Bone density and antiepileptic drugs: a case-controlled study

This case-controlled study explored the relationship between bone mineral density (BMD) and long-term treatment with antiepileptic drugs (AEDs) in older adults with epilepsy. Seventy-eight patients (47 post-menopausal females, 31 males, aged 47-76 years) with epilepsy participated in the study. Each had only ever received treatment with either enzyme-inducing (n = 52) or non-inducing (n = 26) AEDs. Individuals were matched for age, sex, height and weight with a drug-naive control. All patients underwent bone densitometry at the lumbar spine and femoral neck and had blood sampling and urine collected for a range of bone markers. Male patients had lower BMD than controls at the lumbar spine (P < 0.01) and neck of the femur (P < 0.005). Female patients had significantly reduced bone density at the femoral neck (P < 0.05) only. AED usage was independently associated with an overall reduction in bone density at femoral sites and contributed to just over 5% of the variance at the femoral neck. Duration of treatment and type of AED were not independent factors for reduction in BMD. This case-controlled study supports the hypothesis that long-term AED therapy is an independent risk factor for reduced BMD in epileptic patients. Adults receiving treatment for epilepsy are at higher risk of osteoporosis and should be offered bone densitometry.