Background/Purpose: Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease that affects children and adolescents. The disease typically presents with bone pain with or without systemic features. Treatment options for CRMO include non-steroidal anti-inflammatory drugs (NSAIDs), methotrexate, bisphosphonates and TNF inhibitors. To date all presented cohorts were of very small numbers and lack generalizability. We are presenting one of the largest CRMO cohorts, aiming to provide more detailed and generalizable clinical and laboratory features.

Methods: This study was approved by Institutional Review Board. Using retrospective chart review we identified more than 200 subjects with confirmed CRMO seen at our center. Descriptive statistics were used for clinical and laboratory features and chi2 test for comparison of subgroups.

Results: This cohort consisted of 204 patients, of those 141 (69%) were females, and 63 (31%) were males. Age at onset of symptoms ranged from 3 to 17 years of age. Mean age at onset of symptoms was 8 years and 10 years at diagnosis. This demographic and clinical characteristics of the whole cohort is shown in Table (1). The clinical history of the subjects in this study varied between individuals but many of the characteristic symptoms for CRMO were very similar. All patients presented with bone pain at onset. The average number of sites of bone pain was three, and pain was bilateral in 39%. Pain at night was evident in 43% of patients, and 46% of patients had objective swelling at onset. In total, there were 89(43.6%) patients with at least one co-morbid inflammatory disease, with psoriasis in 14.7%. Also, 32% of CRMO patients in the study had either a first or second degree relative with psoriasis. ESR wand CRP were elevated in more than half of the patients. The most common drugs prescribed to patients were NSAIDS with just over 50% of patients being prescribed a type of NSAID at some point in their treatment. Most patients were prescribed approximately two medications during their treatment regimen. Each of the medications prescribed for CRMO were divided into groups based on drug class and reported in (Table1). When assessing location, 170 patients (84%) had evidence of CRMO in the lower body long bones, 29% of patients had spine disease, and 21% had sacroiliac (SI) disease (Figure 1). When comparing males and females, there was not statistically significant difference between males and females in clinical features or site/location (Table 1). Females had a higher percentage of spine, mandible, and clavicle lesions, compared to the males. In contrast, SI disease was more common in males and the difference approached significance at p=0.08, when compared to females (Tabel 1).

Conclusion: CRMO is more likely to be present in females than males and the average age of diagnosis is at approximately 10 years of age. In our study population, lower body CRMO involvement was the most common, and least common in the mandible. Males had higher percentage of sacroiliac disease. There was no significant difference between females and males in demographics or clinical features. Substantial number of patients in the study who had a milder form of CRMO were able to mitigate symptoms with the use of NSAIDs only.

Table 1: Demographics and Clinical Characteristics of Study Population

Table 1: Demographics and Clinical Characteristics of Study Population-Continued

Figure 1: Chronic Recurrent Multifocal Osteomyelitis site of involvement in the total cohort and in male and female subgroups.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/large-retrospective-cohort-study-of-chronic-recurrent-multifocal-osteomyelitis-disease-presentation-clinical-and-laboratory-features/