Hospitalization for Epilepsy -- United States, 1988-1992

Epilepsy is a chronic neurologic condition manifested by repeated unprovoked seizures that affects approximately 1% of the U.S. population (1). Although effective treatment can prevent seizures in most persons with epilepsy, some persons have frequent seizures, which can lead to brain damage, disability, and diminished quality of life (2,3). To assist in characterizing the public health impact of epilepsy in the United States, CDC analyzed data from the National Hospital Discharge Survey (NHDS) for 1988-1992 to estimate the number of hospitalizations for which epilepsy was the first-listed diagnosis.

The NHDS is conducted annually and collects data from a sample of inpatient records obtained from a nationally representative sample of nonfederal general and short-stay specialty hospitals in the United States (4). Hospitalizations for which the first-listed diagnosis was epilepsy were selected by using the International Classification of Diseases, Ninth Revision, Clinical Modification, codes 345.0-345.9. Age-specific and age-adjusted rates were estimated for the civilian population; the direct method was used to age-adjust the estimates to the 1980 U.S. resident population. Because of differences in the racial designation of the denominator population in different years, race-specific rates for the total period could be estimated for whites only and for all other groups combined. Hospitalizations for persons with race not stated were included with whites. To increase the stability of the estimates, data for all 5 survey years were combined. SUDAAN was used to calculate the estimates and standard errors.

From 1988 through 1992, epilepsy was the first-listed diagnosis for an estimated 466,000 hospitalizations; the age-adjusted hospitalization rate was 37 hospitalizations per 100,000 persons Table_1. The age-specific rate per 100,000 persons varied by age group and was highest for persons aged greater than or equal to 65 years (68 per 100,000) and lowest for persons aged 15-64 years (30).

The age-adjusted hospitalization rate was higher for males (40) than females (34); however, age-specific rates for males and females were similar Table_1. The age-adjusted hospitalization rate was higher in the Northeast (49) than in the South (37), North Central (35), and West (27). *

Age-adjusted rates were substantially lower for whites (35) than for all other racial groups combined (51). Age-specific rates were similar for the youngest age group; however, compared with whites, rates were higher in other age groups for the other racial groups combined Figure_1. The ratio of rates increased directly by age group -- 0.9 among persons aged less than 15 years, 1.6 among those aged 15-64 years, and 1.8 among those aged greater than or equal to 65 years.

Reported by: Statistics Br, Div of Chronic Disease Control and Community Intervention, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: Hospitalizations for epilepsy represent a potentially preventable complication of this condition. The findings in this report indicate that, during 1988-1992, approximately 93,000 hospitalizations each year were attributed to epilepsy. These rates are similar to those reported for 1973-1976 (5) and to rates based on studies employing rigorous ascertainment of cases (6).

Comparing these results with the estimated prevalence of self-reported epilepsy (7), approximately 8% of persons with epilepsy are hospitalized each year. The proportion of persons hospitalized is similar for men and women but varies considerably with age; an estimated one fourth of persons with epilepsy aged greater than or equal to 65 years are hospitalized each year with epilepsy as the first-listed diagnosis. This may be attributable to either severity of epilepsy, its underlying causes in older age groups, or underreporting of epilepsy in this population segment.

Although data characterizing the prevalence of epilepsy by racial/ethnic group are limited, the prevalence among whites, in general, has been reported to be lower than for blacks (7,8). In 1992, 20% of NHDS records lacked a designation of race (7). Because most of these persons were discharged from hospitals that historically reported most of their patients as white, these records were included with whites in this analysis, thus resulting in an overestimate of hospitalization rates for whites. Despite this bias, however, the hospitalization rate for whites was different when compared with all other racial groups combined. In this analysis, this disparity increased directly with age, possibly reflecting cumulative differences in disease severity or access to effective therapy.

The findings in this report are subject to at least two limitations. First, the hospitalization data could not be linked to individuals. Persons with particularly refractory seizures may have been hospitalized multiple times during the study period. Second, epilepsy may be the underlying factor for hospitalizations attributed to other causes (e.g., trauma). Therefore, this analysis probably underestimated the total number of hospitalizations for epilepsy.

Although hospitalization accounts for only a small proportion of the total medical and public health impact of epilepsy, rates of hospitalization for epilepsy are especially high in some age groups. In addition, hospitalizations attributable to epilepsy are preventable with effective outpatient management focusing on proper diagnosis, treatment, and patient compliance. Patients with epilepsy refractory to treatment in the primary-care setting or those experiencing difficulties in compliance or adverse effects of antiepileptic medication should be referred to appropriate specialty centers for the diagnosis and treatment of epilepsy (9). CDC is collaborating with representatives of professional and voluntary organizations to develop guidelines for consumers and health-care providers for the management and referral of persons with epilepsy in primary-care settings.

November is National Epilepsy Month. Additional information about epilepsy and its treatment is available from the Epilepsy Foundation of America, telephone (800) 332-1000 or (301) 459-3700.

References

1. Hauser WA, Hesdorffer DC. Epilepsy: frequency, causes, and consequences. New York: Epilepsy Foundation of America, 1990.

2. Annegers JF, Hauser WA, Elveback LR. Remission of seizures and relapse in patients with epilepsy. Epilepsia 1979;20:729-37.

3. Dodrill CB. Correlates of generalized tonic-clonic seizures with intellectual, neuropsychological, emotional, and social function in patients with epilepsy. Epilepsia 1986;27:399-411.

4. NCHS. National Hospital Discharge Survey: annual summary, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, October 1994. (Vital and health statistics; series 13, no. 119).

5. Jerath BK, Kimbell BA. Hospitalization rates for epilepsy in the United States, 1973-1976. Epilepsia 1981;22:55-64.

6. Hauser WA, Kurland LT. The epidemiology of epilepsy in Rochester, Minnesota, 1935 through 1967. Epilepsia 1975;16:1-66.

7. CDC. Prevalence of self-reported epilepsy -- United States, 1986-1990. MMWR 1994;43;810-1,817-8.

8. Haerer AF, Anderson DW, Schoenberg BS. Prevalence and clinical features of epilepsy in a biracial United States population. Epilepsia 1986;27:66-75.

9. Lesser RP. The role of epilepsy centers in delivering care to patients with intractable epilepsy. Neurology 1994;44:1347-52.

* Northeast=Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont; North Central=Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin; South=Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia; West=Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.

TABLE 1. Number and rate * of hospitalizations for epilepsy, + by age group and sex --
United States, 1988-1992
======================================================================================================
                         Women                Men                   Total
                  ------------------   -------------------    --------------------
Age group (yrs)   No. &  Rate (SE @)   No.   Rate    (SE)     No.   Rate    (SE @)
----------------------------------------------------------------------------------
 <=14               51   38   (+/-4)    62    44    (+/-5)    112    41     (+/-4)
15-64              114   28   (+/-2)   132    33    (+/-2)    247    30     (+/-1)
 >=65               62   67   (+/-6)    44    69    (+/-6)    106    68     (+/-4)

Total              228   36   (+/-2)   238    39    (+/-2)    466    37     (+/-1)

Age-adjusted             34   (+/-2)          40    (+/-2)           37     (+/-1)
----------------------------------------------------------------------------------
* Per 100,000 persons in the civilian population.
+ International Classification of Diseases, Ninth Revision, Clinical Modification, codes 345.0-345.9
  as first-listed diagnosis on hospitalization record.
& In thousands. Totals may not add because of rounding.
@ Standard error.
======================================================================================================

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