‘Simple score’ identifies risk level for inflammatory arthritis

Key takeaways:

• A simple score identified patients at low risk for inflammatory arthritis with a false-negative rate of 5%.
• Meanwhile, a comprehensive score identified high-risk patients with a false-positive rate of 29%.

Researchers said they developed a comprehensive score that can identify patients at high risk for inflammatory arthritis, as well as a “simple score” that can identify patients at low risk, both of which “may be useful in clinical care.”

According to Laurence Duquenne, MD, from the Leeds Institute of Rheumatic and Musculoskeletal Medicine at the University of Leeds, and colleagues, inflammatory arthritis (IA) “comprises all immune-related conditions characterized by the presence of clinical synovitis in at least one joint.”

They noted that rheumatoid arthritis — a chronic form of IA — has been linked to several biomarkers that may present “years before the development of clinical synovitis onset,” and a better understanding of these biomarkers could lead to greater preventive measures.

Three IA risk prediction scores have previously been published. However, “the scores were derived from different populations, and no validation has yet been done,” the researchers wrote in Annals of Internal Medicine.

So, Duquenne and colleagues developed two scores to predict IA in at-risk patients: “a simple score designed for informing referral to secondary care and comprehensive scores for stratification when intervention is considered,” they wrote.

The scores were used in a cohort of 455 participants in the United Kingdom with:

• new musculoskeletal symptoms;
• a positive test for anticitrullinated protein antibodies (anti-CCP); and
• no clinical synovitis.

The participants were followed for 48 weeks or more or until they developed IA.

Duquenne and colleagues found that 32.5% of the cohort developed IA. Among them, 15.4% developed it within a year and 4.8% developed it within 2 years.

The simple score identified 249 low-risk patients with a false-negative rate of 5%. It also identified 206 high-risk participants with a false-positive rate of 72%.

The findings provide “evidence that not all persons with positive anti-CCP results should be referred to secondary care,” the researchers wrote. “The data suggest approximately 5% of these at-risk persons not referred to secondary care would develop IA over the first 12 months.”

Meanwhile, the comprehensive score identified 199 high-risk participants with a false-positive rate of 29%, as well as 336 low-risk participants with a false-negative rate of 19%.

Among high-risk participants, 40% developed IA within 1 year and 71% developed it within 5 years.

The researchers noted that the comprehensive score produced a net benefit of 0.11 when compared with not treating anyone.

“This implies that for every 100 persons assessed, 11 participants who would develop IA would be treated while avoiding treatment of persons who would not develop IA,” Duquenne and colleagues wrote. “It shows a clinically significant improvement over the score developed in 2015, which yielded a net benefit of 0.05.”

Limitations of the study included participants being recruited over 13 years, which resulted in varied anti-CPP assays and lower rates of IA development in later recruitment, according to the researchers.

Duquenne and colleagues concluded that the simple score is “reproducible, economical, and practical for use in primary care,” while the comprehensive score can be an important tool for research and clinical management.

“These scores should have a positive effect on persons and health care systems,” they wrote.