A panel of experts and researchers have developed a new classification system for gout, the most common form of inflammatory arthritis. This new system standardizes the classification of this condition using a variety of evidence-based criteria.

Led by a researchers at Boston University School of Medicine (BUSM) and institutions from around the world, the study is a joint publication appearing in two journals simultaneously, Annals of Rheumatologic Disease and Arthritis & Rheumatology.

Gout is characterized by the deposition of a specific type of crystal in joint fluid and various tissues. Numerous new drugs are being developed and tested in trials for gout, and some agents have been approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) in the past few years. These new classification criteria will help standardize how to identify people with gout who should be eligible for enrollment into such trials and other studies.

An international group of investigators with support from the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) developed the classification criteria through a multi-step process. They conducted a systematic review of the literature regarding advanced imaging for gout, conducted a study in which the gold standard to identify gout was presence of monosodium urate crystals, and used a decision analysis scientific approach to generate a comprehensive criteria encompassing multiple domains to guide classification of gout.

The domains comprise clinical, laboratory and imaging parameters and are easily followed using the new stepwise classification system. One key component of the new criteria is negative scoring for the absence of certain parameters. The researchers validated this new system by comparing it to existing published criteria and found that it performed better than those previous ones.

"The implications of this new classification are significant as it provides a means for clinical researchers to use validated criteria for enrollment of subjects with gout into studies. This is particularly important for clinical trials which will use these criteria moving forward, and it is anticipated that these will become the standard expected by the FDA and EMA when evaluating gout clinical trials," explained lead investigator Tuhina Neogi, MD, PhD, associate professor of medicine at BUSM and a rheumatologist at Boston Medical Center.