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Active Epilepsy and Seizure Control in Adults — United States, 2013 and 2015


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Niu Tian, MD, PhD1; Michael Boring, MS1,2; Rosemarie Kobau, MPH1; Matthew M. Zack, MD1; Janet B. Croft, PhD1 (View author affiliations)

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Summary

What is already known about this topic?

Approximately 3 million American adults have active epilepsy (doctor-diagnosed history of epilepsy, currently taking medication or having at least one seizure in the past year, or both). Uncontrolled seizures harm health, impair quality of life, and increase health care costs.

What is added by this report?

Although 90% of adults with active epilepsy were taking epilepsy medication, less than half (44%) of those taking medications were seizure-free in the past year. Seizures were more common among persons with lower household income, the unemployed, and the divorced, separated, or widowed.

What are the implications for public health practice?

Health care and public health should ensure that adults with uncontrolled seizures have appropriate care and self-management support in order to promote seizure control, improve health and social outcomes, and reduce health care costs.

Approximately 3 million American adults reported active epilepsy* in 2015 (1). Active epilepsy, especially when seizures are uncontrolled, poses substantial burdens because of somatic, neurologic, and mental health comorbidity; cognitive and physical dysfunction; side effects of antiseizure medications; higher injury and mortality rates; poorer quality of life; and increased financial cost (2). Thus, prompt diagnosis and seizure control (i.e., seizure-free in the 12 months preceding the survey) confers numerous clinical and social advantages to persons with active epilepsy. To obtain recent and reliable estimates of active epilepsy and seizure control status in the U.S. population, CDC analyzed aggregated data from the 2013 and the 2015 National Health Interview Surveys (NHISs). Overall, an annual estimated 2.6 million (1.1%) U.S. adults self-reported having active epilepsy, 67% of whom had seen a neurologist or an epilepsy specialist in the past year, and 90% of whom reported taking epilepsy medication. Among those taking epilepsy medication, only 44% reported having their seizures controlled. A higher prevalence of active epilepsy and poorer seizure control were associated with low family income, unemployment, and being divorced, separated, or widowed. Use of epilepsy medication was higher among adults who saw an epilepsy specialist in the past year than among those who did not. Health care and public health should ensure that adults with uncontrolled seizures have appropriate care and self-management support in order to promote seizure control, improve health and social outcomes, and reduce health care costs.

NHIS is an annual, nationally representative household survey of the U.S. civilian, noninstitutionalized population. Epilepsy data were collected in the NHIS Sample Adult component, which includes one randomly selected adult aged ≥18 years from each randomly selected household. In 2013, 34,557 adults (61.2% final response rate) responded to the survey, and in 2015, 33,672 adults (55.2% final response rate) responded.§ Data for 2013 and 2015 were aggregated to provide more reliable estimates (58.2% combined response rate). After excluding respondents with missing information on epilepsy history, 68,174 (99.9%) respondents were included in the analysis.

Adult respondents answered three questions about epilepsy to identify persons with active epilepsy and one question regarding specialty care. These case-ascertainment questions have been validated for use in community surveillance (3). Prevalence of active epilepsy and percentages of respondents with epilepsy who had seen a neurologist or epilepsy specialist in the past year, who were taking epilepsy medication, and whose seizures were controlled (i.e., had no seizures during the past year) among those taking epilepsy medication were estimated for each survey year, both survey years, overall, and by selected sociodemographic characteristics. The percentages of adults taking epilepsy medication and the distribution of seizure frequencies among those with active epilepsy by epilepsy specialty care were also estimated. Prevalences and percentages were age-standardized to the projected 2000 U.S. adult population by four age groups: 18–34, 35–54, 55–64, and ≥65 years. Unless otherwise noted, the relative standard error of all estimates was <30.0%. Statistical software that accounted for the respondent sampling weights and the NHIS complex sample design was used for analysis. All reported differences between subgroups were statistically significant (p<0.05 by two-tailed t-tests).

During 2013 and 2015, the annual prevalence of active epilepsy was 1.1% (approximately 2.6 million adults) and was significantly higher in 2015 (1.2%) than in 2013 (0.9%). The age-adjusted prevalence of active epilepsy was significantly higher among respondents who were non-Hispanic white (white) and non-Hispanic black (black); never married, divorced, separated, or widowed; had less than high school diploma; were unemployed, or living in lower-income families (e.g., families earning <200% of federal poverty level [FPL]) than among other groups (Table).

The percentage of respondents with active epilepsy who had seen a neurologist or an epilepsy specialist in the past year was 67%. This percentage was significantly higher among respondents aged 18–34 years, with at least some college education, or who lived in the Northeast than that among respondents aged ≥55 years, who had less than a high school education, or who lived in other regions.

Ninety percent of respondents with active epilepsy took epilepsy medication, and this percentage did not significantly differ by sociodemographic characteristics. Among respondents taking epilepsy medication, 44% reported that their seizures were controlled in the past year. The prevalence of seizure control was significantly higher among adults aged ≥65 years (62.7%) than among those aged 35–54 years (36.9%); among persons who were married/cohabiting (50.0%) than among those who were divorced, separated, or widowed (31.5%); among persons who were employed (54.3%) than among those who were unemployed (37.7%); and among those with higher family incomes (≥200% of FPL; 55.3%) than among those from lower income households (<200% of FPL; 33.2%). By region, the prevalence of seizure control among respondents with epilepsy taking epilepsy medication who lived in the Northeast (60.3%) was significantly higher than those who lived in the South (37.5%).

Among adults with active epilepsy, the age-adjusted prevalence of taking epilepsy medication was higher among those who saw an epilepsy specialist in the past year (95.4%) than among those who did not (78.1%); however, seizure frequency among those with active epilepsy did not differ significantly between those who did and did not see a specialist in the past year (Figure).

Discussion

The number of adults reporting that they have active epilepsy has significantly increased from 2010 (2.3 million) (4) to 2015 (3 million), with about 724,000 more cases identified from 2013 to 2015. In 2010, just over half (52.8%) of adults with active epilepsy saw a neurologist or epilepsy specialist (4). This study found that approximately two thirds (65.7% in 2013 and 68.3% in 2015) of adults with epilepsy saw a specialist. Most (90%) respondents with active epilepsy were taking epilepsy medication. Epilepsy medication use, but not reduced seizure frequency, was more common among those who had seen an epilepsy specialist; however, only 44% of respondents who took epilepsy medication had their seizures controlled in the past year. These results suggest that apart from the improvement associated with prompt diagnosis and treatment, other factors that might affect seizure control need to be addressed. The finding that blacks and respondents with less education and lower income had higher prevalences of active epilepsy is consistent with previous reports (4,5). This study also found that poor seizure control was associated with low income, unemployment, and being divorced, separated, or widowed. Socioeconomic disadvantage among adults with active epilepsy might preclude their accessing health care including specialty care (because of barriers such as cost and transportation) (2), thus affecting seizure control. More importantly, socioeconomic disadvantage (e.g., less education) and social isolation (e.g., lack of social support associated with being divorced, separated, or widowed) (2) might lead to nonadherence to epilepsy medication (6), an important clinical factor that significantly hinders seizure control (6,7).

Among adults taking epilepsy medication, those aged ≥65 years had better seizure control than among younger adults aged 35–54 years. This finding is also consistent with a previous report (8). The apparent better response to epilepsy medication in older adults might be attributable to differences in seizure etiology, drug pharmacokinetics, or better adherence to prescribed antiseizure medication regimens, possibly because of their experience with other chronic conditions or better access to care, including Medicare prescription drug coverage.

Only 44% of respondents with active epilepsy on epilepsy medication in this study were seizure-free in the past year. According to the Institute of Medicine, about 70% of all patients with epilepsy might become seizure-free under appropriate epilepsy treatment (2). To optimize seizure control, clinicians’ decisions to treat epilepsy should be based on individualized assessments of both disease-based (e.g., age of disease onset, seizure etiology, type, and comorbid conditions) and treatment-based factors (e.g., adherence to antiepileptic drugs), as well as patients’ personal characteristics, preferences, and their social context (6,7,9). Improving access to care, providing social support and epilepsy self-management education to improve medication adherence, and encouraging other self-management behaviors such as avoiding seizure triggers (e.g., sleep deprivation, stress, flashing lights, and alcohol or drug use) might also improve seizure control (10).

The findings in this report are subject to at least five limitations. First, estimates of epilepsy prevalence are based on self-reported data and are subject to error; however, because previous studies have validated the NHIS epilepsy questions, this bias is expected to be small (3). Second, active epilepsy might be overestimated because of the mistaken reporting of other nonepileptic seizures (5) or underestimated because of respondents’ reluctance to disclose epilepsy (2), as well as by the exclusion of institutionalized adults (e.g., adults in long-term care facilities and incarcerated persons) from NHIS. Third, these surveys did not objectively measure medication adherence or seizure frequency. Fourth, although respondent survey weights were adjusted to the U.S. population, the potential for nonresponse bias cannot be eliminated, given the low overall response rate (58.2%). Finally, the lack of differences in seizure frequency by seeing a specialist could be confounded by epilepsy severity and other untreated comorbidity such as mood disorder. However, no data regarding epilepsy severity is collected on NHIS

These findings highlight both the substantial burden of uncontrolled seizures in adults with epilepsy and the persistent sociodemographic and socioeconomic disparities in active epilepsy prevalence, access to neurologic specialty care, and seizure control. Health care and public health should ensure that adults with uncontrolled seizures have appropriate care and self-management support in order to promote seizure control, improve health and social outcomes, and reduce health care costs.

Conflict of Interest

No conflicts of interest were reported.


Corresponding author: Niu Tian, NTian@cdc.gov, 770-488-5679.

1Division of Population Health, National Center for Chronic Disease Prevention and Health Promotion, CDC; 2Cutting Edge Technologies and Solutions (Cetechs), Mesa, Arizona.


* Among those reporting that a doctor or health professional had told them they had a seizure disorder or epilepsy, those who reported taking medication, having had one or more seizures in the past year, or both were considered to have active epilepsy.

https://www.cdc.gov/nchs/nhis/index.htm.

§https://www.cdc.gov/nchs/nhis/data-questionnaires-documentation.htm.

1) “Have you ever been told by a doctor or other health professional that you have a seizure disorder or epilepsy?” 2) “Are you currently taking any medicine to control your seizure disorder or epilepsy?” 3) “Think back to last year about the same time. About how many seizures of any type have you had in the past year?” and 4) “In the past year have you seen a neurologist or epilepsy specialist for your epilepsy or seizure disorder?”

References

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  2. Institute of Medicine. Epilepsy across the spectrum: promoting health and understanding. Washington, DC: The National Academy Press; 2012. https://www.nap.edu/read/13379/chapter/3#25
  3. Brooks DR, Avetisyan R, Jarrett KM, et al. Validation of self-reported epilepsy for purposes of community surveillance. Epilepsy Behav 2012;23:57–63. CrossRef PubMed
  4. CDC. Epilepsy in adults and access to care—United States, 2010. MMWR Morb Mortal Wkly Rep 2012;61:909–13. PubMed
  5. Kroner BL, Fahimi M, Kenyon A, Thurman DJ, Gaillard WD. Racial and socioeconomic disparities in epilepsy in the District of Columbia. Epilepsy Res 2013;103:279–87. CrossRef PubMed
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TABLE. Number and age-adjusted* prevalence of active epilepsy, and percentages of adults who accessed specialty care, took epilepsy medications for seizure control, and were seizure-free with epilepsy medication in the past year among doctor-diagnosed active epilepsy, by selected characteristics — National Health Interview Survey, United States, 2013 and 2015Return to your place in the text
Characteristic Adults with active epilepsy Seen a neurologist or epilepsy specialist Taking epilepsy medication to control seizure Seizure-free with epilepsy medication
No. No. (weighted)§ Age-adjusted % (95% CI) No. No. (weighted)§ Age-adjusted % (95% CI) No. No. (weighted)§ Age-adjusted % (95% CI) No. No. (weighted)§ Age-adjusted % (95% CI)
Survey year
2013 367 2,254,000 0.9 (0.8–1.1) 217 1,428,000 65.7 (59.1–71.8) 305 1,948,000 86.3 (81.1–90.3) 136 871,000 45.3 (37.3–53.6)
2015 401 2,978,000 1.2 (1.1–1.4) 255 2,032,000 68.3 (62.1–74.0) 352 2,749,000 93.0 (89.8–95.3) 152 1,184,000 42.4 (35.0–50.2)
Total (crude) 768 2,616,000 1.1 (1.0–1.2) 472 1,730,000 66.2 (61.6–70.5) 657 2,348,000 90.2 (87.4–92.4) 288 1,028,000 44.1 (38.7–49.7)
Total (age-adjusted) 768 2,616,000 1.1 (1.0–1.2) 472 1,730,000 67.0 (62.6–71.2) 657 2,348,000 90.2 (87.4–92.4) 288 1,028,000 43.7 (38.1–49.5)
Sex
Men 354 1,327,000 1.1 (1.0–1.3) 224 919,000 69.7 (62.9–75.7) 313 1,221,000 92.0 (87.5–95.0) 146 538,000 43.7 (36.1–51.5)
Women 414 1,289,000 1.0 (0.9–1.2) 248 811,000 64.5 (58.4–70.1) 344 1,128,000 88.3 (84.2–91.4) 142 490,000 43.5 (35.7–51.6)
Age group (yrs)
18–34 165 803,000 1.1 (0.9–1.4) 116 615,000 76.7 (67.8–83.7) 136 721,000 91.0 (85.8–94.4) 54 303,000 42.3 (30.9–54.5)
35–54 280 867,000 1.0 (0.9–1.2) 175 585,000 67.5 (59.9–74.2) 235 768,000 88.6 (83.1–92.4) 80 280,000 36.9 (28.5–46.1)
55–64 165 540,000 1.4 (1.1–1.6) 95 305,000 56.5 (46.5–66.1) 144 483,000 89.4 (82.9–93.6) 63 209,000 43.7 (33.5–54.5)
>65 158 404,000 0.9 (0.7–1.1) 86 225,000 55.6 (45.0–65.7) 142 377,000 93.1 (88.0–96.1) 91 236,000 62.7 (50.7–73.3)
Race/Ethnicity
White, non-Hispanic 507 1,857,000 1.2 (1.0–1.3) 306 1,246,000 67.9 (62.6–72.8) 440 1,692,000 91.4 (88.0–93.9) 216 811,000 47.5 (40.4–54.6)
Black, non-Hispanic 136 401,000 1.4 (1.1–1.7) 84 233,000 62.8 (50.6–73.7) 114 348,000 88.8 (81.0–93.6) 35 104,000 32.3 (21.5–45.3)
Other 125 357,000 0.7 (0.6–0.9) 82 251,000 70.5 (59.4–79.6) 103 309,000 86.5 (78.8–91.8) 37 113,000 37.3 (26.7–49.3)
Marital status
Never married 246 934,000 2.0 (1.6–2.3) 165 691,000 71.0 (62.5–78.2) 219 862,000 92.7 (87.6–95.8) 87 351,000 44.9 (35.3–55.0)
Married/ Cohabitating 255 1,036,000 0.7 (0.6–0.8) 156 667,000 64.5 (56.4–71.9) 218 932,000 88.3 (82.5–92.3) 106 441,000 50.0 (41.5–58.5)
Divorced/ Separated/ Widowed 266 641,000 1.7 (1.2–2.3) 150 367,000 63.9 (53.4–73.2) 219 550,000 85.8 (76.6–91.8) 95 236,000 31.5 (25.3–38.4)
Education level
Less than HS 194 564,000 1.8 (1.5–2.2) 104 310,000 58.7 (48.9–67.9) 164 498,000 89.4 (82.9–93.6) 63 192,000 39.0 (28.9–50.2)
HS diploma or GED 216 803,000 1.3 (1.1–1.6) 131 496,000 62.4 (53.5–70.5) 190 733,000 92.5 (88.0–95.4) 76 283,000 38.9 (30.2–48.4)
Some college 348 1,203,000 0.8 (0.7–0.9) 231 896,000 74.2 (67.8–79.8) 294 1,074,000 89.0 (84.3–92.4) 144 533,000 49.4 (41.3–57.6)
Current employment
Yes 215 783,000 0.5 (0.4–0.6) 129 538,000 67.9 (59.4–75.5) 183 709,000 89.6 (83.8–93.5) 104 376,000 54.3 (44.1–64.1)
No 553 1,833,000 2.5 (2.2–2.8) 343 1,192,000 67.9 (62.6–72.7) 474 1,639,000 90.1 (86.7–92.8) 184 652,000 37.7 (31.0–45.1)
Poverty status**
<200% of FPL 481 1,383,000 1.9 (1.6–2.1) 284 864,000 64.6 (58.4–70.4) 402 1,222,000 88.2 (84.0–91.4) 143 399,000 33.2 (26.6–40.4)
≥200% of FPL 287 1,233,000 0.8 (0.6–0.9) 188 866,000 70.6 (63.4–76.9) 255 1,126,000 92.1 (87.9–94.9) 145 628,000 55.3 (46.7–63.6)
Region††
Northeast 112 390,000 0.9 (0.7–1.2) 82 316,000 84.3 (74.9–90.7) 97 358,000 89.5 (79.7–94.9) 46 209,000 60.3 (47.1–72.1)
Midwest 157 549,000 1.0 (0.8–1.2) 94 349,000 63.9 (54.8–72.2) 136 491,000 90.1 (83.3–94.4) 67 233,000 47.9 (36.5–59.5)
South 291 1,096,000 1.2 (1.1–1.4) 177 706,000 66.7 (59.9–72.9) 251 977,000 90.3 (85.2–93.7) 98 374,000 37.5 (29.3–46.3)
West 208 580,000 1.0 (0.8–1.3) 119 359,000 61.5 (51.8–70.4) 173 522,000 89.3 (84.0–93.0) 77 212,000 41.4 (31.0–52.5)

Abbreviations: CI = confidence interval; GED = General Educational Development; HS = high school; FPL = federal poverty level.
* Age-adjusted to the 2000 U.S. projected population, aged ≥18 years, using four age groups: 18–34, 35–54, 55–64, and ≥65 years. All prevalence estimates are age-adjusted except those for age groups, and overall (crude).
Doctor-diagnosed active epilepsy was defined as having a diagnosis of epilepsy and either taking medication or having had one or more seizures in the past year, or both.
§ Annualized and weighted number rounded to 1,000s.
Other race/ethnicity includes non-Hispanic American Indian and Alaska Native only; non-Hispanic Asian only; non-Hispanic Native Hawaiian and Pacific Islander only; and non-Hispanic multiple race.
** Poverty status was defined as the ratio of family income to FPL.
†† Northeast region (Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont); Midwest region (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, Wisconsin); South region (Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Mississippi, Maryland, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia); West region (Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming).

Return to your place in the textFIGURE. Age-standardized prevalence of epilepsy medication use and seizure frequency among adults with active epilepsy, by receipt of specialty care in the past year — National Health Interview Survey, United States, 2013 and 2015
The figure above is a bar chart showing the age-standardized prevalence of epilepsy medication use and seizure frequency among adults with active epilepsy, by receipt of specialty care in the past year, in the United States, in 2013 and 2015.

The figure above is a bar chart showing the age-standardized prevalence of epilepsy medication use and seizure frequency among adults with active epilepsy, by receipt of specialty care in the past year, in the United States, in 2013 and 2015.

Suggested citation for this article: Tian N, Boring M, Kobau R, Zack MM, Croft JB. Active Epilepsy and Seizure Control in Adults — United States, 2013 and 2015. MMWR Morb Mortal Wkly Rep 2018;67:437–442. DOI: http://dx.doi.org/10.15585/mmwr.mm6715a1.

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