Classification Criteria for Pediatric Chronic Nonbacterial Osteomyelitis Released

Although the criteria are primarily intended to distinguish CNO from mimicker conditions for research purposes, not diagnosis, some clinicians “may have different thresholds of making the diagnosis based on known diagnostic criteria” and choose biopsy, although biopsy is not always required for clinical diagnosis, Dr. Zhao says. Neither is biopsy required in classification criteria. However, in patients with features of mimicker conditions, it may be indicated for clinical diagnosis, he adds.

Dr. Sandrine Lacassagne

A bone biopsy makes classification easier, says Sandrine Lacassagne, MD, MSc, a consultant in pediatric rheumatology at Great Ormond Street Hospital for Children, London. She points out that up to 17 points out of a total of 55 can potentially come from biopsy results.

The bone biopsy domain may be subject to debate because not all patients have a bone biopsy and the criteria do not guide on the decision to perform a bone biopsy, Dr. Zhao notes.

Another criterion that may spur debate is an exclusion criterion calling for complete and sustained response to antimicrobials alone. This criterion does not suggest every patient should receive a trial of antibiotics, according to Dr. Zhao.

“Vitamin C deficiency, a mimicker condition, can be more common than we expect in western countries, and it is important to exclude it before applying the criteria because all other features can be very similar to CNO,” he adds.

Looking for Better Treatments

An important area of CNO research focuses on better therapies. Currently, the most used drugs to treat CNO in­clude non-steroidal anti-inflammatory drugs (NSAIDs), cytokine-blocking agents, bisphosphonates and Janus kinase (JAK) inhibitors. At least half of CNO patients continue to need medi­cations for CNO during adulthood.

Dr. Zhao is collecting clinical data to characterize the long-term outcomes of several drugs. In an ongoing study to establish the Chronic Nonbacterial Osteomyelitis International Registry (CHOIR), he aims to build a prospective disease registry for CNO to investigate the responses of patients to different clinical management over 10 years and better define the natural history of the disease. Drugs included in the study include methotrexate, sulfasalazine, leflunomide, pamidronate, zoledronic acid, etanercept, adalimumab, certolizumab, infliximab, golimumab and NSAIDs, according to clinicaltrials.gov. Currently, the study has 600 patients at 17 sites, Dr Zhao says.

His study will use the new criteria. According to Dr. Ozen, studies in Turkey are also using the criteria. The studies include efforts to examine how bone parameters change within the disease and to validate the classification criteria she and Dr. Zhao established.