Prevalence and incidence of vertebral fractures: a 7-year follow-up study in institutionalized adults with refractory epilepsy and intellectual disability

Objective: The main objective of this cohort study is to determine the prevalence and incidence of morphometric vertebral fractures (VFs) over 7 years follow-up, in institutionalized adults with refractory epilepsy and intellectual disability (ID).

Methods: Dual-energy X-ray Absorptiometry (DXA) and Vertebral Fracture Assessment (VFA) were performed in 2009 and 2016. Vertebrae T4-L4 were assessed using quantitative morphometry. Severity of VFs was graded as 1 (mild; 20-25% reduction in height), 2 (moderate; 25-40% reduction) or 3 (severe; >40% reduction) according to the method described by Genant. Prevalent VFs were analyzed at baseline. VFs (grade 1, 2 or 3) present at follow-up, but not at baseline, were considered new VFs. Worsening VFs were defined as VFs with at least one grade deterioration at follow-up, compared to baseline (grade 1 to 2 or 3, or grade 2 to 3). Patients were treated with anti-osteoporosis treatment according to the Dutch guideline.

Results: Baseline and follow-up DXA and VFA could be obtained in 141 patients (87 male) aged between 18-79 years old (mean 44.8 +/- 15.7). At baseline, 56 patients had at least one prevalent VF. Patients with a prevalent VF were significantly older than patients without (49.2 +/- 13.7 vs 41.9 +/- 16.4, p <.01). After 7 years follow-up, 38 new VFs occurred in 27 patients and 15 patients had a worsening VF, leading to an overall cumulative incidence of 27.0%. VF incidence was significantly higher in patients with at least one prevalent VF at baseline (48.2% vs 12.9%, respectively, p <.01) compared to no VF.

Significance: In adults with refractory epilepsy VFA is challenging, due to physical and behavioral aspects, resulting in a substantial proportion of unevaluable vertebrae and scans. Nevertheless, 40% of the patients had a VF at baseline and after 7 years follow-up, 27% had at least one new and/or worsening VF despite adequate anti-osteoporosis treatment.