Randomized Clinical Trials in Single Patients

To the Editor.  —Dr Larson and colleagues have performed a valuable service by showing us that single patient, or N=1, trials are successful for the majority of patients and are cost competitive with other conventional services.¹ The SPT has greater intuitive appeal to active clinicians because the patient serves as his or her own control, each experiment is seminal, and the generalizability of each result becomes moot. For the practitioner faced with an individual patient, perceptions and expectations often displace the mean, the mode, and the odds ratio as operational paradigms.²Clinicians often worry how factors important for randomized controlled trials (RCTs) such as sample size, exclusion criteria, and randomization affect the usefulness of results for individual patients. Counterinference (the application of the results of large RCTs to an individual patient) is frequently problematic. The application of clinical or experimental knowledge for the individual patient is tempered by