Antiepileptic drugs and high prevalence of low bone mineral density in a group of inpatients with chronic epilepsy

Purpose - Long-term antiepileptic drug use is associated with low bone mineral density (BMD), fractures and abnormalities in bone metabolism. We aimed at determining the prevalence of bone mineral disorders in patients with refractory epilepsy treated with antiepileptic drugs. Methods - A cross-sectional survey was conducted in adult patients (n=205) from a residential unit of a tertiary epilepsy centre. Screening for bone mineral disorders was performed with dual-energy X-ray absorptiometry (DXA) scan of spine and hip (including bone mineral density and vertebral fracture assessment) and laboratory measurements. Patient information regarding demography, epilepsy characteristics and medication use was recorded. Based on DXA T-scores, prevalence of bone mineral disorders (osteopenia and osteoporosis) was calculated. Correlations between DXA T-scores and epilepsy parameters were explored. Results - Of the 205 patients, there were 10 dropouts. 80% (n=156/195) of the patients had low BMD: 48.2% had osteopenia and 31.8% had osteoporosis. Of those having low BMD, 51.9% (n=81/195) was between 18 and 50years. The T-score of the femoral neck correlated significantly with total duration of epilepsy, cumulative drug load and history of fractures. Linear regression analysis showed that of the epilepsy-related parameters, only cumulative drug load significantly predicted low femoral neck T-score (P=0.001). Conclusion - In this high-risk population, we obtained a very high prevalence of 80% of low BMD. Both men and women were affected as well as patients <50years of age. This study illustrates the magnitude of the problem of bone mineral disorders in chronic epilepsy.