medwireNews: Children with osteogenesis imperfecta (OI) are more likely to use anti-fracture drugs (AFD) than their older counterparts, but underuse is common across all age groups, US study findings indicate.
“Despite the high fracture risk in OI patients, AFD use was relatively uncommon, even in children with severe OI, whose fracture risks are considered very high,” report Winnie Liu (Oregon Health and Science University, Portland, USA) and co-authors in The Journal of Clinical Endocrinology & Metabolism.
Their findings are based on an analysis of insurance claims data for 6475 people with OI – 20% of whom had severe OI, as defined by long-term wheelchair use – and 32,375 matched individuals without the condition. The participants had a median age of 21 years, 58% were women, and 44% were younger than 18 years of age.
The researchers report that, overall, 25.9% of participants with OI used an AFD compared with 1.9% of controls. Bisphosphonates – the standard of care for moderate and severe OI – were the most widely used AFDs, but usage differed by age, sex, and OI severity. “As predicted, children with OI in our cohort did not receive denosumab, [parathyroid hormone] analogs, or romosozumab in light of insufficient efficacy and safety data for these options,” they add.
AFD use was highest in children (≤18 years), much lower in young adults (18–30 years), and then rose gradually with increasing age.
Specifically, 48.7% of 624 children with severe OI and 23.4% of 2235 children with milder OI used an AFD. In all severe paediatric OI cases and all but three milder paediatric OI cases, the AFD of choice was a bisphosphonate.
Intravenous (IV) bisphosphonates were prescribed more often than oral bisphosphonates in both the severe (45.0 vs 6.3%) and milder (20.6 vs 3.7%) paediatric OI groups, with pamidronate and alendronate most common in their respective IV and oral categories.
Liu et al say it is “notable that in our analysis, pamidronate was the most used IV bisphosphonate in children,” because zoledronate has been identified “as a more attractive alternative due to the need for less frequent administration to reach similar efficacy, when compared to pamidronate.”
In the current study, zoledronate was the most prescribed IV bisphosphonate in all adult age groups but IV AFD use overall was less common than oral treatment in adults aged 31 years and older. In young adults with severe OI, IV bisphosphonate treatment was more common than oral treatment whereas the reverse was true for those with milder OI.
The rate of AFD use was similar for both boys and girls with OI, regardless of severity. By contrast, among the older study participants (≥31 years) women were more likely to be prescribed an AFD than men.
This pattern “mirrors the general population and likely reflects a general recognition of an age-related increased fracture risk in women,” Liu and co-investigators remark.
They add: “The low rate of medication use in older men with OI may reflect the general under-recognition and undertreatment of bone fragility in older men.”
The researchers believe that their study, which represents an estimated 13–20% of all OI individuals in the USA, highlights the “relatively low rates of AFD use in adults and children with both milder and severe OI.”
They say: “This finding may reflect the lack of strong evidence supporting anti-fracture drug use in OI, but may underscore a lack of access to appropriate clinical expertise concerning this rare disease.”
By Laura Cowen
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