Early Extended Pamidronate May Help Reduce Chronic Nonbacterial Osteomyelitis Activity

Study showed that pamidronate might contribute to clinical improvement and improvement of radiologic outcome in chronic nonbacterial osteomyelitis, however, relapses were frequent.

In children diagnosed with extended chronic nonbacterial osteomyelitis, early-onset pamidronate therapy reduced radiologic and clinical activity substantially over 2 years, although there were cases of continually active disease as well as relapses following remission during this period, according to a report published in The Journal of Rheumatology.

With a variable clinical course, treatment for this disease is often empiric, with nonsteroidal anti-inflammatory drugs used as first-line therapy, and amino-bisphosphonate pamidronate and/or tumor necrosis factor alpha inhibitors used as second-line therapies for those whose disease does not respond to first-line therapy. Investigators sought to determine whether pamidronate treatment in pediatric patients helped improve clinical and radiologic disease activity over 2 years.

A retrospective cohort study conducted at a single Danish center identified 51 patients (mean age at diagnosis, 10.7 years; 62.7% female; median time between first symptoms and diagnosis, 9 months; median follow-up time, 4 years; median erythrocyte sedimentation rate at diagnosis, 11 mm; HLA-B27 positivity, 14%) diagnosed from 2007 through 2015 with extended (n=32; 63%) or limited (n=19; 37%) chronic nonbacterial osteomyelitis according to the Bristol criteria. A total of 15 patients (29%) had inflammatory comorbidity at baseline.

Radiologic assessment at baseline was performed using whole-body and/or local magnetic resonance imaging (MRI), and/or bone scintigraphy. Extended disease was defined by multifocal or spinal inflammation not responsive to nonsteroidal anti-inflammatory drugs. In these individuals, clinical activity was evaluated annually, and whole-body MRI was performed at baseline and at 1 and 2 years in 88%, 84%, and 91% of cases, respectively. Those with extended disease were treated with a 2-year intravenous pamidronate regimen (0.5 mg/kg/d initially, followed by 1 mg/kg/d over 3 consecutive days every 3 months).

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Radiologic remission required no bone lesions on follow-up MRI; clinical remission required patients to have no inflammatory signs or symptoms and normal erythrocyte sedimentation rate. On medication, clinical remission was defined as inactive disease for 6 months; off medication, remission required inactive disease for ≥12 months.

A median of 5 bone lesions were present at baseline in all children, with the tibia the most common location; 13 of 51 (25%) had spinal lesions, with the thoracic spine the most frequent site. Over the course of the first year, there were significant reductions in spinal bone lesions (P =.01) and lesions per patient, with the median decreasing from 6 to 2 in patients with extended disease (P =.01).

After the first year of pamidronate therapy, 12 of 32 (38%) of those with extended disease had clinical remission; 8 of these 12 (67%) eventually had relapse of disease. Radiologic results showed that 7 of 31 (23%) children from the extended group achieved remission, but 3 of 7 (43%) had relapse of disease after 24 months, and 10 of 31 (32%) had disease remission at 2 years. For those with limited disease, after 1 and 2 years, respectively, 10 of 19 (53%) and 10 of 16 (63%) patients were in clinical remission on and off medication, respectively.

Study limitations included a nonvalidated disease definition, treatment strategy according to institutional standards, retrospective design, and non-blinded assessments by pediatric radiologists.

“We found that pamidronate might contribute to clinical improvement and improvement of radiological outcome in [chronic nonbacterial osteomyelitis]. However, relapse is rather frequent,” noted the authors. They recommended that future research involve placebo-controlled designs that further develop outcome measures and evaluate treatment responses.

Reference

Andreasen CM, Jurik AG, Glerup M, et al. Response to early-onset pamidronate treatment in chronic non-bacterial osteomyelitis: a retrospective single center study [published online April 15, 2019]. J Rheumatol. doi:10.3899/jrheum.181254

This article originally appeared on Rheumatology Advisor