Quantitative ultrasound for monitoring bone status in institutionalized adults with refractory epilepsy and intellectual disability: A 7-year follow-up study.

Purpose: Long-term exposure to anti-epileptic drugs has been shown to decrease bone mineral density (BMD). The aim of this 7-year follow-up study was to explore changes in bone status, using quantitative ultrasound (QUS) and Dual-energy X-ray Absorptiometry (DXA) in adults with refractory epilepsy and intellectual disability (ID) residing at a long-term care facility. Both measurements can be challenging to conduct in this population.

Methods: In 2009 and 2016, a total of 126 patients (18-79 years) underwent QUS of the heel and DXA of lumbar spine (LS) and hip (femoral neck (FN) and total hip (TH)). Subgroup analysis was performed for patients with (group A, n = 53) and without (group B, n = 73) bisphosphonate use during follow-up.

Results: Overall, weak to moderate correlations between changes in DXA and QUS parameters were found. For group A, correlations varied from r = .31 to .59, whereas correlations did not exceed r = .40 in group B. Patients in group A showed a larger increase or a smaller decrease in BMD for all DXA regions during follow-up (p < .001 for ΔLS and ΔFN BMD, p = .001 for ΔTH BMD). For change in QUS parameters, no significant difference between groups was found.

Conclusion: In this study we demonstrated the limited use of QUS in the monitoring of bone status in our study population. Although correlations between changes in QUS parameters and axial DXA are positive and mostly significant, QUS only explains little of the variability in DXA values and is inadequate for measuring treatment response in this population.