Quantitative Measures of Assessment
Gus A. Baker
Orrin Devinsky
Joanne Taylor
Joyce A. Cramer
Introduction
Quality of life refers to an individual’s overall well-being and daily functioning. Health-related quality of life (HRQOL) can be divided into three principal components: (a) physical health (e.g., general health, daily functioning, symptoms such as pain and seizures and side effects of drugs, strength, ability to walk); (b) mental health (e.g., mood, self-esteem, perception of well-being, perceived stigma); and (c) social health (e.g., social activities and relationships). Economic and environmental factors, encompassed by overall quality of life, are not usually included within health-related quality of life. Epilepsy and other disorders have a significant effect on economic and environmental aspects of life, but these areas are beyond the scope of HRQOL.
Quality-of-life issues are most relevant in chronic disorders such as epilepsy, in which mental and social problems extend well outside the usual range of symptoms of disease.22 Unfortunately, there is often a poor correlation between a doctor’s and a patient’s assessment of the patient’s quality of life, despite the expectation that such perspectives would be very similar. Thus, when used to evaluate the effects of epilepsy and its treatment, HRQOL measures can provide important and complementary information to traditional assessments focusing on seizure control and adverse effects of antiepileptic drugs. Interest in the effects of disease on the patient’s HRQOL began in the late 1940s with Karnovsky’s rating scale for cancer patients and has grown exponentially during the past decade. Quality-of-life measurement has been increasingly reported in clinical trials, nonexperimental outcome studies, cost-utility analyses, and studies of quality of care.37,71
Although the concept of HRQOL is attractive and important, its quantification remains a challenge. Items included in HRQOL scales are often derived mainly from “medical experts,” whereas the patient’s opinion of what is important should be given higher priority.37 Other limitations in HRQOL research include lack of definition of HRQOL or targeted domains, failure to distinguish overall quality of life from HRQOL, and validation. Validation of HRQOL instruments is especially challenging because no gold standards are available. Validation is often based on medical outcomes, which is what HRQOL is intended to avoid.
Assessments of HRQOL may be generic or targeted toward a specific disease or disorder. Generic instruments assess a range of issues of functioning and well-being and can evaluate diverse patient populations. Commonly used generic HRQOL instruments include the RAND 36-Item Health Survey,42 the Sickness Impact Profile,12 and the McMaster Health Index Questionnaire.67 Generic measurements permit comparisons among patients with different diseases, but they often lack sensitivity to change or responsiveness to intervention. For example, if a generic instrument does not assess HRQOL areas relevant to a certain patient group, positive or negative changes in these areas will not be detected when an intervention is made during a longitudinal study.
Disease-specific instruments use information about the ways in which a particular disease affects HRQOL. Such knowledge may be derived from patient interviews, medical and lay literature, expert opinion, or a combination of these sources.37 Disease-specific instruments assess HRQOL domains that are most relevant to these patients, but they include areas that are less important and omit areas that are more important to patients with other disorders. Disadvantages of disease-specific HRQOL instruments include the time and monetary expenses in their development and the limitations on making comparisons among groups with different disorders. A generic core can be combined with a disease-specific supplement to provide the benefits of both.
Epilepsy: A Chronic Disorder with Special Issues
Epilepsy is often a chronic illness. Chronically ill patients strive not only to minimize their symptoms and survive, but also to lead normal lives despite the problems associated with their illness and its treatment. For most people with epilepsy, the first of these objectives can be realized. However, particularly for those patients with epilepsy that is difficult to control, the restrictions imposed on daily living often make the second objective difficult or impossible to attain.
Special Problems
Outcome measures for epilepsy patients traditionally include seizure frequency, severity, morbidity (e.g., seizure-related trauma), and drug side effects such as sedation, nausea, and tremor. The traditional medical factors—seizures and antiepileptic drugs—are viewed quite differently by patients and physicians. “Occasional” or “mild” seizures and “infrequent” and “tolerable” side effects are often considered as acceptable by physicians. For patients, such seizures and adverse effects can be very troublesome and are not “acceptable.” In many cases, patients have difficulty expressing their feelings to doctors, or doctors may be insensitive to complaints that do not fit their conventional wisdom (e.g., disabling lethargy or confusion associated with subtherapeutic or low therapeutic doses of a “cognitively benign” antiepileptic drug). In either case, the physicians remain unaware of the problems.
People with epilepsy have higher rates of psychosocial problems and psychopathology. Once a person has had two seizures and received the diagnosis of epilepsy, the disorder may cause the greatest HRQOL problems during the seizure-free intervals. The duration of medical therapy is often long, drugs often need to be taken several times a day and can cause side effects that affect a person’s daily life, and the psychological and social consequences of epilepsy are often enormous. People with epilepsy may be limited in social, educational, and employment opportunities and modes of transportation—restrictions that may be either real or perceived. There are often parental and societal attitudes that foster low self-esteem and dependence, stigma, discrimination, and restrictions. In considering epilepsy as a chronic burden, one must carefully examine the neglected social, psychological, and behavioral problems as well as physical problems.
Physical Issues
Seizures increase the risk for bruises, lacerations, bone fractures and dislocations, burns, and drowning, as well as unexplained death.41 Daily drugs reduce the seizure threshold but can cause adverse physical effects (e.g., gingival hyperplasia, sedation, nausea, double vision, tremor, hirsutism) and mental effects (e.g., memory impairment), some of which are subtle but chronic.54 Quality-of-life measures show impairments in people who have systemic or neurologic adverse effects.32
Psychological Consequences
Patients with epilepsy have higher rates of certain behavioral disorders, such as depression and anxiety, and cognitive problems, such as impaired short-term memory and naming. Anxiety about the occurrence of seizures is a common concern, not only because of the suddenness of events, but also because of the possibility of negative sequelae. This loss of control over one’s life can underlie many psychological problems. Fear of public exposure or injury can underlie self-imposed social and vocational restrictions. The actual or perceived sense of dependency can be fostered by parents of children with epilepsy and by spouses and families of adult patients. Children with epilepsy had twice as many referrals for mental health services (12% vs. 23%) as the local population of children.17
Because anxiety and depression are the most frequent behavioral problem in adults with epilepsy, HRQOL instruments should be used as screening tools to help clinicians measure a patient’s mood status.26 This is especially important, given that Cramer et al.,29 in a survey of a community sample of people with epilepsy, found clinical depression to be significantly associated with poorer HRQOL.
Social Consequences
The social label of epilepsy can be paralyzing. Both children and adults with epilepsy may feel and actually become removed from their social group and activities. People with epilepsy may be made to feel “different” by the need to go to the school nurse for medication at lunchtime, being restricted from driving or recreational activities, worries that antiepileptic drugs will be identified during urine tests administered by employers or prospective employers, and fears of rejection by peers if a seizure should occur in public. Epilepsy differs from most other medical and neurologic disorders because of these associated legal restrictions and requirements. Other patients fear dating, marriage (seizures during sex, possible decreased fertility), pregnancy (increased rate of pregnancy complications and birth defects), and parenthood (dangers of a seizure occurring while holding a baby or giving the baby a bath). Employment opportunities are restricted for many people with epilepsy, with unemployment and underemployment prevalent among adults with epilepsy. Employment problems limit financial and health insurance resources.
Multiple etiologies may contribute to the behavioral problems and psychopathology in epilepsy, including social, biologic, and drug-related factors. For example, a social withdrawal syndrome with low rates of employment and marriage may result from a combination of low educational attainment and self-esteem, legislative restrictions, perceived stigma and actual discrimination, and cognitive and behavioral deficits (impaired memory, hyposexuality).45 Biologic (e.g., cognitive impairment) and drug-related factors (e.g., lethargy, tremor) can further complicate this syndrome. Some of these concerns can be related to incomplete compliance with medication as an aspect of quality of life for individuals.21
The selection of which scale to include in a quality-of-life questionnaire is governed by the clinical question being addressed. Measures applied to assessing the effect of treatment in patients with newly diagnosed epilepsy may be different from those assessing therapy for patients with chronic epilepsy or undergoing epilepsy surgery. This approach to individual clinical questions has also incorporated contributions from patients in assessments of their therapy and management. Cramer23,25 and Leone and colleagues52 have reviewed the types of measures available and under development for assessment of people with epilepsy.
Early Initiatives in Measuring Psychosocial Outcome in Epilepsy
Recognizing the cognitive and behavioral problems that can accompany epilepsy, many studies have used neuropsychologic testing to define functional brain deficits and the Minnesota Multiphasic Personality Inventory (MMPI) to assess personality issues. More recently, other psychiatric rating scales have been used to assess specific behavioral problems, such as anxiety or depression.
The Washington Psychosocial Seizure Inventory (WPSI)36 was the first epilepsy-specific psychosocial measure. This 132-item inventory is a self-report measure consisting of eight psychosocial scales (Family Background; Emotional, Interpersonal, and Vocational Adjustment; Financial Status; Adjustment to the Diagnosis of Seizures and Epilepsy; Satisfaction with Medical Management; Overall Psychosocial Functioning) and three validity scales. The WPSI has been widely used in assessing psychosocial outcome among epilepsy patients and in assessing changes in psychosocial functioning before and after a specific intervention, such as epilepsy surgery or a new antiepileptic drug.35
The Well-being Scale was developed by Collings.20 This scale of overall well-being includes six subscales: Self-esteem, Life Fulfillment, Social Difficulty, Physical Symptoms, Worries, and Affect Balance. Testing in 392 patients with active epilepsy showed lower well-being on all scales than in nonepilepsy control groups. The visibility of severe seizures and frequency of seizures were directly related to well-being. Self-image (perception of self) and epilepsy were most predictive of overall well-being. Other important variables included few seizures, mild seizures, recent diagnosis, confidence in the diagnosis, and employment.
The Social Effects scale was developed by Chaplin and colleagues as a postal questionnaire to investigate social aspects of epilepsy in a wide range of epilepsy patients. The Social Effects scale was designed following extensive patient interviews. Initially, 21 areas of concern were identified, but only 14 were included in the final version. Scale reliability, assessed by the test–retest method, was only moderate. Validity was established through a comparison of patient responses and their behavior as observed by medical staff criticism. Further evaluation of the scale is necessary, although the authors have applied the scale successfully in the National General Practice Survey of Epilepsy.18,19
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Table 1 Epilepsy Surgery Inventory-55 | ||||||||||||||||||||||||||||||
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Current Measures of Outcome in Adults
Epilepsy Surgery Inventory-55
Vickrey et al.75 developed a new inventory to assess HRQOL in epilepsy, the Epilepsy Surgery Inventory-55 (ESI-55). Using the RAND 36-Item Health Survey78 as the generic core, they added 19 items, the majority of which are epilepsy specific. Fifty-four items, shown in Table 1, make up 11 unique scales tapping into distinct dimensions of HRQOL; another item assesses change in health during the preceding year.
The ESI-55 was developed to assess HRQOL outcome after epilepsy surgery. Patients who continued to have seizures after surgery had lower ESI-55 scores (i.e., worse HRQOL) than those who were completely seizure free on all 11 scales (p <.05). The ESI-55 was developed to assess HRQOL in a group of postsurgical patients, a small and skewed group of patients with epilepsy. In addition, some aspects of HRQOL were underrepresented in the ESI-55, particularly in regard to social health, for which there is only a two-item Social-Functioning scale.
Liverpool Quality-of-Life Battery
The Liverpool battery began as a way to assess the psychosocial outcomes after a decision to withdraw or not withdraw from antiepileptic drugs.50 Since then, this group has applied quality-of-life measures to several critical epilepsy issues, including the assessment of a novel antiepileptic drug in patients with refractory epilepsy,70 quality of life and quality of services for a community-based population, efficacy of a novel antiepileptic drug in children with epilepsy and learning disabilities, and psychosocial outcomes of immediate versus delayed treatment in single seizures and early epilepsy.
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Table 2 Liverpool assessment battery | ||||||||||||||||||||||||||||||||||
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This group has used a developmental model encompassing measures of physical functioning (Seizure Severity,9 Seizure Frequency, Activities of Daily Living,15 Social Functioning, Life Fulfillment,8 Stigma,48 Impact of Epilepsy49) and of psychological functioning (Affect and Balance scale,13 Hospital Anxiety and Depression scale,80 Self-esteem,65 Mastery scale61) as shown in Table 2. Some of these scales were developed to assess the effects of epilepsy and its treatment; others were designed to assess other disorders but were successfully validated in people with epilepsy. Evidence of the psychometric validity has been reported.8,10,48
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