Epilepsy, osteoporosis and fracture risk - a meta-analysis

This meta-analysis assesses the effects of epilepsy on fracture risk and changes in bone mineral density (BMD) in patients with epilepsy. A search of PubMed was conducted using the key words epilepsy, fracture, and bone mineral. A weighted estimate of relative risk of fractures and changes in BMD (Z-score) was calculated. From the changes in BMD, expected increase in relative fracture risk was calculated. A total of 11 studies on fracture risk and 12 studies on BMD were retrieved. The relative risk of any fracture was increased (2.2, 95% CI: 1.9-2.5, five studies), as was the risk of hip (5.3, 3.2-8.8, six studies), forearm (1.7, 1.2-2.3, six studies), and spine fractures (6.2, 2.5-15.5, three studies). A large proportion of fractures (35%) seemed related to seizures. Spine (mean +/- SEM: -0.38 +/- 0.06) and hip (-0.56 +/- 0.06) BMD Z-scores were significantly decreased, hip more than spine (2P < 0.05). The expected increases in relative risk of any fracture from BMD Z-scores were 1.2-1.3, and significantly lower than observed (2P < 0.05). The deficit in BMD in patients with epilepsy is too small to explain the observed increase in fracture risk. The remainder of the increase in fracture risk may be linked to seizures.