from as well as the value of case studies. "As with most research studies, N of 1 studies gain their power through data points. But instead of taking a few measurements from many people, researchers can conduct many measurements from one person over time. A study might compare the results of two different interventions, perhaps two different pain medications or two different diets. Or it might compare an intervention to a placebo to see if a treatment had any real effect beyond wishful thinking. Throughout the process, the subject often has the power to change the approach and goal of the study to meet their own needs."

Woolston's essay describes several N of 1 trials such as nutritional interventions, studies that take advantage of genetic, personal habits and microbial differences, and self-studies in which a patient studies herself, in this case, the effects of a drug on the side effects caused by another medication."In a letter published in JAMA Internal Medicine in 2019, (a research team) wrote that widespread use of N of 1 trials could help people learn to improve their health through a better understanding of their diet, exercise, and medications. As a bonus, they would get a firsthand experience with the rigors of scientific research, which would improve their scientific literacy as well as their self-care."

Woolston points out that "Not every attempt at N of 1 research has been a complete success. A 2018 study....compared N of 1 trials to standard care for a group of 215 people with chronic musculoskeletal pain. The 108 patients in the N of 1 group essentially ran their own studies. They chose two treatments for comparison — such as acetaminophen and acupuncture — and they also chose the study length. Subjects used smartphones or tablets to track their results. The other 107 subjects received usual care. Both groups reported better control of pain one year later, and the N of 1 group consistently fared better on a wide array of outcomes at different times (for example, pain intensity at six and 12 months). But by the study’s end, there was no significant difference in pain-related interference with daily activities."

And finally, "Smartphone apps... should help open up a new world of N of 1 studies, says Christopher Schmid, a biostatistician at Brown University in Providence, Rhode Island, allowing individuals to do their own studies in collaboration with their physicians. “'Advances are being made in the way that people collect their own data,'” he says. “'It brings research to people who don’t normally think about doing research.'”