Epilepsy in Adults and Access to Care — United States, 2010

Epilepsy is a neurologic disorder that negatively affects the quality of life for millions of persons in the United States (1); however, nationally representative U.S. estimates of the prevalence of epilepsy are scant (2). To determine epilepsy prevalence among adults, assess their access to care, and provide baseline estimates for a Healthy People 2020 objective ("Increase the proportion of persons with epilepsy and uncontrolled seizures who receive appropriate medical care") (3), CDC analyzed data from the 2010 National Health Interview Survey (NHIS). The results of that analysis indicated that, in 2010, an estimated 1.0% of U.S. adults and 1.9% of those with annual family income levels ≤$34,999 had active epilepsy. In addition, only 52.8% of adults with active epilepsy reported seeing a neurologic specialist in the preceding 12 months. Public health agencies can work with Epilepsy Foundation state affiliates and other health and human service providers to eliminate identified barriers to care for persons with epilepsy (2,4).

National estimates of epilepsy prevalence using NHIS data have not been reported since 1994 (5), and no recent estimates of access to care have been reported using nationally representative samples of adults with epilepsy. To estimate epilepsy prevalence among adults aged ≥18 years, CDC analyzed data from the 2010 NHIS, an annual cross-sectional survey of the civilian, noninstitutionalized U.S. population.* Data were analyzed from the NHIS Sample Adult component, which included supplemental questions on epilepsy.† Adults who responded "yes" to ever having been told by a doctor or other health professional that they had a seizure disorder or epilepsy were considered as having a history of epilepsy ("any epilepsy"). Respondents classified as having "active epilepsy" reported a history of epilepsy and either were currently taking medication to control it, or had one or more seizures in the past year, or both (6). Those who had a history of epilepsy but were not taking medication for epilepsy and had not had a seizure in the past year were classified as having "inactive epilepsy" (6).§ These case-ascertainment questions and case-classification definitions follow standards for epidemiologic studies of epilepsy (4) and have acceptable positive predictive value for identifying clinical cases of epilepsy (7).

Epilepsy status was compared across selected demographic and health-care access characteristics: age group, sex, race/ethnicity, education level, and annual family income (using unimputed data). Those with a history of epilepsy were asked about their visits to general doctors and neurologists or epilepsy specialists ("In the past year have you seen a neurologist or epilepsy specialist for your epilepsy or seizure disorder?"). Those without epilepsy were asked about their visits to general doctors. Statistical software was used to account for the complex survey design by using stratification, clustering, and weighting to obtain appropriate population estimates, standard errors, and 95% confidence intervals (CIs). Estimates were considered statistically significantly different if their CIs did not overlap. Prevalence estimates were directly age-adjusted to the 2000 U.S. Census population. Respondent numbers in each group are unweighted; percentage estimates are weighted.

Of 27,139 adults surveyed,¶ 480 (weighted estimate = 1.8%; approximately 4.1 million adults) reported ever being told they had epilepsy (Table 1). Of these, 275 (1.0%; approximately 2.3 million adults) were classified as having active epilepsy, and 198 (0.8%; approximately 1.7 million adults) as having inactive epilepsy. The prevalence of any epilepsy and active epilepsy did not differ significantly by age, sex, or education level. However, those with a history of epilepsy or active epilepsy were significantly more likely to be white or black or live in families at the lowest income level. Among those living in families with annual incomes of ≤$34,999, 1.9% had active epilepsy and 3.1% had any epilepsy.

Significantly more adults with active epilepsy (86.4%) or any epilepsy (76.6%) had visited a general doctor in the past 12 months than those without epilepsy (66.1%) (Table 2). More persons aged ≥65 years with any epilepsy (93.1%) saw a general doctor than those aged 18–34 years with any epilepsy (65.7%).

Among adults with active epilepsy, 52.8% had visited a neurologist or epilepsy specialist in the past 12 months, as had 33.4% of those with any epilepsy (Table 2). The percentage of adults with any epilepsy and active epilepsy who had seen a neurologist or epilepsy specialist in the past 12 months did not differ by age, sex, or race-ethnicity.

Reported by

Rosemarie Kobau, MPH, Yao-Hua Luo, PhD, Matthew M. Zack, MD, Sandra Helmers, MD, David J. Thurman, MD, Div of Population Health, National Center for Chronic Disease Prevention and Health Promotion, CDC. Corresponding contributor: Rosemarie Kobau, rkobau@cdc.gov, 770-488-6087.

Editorial Note

Epilepsy, or seizure disorder, is a brain disorder characterized by a tendency to have recurrent seizures. New cases of epilepsy are most common in children and older adults because risk factors are most common in these age groups. Preventable causes of epilepsy include traumatic brain injuries, stroke, cerebral infections, lead exposure, and perinatal complications; other causes include neoplasms and disorders of cerebral metabolism (1). Although many persons with epilepsy live full, productive lives, some face challenges, including barriers to care, untreated comorbidities, social disadvantages, and public misunderstanding about epilepsy or the abilities of persons with epilepsy (2). Such challenges are manifested in lower quality of life of persons with epilepsy (2,6).

The findings in this report indicate that estimates of epilepsy prevalence are consistent with previous estimates from the Behavioral Risk Factor Surveillance System (6) and other population studies (8,9) but slightly higher than other estimates (10). Data from NHIS surveys during 1986–1990 indicate an overall prevalence of epilepsy in persons of all ages of 0.47% (5). However, the case definitions, sampling strategy, and population distribution differ substantially between that study and this study, limiting comparisons.

Only 52.8% of those with active epilepsy had seen a neurologist or an epilepsy specialist in the past 12 months, confirming a treatment gap related to specialty care in adults with active epilepsy that is consistent with that found in previous reports (6). Epilepsy is a spectrum of disorders that require adequate access to appropriate care to ensure effective treatment to improve seizure control and quality of life. Cultural beliefs and practices, referral to and availability of specialty care, transportation barriers, and cost, might affect access to specialty care (2,4,6). Increased generalist care among older adults with epilepsy compared with those without epilepsy highlights the likelihood of multiple underlying health problems common with epilepsy (2). Increased generalist care among older adults with any epilepsy compared with youngest adults with any epilepsy might result from greater access to health-care coverage in the former.

The findings in this report are subject to at least five limitations. First, because the estimates are based on self-reported data, they might be subject to reporting bias. However, comparability of findings with BRFSS and other population surveys suggests these types of bias might be small. Second, the reported cases of epilepsy are not classified by seizure type, severity, or etiology. Third, certain acute symptomatic seizures or nonepileptic seizures might have been misclassified as epilepsy, thus overestimating prevalence. However, the small percentage of adults with nonepileptic seizures suggests that significant skewing of results is unlikely (6,7). Fourth, epilepsy prevalence might be underestimated because of underreporting associated with repercussions in disclosing epilepsy (1,2) and because of the exclusion of institutionalized adults from NHIS. Finally, because the questions on access to care in this study provide only limited information on epilepsy care, NHIS can only inform about broader determinants of access to care.

These data provide a baseline estimate to develop a target for a Healthy People 2020 objective on epilepsy and can be used to monitor progress over the decade. Future studies can further examine associations from this study. Public health agencies can work with Epilepsy Foundation state affiliates and other health and human service providers to eliminate known barriers to care for persons with epilepsy (4).

References

1. Avanzini G, Beghi E, de Boer H, et al. Epilepsy. In: World Health Organization. Neurological disorders: public health challenges. Geneva, Switzerland: World Health Organization; 2006:56–69. Available at http://www.who.int/mental_health/neurology/neurodiso/en/index.html. Accessed November 9, 2012.
2. Institute of Medicine. Epilepsy across the spectrum: promoting health and understanding. Washington, DC: The National Academy Press; 2012. Available at http://www.iom.edu/epilepsy. Accessed November 8, 2012.
3. US Department of Health and Human Services. Healthy people 2020. Disability and health objectives: barriers to health care. DH-6. Washington, DC: US Department of Health and Human Services; 2010. Available at http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=9. Accessed November 9, 2012.
4. Thurman DJ, Beghi E, Begley CE, et al. Standards for epidemiologic studies and surveillance of epilepsy. Epilepsia 2011;52(Suppl 7):2–26.
5. CDC. Current trends prevalence of self-reported epilepsy—United States, 1986–1990. MMWR 1994;43:810–1, 817–8.
6. Kobau R, Zahran H, Thurman DJ, et al. Epilepsy surveillance among adults—19 states, Behavioral Risk Factor Surveillance System, 2005. MMWR 2008;57(No. SS-6).
7. Brooks DR, Avetisyan R, Jarrett KM, et al. Validation of self-reported epilepsy for purposes of community surveillance. Epilepsy Behav 2012;23:57–63.
8. Holden EW, Nguyen HT, Grossman E, et al. Estimating prevalence, incidence, and disease-related mortality for patients with epilepsy in managed care organizations. Epilepsia 2005;46:311–9.
9. Ottman R, Lipton RB, Ettinger AB, et al. Comorbidities of epilepsy: results from the Epilepsy Comorbidities and Health (EPIC) survey. Epilepsia 2011;52:308–15.
10. Hirtz D, Thurman DJ, Gwinn-Hardy K, Mohammed M, Chaudhuri AR, Zalutsky R. How common are the "common" neurologic disorders? Neurology 2007;68:326–37.