Osteoprotective Knowledge in a Multiethnic Epilepsy Population

Abstract and Introduction

Abstract

Antiepileptic drugs (AEDs) are known to cause bone loss. People with epilepsy have twice the fracture rate of nonepilepsy populations. Osteoprotective knowledge related to calcium and exercise has not been assessed in people with epilepsy. The Osteoporosis Knowledge Test (OKT), a validated, 24-item test, was administered to 94 epilepsy patients (28 males and 66 females) to measure knowledge of risk factors for osteoporosis and strategies for prevention related to calcium and exercise. The mean age of participants was 45 years with an average AED exposure of 20 years. Fifty participants were Caucasian and 44 were non-Caucasian. No significant differences related to age or gender for the OKT were found. One-way analysis of variance (ANOVA) of ethnicity showed that non-Caucasians had much lower calcium (F = 8.15, p = .005) and exercise (F = 7.71, p = .007) knowledge. The total mean OKT score was 11.71 (4.92), reflecting a correct response rate of 49%. In previous studies of nonepilepsy populations, the mean OKT score ranged from 7.83 to 21.8, with a correct response ranging from 32.9% to 90.8%. Independent t tests of the individual OKT questions revealed specific knowledge deficiencies in the areas of risk factors, exercise, and reasons for calcium supplementation for non-Caucasians. Results of this study reveal that people with epilepsy, who are at greater risk for metabolic bone loss, have lower knowledge scores for calcium and exercise than nonepilepsy populations of various ages and genders. Culturally relevant epilepsy materials and programs may improve knowledge and adoption of preventative behavior.

Introduction

An estimated 1.5 million people suffer a bone disease-related fracture annually in the United States (U.S. Department of Health and Human Services, 2004). Costs for the treatment of incident osteoporotic fractures were estimated to be $34 billion in 2004 (Vanness & Tosteson, 2005). Two large cohort studies found double the fracture incidence in people with epilepsy when compared to a nonepilepsy population (Gaitatzis, Carroll, Majeed, & Sander, 2004; Souverein et al., 2005).

Studies have demonstrated that bone loss can occur after as little as 2 years of antiepileptic drug (AED) exposure (Chung & Ahn, 1994). Pack and colleagues (2003) found that people with epilepsy who take enzyme-inducing AEDs are prone to significant loss of bone mass, based on current World Health Organization guidelines. Only 42% had normal bone density compared to the 84% expected in the normal population (Pack et al., 2003). Bone loss in epilepsy is often thought to be the result of vitamin D deficiency, secondary to use of enzyme-inducing AEDs (Pack, 2003). Results of studies of the effects on bone of antiepileptic drugs that are not enzyme inducing, such as valproic acid and lamotrigine, have been mixed (Pack et al., 2005; Sato et al., 2001; Sheth et al., 1995). In a previous investigation of bone health in people with epilepsy (African American = 74, Caucasian = 57, and Latino = 27) that was conducted in our clinic setting, African Americans had the worst T-scores on dual-energy X-ray absorptiometry (DEXA), followed by Caucasians and Latinos. In addition, T-scores and bone mineral density measurements suggest bone loss is similar across both age and gender (Elliott, Jacobson, & Haneef, 2007).

A survey by the Epilepsy Action organization (Epilepsy Action, 2003) found that 75% of members reported never being told that osteoporosis and osteomalacia were possible side effects of long-term (>5 years) use of AEDs. Those who were informed of bone health issues reported their epilepsy specialist as the primary information source (Epilepsy Action, 2003). In another study, more than 90% of patients reported wanting more information about epilepsy, and 75% reported they were not given enough information about AED side effects (Jain, Patterson, & Morrow, 1993). Furthermore, a study of practice patterns in neurologists found that few evaluate their patients for AED-induced bone loss (Valmadrid, Voorhees, Litt, & Schneyer, 2001).

Up to 95% of total bone development is completed by the age of 18 years (Schettler & Gustafson, 2004). Adequate calcium intake in adolescence can result in a 5% to 10% difference in peak bone mass, which may reduce the risk of hip fracture in old age by 50% (Council on Scientific Affairs, American Medical Association, 1997). Calcium intake among youth ages 9–18 years was found to be 1,180 mg/day for Caucasians, 896 mg/day for Hispanics (Novotny et al., 2003), and 697–882 mg/day for African Americans (Fulgoni et al., 2007). The Institute of Medicine, Food and Nutrition Board recommends 1,300 mg of calcium daily for adolescents ages 9–18 years, 1,000 mg for adults ages 19–50 years, and 1,200 mg for those older than 50 years of age (Greer, Krebs, & Committee on Nutrition, 2006).

Regular, weight-bearing physical activity increases muscle and bone strength, increases lean muscle, and decreases body fat (U.S. Department of Health and Human Services, 2000). Rates of leisure-time physical inactivity for adult males have been estimated as 18.4% for Caucasians, 27% for African Americans, and 32.5% for Hispanics. For women, inactivity rates are even higher: 21.6% for Caucasians, 33.9% for African Americans, and 39.6% for Hispanics (Centers for Disease Control and Prevention, 2005).

Forty percent of surveyed people with epilepsy reported no physical activity in the past month and 34% were obese (Kobau et al., 2004). A majority of people with epilepsy had no adverse effects from exercise, and up to 36% have reported that regular exercise contributed to better seizure control (Nakken, 1999). Although most people with epilepsy had little to no exercise, they believed exercise may improve their medical treatment (Arida et al., 2003).