Dr. Farrar has been involved in clinical research for more than 30 years, with a major focus on the study of the efficacy of pain therapeutics and on novel methodology in the design and execution of clinical trials. As a neurologist and a pharmaco-epidemiologist, he has been involved in numerous studies including randomized trials (RCTs), cohort studies, and methodologic studies of pain and associated symptoms such as fatigue, depression, and quality of life in clinical research and practice; these have been conducted with funding he has received from the National Institutes of Health, the U.S. Food and Drug Administration (FDA), private foundations, and industry sources.

Currently, Dr. Farrar serves as the principal investigator of the NIH HEAL EPPIC-Net Clinical Center at the University of Pennsylvania and directs the evaluation component of Penn's current Clinical and Translational Science Award (CTSA), and is a collaborator with the data coordinating center for the U54 multicenter Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) study. Nationally, he has served on advisory boards for the FDA, on the National Academy of Science (NAS) committee on Missing Data in Clinical Trials, and on the Institute of Medicine’s (IOM) committee on Relieving Pain in America. He continues to serve roles as an ad hoc reviewer for NIH and the FDA, and as Clinical Trials specialty editor for the Frontiers Journal of Pain Research.

His current research is focused on the evaluation of new methodologies for understanding how patients report their pain, studies in a large population of patients with pelvic pain, and functional brain imaging in people with pain. At the University of Pennsylvania, he also serves as the co-director of the Master of Science in Clinical Epidemiology program and of the Biostatistics and Epidemiology Consulting Center.