Assessing the severity of seizures and epilepsy: which scales are valid?

Psychometric evaluation of clinician- and caregiver-reported clinical severity assessments for individuals with CDKL5 deficiency disorder

OBJECTIVE

The CDKL5 Clinical Severity Assessment (CCSA) is a comprehensive, content-validated measurement tool capturing the diverse challenges of cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD), a genetically caused developmental epileptic encephalopathy (DEE). The CCSA is divided into clinician-reported (CCSA-Clinician) and caregiver-reported (CCSA-Caregiver) assessments. The aim of this study was to evaluate the factor structure of these measures through confirmatory factor analysis (CFA) and evaluate their validity and reliability.

METHODS

Participants were recruited from the International CDKL5 Clinical Research Network to take part in an in-clinic CCSA-Clinician evaluation (n = 148) and/or complete the CCSA-Caregiver questionnaire (n = 198). CFA was used to determine domains, and factor loadings and validity were assessed. For the CCSA-Clinician, inter-rater reliability was assessed by nine CDD experienced clinicians via 14 pre-recorded evaluations. Eight clinicians re-viewed and re-scored the videos after 4 weeks to evaluate intra-rater reliability. The CCSA-Caregiver was completed on a second occasion by 34 caregivers after 2-4 weeks to assess test-retest reliability.

RESULTS

CFA resulted in three domains for the CCSA-Clinician (motor and movement, communication, vision) and four domains for the CCSA-Caregiver (seizures, behavior, alertness, feeding), with good item loadings across both measures. Structural statistics, internal consistency, discriminant validity, and reliability were satisfactory for both measures, and scores were consistent between known groups.

SIGNIFICANCE

This study provides strong evidence that the CCSA measures are suitable to assess the clinical severity of individuals with CDD, supporting their use in clinical trials. Further evaluation of responsiveness to change in a longitudinal assessment is planned. Use may also be appropriate in similar DEEs but would require validation in those populations.

Global brain delivery of neuroligin 2 gene ameliorates seizures in a mouse model of epilepsy

BACKGROUND

Despite the increasing availability of effective drugs, around one-third of patients with epilepsy are still resistant to pharmacotherapy. Gene therapy has been suggested as a plausible approach to achieve seizure control, in particular for patients with focal epilepsy. Because seizures develop across wide spans of the brain in many forms of epilepsy, global delivery of the vectors is necessary to tackle such generalized seizures. Neuroligin 2 (NL2) is a postsynaptic cell adhesion molecule that induces or strengthens inhibitory synaptic function by specifically combining with neurexin 1.

METHODS

In the present study, we applied an adeno-associated virus (AAV) type 9 vector expressing NL2 to modulate neuronal excitability in broad areas of the brain in epileptic (EL) mice, a model of polygene epilepsy. We administered the AAV vector expressing Flag-tagged NL2 under the synapsin I promoter (AAV-NL2) via cardiac injection 6 weeks after birth.

RESULTS

Significant reductions in the duration, strength and frequency of seizure were observed during a 14-week observation period in NL2-treated EL mice compared to untreated or AAV-green fluorescent protein-treated EL mice. No behavioral abnormality was observed in NL2-treated EL mice in an open-field test. Immunohistochemical examination at 14 weeks after AAV-NL2 injection revealed the expression of exogenous NL2 in broad areas of the brain, including the hippocampus and, in these areas, NL2 co-localized with postsynaptic inhibitory molecule gephyrin.

CONCLUSIONS

Global brain delivery of NL2 by systemic administration of AAV vector may provide a non-invasive therapeutic approach for generalized epilepsy.

Evaluating the impact of pharmaceutical care services on the clinical outcomes of epilepsy: a randomised controlled trial

BACKGROUND

The involvement of pharmacists in the provision of specialised care to patients with epilepsy is poor.

OBJECTIVE

To evaluate the impact of pharmaceutical care services on the clinical outcomes of epilepsy.

SETTING

Two selected major referral epilepsy treatment centres in southern Nigeria were used for the study. Patients were recruited from the Neurology and Medical out-patient clinics of the hospitals.

METHOD

An open randomised controlled study was carried out on epilepsy patients receiving clinical care at the selected hospitals. Patients in the intervention group were offered pharmaceutical care services. The impact of the pharmaceutical care services on the clinical outcomes of epilepsy (seizure frequency and severity) was evaluated.

MAIN OUTCOME MEASURE

The effect of pharmaceutical care services on seizure frequency and severity in patients with epilepsy.

RESULTS

There was a statistically significant difference between the usual care (UC) and the pharmaceutical care (PC) group on the clinical outcomes of epilepsy post-PC intervention. Comparison between the groups (UC versus PC) revealed that patients in the PC group had a significantly lower seizure frequency score than those in the UC group at 3 months and 6 months-(pre-intervention: 3.09 versus 3.34; t = -1.685; p = 0.094) (3 months 2.45 versus 1.68; t = 4.494; p = 0.001), (6 months: 1.97 versus 0.92; t = -3.137; p = 0.001). Also, comparisons between the groups (UC versus PC) showed that patients in the PC group had a significantly lower seizure severity score than those in the UC group at 3 months and 6 months-(pre-intervention 18.46 versus 20.38; t = -3.102; p = 0.01) (3 months: 17.51 versus 14.79; t = 4.202; p = 0.001) (6 months 16.41 versus 11.66; t = 8.930; p = 0.001).

CONCLUSION

Pharmaceutical care interventions may significantly reduce seizure frequency and severity in patients with epilepsy.

IMPACT OF FINDINGS ON PRACTICE

These findings provide justification for the integration of pharmaceutical care services with other elements of health care for epilepsy patients.

Awareness of sudden unexpected death in epilepsy among parents of children with epilepsy in a tertiary center

OBJECTIVE

Sudden unexpected death in epilepsy (SUDEP) is the second leading neurological cause of potential years of lifelost after stroke. Despite growing numbers of studies on social aspects of epilepsy, there is a paucity of research on the awareness of SUDEP among the parents of children with epilepsy (CWE), especially in Turkey. In this study, we aimed to evaluate the knowledge of parents of the CWE regarding SUDEP in the tertiary setting.

MATERIAL AND METHODS

A total of 146 parents (108 female) aged 19 to 55 years (median age:34) of CWE were included at Marmara University, School of Medicine, Department of Pediatric Neurology outpatient clinic between May 2018 and September 2018. A total of 30 multiple-choice questions and a written survey were administered, which consisted of three sections. In the first section, the sociodemographics of parents and CWE were questioned. In the second section, the severity of epilepsy was evaluated. In the third section, the knowledge level and awareness of parents of CWE were assessed.

RESULTS

Of 146 parents, only 16.6% previously heard about SUDEP, while 45% of them heard from their relatives. The presence of prior knowledge of SUDEP was associated with the presence of prolonged postictal confusion and longer duration of epilepsy (p < 0.05). Ninety-seven (66%) parents desired to be informed about SUDEP, while 76 (54.7%) of them agreed that this information should be given at the time of diagnosis. The degree of anxiety in parents regarding death of epilepsy-related causes was significantly related with prolonged postictal confusion (p < 0.001) and using three or more antiepileptic drugs (p = 0.005).

CONCLUSION

Our data suggest that knowledge about SUDEP among parents with CWE found inadequate in Turkey. There should be much effort to inform parents and caregivers in epilepsy clinics on SUDEP, which may help to reduce the associated risk factors.

Global assessment of the severity of epilepsy (GASE) Scale in children: Validity, reliability, responsiveness

OBJECTIVE

The Global Assessment of Severity of Epilepsy (GASE) Scale is a single-item, 7-point global rating scale designed for neurologist-report of overall severity of epilepsy in children. Building on previous preliminary evidence of its validity and reliability for research and clinical use, this study evaluated the GASE Scale's construct validity, reliability, and responsiveness to changes in severity of epilepsy.

METHODS

Data used for the study arose from the Health-Related Quality of Life in Children with Epilepsy Study (HERQULES), a 2-year multicenter prospective cohort study (n = 374) with observations taken at baseline, and 6, 12, and 24 months after diagnosis. Construct validity and reliability were quantified using Spearman's correlation and intraclass correlation coefficient (ICC). Responsiveness was assessed using both distribution-based and anchor-based indices.

RESULTS

The GASE Scale was at least moderately correlated (r ≥ 0.30) with several key clinical aspects and most strongly correlated with frequency and intensity of seizures and interference of epilepsy or drugs with daily activities (r > 0.30). Total variation in GASE Scale scores explained by seven core clinical aspects of epilepsy increased over time (R(2) = 28% at baseline to R(2) = 70% at 24 months). The GASE Scale had modest test-retest reliability (ICC range: 0.52-0.64) and was responsive to changes in clinical criteria (standardized response mean range: 0.49-0.68; probability of change range: 0.69-0.75; Guyatt's responsiveness statistic range: 0.56-0.84). The GASE Scale showed potential to discriminate "stable" and "changed" patients according to select criteria and to a composite score (area under the receiver operating characteristic [ROC] curve range: 0.50-0.67).

SIGNIFICANCE

Results offer additional evidence in support of the GASE Scale's validity, reliability, as well as responsiveness to changes in severity of epilepsy in children. We conclude that the GASE Scale is a potentially useful tool for assessing the severity of epilepsy in both clinical and research settings.

Determinants of disease severity in adults with epilepsy: Results from the Neurological Diseases and Depression Study

BACKGROUND

Epilepsy severity has been recognized as a significant predictor of health-related quality of life in patients with epilepsy. However, clinical markers of epilepsy severity such as seizure frequency often fail to capture important aspects of the disease. This study investigates the factors associated with patient-reported severity of epilepsy, assessed by the Global Assessment of Severity of Epilepsy (GASE) scale in adults with epilepsy.

METHODS

Data from a cohort of 250 patients consecutively enrolled in the Neurological Diseases and Depression Study (NEEDS) were used to assess the determinants of epilepsy severity as measured by the GASE scale. Multiple linear regression analyses were used to examine the mediation effect of clinical and sociodemographic characteristics on patients' ratings on the GASE scale.

RESULTS

The mean age of the study participants was 39.8 (SD=14.9) years, of which 44.4% were male. About 66.8% of the participants reported "not at all severe" or "a little severe" epilepsy, while 0.4% reported "extremely severe" epilepsy. One-year seizure freedom, number of antiseizure medications, medication side effects, depression, anxiety, and seizure-related disability were identified as significant determinants of patients' ratings of epilepsy severity. Seizure-related disability mediated the effects of 1-year seizure freedom, number of antiseizure medications, and medication side effects on epilepsy severity.

CONCLUSION

Overall, patients with epilepsy who reported higher GASE scores were less likely to achieve 1-year seizure freedom and more likely to be on more antiseizure medications, experience more side effects from medication, endorse more depression and anxiety symptoms, and have increased self-reported seizure-related disability. The identified determinants of global, self-rated epilepsy severity can aid the design of appropriate interventions and support services for patients with severe epilepsy.

Developing the Pediatric Refractory Epilepsy Questionnaire: a pilot study

PURPOSE

Up to 14% of children with epilepsy continue to experience seizures despite having appropriate medical therapy and develop medically refractory epilepsy (MRE). Assessing clinical outcomes and therapeutic efficacy in children with MRE undergoing palliative epilepsy surgery has been challenging because of the lack of a quantitative instrument capable of estimating the clinical status of these patients. The ideal instrument would at once consider seizure control, neurodevelopment, caregiver burden, and quality of life. The purpose of this study was to develop and pilot the Pediatric Refractory Epilepsy Questionnaire (PREQ), a quantitative instrument to assess the severity and individual burden of epilepsy in children with MRE undergoing palliative epilepsy treatments.

METHODS

The caregivers of 25 patients with MRE completed the PREQ and the Quality of Life in Childhood Epilepsy (QOLCE) measure and participated in a semistructured interview. Medical records of the patients were reviewed, an Early Childhood Epilepsy Severity Scale (E-CHESS) score was calculated, and a Global Assessment of Severity of Epilepsy (GASE) score was obtained for each patient.

KEY FINDINGS

The initial PREQ was modified based on the analysis of responses, association with previously validated scales, comments from caregivers, and expertise of the PREQ panelists. Pediatric Refractory Epilepsy Questionnaire subscale scores were calculated based on clinical paradigm and compared with independent measures of seizure severity and quality of life. Significant correlations were observed between the seizure severity subscale and the GASE score (r=0.55) and between the mood subscale and the well-being score (r=0.61) on the QOLCE. Significant correlations were also observed between the caregiver rating of seizure severity and the GASE score (r=0.53), the social activity score (r=0.57), and the behavior score (r=0.43) on the QOLCE. Correlations between the caregiver rating of quality of life and the quality of life score (r=0.58) and the number of AEDs used (r=0.45) were also significant.

SIGNIFICANCE

This pilot study is an initial, critical step in the development of the PREQ. The significant correlations between the PREQ subscales and the external epilepsy severity and quality of life measures lend preliminary support to our hypothesis that the PREQ is assessing the severity of epilepsy along with other important domains, such as mood, neurodevelopment, and quality of life. A larger prospective study of this modified PREQ is currently underway to further develop the PREQ.

Psychometric properties of Chinese language Liverpool Seizure Severity Scale 2.0 (LSSS 2.0) and status and determinants of seizure severity for patients with epilepsy in China

OBJECTIVES

This study aimed to translate and validate the Liverpool Seizure Severity Scale (LSSS) in Chinese-speaking patients with epilepsy and explore the determinants of seizure severity in China.

METHODS

Accepted procedures were followed to translate the LSSS. Each participant was interviewed to complete the LSSS, Seizure Severity Index, Quality of Well-being Scale Self-Administered (QWB-SA), EuroQol (EQ-5D), and Mini Mental State Examination (MMSE). Construct validity and internal consistency were assessed. The determinants of seizure severity were explored.

RESULTS

The construct validity of the LSSS was demonstrated by good convergent and discriminant validities. Cronbach's alpha and the intraclass correlation coefficient were 0.886, respectively. In the multivariate analysis, seizure types (p=0.001), seizure frequency (p=0.001), and numbers of antiepileptic drugs (p=0.042) predicted the scores on the LSSS. Types of antiepileptic drugs also contributed to the variation in the LSSS scores.

CONCLUSIONS

Chinese LSSS is a valid, reliable, and sensitive seizure severity scale. Seizure frequency, seizure types, and quantities and types of AEDs predict seizure severity.

Determining minimally important change thresholds for the Seizure Severity Questionnaire (SSQ)

The Seizure Severity Questionnaire (SSQ) was developed to evaluate changes in seizure severity and bothersomeness. Determination of a threshold value reflecting meaningful patient benefit on the SSQ would improve clinical interpretation of scale results. The objective of this analysis was to define a minimally important change (MIC) threshold for the SSQ, using data from patients with treatment-resistant partial-onset seizures from two clinical trials (N=776). Minimally important change thresholds were calculated using standard anchor-based methods, with the Patient Global Impression of Change (PGIC) score as the anchor with the categories of 'much improved,' 'minimally improved,' 'much worsened,' and 'minimally worsened' combined. The calculated MIC thresholds (range: 0.34 to 0.50) suggest that a 0.48-point change in the SSQ total score reflects a clinically meaningful change in seizure severity from the patients' perspective.

Sensitivity testing of the Seizure Severity Questionnaire (SSQ)

The sensitivity of the Seizure Severity Questionnaire (SSQ) was evaluated using pooled data from open-label extensions of two clinical trials in patients with partial-onset seizures. The SSQ includes questions relating to frequency and helpfulness of warning signs as well as frequency, severity, and bothersomeness of ictal and postictal effects. Differences between mean change from baseline for each SSQ item for responders and nonresponders were described and compared between patients solely with complex partial seizures (CPSs: responders, n=166; nonresponders, n=127) and those solely with secondarily generalized partial seizures (SGPSs: responders, n=26; nonresponders, n=24) at baseline. Seizure Severity Questionnaire total score and individual SSQ items related to ictal movement, consciousness, bothersomeness of postictal effects, and frequency of postictal emotional effects showed differentiation between seizure type responders. These data provide further validation of the SSQ by demonstrating its sensitivity in describing treatment effects.

Patient Reported Outcome (PRO) assessment in epilepsy: a review of epilepsy-specific PROs according to the Food and Drug Administration (FDA) regulatory requirements

Despite collection of patient reported outcome (PRO) data in clinical trials of antiepileptic drugs (AEDs), PRO results are not being routinely reported on European Medicines Agency (EMA) and Food and Drug Administration (FDA) product labels. This review aimed to evaluate epilepsy-specific PRO instruments against FDA regulatory standards for supporting label claims. Structured literature searches were conducted in Embase and Medline databases to identify epilepsy-specific PRO instruments. Only instruments that could potentially be impacted by pharmacological treatment, were completed by adults and had evidence of some validation work were selected for review. A total of 26 PROs were reviewed based on criteria developed from the FDA regulatory standards. The ability to meet these criteria was classified as either full, partial or no evidence, whereby partial reflected some evidence but not enough to comprehensively address the FDA regulatory standards. Most instruments provided partial evidence of content validity. Input from clinicians and literature was common although few involved patients in both item generation and cognitive debriefing. Construct validity was predominantly compromised by no evidence of a-priori hypotheses of expected relationships. Evidence for test-retest reliability and internal consistency was available for most PROs although few included complete results regarding all subscales and some failed to reach recommended thresholds. The ability to detect change and interpretation of change were not investigated in most instruments and no PROs had published evidence of a conceptual framework. The study concludes that none of the 26 have the full evidence required by the FDA to support a label claim, and all require further research to support their use as an endpoint. The Subjective Handicap of Epilepsy (SHE) and the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) have the fewest gaps that would need to be addressed through additional research prior to any FDA regulatory submission, although the NDDI-E was designed as a screening tool and is therefore unlikely to be suitable as an instrument for capturing change in a clinical trial and the SHE lacks the conceptual focus on signs and symptoms favoured by the FDA.

The development of a simple questionnaire to screen patients with SLE for the presence of neuropsychiatric symptoms in routine clinical practice

Aim: The creation of a physician-administered questionnaire to screen patients with Systemic Lupus Erythematosus (SLE) for the presence of symptoms suggestive of neuropsychiatric involvement (NPSLE).

Methods: The development of the questionnaire followed three phases. First, a list of manifestations was prepared based on the ACR case definitions for NPSLE. A first questionnaire was constructed including 119 items. To reduce their number, a Delphi analysis was carried out and a second questionnaire with 62 questions was developed. This questionnaire was administered to 139 patients with SLE (58 with NPSLE: 29 active, 29 inactive; and 81 without NPSLE: 39 active, 42 inactive). Questions relevant to the screening of patients were selected on the basis of the receiver operating characteristic (ROC) curve analysis.

Results: Twenty-seven questions concerning central nervous system and psychiatric manifestations were found to be relevant; the remaining could be eliminated without significantly affecting AUC. The area under the ROC curve (AUC) was 0.69 (95% CI 0.61–0.78). A score above 17 was considered as suggestive of the presence of NPSLE with a sensitivity of 92.9% (95% CI 85.1–97.3 %) and specificity of 25.4% (95% CI 14.7–39.00 %).

Conclusions: This questionnaire could represent a ‘core set’ of questions that could help in clinical practice to identify patients with neuropsychiatric symptoms requiring further evaluation.

Living environment of persons with severe epilepsy and intellectual disability: a prospective study

We studied a population with intellectual disability (ID) and epilepsy and analyzed aspects of the living environment. Using an epilepsy impact score (EPIEK, the Epilepsy Impact Scale Kempenhaeghe), we found that epilepsy is more severe in younger persons than in older persons until about age 60 years. Individuals with more adaptive behavior had less severe epilepsy. Compared with persons with ID, the subjects in this study had fewer sensory problems and many more mobility problems, and more often saw a general practitioner. We concluded that people with severe epilepsy and ID have, in some ways, the same needs as people with only ID, and yet, in other ways (development of adaptive skills and aspects of living environment), distinctly different needs.

Assessing severity of epilepsy in children: preliminary evidence of validity and reliability of a single-item scale

The development and initial validity and reliability testing of a single-item, 7-point global rating scale designed for neurologists to assess the overall severity of epilepsy in children, the Global Assessment of Severity of Epilepsy (GASE) Scale, is described. The GASE Scale was quick and easy to use. Median epilepsy severity in the development sample was 3 (moderately severe), with a range from 1 ("not severe at all") in 36 patients (26.9%) to 7 ("extremely severe") in 7 patients (5.2%). Preliminary evidence of construct validity was found in support for our a priori predictions of associations between GASE scores and neurologists' ratings of seven individual clinical aspects of epilepsy and in a cumulative R(2) for the GASE score of 81% using ratings of the clinical aspects of epilepsy. Weighted kappa was 0.85 (95% CI: 0.79, 0.90) for inter-rater reliability and 0.90 (95% CI: 0.82, 0.98) and 0.95 (95% CI: 0.91, 0.98) for test-retest reliability for each of two raters. These promising initial results support continuation of the multistage process of testing the validity and reliability of the GASE Scale within various clinical contexts.

The Influence of Comorbid Depression on Seizure Severity

PURPOSE

To determine the relation between depressive symptoms and seizure severity among people with epilepsy.

METHODS

A postal questionnaire was used to survey a nationwide community sample about seizures and depression. The Seizure Severity Questionnaire (SSQ) assessed the severity and bothersomeness of seizure components. The Centers for Epidemiological Studies-Depression scale categorized levels of depression.

RESULTS

Respondents categorized as having current severe (SEV, n = 166), mild-moderate (MOD, n = 74), or no depression (NO, n = 443) differed significantly in SSQ scores (all p < 0.0001). People with SEV or MOD reported significantly worse problems than did those with NO depression for overall seizure recovery (mean, 5.3, 4.9, 4.5, respectively); overall severity (5.0, 4.5, 4.2); and overall seizure bother (5.3, 4.8, 4.4) (all p < 0.005). Cognitive, emotional, and physical aspects of seizure recovery also were rated worse among people with SEV than with NO depression (all p < 0.05). Symptoms of depression were significantly correlated with higher levels of all components of generalized tonic-clonic seizure severity (r = 0.33-0.48; all p < 0.0001), and partial seizures (r = 0.31-0.38; all p < 0.01).

CONCLUSIONS

Clinically depressed people with epilepsy reported higher levels of perceived severity and bother from seizures, as well as greater problems with overall seizure recovery than did nondepressed people experiencing similar types of seizures. The pervasive influence of depressive symptoms on reports of seizure activity suggests that people with epilepsy should be screened for depression. These data highlight the importance of detecting and treating depression among people with epilepsy.

Measuring the efficacy of antiepileptic drugs

Clinical trials of new antiepileptic drugs (AEDs) include regulatory studies aimed at demonstrating efficacy and reasonable safety, post-marketing open-open label studies and longer term outcome studies. Regulatory trials involve a carefully selected population of patients and are conducted under rigorously standardised conditions. Data from such studies cannot often be translated into clinical practice. Pragmatic post-marketing studies using flexible dosing schedules allow clinicians to better judge the utility of the new drug in a wider population of patients with epilepsy and decide the most appropriate dosing schedules. This paper discusses some of the issues surrounding the measurement of efficacy of new AEDs in both pre- and post-marketing phases of their development. All of the newer AEDs are initially used in patients with refractory partial seizures as adjunctive treatment. These trials are generally parallel-group studies although cross-over designs have been employed. The use of placebo-control is uncontroversial in this type of study. Efficacy endpoints are generally manipulations of seizure frequency on study drug compared to control. Global outcome measures and health related quality of life scores can also be used to measure efficacy. As the standard AEDs are associated with a high rate of seizure remission in patients who receive them as monotherapy, demonstration of superior efficacy of a new agent in a comparative trial will require large numbers of patients in a design that takes into account the natural history of treated epilepsy. Comparing investigational agents to a standard AED in an 'active-control' study with demonstration of equivalent efficacy would seem to be an acceptable way of assessing efficacy of new AEDs in this population. Some regulators, however, do not accept equivalence as proof of efficacy and insist on demonstration of superiority compared to a control. The use of placebo alone in the control group is ethically dubious. Several innovative study designs have, therefore, been used to satisfy regulatory requirements, while maintaining patient safety including withdrawal to monotherapy using high versus low dose comparators. Observational outcome studies provide the best opportunity of exploring the long-term utility of individual AEDs. Such studies largely follow standard clinical practice and need considerable time and resources. They can, however, yield valuable information about the effectiveness of AEDs in everyday clinical practice. Data from regulatory trials should be complemented by postmarketing studies and longer term studies of outcome to help clinicians decide the best way of utilising new AEDs and establishing their role in the therapeutic armamentarium.

Development of a new seizure severity questionnaire: initial reliability and validity testing

PURPOSE

This report describes the initial steps for development of a new scale to assess seizure severity as a treatment response.

METHODS

Standard methodology was used to develop the test instrument. Item generation was performed by selecting items from other questionnaires, and asking patients and epileptologists about seizure components. Face and content validity were assessed in a pilot study with patients and observers. The questionnaire was formatted as a structured interview for a reliability study. Construct validity was assessed with three existing questionnaires. Inter-rater reliability and test-retest reliability were performed as two independent ratings on one day, and one re-interview.

RESULTS

Based on item generation and pilot testing (33 patients, 28 observers), the Seizure Severity Questionnaire (SSQ) was organized into warning, activity-movement, and recovery (cognitive, emotional, and physical aspects) stages of seizures. Questions reviewed duration, severity, bothersomeness and overall ratings, and the most bothersome aspect of seizures. The mean SSQ Summary Score was 5.78+/-3.24, inter-rater reliability was 0.76 (N=91), and test-retest reliability was 0.74 (N=63). Construct validity showed statistically significant correlations with other scales.

CONCLUSION

This study has explored the psychometric properties of the SSQ for face and content validity, inter-rater and test-retest reliability, and construct validity. The Summary Score reliably represents the major components of seizures.