American College of Rheumatology (ACR) reports on a draft of new classification criteria for antiphospholipid syndrome (APS) at ACR Convergence 2022 featuring Medha Barbhaiya, MD, MPH, and Doruk Erkan, MD, MPH, rheumatologists at HSS. The previous criteria were developed in 1999 and revised in 2006.

The classification criteria are under review by ACR/EULAR for endorsement and pending final approval. Detailed results and consensus discussions will be presented in future manuscripts.

“Today we present our international, multidisciplinary effort to develop new, rigorous, consensus- and evidence-based, highly specific classification criteria to identify patients with high likelihood of APS for clinical research,” said Dr. Barbhaiya.

Dr. Barbhaiya, Dr. Erkan, and Stéphane Zuily, MD, PhD, professor of medicine, at Lorraine University, France, presented the methodology, novel aspects, and application of the draft criteria on Sunday, 11/13. 

“The goal for classification is to identify a well-defined study sample representative of the majority,” said Dr. Barbhaiya. “We tried to achieve high specificity, sometimes at the cost of sensitivity.”

The methodology involved four phases—item generation, item reduction, weighting of items and threshold identification, and validation—each balancing expert-based and data-driven processes.

Dr. Barbhaiya listed several strengths of the methodology, such as rigorous clinical and laboratory criteria definitions and international cases, and the inclusion of international cases that captured the APS spectrum, reducing the risk of selection bias and increasing generalizability.

Dr. Erkan demonstrated the draft criteria in action, starting with the entry criteria of at least one documented clinical criterion plus a positive aPL test within three years of the clinical criterion. But he offered an important reminder: “Do not count a criterion if there is an equally or more likely explanation than APS. Within each domain, only count the highest weighted criterion toward the total score.”

Dr. Erkan also highlighted the point system for domains presented by Dr. Zuily, noting that the final classification criteria manuscript includes specific definitions and instructions.

If a case does not meet the APS classification criteria, the case may still be uncertain or equivocal rather than “not APS,” Dr. Erkan said. Uncertain or controversial cases should be studied separately to guide future updates of the new criteria.

“We believe our criteria reflect the current thinking about APS, providing high specificity and a stronger foundation for APS research,” concluded Dr. Erkan.

Read the full article at acrconvergencetoday.org/.

Additional coverage: medscape.com/.  and the-rheumatologist.org/.