Abstracts

Rationale: Bone fractures are common in patients with epilepsy; however, there is uncertainty as to whether supplementation with calcium and vitamin D decreases the risk of bone fractures in this population. The objectives of this study are to: 1. determine whether supplementation with calcium and vitamin D reduces the risk of bone fractures and 2. to determine the antiepileptic drugs (AED) associated with fractures in adult patients with epilepsy. Methods: We retrospectively evaluated a total of 3,303 patients with epilepsy on at least one AED from a VA Hospital. 329 patients had at least one fracture. Subject characteristics are shown in table 1. The proportion of bone fractures in patients on AEDs who took supplements was compared to that of patients on AEDs who did not take supplements using the chi-square test. Logistic regression was used to assess the influence of age, sex, time on AED, and supplement use on occurrence of fractures and to assess the effect of individual AED on the risk of fractures. Results: Patients with epilepsy on long-term AEDs who took calcium and vitamin D were as likely to have fractures as those who did not (10.4% vs. 9.1%, χ2 = 0.35, p = 0.55). Risk of fracture is predicted by: time on AED: (OR: 1.26; CI: 0.98 - 1.63;, Age: (OR: 1.07; 1.01- 1.13); Gender (women): (OR: 5.85,1.16- 29.61). Patients supplemented with Calcium and vitamin D had a significant risk of fractures (OR= 1.70; 1.27- 2.27) Phenytoin demonstrated an increased risk of fractures (OR = 1.56CI: 1.10-2.24); there was no significant association between fractures and consumption of divalproex 1.36 (0.98 - 1.88), carbamazepine 1.04 (0.71-1.50), gabapentin 0.97 (0.75 - 1.25), clonazepam 0.81 (0.62, 1.08), valproic acid 0.89 (0.32, 2.50), levetiracetam 0.32 (0.04 - 2.41), primidone 1.10 (0.59 - 2.05) and topiramate 0.61 (0.26 - 1.41). No fractures (0/52 patients) were reported in patients taking lamotrigine. Conclusions: In this group of patients with epilepsy, bone fractures occurred slightly more often in patients taking calcium and vitamin D supplements, but the difference was not statistically significant. This may reflect an increased perceived risk of fracture by the subject or treating physician, rather than an actual negative effect of calcium and vitamin D supplementation. Phenytoin was significantly associated with an increased risk of fractures. There were no fractures in the patients taking lamotrigine.