Background Chronic multifocal recurrent osteomyelitis (CRMO) is a rare autoimmune, inflammatory disorder that primarily affects children. The disease is characterised by non-infectious, recurrent osteomyelitis, which can be severe and disabling if left untreated. The diagnosis is often made delayed, patients are treated unnecessarily with antibiotics and there is a paucity of information on outcome and disease course.

Objectives The aim of this study was to assess clinical presentation and outcome in a Norwegian Cohort of patients with CRMO.

Methods Retrospective chart review was performed in the 26 patients with CRMO registered at the hospital between 2002 and 2013. Data collected were: age, symptoms at presentation, diagnostics and imaging, delay of diagnosis, number of affected skeletal sites, history and effect of medication, state of disease at latest visit: active disease, clinical partial or full remission (defined as minimum 6 months of continious inactive disease). Patients with minor symptoms, but otherwise inactive disease were categorised as having partial remission.

Results Mean age at disease-onset was 10.5 years (range 5.4-14.0 years), 77% were female, and all patients were Caucasians (26 patients). The mean delay in diagnosis was 1.5 year (range 0.08 - 4.3) and 39% were initially treated with antibiotics. Disease onset was multifocal in 73% and symmetrical manifestations were seen in 25%. Mean disease duration was 4.0 years (range 0.3 -11.3 years). During disease course 85% developed multifocal disease. The most commonly affected skeletal regions were the fibula (65%), followed by the tibia (50%), the femur (42%), the pelvis (35%) and the clavicula (26%). A biopsy was taken in 70%. NSAIDs were given in most patients (89%), resulting in partial (54%) or total (23%) remission in those treated. Methotrexate and corticosteroids were infrequently used (respectively in 8% and 10%). None of the patients were treated with biologics or bisphosphonates. At the latest follow-up 20% still had active disease, 50% were in partial remission and 30% were in total remission, but only 22% were off all medication.

Conclusions We conclude that after a mean disease duration of 4.0 years the majority of patients (80%) obtained a state of remission (partial or total remission), but only a minority (22%) of off all medication. Persistently active disease was seen in 20% of the patients. Methotrexate and corticosteroids were infrequently used and none of our patients were treated with biologics or bisphosphonates. The results may suggest a relative benign disease course in this Norwegian cohort, although few patients reached remission off medication.

References

1. Ferguson PJ and Sandu M. Current understanding of the pathogenesis and management of chronic recurrent multifocal osteomyelitis. Curr Rheumatol Rep 2012: 130 -141

2. Hedrich et al. Autoinflammtory bone disorders with special focus on chronic recurrent multifocal osteomyelitis. Pediatric Rheumatology 2013, 11:47

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.3215