Disability in people with epilepsy: A nationally representative cross-sectional study

Association of dietary fiber intake with epileptic seizures in U.S. adults: A Population-base study of 13,277 participants

OBJECTIVE

Epilepsy, a neurological disorder, is identified by the presence of recurrent seizures. We aimed to detect dietary fiber intake and its association with epilepsy prevalence in U.S. adults.

METHODS

This cross-sectional study obtained data from the 2013-2018 National Health and Nutrition Examination Survey database. Univariate and multivariate logistic regression models were employed to estimate the association between dietary fiber intake and epilepsy prevalence. The restricted cubic spline (RCS) model was also applied to investigate the dose-response relationships between dietary fiber intake and epileptic seizure events(ESEs).

RESULTS

Our final sample included 13,277 NHANES participants, with the average prevalence of ESEs being 1.09 % (145/13277). After adjusting for all confounding factors, the third quartile of dietary fiber intake levels remained significantly associated with a decreased risk of ESEs[odds ratios (OR) 0.54,95 % confidence interval (CI) 0.33-0.88, P = 0.014)] compared to the first quartile. Higher fiber intake indicated a stable negative association with ESEs in the multivariate logistic regression analysis, weighted generalized additive model. A nonlinear dose-response relationship was observed between dietary fiber intake levels and decreased ESEs risk (P for overall=0.017, P for nonlinear=0.155). Interaction tests showed no significant effect of demographic and disease status on the association between dietary fiber intake and ESEs.

CONCLUSION

In this cross-sectional study, people with a high dietary fiber intake were at a reduced risk of ESEs. However, further prospective studies are needed to investigate the effect of dietary fiber intake in epilepsy events and to determine causality.

Association between dietary carbohydrate intake percentage and epilepsy prevalence in the NHANES 2013-2018: a cross-sectional study

BACKGROUND

Epilepsy is a neurological disorder characterized by recurrent seizures. We aimed to investigate the association between the percentage of dietary carbohydrate intake (DCI) and epilepsy prevalence among American adults.

METHODS

We analyzed the data from 9,584 adults aged 20-80 years who participated in the National Health and Nutrition Examination Survey from 2013 to 2018. Logistic regression was applied to explore the association between the percentage of DCI and epilepsy prevalence.

RESULTS

A total of 146 (1.5%) individuals with epilepsy were enrolled in this study. The average age of the participants was 56.4 years, and 5,454 (56.9%) individuals were female. A high DCI was associated with an increased prevalence of epilepsy (odds ratio [OR], 4.56; 95% confidence interval [CI], 1.11-18.69; P = 0.035) after adjusting for age, sex, marital status, race/ethnicity, educational level, family income, body mass index, smoking status, drinking status, hypertension, diabetes, and cardiovascular disease. Stratified analyses indicated a positive correlation between DCI and epilepsy prevalence in adults with different characteristics. Compared with individuals in quartile 1 of DCI (<40.5%), those in quartile 4 (>55.4%) had an adjusted OR for epilepsy of 1.72 (95% CI, 1.09-2.73, P = 0.02, P for trend = 0.012).

CONCLUSIONS

A high percentage of DCI was associated with an increased prevalence of epilepsy. The risk of epilepsy increased 3.5-fold with a 1% increase in DCI. These results suggest an important role of DCI in the dietary management of epilepsy.

Incident Epilepsy Among US Medicare Beneficiaries, 2019: Differences by Age, Sex, and Race/Ethnicity

BACKGROUND AND OBJECTIVES

Epilepsy is common among older adults, but previous incident studies have had limited ability to make comparisons across key subgroups. We aimed to provide updated epilepsy incidence estimates among older adults, comparing across age, sex, and race/ethnicity.

METHODS

Using a random sample of 4,999,999 US Medicare beneficiaries older than 65 years, we conducted a retrospective cohort study of epilepsy incidence using administrative claims for 2016-2019. Sampled beneficiaries were enrolled in the Fee-for-Service (FFS) program in each of 2016-2018 and had no epilepsy claims in those years. Non-Hispanic Black and Hispanic beneficiaries were oversampled to ensure adequate cases for detailed comparisons. Incidence in 2019 was identified in the Master Beneficiary Summary File as ≥1 inpatient claim or ≥2 outpatient nondrug claims occurring at least 1 day apart (ICD-10 G40.x). Incidence models were estimated by age, sex, race/ethnicity, and combinations thereof, with adjustment for the racial/ethnic oversampling.

RESULTS

We identified 20,545 incident epilepsy cases. The overall epilepsy incidence rate (IR) was 393 per 100,000 (99% CI 385-400). Incidence peaked at ages 85-89 (504 [481-529]) and was higher for men (396 [385-407]) than women (376 [366-385]). The sex difference in IRs was constant with age. Incidence was higher for non-Hispanic Black (678 [653-702]) and Hispanic (405 [384-426]), and lower for non-Hispanic Asian/Pacific Islander (272 [239-305]) beneficiaries, compared with non-Hispanic White beneficiaries (354 [299-408]). The age-specific IRs significantly differed by race/ethnicity and sex, but only among non-Hispanic Black beneficiaries-where men had higher rates at younger ages and women at older ages.

DISCUSSION

We found higher epilepsy IRs among those enrolled in the Medicare FFS system 2016-2019 than previous studies using Medicare claims data from at least a decade ago. The risk of epilepsy onset is higher for those in their late 80s, men, and non-Hispanic Black and Hispanic older adults. There is also evidence that these age-graded risks operate differently for Black men and Black women. Efforts to provide care and services that improve quality of life for older adults living with epilepsy should consider differences by multiple social characteristics simultaneously: age, sex, and race/ethnicity.

The association between epilepsy and sleep disturbance in US adults: the mediating effect of depression

BACKGROUND

People with epilepsy (PWE) frequently experience sleep disturbances that can severely affect their quality of life. Depression is also a common symptom in the PWE population and can aggravate sleep problems. However, the interplay between epilepsy, depression, and sleep disturbances is not yet fully understood. Our study was designed to investigate the association between epilepsy and sleep disturbances in US adults and to determine whether depressive symptoms play a mediating role in this relationship.

METHODS

We examined data from the National Health and Nutrition Examination Survey (NHANES) spanning January 1, 2015, to March 2020, before the pandemic.A total of 10,093 participants aged ≥ 20 years with complete data on epilepsy and sleep disturbance were included. Weighted multiple logistic regression and mediation analysis were used to explore the associations among depression, epilepsy, and sleep disturbance. Interaction effects of epilepsy with various covariates were also investigated.

RESULTS

Epilepsy was associated with depression and sleep disturbances. Weighted logistic regression analysis revealed a significant association between epilepsy and sleep disturbances (OR = 3.67, 95% CI = 1.68-8.04). Depression partially mediated this relationship, demonstrating a mediation effect of 23.0% (indirect effect = 0.037, P < 0.001). Subgroup analyses revealed variations in the relationship between epilepsy and sleep disturbances among different groups. Furthermore, interaction analyses revealed significant interactions between epilepsy and age (P = 0.049) and hypertension (P = 0.045).

CONCLUSIONS

Our study utilizing NHANES data confirmed that depression partially mediated the association between epilepsy and sleep disturbance. Additionally, we observed differences in this association across demographic groups. Addressing depressive symptoms in PWE may improve their sleep quality, but further research is needed to explore the underlying mechanisms.

Differences in health-related quality of life and somatic symptoms in employed and unemployed patients with epilepsy

This study compared overall and specific aspects of health-related quality of life (HRQOL) and self-report of somatic, anxiety, and depressive symptoms between employed (n = 71) and unemployed (n = 48) patients with epilepsy (PWE). The Quality of Life in Epilepsy (QOLIE-89) and the Personality Assessment Inventory (PAI) were examined. The unemployed group reported significantly worse overall HRQOL including aspects of HRQOL related to epilepsy, physical health, mental health, and cognitive function. Among these four, physical health related HRQOL revealed the most difference between groups. While there were no differences between the groups in the level of social support and social isolation, the unemployed group reported worse social function with respect to work and driving. The unemployed group reported significantly greater somatic symptoms, but not anxiety and depressive symptoms. When specifically examining the subscales of the Somatic Concerns scale, conversion and health concerns, but not somatization, were greater in the unemployed group. Among the Depression subscales, the unemployed group reported greater physiologically manifested depressive symptoms. These findings suggest that along with optimizing seizure control, identifying and addressing presence of physical limitations, dysfunction, and somatic symptoms are also of importance in the care of PWE, particularly for those who are unemployed.

Somatic symptoms and related disorders in a large cohort of people with epilepsy: A cohort study

OBJECTIVE

This study was undertaken to characterize somatic symptoms and related disorders (SSD) in epilepsy.

METHODS

Adults with epilepsy under active follow-up at a tertiary epilepsy center were consecutively enrolled. The diagnosis of SSD was performed by an experienced psychologist based on the structured clinical interview for Statistical Manual of Mental Disorders, 5th edition. Detailed social/demographic data, epilepsy features, psychiatric features, life quality, disability, and economic burden were collected and compared between people with SSD and those without. Bodily distress syndrome checklist, Somatic Symptom Disorder-B Criteria Scale, Patient Health Questionnaire-9, and Generalized Anxiety Disorder seven-item scale (GAD-7) were used to evaluate SSD individuals' somatic symptoms, symptom-related psychological distress, and depressive and anxious symptoms. Quality of life and disability were assessed by Quality of Life in Epilepsy Inventory 31 (QOLIE-31) and World Health Organization Disability Assessment Schedule V.2.0 (WHO DAS 2.0). A risk prediction nomogram was generated using least absolute shrinkage and selection operator (LASSO) analysis and validated.

RESULTS

One hundred fifty of 631 participants (24%) were diagnosed with SSD. In people with SSD, the top three most common somatic symptoms were memory impairment, headache, and dizziness (85%, 80%, and 78%, respectively), and multiple systems were involved in most (82%) people with SSD. Compared with people without SSD, those with SSD had lower QOLIE-31 total scores, and higher WHO DAS 2.0 scores and disease economic burdens. LASSO analysis suggested that a history of severe traumatic brain injury, hippocampal sclerosis, low seizure worry and medication effects scores on QOLIE-31, multiple systems affected by somatic symptoms, and a high GAD-7 score were risk factors of SSD. The nomogram was validated for good accuracy in the training and testing cohorts.

SIGNIFICANCE

SSD are likely to be a common comorbidity in epilepsy and harm epilepsy prognosis. Our risk prediction nomogram was successfully developed but needs further validation in larger cohorts.

Factors associated with illness representations in adults with epileptic and functional seizures: A systematic review

Illness representations refer to a person's beliefs about their health condition and are thought to influence clinical outcomes. By understanding factors related to illness representations, potentially modifiable targets for psychological intervention can be identified. The aim of this systematic review was to synthesise the literature on factors associated with illness representations in people with epilepsy and functional seizures. Three electronic databases (Psychinfo, EMBASE, and Proquest (Theses and dissertations)) were searched for studies that reported on associations between Illness Perception Questionnaire scores (or variations thereof) and biopsychosocial factors in people with epilepsy or people with functional seizures. Seventeen studies met inclusion criteria and were assessed with a bespoke quality appraisal tool. Overall, there was moderately strong evidence for an association between more threatening illness representations and poorer clinical outcomes relating to seizure characteristics, distress, coping, and quality of life; the evidence for these relationships was stronger for people with epilepsy than functional seizures. There was no clear difference between the illness representations of the two groups. The results of this review highlight the clinical importance of illness representations in people with seizure disorders, as well as opportunities for further research.

Co-morbid mental health conditions in people with epilepsy and association with quality of life in low- and middle-income countries: a systematic review and meta-analysis

BACKGROUND

Comorbid mental health conditions are common in people with epilepsy and have a significant negative impact on important epilepsy outcomes, although the evidence is mostly from high-income countries. This systematic review aimed to synthesise evidence on the association between comorbid mental health conditions and quality of life and functioning among people with epilepsy living in low- and middle income countries (LMICs).

METHODS

We searched PubMed, EMBASE, CINAHL, Global Index medicus (GID) and PsycINFO databases from their dates of inception to January 2022. Only quantiative observational studies were included. Meta-analysis was conducted for studies that reported the same kind of quality of life and functioning outcome. Cohen's d was calculated from the mean difference in quality-of-life score between people with epilepsy who did and did not have a comorbid depression or anxiety condition. The protocol was registered with PROSPERO: CRD42020161487.

RESULTS

The search strategy identified a total of 2,101 articles, from which 33 full text articles were included. Depression was the most common comorbid mental health condition (33 studies), followed by anxiety (16 studies). Meta-analysis was conducted on 19 studies reporting quality of life measured with the same instrument. A large standardized mean effect size (ES) in quality of life score was found (pooled ES = -1.16, 95% confidence interval (CI) - 1.70, - 0.63) between those participants with comorbid depression compared to non-depressed participants. There was significant heterogeneity between studies (I2 = 97.6%, p < 0.001). The median ES (IQR) was - 1.20 (- 1.40, (- 0.64)). An intermediate standard effect size for anxiety on quality of life was also observed (pooled ES = -0.64, 95% CI - 1.14, - 0.13). There was only one study reporting on functioning in relation to comorbid mental health conditions.

CONCLUSION

Comorbid depression in people with epilepsy in LMICs is associated with poor quality of life although this evidence is based on highly heterogeneous studies. These findings support calls to integrate mental health care into services for people with epilepsy in LMICs. Future studies should use prospective designs in which the change in quality of life in relation to mental health or public health interventions across time can be measured.

Incidence of and predictors for antiseizure medication gaps in Medicare beneficiaries with epilepsy: a retrospective cohort study

BACKGROUND

For the two-thirds of patients with epilepsy who achieve seizure remission on antiseizure medications (ASMs), patients and clinicians must weigh the pros and cons of long-term ASM treatment. However, little work has evaluated how often ASM discontinuation occurs in practice. We describe the incidence of and predictors for sustained ASM fill gaps to measure discontinuation in individuals potentially eligible for ASM withdrawal.

METHODS

This was a retrospective cohort of Medicare beneficiaries. We included patients with epilepsy by requiring International Classification of Diseases codes for epilepsy/convulsions plus at least one ASM prescription each year 2014-2016, and no acute visit for epilepsy 2014-2015 (i.e., potentially eligible for ASM discontinuation). The main outcome was the first day of a gap in ASM supply (30, 90, 180, or 360 days with no pills) in 2016-2018. We displayed cumulative incidence functions and identified predictors using Cox regressions.

RESULTS

Among 21,819 beneficiaries, 5191 (24%) had a 30-day gap, 1753 (8%) had a 90-day gap, 803 (4%) had a 180-day gap, and 381 (2%) had a 360-day gap. Predictors increasing the chance of a 180-day gap included number of unique medications in 2015 (hazard ratio [HR] 1.03 per medication, 95% confidence interval [CI] 1.01-1.05) and epileptologist prescribing physician (≥25% of that physician's visits for epilepsy; HR 2.37, 95% CI 1.39-4.03). Predictors decreasing the chance of a 180-day gap included Medicaid dual eligibility (HR 0.75, 95% CI 0.60-0.95), number of unique ASMs in 2015 (e.g., 2 versus 1: HR 0.37, 95% CI 0.30-0.45), and greater baseline adherence (> 80% versus ≤80% of days in 2015 with ASM pill supply: HR 0.38, 95% CI 0.32-0.44).

CONCLUSIONS

Sustained ASM gaps were rarer than current guidelines may suggest. Future work should further explore barriers and enablers of ASM discontinuation to understand the optimal discontinuation rate.

Adherence to Antiseizure vs Other Medications Among US Medicare Beneficiaries With and Without Epilepsy

BACKGROUND AND OBJECTIVE

The objectives of this study were to compare adherence to antiseizure medications (ASMs) vs non-ASMs among individuals with epilepsy, to assess the degree to which variation in adherence is due to differences between individuals vs between medication classes among individuals with epilepsy, and to compare adherence in individuals with vs without epilepsy.

METHODS

This was a retrospective cohort study using Medicare. We included beneficiaries with epilepsy (≥1 ASM, plus ICD-9-CM diagnostic codes) and a 20% random sample without epilepsy. Adherence for each medication class was measured by the proportion of days covered (PDC) in 2013 to 2015. We used Spearman correlation coefficients, Cohen κ statistics, and multilevel logistic regressions.

RESULTS

There were 83,819 beneficiaries with epilepsy. Spearman correlation coefficients between ASM PDCs and each of the 5 non-ASM PDCs ranged from 0.44 to 0.50; Cohen κ ranged from 0.33 to 0.38; and within-person differences between the PDC of each ASM minus the PDC of each non-ASM were all statistically significant (p < 0.01), although median differences were all very close to 0. Fifty-four percent of variation in adherence across medications was due to differences between individuals. Adjusted predicted probabilities of adherence were as follows: ASMs 74% (95% confidence interval [CI] 73%-74%), proton pump inhibitors 74% (95% CI 74%-74%), antihypertensives 77% (95% CI 77%-78%), selective serotonin reuptake inhibitors 77% (95% CI 77%-78%), statins 78% (95% CI 78%-79%), and levothyroxine 82% (95% CI 81%-82%). Adjusted predicted probabilities of adherence to non-ASMs were 80% (95% CI 80%-81%) for beneficiaries with epilepsy vs 77% (95% CI 77%-77%) for beneficiaries without epilepsy.

DISCUSSION

Among individuals with epilepsy, ASM adherence and non-ASM adherence were moderately correlated, half of the variation in adherence was due to between-person rather than between-medication differences, adjusted adherence was slightly lower for ASMs than several non-ASMs, and epilepsy was associated with a quite small increase in adherence to non-ASMs. Nonadherence to ASMs may provide an important cue to the clinician to inquire about adherence to other potentially life-prolonging medications as well. Although efforts should focus on improving ASM adherence, patient-level rather than purely medication-specific behaviors are also critical to consider when developing interventions to optimize adherence.

Polypharmacy composition and patient- and provider-related variation in patients with epilepsy

OBJECTIVE

To describe polypharmacy composition, and the degree to which patients versus providers contribute to variation in medication fills, in people with epilepsy.

METHODS

We performed a retrospective study of Medicare beneficiaries with epilepsy (antiseizure medication plus diagnostic codes) in 2014 (N = 78,048). We described total number of medications and prescribers, and specific medications. Multilevel models evaluated the percentage of variation in two outcomes (1. number of medications per patient-provider dyad, and 2. whether a medication was filled within thirty days of a visit) due to patient-to-patient differences versus provider-to-provider differences.

RESULTS

Patients filled a median of 12 (interquartile range [IQR] 8-17) medications, from median of 5 (IQR 3-7) prescribers. Twenty-two percent filled an opioid, and 61% filled at least three central nervous system medications. Levetiracetam was the most common medication (40%), followed by hydrocodone/acetaminophen (27%). The strongest predictor of medications per patient was Charlson comorbidity index (7.5 [95% confidence interval (CI) 7.2-7.8] additional medications for index 8+ versus 0). Provider-to-provider variation explained 36% of variation in number of medications per patient, whereas patient-to-patient variation explained only 2% of variation. Provider-to-provider variation explained 57% of variation in whether a patient filled a medication within 30 days of a visit, whereas patient-to-patient variation explained only 30% of variation.

CONCLUSION

Patients with epilepsy fill a large number of medications from a large number of providers, including high-risk medications. Variation in medication fills was substantially more related to provider-to-provider rather than patient-to-patient variation. The better understanding of drivers of high-prescribing practices may reduce avoidable medication-related harms.

The overlapping relationship among depression, anxiety, and somatic symptom disorder and its impact on the quality of life of people with epilepsy

Background:

Emotional disorder is an important indicator for assessing the quality of life (QOL) of people with epilepsy (PWE). Depression, somatic symptom disorder (SSD) and anxiety are among the most frequently occurring mental disorders and overlap with each other.

Objectives:

This study examines the overlap of these three emotional disorders and their effects separately and in combination on the QOL of PWE.

Design:

Cross-sectional study.

Data Sources and Methods:

Adults attending our epilepsy clinic between 1 July 2020 and 1 May 2022 were consecutively enrolled. They were screened for depression, SSD, and anxiety by structured interviews, and demographic, epilepsy-related and QOL indicators were collected. Multivariate analysis, propensity score matching (PSM) and stratified analysis were used to explore the effects of their respective and combined effects on QOL.

Results:

Among the 749 patients, 189 patients (25%) were diagnosed with depression, 183 patients (24%) were diagnosed with SSD, and 157 patients (21%) were diagnosed with anxiety. The frequency of occurrence of each emotional disorder together with other emotional disorders was higher than the frequency of occurrence of an emotional disorder alone. Depression, SSD, and anxiety all had an independent effect on QOL of PWE ( p < 0.001). Depression had the greatest effect, followed by SSD, and then anxiety ( β: multivariate analysis, −11.0 versus –7.8 versus –6.5; PSM, −14.7 versus –9.4 versus –6.8). The QOL of PWE decreased more significantly with the increasing number of comorbid emotional disorders ( β: –12.1 versus –20.7 versus –23.0).

Conclusion:

It is necessary to screen for three emotional disorders, that is, depression, SSD, and anxiety, in PWE. Attention should be paid to people with multiple comorbid emotional disorders.

Knowledge, attitudes, and practices of physiotherapists with regard to epilepsy and patients with epilepsy: A systematic scoping review

BACKGROUND

In today's healthcare systems, physiotherapists are one of the most important providers of care services to patients with disabilities including those with epilepsy. The aims of this systematic scoping review were to identify, summarize, and present narrative synthesis of qualitative evidence on knowledge, attitudes, and practices of physiotherapists toward epilepsy and patients with epilepsy.

METHODS

Primary studies were searched in Medline/PubMed, Embase, Science Direct, SpringerLink, CInAHL/EBSCO, Cochrane library, and Scopus as late as July 02, 2021. Appraisal of the methodological quality was conducted for the studies included in this systematic scoping review. Due to the heterogenous nature of the collected data, results of this study are presented as narrative synthesis.

RESULTS

A total of 11 were finally included in the qualitative synthesis. The selected studies were published in the period between 2016 and 2020. The studies included in this review had acceptable methodological quality in many of the 11 domains of the quality assessment tool. Contents of the included studies were grouped into the 11 themes and 8 subthemes. The major themes were related education/access to information, interaction with patients, witnessing seizures, barriers and promoters of adequate knowledge and attitudes, and interventions to improve knowledge and attitudes.

CONCLUSION

Currently, high-quality interventional studies are needed to improve knowledge, attitudes, and practices of physiotherapists with regard to epilepsy and patients with epilepsy. Future studies are still needed to investigate if improving knowledge, attitudes, and practices of physiotherapists with regard to epilepsy and patients with epilepsy can improve health-related outcomes of the patients.

Risk Factors for Epilepsy: A National Cross-Sectional Study from National Health and Nutrition Examination Survey 2013 to 2018

Objective

The purpose of this study is to investigate the risk factors of epilepsy based on the National Health and Nutrition Examination Survey (NHANES).

Methods

The data in this study was obtained from the NHANES database between 2013 and 2018. It included 14,290 participants aged between 20 and 80. We defined people with epilepsy (PWE) when they self-reported took at least one treatment medication for seizures or epilepsy. Analysis of risk factors for epilepsy mainly includes Student’s t-test, chi-square test, univariate and multivariate logistic regression analysis.

Results

People aged 40–59 shared 1.8 times the risk of epilepsy than those who aged 20–39, P=0.034. People who never married had a 2.8-fold higher risk of epilepsy than those who married/living with partner, P<0.001. The risk of epilepsy in subjects with very good/good general health was 0.4 times than that of subjects with fair/poor general health, P<0.001. Moreover, subjects without sleep disorders had a 0.4-fold higher risk of epilepsy than those who had sleep disorders, P=0.042.

Conclusion

People who are older, unmarried, and have sleep disorders are at higher risk of epilepsy. In addition, good/good general health condition is associated with a lower risk of epilepsy.

Use of item response theory to investigate disability-related questions in the National Health and Nutrition Examination Survey

OBJECTIVES

Accurately measuring disability is critical toward policy development, economic analyses, and determining individual-level effects of health interventions. Nationally representative population surveys such as the National Health and Nutrition Examination Survey provide key opportunities to measure disability constructs such as activity limitations. However, only very limited work has previously evaluated the item response properties of questions pertaining to limitations in National Health and Nutrition Examination Survey.

METHODS

This was a cross-sectional study. We included participants ⩾20 years old for the 2013-2018 National Health and Nutrition Examination Survey cycles. Activity limitations, and a smaller number of body function impairments or participation restrictions, were determined from interview questions. We performed item response theory models (a two-parameter logistic and a graded response model) to characterize discriminating information along the latent continuum of activity limitation.

RESULTS

We included 17,057 participants. Although each particular limitation was somewhat rare (maximally 13%), 7214 (38%) responded having at least one limitation. We found a high amount of discriminating information at 1-2 standard deviations above average limitation, though essentially zero discrimination below that range. Items had substantial overlap in the range at which they provided information distinguishing individuals. The ordinal graded response model including 20 limitations provided greater information than the dichotomous two-parameter logistic model, though further omitting items from the graded response model led to loss of information.

CONCLUSION

National Health and Nutrition Examination Survey disability-related questions, mostly specifically activity limitations, provided a high degree of information distinguishing individuals with higher than average limitations on the latent continuum, but essentially zero resolution to distinguish individuals with low or average limitations. Future work may focus on developing items which better distinguish individuals at the "lower" end of the limitation spectrum.