SEARCH

SEARCH BY CITATION

Keywords:

  • Socioeconomic status;
  • Epilepsy;
  • Epidemiology;
  • Case–control study

Abstract

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

Summary: Purpose: Two earlier population-based studies provide conflicting information on the association between low socioeconomic status (SES) and risk for epilepsy. Seizure etiologies (e.g., head injury, stroke) associated with low SES were not addressed in prior analyses. We assess the relation between SES indices and incident epilepsy separately for children and adults and in subgroups defined by seizure etiology.

Methods: In this population-based case–control study, a surveillance system identified incident unprovoked seizure or first diagnosis of epilepsy throughout Iceland (n = 418). Controls were selected from the population registry as the next two same-sex births alive, residing in Iceland at the time of the index seizure, and without a history of unprovoked seizure on the date of the case's incident seizure (n = 835). The odds ratio measured the association between SES and epilepsy.

Results: An association was found between epilepsy and SES among adults, but not among children. Among adults, low education was associated with an increased risk for epilepsy [odds ratio (OR), 2.29; 95% confidence interval (CI), 1.21–4.34), and home ownership was protective (OR, 0.63; 95% CI, 0.43–0.92). When analyses were repeated by seizure etiology, this association remained only in the group with epilepsy of unknown cause, even after adjusting for alcohol consumption.

Conclusions: Low SES, indexed by low education or lack of home ownership, is a risk factor for epilepsy in adults, but not in children, suggesting a cumulative effect of SES on risk for epilepsy. This association is not explained by established risk factors for epilepsy (e.g., head injury, stroke). We find no evidence of a downward social drift among cases whose parents had epilepsy.

Socioeconomic Status (SES) describes the distribution of income, education, occupation, and social class. Low SES is associated with increased prevalence of epilepsy (1,2). Such cross-sectional studies do not clarify whether low SES is a risk factor for epilepsy or a consequence of the disorder. Two previous community-based studies of SES and risk for epilepsy are conflicting (3,4). An incident case–control study found no difference in SES between cases and controls (3). A prospective study, using a composite measure of SES, concluded that low SES is a risk factor for the development of epilepsy (4).

Indices of low SES are associated with many established risk factors for epilepsy, including cerebrovascular disease (5,6), head trauma (7), congenital malformations (8), central nervous system infection (meningitis, encephalitis) (9), alcohol intake or abuse (10), brain neoplasms (11), and Alzheimer's disease (12). Previously observed associations between epilepsy and low SES could be limited to cases with these symptomatic etiologies. We address the question of whether an association exists between SES and a first diagnosis of unprovoked seizure or epilepsy, and if so, whether this association exists for all etiologic subtypes of unprovoked seizure (13) and is consistent for adults and children.

METHODS

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

We conducted a population-based case–control study in Iceland from1995 through 1999 to evaluate risk factors for epilepsy, including SES.

Study subjects

A nationwide surveillance system was established that included all hospitals, emergency rooms, regional health care centers, nursing homes, and other health care facilities throughout Iceland. Each facility was contacted on a regular basis to identify potential new cases of seizure disorders. Additionally, all four radiology laboratories in the country with magnetic resonance (MR)/computed tomography (CT) facilities and the two EEG laboratories in the country were screened to identify referrals for episodic symptoms potentially of epileptic origin.

Cases

Our cases were drawn from this active seizure-surveillance system. Once a study nurse identified a potential case, medical records were reviewed to verify the occurrence of an incident seizure disorder. Unprovoked seizure was defined as a seizure without an identified proximate precipitant (e.g., fever, head trauma, stroke) (13). Epilepsy was defined as at least two unprovoked seizures.

Once the treating physician received permission for us to contact parents, guardians, adults, or their representatives, an introductory letter explaining the purpose of the study was sent, followed by a phone contact, at which time verbal agreement to participate in the study was obtained and a time scheduled to administer the structured interviews. The participation rate among cases was 84.3%.

Controls

Age-matched controls were selected from the population registry as the next two same-sex births who were alive, resided in Iceland at the time of the index seizure, and did not have a history of unprovoked seizure on the date of the case's incident seizure.

A letter was sent to potential controls or to parents or guardians, explaining the study, followed by a telephone contact to determine willingness to participate. If permission was not granted, the next eligible control was identified and the same procedure followed until two controls agreed to participate. Potential controls were excluded if they had a history of unprovoked seizure or were a sibling of the case. Among controls, the participation rate was 81.5%.

Measures and assessments

Neurologic assessment

Study neurologists (W.A.H., P.L., E.O., G.G.) reviewed all information, including results of neuroimaging and electroencephalography.

Seizure etiology

The classification of seizure etiology was based on the medical record and information obtained from cases, their parents, or guardians. Seizures were categorized according to the recommendation of the International League Against Epilepsy Commission on Epidemiology (13). Seizures were considered remote symptomatic in the presence of a history of a central nervous system (CNS) insult associated with an increased risk of epilepsy (e.g., stroke, head trauma, mental retardation, cerebral palsy, meningitis). The interval between the seizure and the neurologic insult had to be >1 week but was usually months or years. Seizures were considered progressive symptomatic in the presence of nonstatic CNS conditions (tumors, degenerative diseases). Seizures were considered idiopathic/cryptogenic in the absence of an acute precipitating factor or a history of neurologic insult.

Assessment of socioeconomic status

Separate parallel questionnaires were administered to parents of children and to adults to ascertain SES. This was done because parents determine a child's SES, whereas adults determine their own SES. Because the age of majority in Iceland was 16 years at the time of the study, children are defined as younger than 16 years (n = 420) and adults as 16 years or older (n = 833). SES was assessed in a telephone interview at the time of study enrollment and included information accurate at time of the index seizure for cases and their controls. No information on SES was obtained from refusals.

SES was measured by monthly household income, educational attainment of the subject (if adult) and of the main wage earner of the household, home ownership, car ownership, number of people in the home, and number of rooms in the home. These measures of SES have been used commonly in other studies (14–19). The number of people per room was computed by dividing the number of people in the household by the total number of rooms in the household.

Education was categorized as low (no school, some elementary school, or special school), medium (elementary school graduate, some secondary school, or secondary school graduate), or high (some college through postgraduate education).

Downward social drift

Downward social drift would be considered to be present if a parent of the case had epilepsy and the parent's SES caused the case to fall into the low-SES categories. Examples of how SES might decrease in association with epilepsy in a parent might include inability to be employed, successfully complete school, or earn an income consistent with a high SES. Although we were unable to measure the SES of parents of adult cases and controls, we did have information on family history of epilepsy in parents and SES of the adult study participants. If downward social drift exists in our data, then markers of high SES associated with epilepsy in the case–control study would be less likely in cases with a parent with epilepsy than in cases whose parent did not have epilepsy: the same would be seen in controls.

Assessment of alcohol intake

Alcohol intake, a known correlate of SES (20) and of seizures (21) is a potential confounder of the relation between SES and seizures. Frequency and amount of alcohol intake, collected by decade of life, beginning in the teenage years, was used to calculate cumulative alcohol intake up until the decade of the index date for cases and controls.

Human subjects

The study was approved by the Icelandic Data Protection Commission (Tolvunefnd rikisins), the Ethics committee of the Chief Medical Officer of Iceland, the Medical Ethics Board of the National University Hospital of Iceland (Landspitalinn), the Institutional Review Board of the College of Physicians and Surgeons of Columbia University, and the Review Board of the National Institutes of Health (OPRR).

Statistical analysis

Analyses were conducted separately for children and adults, because adults determine their own SES and the SES of children is determined by their parents. χ2 was used for categoric variables, and t tests were used for continuous variables. Conditional logistic regression models were fitted with case status as the dependent variable. Univariate analyses examined each SES indicator individually. Analyses were repeated by seizure etiology, and the final analysis was adjusted for cumulative alcohol intake.

To determine if a trend existed in the risk for epilepsy by level of education, we created an ordinal value for each category. For example, low education was coded as 1, medium education was coded as 2, and high education was coded as 3. We then ran a logistic regression to test if the coefficient was equal to 0.

RESULTS

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

Children

Among the 140 cases and 280 controls, The mean age was 7.4 years for cases (range, 0.03–15.9 years) and 7.4 years for controls (range, 0.03–15.9 years). Boys accounted for >50% of cases and controls (Table 1). Most children resided in the area around the capital of Reykjavik.

Table 1. Characteristics of childhood cases and controls
CharacteristicsCases (n = 140)Controls (n = 280)
  1. Low education: no school, some elementary school or special school; middle education: completed elementary school, some secondary school or secondary school graduate; high education: some college, college graduate, grad school graduate, postgraduate education;

  2. IR: interquartile range; NA, Not applicable.

  3. *Age ranges: 0 to 4 means 0 through 4 years, 0 days;

  4. 4 to 9, 4 years, 1 day through 9 years, 0 days.

Area of residence
 Capital area90 (64.29%)175 (62.50%) 
 Others50 (35.71%)105 (37.50%)*
Age group (yr)*
 0 to 439 (27.86%)78 (27.86%)
 4 to 948 (34.29%)96 (34.29%)
 9 to 1653 (37.86%)106 (37.86%) 
Gender
 Male78 (55.71%)156 (55.71%) 
 Female62 (44.29%)124 (44.29%) 
Educational level for child
 Low education134 (95.71%) 247 (88.21%) 
 Middle education0 (0)    3 (1.07%)
 High education4 (2.86%)10 (3.57%) 
 Missing2 (0.71%)20 (7.14%) 
Educational level of main wage earner
 Low education3 (2.14%)5 (1.79%)
 Middle education72 (51.43%)155 (55.36%) 
 High education64 (45.71%)119 (42.50%) 
 Missing1 (0.71%)1 (0.36%)
Educational level of other wage earner
 Low education4 (2.86%)3 (1.07%)
 Middle education58 (41.43%)120 (42.86%) 
 High education60 (42.86%)125 (44.64%) 
 Missing18 (12.86%)32 (11.43%)
Monthly household income
 <80,000 kronur10 (7.14%) 21 (7.50%) 
 80,000–149,999 kronur44 (31.43%)60 (21.43%)
 150,000–199,999 kronur32 (22.86%)65 (23.21%)
 200,000–300,000 kronur26 (18.57%)68 (24.29%)
 >300,000 kronur16 (11.43%)23 (8.21%) 
 Missing12 (8.57%) 43 (15.36%)
Car ownership
 No6 (4.29%)17 (6.07%) 
 Yes134 (95.71%) 263 (93.93%) 
Home ownership
 No25 (17.86%)39 (13.93%)
 Yes115 (82.14%) 241 (86.07%) 
No. people per room (median ± IR)1.06 ± 0.401.08 ± 0.31
Etiology
 Idiopathic/cryptogenic124 (88.57%) NA
 Remote symptomatic13 (9.29%) NA
 Progressive symptomatic3 (2.14%)NA
Seizure type
 Partial65 (46.43%)NA
 Generalized75 (53.57%)NA
Family history
 Yes5 (3.57%)2 (0.71%)
 No126 (90.00%) 267 (95.36%) 
 Missing9 (6.43%)11 (3.93%) 

In conditional logistic regression analyses, epilepsy was not statistically significantly associated with any SES indicator studied (Table 2). Few odds ratios exhibited a pattern consistent with low SES as a risk factor for unprovoked seizure or epilepsy.

Table 2. Socioeconomic status as a risk factor for incident unprovoked seizure in Icelandic children
SES indicatorsOdds ratio (95% confidence interval)
  1. Low education: no school, some elementary school, or special school; middle education: completed elementary school, some secondary school, or secondary school graduate; high education: some college, college graduate, grad school graduate, postgraduate education.

Educational level of main wage earner
 Low1.10 (0.26–4.67)
 Medium0.85 (0.55–1.30)
 High1.0 (Referent)  
Educational level of other wage earner
 Low 2.20 (0.48–10.02)
 Medium0.98 (0.62–1.54)
 High1.0 (Referent)  
Car ownership
 No1.0 (Referent)  
 Yes1.46 (0.56–3.85)
Home ownership
 No1.0 (Referent)  
 Yes0.71 (0.40–1.29)
Monthly household income
 <80,000 kronur1.0 (Referent)  
 ≥80,000 kronur1.22 (0.54–2.74)
 Number of people per room0.88 (0.49–1.60)

Adults

Among the 278 cases and 555 controls, one elderly case could only be matched to one control. The mean age was 45.2 years for cases (range, 16.1–89.8 years) and 45.2 years for controls (range, 16.1–89.8 years). The majority resided in the capital area (Table 3).

Table 3. Characteristics of adult cases and controls
VariablesCases (n = 278)Controls (n = 555)
  1. Low education: no school, some elementary school, or special school; middle education: completed elementary school, some secondary school, or secondary school graduate; high education: some college, college graduate, grad school graduate, postgraduate education;

  2. IR, interquartile range; NA, not applicable.

  3. *Age ranges: 16 to 24 means 16 years, 1 day through

  4. 24 years, 0 days; 24 to 65, 1 day through 65 years 0 days.

Area of residence
 Capital area183 (65.83%)327 (58.92%)
 Other 81 (29.14%)217 (39.10%)
 Missing14 (5.04%)11 (1.98%)
Age group (yr)*
 16 to 24 67 (24.10%)134 (24.14%)
 24 to 65138 (49.64%)276 (49.73%)
 65 and older 73 (26.26%)145 (26.13%)
Gender
 Male137 (49.28%)274 (49.37%)
 Female141 (50.72%)281 (50.63%)
Educational level of participant
 Low education26 (9.35%)36 (6.49%)
 Middle education139 (50.00%)284 (51.71%)
 High education 99 (35.61%)227 (40.90%)
 Missing14 (5.04%) 8 (1.44%)
Educational level of other
 Adult wage earner
 Low education12 (4.32%)20 (3.60%)
 Middle education 98 (35.25%)225 (40.54%)
 High education 73 (26.26%)171 (30.81%)
 Missing 95 (34.17%)139 (25.05%)
Monthly household income
 <80,000 kronur 49 (17.63%) 91 (16.40%)
 80,000–149,999 kronur 76 (27.34%)158 (28.47%)
 150,000–199,999 kronur 31 (11.15%) 93 (16.76%)
 200,000–300,000 kronur 28 (10.07%) 65 (11.71%)
 >300,000 kronur14 (5.04%)39 (7.03%)
 Missing 80 (28.78%)109 (19.64%)
Car ownership
 No 46 (16.55%) 74 (13.33%)
 Yes212 (76.26%)470 (84.68%)
 Missing20 (7.19%)11 (1.98%)
Home ownership
 No 60 (21.58%) 90 (16.22%)
 Yes198 (71.22%)453 (81.62%)
 Missing20 (7.19%)12 (2.16%)
No. people per room (mean ± SD)0.81 ± 0.360.77 ± 0.35
Etiology
 Idiopathic/cryptogenic174 (62.59%)NA
 Remote symptomatic 62 (22.30%)NA
 Progressive symptomatic 42 (15.11%)NA
Seizure type
 Partial 97    (34.89%)NA
 Generalized 181    (65.11%)NA
Family history in parents
 Yes 9 (3.24%) 4 (0.72%)
 No234 (84.17%)514 (92.61%)
 Missing 35 (12.59%)37 (6.67%)

Among adults, low SES increased the risk for epilepsy, whereas high SES was protective (Table 4). In adjusted analyses, low SES, indexed by low education, increased the risk for epilepsy (OR, 2.29; 95% CI, 1.21–4.34), whereas high SES, indexed by home ownership, was protective for the development of epilepsy (OR, 0.63; 95% CI, 0.43–0.92). We found no trend by level of education (p = 0.08). The risk for incident unprovoked seizure or epilepsy decreased with increasing income in univariate analyses (OR, 0.56; 95% CI, 0.33–0.92), but was no longer significant in multivariate analyses (see Table 4).

Table 4. Socioeconomic status as a risk factor for incident unprovoked seizure in Icelandic adults
SES indicatorsCrude odds ratio (95% Confidence interval)Adjusted odds ratio (95% Confidence interval)
  1. Low education: no school, some elementary school, or special school; middle education: completed elementary school, some secondary school, or secondary school graduate; high education: some college, college graduate, grad school graduate, postgraduate education.

Whole group (278 cases and 555 controls)
  Educational level of main wage earner
   Low1.76 (0.97–3.18)2.29 (1.21–4.34)
   Medium1.13 (0.82–1.56)1.17 (0.84–1.62)
   High1.0 (Referent)  1.0 (Referent)  
  Educational level of other adult wage earner
   Low1.38 (0.54–3.49) 
   Medium0.95 (0.64–1.43) 
   High1.0 (Referent)   
  Car ownership
   No1.0 (Referent)   
   Yes0.63 (0.41–0.97) 
  Home ownership
   No1.0 (Referent)  1.0 (Referent)  
   Yes0.64 (0.44–0.93)0.63 (0.43–0.92)
  Monthly household income
   <80,000 kronur1.0 (Referent)   
   ≥80,000 kronur0.56 (0.33–0.92) 
   Number of people per room1.52 (0.94–2.46) 
Idiopathic/cryptogenic group (174 cases and 348 controls)
  Educational level of main wage earner
   Low2.46 (1.11–5.42)2.79 (1.24–6.31)
   Medium1.08 (0.73–1.60)1.16 (0.78–1.74)
   High1.0 (Referent)  1.0 (Referent)  
  Educational level of other adult wage earner
   Low1.32 (0.36–4.82) 
   Medium0.99 (0.61–1.61) 
   High1.0 (Referent)   
  Car ownership
   No1.0 (Referent)   
   Yes0.68 (0.40–1.16) 
  Home ownership
   No1.0 (Referent)  1.0 (Referent)  
   Yes0.58 (0.37–0.90)0.59 (0.37–0.93)
  Monthly household income
   <80,000 kronur1.0 (Referent)   
   ≥80,000 kronur0.53 (0.28–1.02) 
   Number of people per room1.41 (0.78–2.52) 
Remote symptomatic group (62 cases and 124 controls)
  Educational level of main wage earner
   Low1.14 (0.36–3.67) 
   Medium0.93 (0.47–1.84) 
   High1.0 (Referent)   
  Educational level of other adult wage earner
   Low 1.67 (0.22–12.41) 
   Medium1.56 (0.55–4.45) 
   High1.0 (Referent)   
  Car ownership
   No1.0 (Referent)   
   Yes0.41 (0.16–1.02) 
  Home ownership
   No1.0 (Referent)   
   Yes0.66 (0.29–1.50) 
  Monthly household income
   <80,000 kronur1.0 (Referent)   
   ≥80,000 kronur0.47 (0.18–1.27) 
   Number of people per room1.43 (0.47–4.41) 
Progressive symptomatic group (42 cases and 83 controls)
  Educational level of main wage earner
   Low1.68 (0.34–8.26) 
   Medium2.35 (0.79–6.99) 
   High1.0 (Referent)   
  Educational level of other adult wage earner
   Low1.24 (0.18–8.75) 
   Medium0.49 (0.17–1.43) 
   High1.0 (Referent)   
  Car ownership
   No1.0 (Referent)   
   Yes0.94 (0.29–3.08) 
  Home ownership
   No1.0 (Referent)   
   Yes1.41 (0.39–5.12) 
  Monthly household income
   <80,000 kronur1.0 (Referent)   
   ≥80,000 kronur1.00 (0.23–4.35) 
  Number of people per room2.46 (0.64–9.42) 

We examined our data to see whether downward social drift might explain our findings. Among cases, 87.50% of those with a family history of epilepsy in a parent owned a home, compared with 80.28% of those without such a family history (p = 1.0). Similarly, among cases, 37.50% of those with a family history of epilepsy in a parent were classified as high education compared with 39.45% of those without such a family history (p = 0.2). Similar results were observed in controls (data not shown).

We examined each measure of SES separately according to seizure etiology (see Table 4). No SES variables were associated with the occurrence of epilepsy, either for remote symptomatic etiology or for progressive symptomatic etiology; this was true even after combining the two etiologic groups (data not shown). In the group with idiopathic/cryptogenic seizures, low education was associated with an increased risk for epilepsy (OR, 2.79; 95% CI, 1.24–6.31), and home ownership was protective (OR, 0.59; 95% CI, 0.37–0.93) in adjusted models. Further adjustment for cumulative alcohol consumption did not change the results (OR for home ownership, 0.62; 95% CI, 0.39–0.98; OR for low education, 2.77; 95% CI, 1.21–6.31; OR for middle education, 1.19; 95% CI, 0.79–1.79).

DISCUSSION

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

We found no association between SES and incident unprovoked seizure or epilepsy among children. Among adults, low SES indexed by low education was associated with an increased risk for epilepsy, and high SES indexed by home ownership was protective for the development of epilepsy. The risk for epilepsy increased with low education, and the risk for epilepsy decreased with home ownership for all adult cases and controls, and for the subgroup with idiopathic/cryptogenic etiology. None of the SES indices were differentially associated with epilepsy in those with remote symptomatic or with progressive symptomatic etiology; however, numbers were small in these subgroups. Downward social drift did not seem to explain the results, because the SES of cases whose parents had epilepsy did not differ from that of cases whose parents did not; however, information on the SES of parents of adult participants was unavailable.

One prior prospective study found an association between low SES and epilepsy (4). This study compared the incidence of epilepsy by categories of Carstairs score, a composite based on overcrowding, social class of the head of the household, car ownership, and unemployment. The incidence of epilepsy in the lowest fifth of the Carstairs scores was 2.3-fold greater than that in the highest fifth (4). Our results are consistent with these findings, but suggest that the effect of low SES may be limited to unprovoked seizures of unknown etiology.

Major strengths of our study are its individual ascertainment of SES and population-based design. This design avoids the potential effects of selection bias. A weakness of the study is that the association between SES and epilepsy is investigated in an egalitarian society, potentially leading to an underestimate of the effect of low SES on the risk for epilepsy.

Iceland is a society in which universal health care and state assistance programs remove much of the association between SES and access to health care. Nonetheless, associations between SES and health status exist worldwide (14) and are found in Scandinavian countries, which are similar to Iceland (14,16,18). In light of universal access to healthcare in Iceland, the association between SES and epilepsy in adults, but not in children, is notable. This absence of an association in children may be real or due to the narrow range of SES in Iceland, masking an effect that truly exists. It is difficult to determine which explanation is more likely. However, our control group appears to be representative of the Icelandic population, because the distribution of family income in our control children is very similar to that reported in a study of a representative sample of 3,007 Icelandic school children, aged 2 to 17 years (19). Other studies of Icelandic children report associations between low SES and ill health (19), high SES and increased leisure time physical activity (22), and between SES and headache (23), suggesting that the absence of an effect of SES on epilepsy in children may be real. Alternatively, SES may influence the risk for epilepsy through risk factors and diseases that are more common in adults (e.g., hypertension, stroke, Alzheimer's disease) than in children. This is consistent with the notion of a cumulative impact of SES over the life course.

The impact of SES on disease in Icelandic adults is not limited to epilepsy. Despite universal access to healthcare and state assistance, the literature reports three studies of the association between SES and disease in Icelandic adults. Low educational level has been reported to increase the risk for coronary heart disease risk factors in 18,919 adults living in Reykjavik (24). Among a random sample of 1,023 adults in Reykjavik, total and partial edentulousness was more frequent in the lower-SES group, defined by employment (25). Female industrial workers in Iceland have an almost twofold increased mortality compared with the general population (standardized mortality ratio, 1.79; 95% CI, 1.45–2.19) (26).

It is notable that some measures of low SES were associated with an increased risk for epilepsy in people with seizures of unknown etiology in our study. The lack of an association between low SES and epilepsy for remote symptomatic and for progressive symptomatic etiologies is surprising, because many of the causes of these seizures are themselves associated with low SES in other populations (5–12). However, small subgroup size for these etiologies may have contributed to an inability to detect an effect.

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

Our findings support the association between low SES and increased risk for epilepsy found by Heaney et al. (4) and indicate that the relation between SES and epilepsy may be limited to adults. Additionally, we find that the association is unlikely to be due to downward social drift. Further study of this association in adults with seizures of unknown etiology may clarify pathways through which SES influences the risk for epilepsy. Finally, additional population-based studies of the relation between SES and risk for epilepsy are needed among children living in communities with greater socioeconomic variation to confirm the absence of an association in this group.

Acknowledgments

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES

Acknowledgment:  This work was supported by grants from the National Institute of Neurological Disorders and Stroke (5R01 NS 32663) and the Health Sciences Student Fellowship from the Epilepsy Foundation (of America). This manuscript was independent of the funding agency.

REFERENCES

  1. Top of page
  2. Abstract
  3. METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONCLUSIONS
  7. Acknowledgments
  8. REFERENCES
  • 1
    Shamansky SL, Glaser GH. Socioeconomic characteristics of childhood seizure disorders in the New Haven area: an epidemiologic study. Epilepsia 1979;20: 45774.
  • 2
    Morgan CL, Ahmed Z, Kerr MP. Social deprivation and prevalence of epilepsy and associated health usage. J Neurol Neurosurg Psychiatry 2000;69: 137.
  • 3
    Forsgren L, Nystrom L. An incident case-referent study of epileptic seizures in adults. Epilepsy Res 1990;6: 6681.
  • 4
    Heaney DC, MacDonald BK, Everitt A, et al. Socioeconomic variation in incidence of epilepsy: prospective community based study in southeast England. BMJ 2002;325: 10136.
  • 5
    Chang C-L, Marmot MG, Farley TMM, et al. The influence of economic development on the association between education and the risk of acute myocardial infarction and stroke. J Clin Epidemiol 2002;55: 7417.
  • 6
    Gudmundsson K, Hardarson P, Sigvaldason H, et al. Relationship between education and risk factors for coronary artery disease. Nordisk Med 1997;112: 16975.
  • 7
    Cubbin C, LeClere FB, Smith GS. Socioeconomic status and the occurrence of fatal and nonfatal injury in the United States. Am J Public Health 2000;90: 707.
  • 8
    Vrijheid M, Dolk H, Stone D, et al. Socioeconomic inequalities in risk of congenital anomaly. Arch Dis Child 2000;82: 34952.
  • 9
    Jones IR, Urwin G, Feldman RA, et al. Social deprivation and bacterial meningitis in north east Thames region: three year study using small area statistics. BMJ 1997;314: 7945.
  • 10
    Hemmingsson T, Lundberg I, Diderichsen F. The roles of social class of origin, achieved social class and intergenerational social mobility in explaining social-class inequalities in alcoholism among young men. Soc Sci Med 1999;49: 10519.
  • 11
    Faggiano F, Partanen T, Kogevinas M, et al. Socioeconomic differences in cancer incidence and mortality. IARC Sci Pub 1997;138: 65176.
  • 12
    Karp A, Kareholt I, Qiu C, et al. Relation of education and occupation-based socioeconomic status to incident Alzheimer's disease. Am J Epidemiol 2004;59: 17583.
  • 13
    Commission on Classification and Terminology of the International League Against Epilepsy. Guidelines for epidemiologic studies on epilepsy. Epilepsia 1993;34: 5926.
  • 14
    Feinstein JS. The relationship between socioeconomic status and health: a review of the literature. Milbank Q 1993;71: 279322.
  • 15
    Huisman M, Kunst AE, Mackenbach B. Socioeconomic inequalitites in morbidity among the elderly: a European overview. Soc Sci Med 2003;57: 86173.
  • 16
    Laaksonen M, Sarlio-Lahteenkorva S, Lahelma E. Multiple dimensions of socioeconomic position and obesity among employees: the Helsinki Health Study. Obesity Res 2004;12: 18518.
  • 17
    Pollack CE, Von Dem Knesebeck O, Siegrist J. Housing and health in Germany. J Epidemiol Comm Health 2004;58: 21622.
  • 18
    Avendaño M, Kunst AE, Van Lenthe F, et al. Trends in socioeconomic disparities in stroke mortality in six European countries between 1981–1985 and 1991–1995. Am J Epidemiol 2005;161: 5261.
  • 19
    Halldórsson M, Cavelaars AEJM, Kunst AE, et al. Socioeconomic differences in health and well-being of children and adolescents in Iceland. Scand J Public Health 1999;1: 437.
  • 20
    Schnohr C, Hojbjerre L, Riegels M, et al. Does educational level influence the effects of smoking, alcohol, physical activity, and obesity on mortality? A prospective population study. Scand J Public Health 2004;32: 2506.
  • 21
    Ng SKC, Hauser WA, Brust JCM, et al. Alcohol consumption and withdrawal in new-onset seizures. N Engl J Med 1988;319: 66673.
  • 22
    Kristjansdottir G, Vilhjalmsson R. Sociodemographic differences in patterns of sedentary and physically active behavior in older children and adolescents. Acta Pediatr 2001;90: 42935.
  • 23
    Kristjansdottir G, Wahlberg V. Sociodemographic differences in the prevalence of self-reported headache in Icelandic schoolchildren. Headache 1993;33: 37680.
  • 24
    Gurdmundsson K, Hardarson P, Sigvaldason H, et al. Relationship between education and risk factors for coronary heart disease. Nordisk Med 1997;112: 16975.
  • 25
    Ragnarsson E, Eliasson ST, Olafsson SH. Tobacco smoking, a factor in tooth loss in Reykjavik, Iceland. Scand J Dent Res 1992;100: 32226.
  • 26
    Gunnarsdottir HK, Tomasson K. Mortality among female industrial workers in Iceland. Work 2004;22: 638.