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Prevalence of Epilepsy and Health-Related Quality of Life and Disability Among Adults with Epilepsy --- South Carolina, 2003 and 2004

Epilepsy is a common neurologic disorder and poses substantial burdens on physical and mental health. Epilepsy can interfere with social functioning by limiting employment, educational opportunities, and interpersonal relationships and can increase the risk for death (1). The annual cost of cases of epilepsy in the United States, including direct medical costs and productivity losses, was estimated at $12.5 billion in 1995 (2). Depending on case definitions and populations studied, epilepsy affects an estimated 0.4%--1.0% of the population (3,4) with a lifetime prevalence of 1.8%--2.6% in certain state populations (5,6). This report analyzes data from the 2003 and 2004 South Carolina Behavioral Risk Factor Surveillance System (BRFSS) surveys, which included questions on epilepsy, health-related quality of life (HRQOL), and disability. This report summarizes the results of that analysis, which determined that 2.2% of adults in South Carolina had ever been told they had epilepsy, 1.1% had active epilepsy, and both groups reported worse HRQOL and higher prevalence of disability than those who had never had epilepsy. Health-care providers should screen epilepsy patients for cognitive, emotional, and physical health problems that might negatively affect HRQOL (6--8). Patients with active epilepsy and recent seizures should be targeted with interventions that will decrease the risk for adverse physical (e.g., injury) and psychosocial (e.g., unemployment) outcomes that accompany continued seizures (8).

BRFSS is a state-based, random-digit-dialed telephone survey of the noninstitutionalized, U.S. civilian population aged >18 years. Data were weighted by sex, race, and age to adjust for differences between the survey population and the South Carolina population. A total of 5,926 respondents participated in the 2003 survey and 7,114 in the 2004 survey, for response rates of 41.6% and 43.8%, respectively. Results were considered significantly different if 95% confidence intervals (CIs) did not overlap.

BRFSS includes standard questions on key health-related behaviors and demographic characteristics; states can choose to add optional questions. In 2003 and 2004, South Carolina added four questions regarding epilepsy. The first question was "Have you ever been told by a doctor that you have a seizure disorder or epilepsy?" The lifetime prevalence of self-reported epilepsy was based on responses to this question, which had a response rate of 90.3%. Participants who answered yes to this question were also asked (where appropriate), "Are you currently taking any medicine to control your seizure disorder or epilepsy?", "How many seizures have you had in the last 3 months?", and "During the past 30 days, to what extent has epilepsy or its treatment interfered with your normal activities like working, school, or socializing with family or friends?" Respondents were considered to have active epilepsy if they 1) reported ever having been told by a doctor that they had a seizure disorder or epilepsy and 2) either were currently taking medicine to control epilepsy or had had one or more episodes of seizure during the preceding 3 months. Active epilepsy was categorized further by whether the respondent had had one or more seizures during the preceding 3 months.

In addition, all respondents, with and without epilepsy, were asked the following BRFSS core questions on HRQOL and activity limitation: "Now thinking about your physical health, which includes physical illness and injury, for how many days during the past 30 days was your physical health not good?", "Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?", and "During the past 30 days, for about how many days did poor physical or mental health keep you from doing your usual activities, such as self-care, work, or recreation?" CDC methods for calculating HRQOL were used (9). Finally, to determine whether respondents were disabled, they were asked the BRFSS core question, "Are you limited in any way in any activities because of physical, mental, or emotional problems?"

Results indicated that an estimated 2.2% (95% CI = 1.8%--2.5%) of South Carolina adults had ever had epilepsy and that 1.1% (CI = 0.9%--1.4%) had active epilepsy (Table). Among those with active epilepsy, an estimated 50.5% (CI = 38.9%--62.1%) had had one or more seizures during the preceding 3 months.

Adults who had ever had epilepsy had more mentally, physically, and overall unhealthy days and more activity-limitation days than those without epilepsy. Nearly half (46.7%) of those who had ever had epilepsy and 63.5% of those with active epilepsy reported some form of disability, compared with 17.9% of those without epilepsy. HRQOL factors were worse for those taking medicine to control their epilepsy than for those not taking medicine. Adults with active epilepsy had more than twice as many physically, mentally, and overall unhealthy days and activity-limitation days than those without epilepsy, and more overall unhealthy days and activity-limitation days than those with inactive epilepsy (Table). Finally, a larger proportion of adults with active epilepsy reporting a seizure during the preceding 3 months reported disability than those without epilepsy, those with inactive epilepsy, or those with active epilepsy but no seizures during the preceding 3 months.

Reported by: PL Ferguson, PhD, AW Selassie, DrPH, BB Wannamaker, MD, Medical Univ of South Carolina; B Dong, MD, South Carolina Dept of Health and Environmental Control. R Kobau, MPH, DJ Thurman, MD, Div of Adult and Community Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note:

The 2.2% estimated lifetime prevalence of epilepsy in South Carolina is similar to recent estimated lifetime prevalence rates calculated from BRFSS data in Texas, Georgia, and Tennessee (5,6), and the 1.1% prevalence of active epilepsy is similar to that reported for Georgia in 2002 (6). Results of the South Carolina BRFSS also confirm previous results indicating worse HRQOL (5) and indicate higher rates of disability among adults who have ever had epilepsy than among those without epilepsy. Results from the 2002 National Health Interview Survey indicated that adults who reported having seizures met criteria for serious mental illness more than four times as often as those who did not report having seizures (7). Nonetheless, persons with epilepsy often remain undiagnosed and untreated for depression (1,8,10).

Most of the overall cost of epilepsy results from treatment of persons with continuing seizures (2); approximately half of those in this study with active epilepsy reported seizures during the preceding 3 months. The goal of epilepsy treatment is to eliminate seizures and treatment side effects (1); continuing seizures might indicate inadequate treatment.

The findings in this report are subject to at least four limitations. First, all data are self-reported and not based on clinical diagnoses; self-reporting of epilepsy is subject to potential bias. Prevalence might be overestimated by persons reporting nonepileptic seizures, childhood febrile seizures, or seizures associated with alcohol abuse. Prevalence might be underestimated because of reluctance to disclose a stigmatizing condition (1) or because misdiagnosis occurred with symptoms associated with other conditions (e.g., dementia). However, the follow-up questions (e.g., regarding medication and number of seizures) tend to increase the likelihood that epilepsy prevalence data are accurate. Second, BRFSS data exclude children and adolescents, for whom prevalence is high (1), and also exclude persons with no telephone or only cellular phones and those who are institutionalized. Thus, findings are not generalizable to the entire state population. Third, response rates were low (41.6% and 43.8%) for the surveys described in this report. Finally, the cross-sectional design of the study prevents causal relationships (e.g., between epilepsy and mental health) from being assigned.

CDC, the National Epilepsy Foundation, and 19 state health departments are working together to expand BRFSS surveillance to assess the burden of epilepsy.* In addition, CDC and the Epilepsy Foundation are working to help educate school staff, clinicians, and the public about epilepsy and its treatment, and three CDC Prevention Research Centers are evaluating self-management programs designed to improve health outcomes in persons with epilepsy.

References

  1. Living well with epilepsy II: report of the 2003 National Conference on Public Health and Epilepsy. Landover, Maryland: Epilepsy Foundation; 2003. Available at http://www.cdc.gov/epilepsy/pdfs/living_well_2003.pdf.
  2. Begley CE, Famulari M, Annegers JF, et al. The cost of epilepsy in the United States: an estimate from population-based clinical survey data. Epilepsia 2000;41:342--51.
  3. CDC. Prevalence of self-reported epilepsy---United States, 1986--1990. MMWR 1994;43:810--1.
  4. Hauser WA, Annegers JF, Kurland LT. Prevalence of epilepsy in Rochester, Minnesota: 1940--1980. Epilepsia 1991;32:429--45.
  5. CDC. Health-related quality of life among persons with epilepsy---Texas, 1998. MMWR 2001;50:24--6.
  6. Kobau R, DiIorio CA, Price PH, et al. Prevalence of epilepsy and health status of adults with epilepsy in Georgia and Tennessee: Behavioral Risk Factor Surveillance System, 2002. Epilepsy Behav 2004;5:358--66.
  7. Strine TW, Kobau R, Chapman DP, Thurman DJ, Price P, Balluz LS. Psychological distress, comorbidities, and health behaviors among U.S. adults with seizures: results from the 2002 National Health Interview Survey. Epilepsia 2005;46:1133--9.
  8. Gilliam F. Optimizing health outcomes in active epilepsy. Neurology 2002;58:S9--20.
  9. Moriarty DG, Zack MM, Kobau R. The Centers for Disease Control and Prevention's Healthy Days Measures---population tracking of perceived physical and mental health over time. Health Qual Life Outcomes 2003;1:37.
  10. Kanner AM, Balabanov A. Depression and epilepsy: how closely related are they? Neurology 2002;58(8 Suppl 5):S27--39.

* Additional information is available at http://www.cdc.gov/epilepsy/state_activities.htm.

Additional information is available at http://www.cdc.gov/epilepsy/research_projects.htm.

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