The draft IgG4-RD classification criteria target a specificity of >90% & a sensitivity of >80%.
20-Point Threshold
Through a process of multicriteria decision analysis facilitated by 1000minds software, the working group established a minimum preliminary threshold of 20 points for the IgG4-RD classification criteria. They then evaluated 908 new cases and mimickers in the validation and testing phase of the effort to determine how the 20-point threshold would fare in a new set of patients. They found it had a sensitivity of 85.5% and a specificity of 99.2%. “I think given the protean, multi-organ nature of this disease, this is extraordinary,” said Dr. Stone.
When the working group used the inclusion criteria, but removed the exclusion criteria, they found the specificity decreased to 88.5% and the sensitivity increased to 90%. Thus, although the exclusion criteria are important, the inclusion criteria are also useful. Dr. Stone reminded the audience that classification criteria are not diagnostic criteria. Thus, if a healthcare provider feels a patient has IgG4-RD, then that patient should be treated for IgG4-RD.
He concluded by stating rheumatologists have come a long way in 10–15 years, as indicated by the draft classification criteria—the first ACR criteria drafted to involve specific exclusion criteria. The goal is to use the classification criteria to accelerate the pace of progress in understanding IgG4-RD.
Lara C. Pullen, PhD, is a medical writer based in the Chicago area.
