Survey of risk factors for osteoporosis and osteoprotective behaviors among patients with epilepsy

Highlights

• The majority of patients with epilepsy do not engage in bone-protective behaviors.

• Undergoing a DXA scan was associated with calcium/vitamin D supplementation.

• Many patients failed to accurately self-report DXA scan results.

• Initiatives should be explored to improve bone-protective behaviors.

Abstract

The prevalence of risk factors for osteoporosis in persons with epilepsy, patients' awareness of their risk, and their engagement in osteoprotective behaviors were assessed in this study. Two hundred and sixty patients with epilepsy (F = 51.5%, average age = 42) completed a survey tool. Of 106 patients with a dual energy X-ray absorptiometry (DXA) result, 52% had low bone mineral density, and 11% had osteoporosis. The results suggest that the majority of patients with epilepsy do not engage in bone-protective behaviors. Those who have undergone a DXA scan may be more likely to take calcium and vitamin D supplementation compared with those who did not undergo a DXA scan, but they do not engage in other osteoprotective behaviors. Many patients did not accurately report their DXA results, indicating that better patient education is warranted.

Introduction

Patients with epilepsy are two to six times more likely to fracture a bone compared with the general population [1], [2]. While patients with epilepsy are predisposed to fracture due to seizure-related falls, a meta-analysis attributed seizures as a cause for only one-third of the fractures [2]. The risk of falls and subsequent fracture is exacerbated by impaired balance from adverse effects of antiepileptic drugs (AEDs) and/or comorbid neurological deficits [3], [4], [5]. Concomitantly, there is a high prevalence of osteopenia and osteoporosis found in the patient population with epilepsy, especially in groups normally considered with a low risk of developing bone disease, such as males under the age of 50 and women in the premenopausal period [1], [6], [7], [8], [9], [10]. Therefore, bone disease, specifically osteopenia and osteoporosis, contributes to the high fracture rate in this population.

Antiepileptic medications increase patients' risk of debilitating osteoporosis. Older enzyme-inducing AEDs (phenytoin, phenobarbital, primidone, and carbamazepine) accelerate vitamin D metabolism and adversely affect bone mineral density (BMD), bone quality, and bone turnover. However, other mechanisms, such as a direct effect on bone cells, the endocrine system, and vitamin K, may also cause bone loss as low BMD is observed with AEDs that are not enzyme inducers (e.g., valproic acid) [11], [12], [13], [14], [15]. Most likely, multiple factors, in addition to AED exposure, may lead to poor bone health in patients with epilepsy.

Other medications prescribed to patients with epilepsy may further increase their risk of bone loss. Depot medroxyprogesterone acetate injection (Depo-Provera®), a progestin-based contraceptive, is often recommended to women of child-bearing age with epilepsy, but studies find that it reduces BMD by as much as 3% in adolescents and young women at an age when increases of BMD are a norm [16], [17], [18]. Consequently, Depo-Provera® has a black box warning indicating that women may lose significant BMD, and long-term use (greater than two years) should be limited to patients in whom other birth control methods are inadequate. The bone-reducing effects may be reversible, but studies are lacking to determine whether reaching peak bone mass is impeded by the use of the contraceptive and if it increases risk of fracture at an older age [19], [20], [21].

Behavioral risk factors for osteoporosis include low calcium intake, vitamin D insufficiency, increased alcohol intake, inadequate physical activity, smoking, and falling [22]. However, few studies have investigated the prevalence of these risk factors among patients with epilepsy. Population surveys in Ohio, Georgia, and Tennessee using the Behavioral Risk Factor Surveillance System (BRFSS) found that persons with a history of epilepsy report that they exercise less frequently and smoke more compared with the general population [23], [24]. In contrast, the 2005 California Health Interview Survey (CHIS) found no difference in exercise patterns [25]. To date, there are no studies that determine which risk factors are most prevalent or predict low BMD in patients with epilepsy.

Patients with epilepsy may also be less likely to engage in bone-protective behaviors. Awareness among patients with epilepsy of their increased risk of bone disease may increase their likelihood of engaging in bone-protective behaviors [26]. Interestingly, studies of other populations found that patients who were told that they have low BMD results after dual energy X-ray absorptiometry (DXA) testing were more likely to increase dietary calcium, start an exercise program, and stop smoking compared with patients with normal BMD results [27]. Unfortunately, trends in adoption of osteoprotective behaviors in patients with epilepsy have not been studied.

Thus, it is important that the relationship between risk factors for osteoporosis and epilepsy be understood in order for better preventative measures to be adopted to minimize the risk of debilitating osteoporosis. This study aimed to assess the following: (1) risk factors for developing osteoporosis in patients with epilepsy and (2) patients' awareness of their risk and engagement in osteoprotective behaviors.