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Epilepsy & Behavior 8 (2006) 703–712

Quality of life among people with epilepsy and mildintellectual disabilities in residential care

Michael Endermann *

von Bodelschwinghsche Anstalten Bethel, Psychosozialer Dienst im Stiftungsbereich Behindertenhilfe Bielefeld, Remterweg 58, 33617 Bielefeld, Germany

Received 13 December 2005; revised 17 February 2006; accepted 23 February 2006Available online 18 April 2006

Abstract

This study examined quality-of-life (QOL) evaluations among people with epilepsy and mild intellectual disabilities in residential careto determine their covariation and potential determinants. Participants were 111 clients of the Bethel Institute, Bielefeld, Germany. Theycompleted questionnaires on their overall QOL and life satisfaction, the PESOS scales on epilepsy-related QOL, the Brief SymptomInventory (BSI), and scales on activities of daily life and work-related problems in face-to-face-interviews. QOL evaluations differedin the various domains and tended to be better on more concrete items. Correlations of generic QOL parameters with scales on epilep-sy-related QOL were only weak. BSI scores reflecting the current emotional state were identified as the most influential predictors of allQOL measures. The weak relationship between non-health-related parameters of subjective QOL and epilepsy-related QOL requires fur-ther investigation and theoretical explanation, whereas the influence of negative affect on different QOL dimensions is in line with pre-vious QOL findings.� 2006 Elsevier Inc. All rights reserved.

Keywords: Epilepsy; Mild intellectual disabilities; Overall quality of life; Life satisfaction; Epilepsy-related quality of life

1. Introduction

Studies on quality of life (QOL) have been performed(1) as population surveys, (2) with a focus on health-re-lated QOL, and (3) with respect to specific subpopula-tions such as people with intellectual disabilities. Cleardistinctions cannot always be drawn. Generally, QOLhas come to be identified more and more with subjectiveQOL.

1. Social scientific and psychological studies of the pastdecades have examined life satisfaction, happiness, oremotional well-being and have, for example, tried toidentify the impact of socioeconomic variables on suchparameters [1]. These are basically psychological vari-ables, and may be regarded as aspects of subjective

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doi:10.1016/j.yebeh.2006.02.009

* Fax: +49 521144 6274.E-mail address: michael.endermann@bethel.de.

QOL. Studies within this context have found thatchronic disease negatively influences emotional well-be-ing [2].

2. During the 1990s, the number of publications on epilep-sy-related QOL increased. QOL investigations in thefield of epilepsy follow the WHO definition thathealth-related QOL refers to evaluation by the patientand is a multidimensional construct [3,4]. Studies havedealt with the development and psychometric evaluationof appropriate epilepsy-specific questionnaires, withcomparisons of different epilepsy groups, and with com-parisons of people with epilepsy in different countries [5–8]. Moreover, epilepsy-related QOL was established as ameasure of outcome, in addition to seizure control, instudies on the effects of epilepsy treatments [9,10]. Thisis the field in epilepsy in which the clinical importanceof the QOL construct is most striking.

3. Publications on QOL of people with intellectual disabili-ties do not always follow the WHO definition of health-re-lated QOL. Studies have been conducted with a focus on

704 M. Endermann / Epilepsy & Behavior 8 (2006) 703–712

objective circumstances, as well as on subjective apprais-als of the living situation. Moreover, proxy ratings seemedto be the only way to gain information on QOL on peoplewhose verbal communication competency was insufficientfor life evaluations [11,12]. In reference to sociopoliticalprinciples such as normalization and self-determination,in studies on subjective QOL, people with only mild intel-lectual disabilities were often asked how satisfied theywere with their living situation and opportunities forsocial participation. Differences were expected to emergedependent on different living conditions and care modali-ties [13], but service evaluation by users with QOL mea-sures has been markedly criticized as well [14].

Despite the frequency of such QOL research, neither stud-ies in the field of epilepsy nor those in the field of intellectualdisability have, to the author’s knowledge, investigated bothQOL aspects with differentiation, that is, generic non-health-related subjective QOL and specific epilepsy-related QOL.This study of people with epilepsy and mild intellectual dis-abilities in residential care aims to analyze the relationshipbetween these different aspects of subjective QOL. In thiscontext, there is no theoretical differentiation between sub-jective QOL, life satisfaction, and emotional well-being,and these terms are regarded as largely synonymous[11,15]. Instead, the differentiation is made between genericnon-health-related QOL, composed of two scales, andepilepsy-related QOL, composed of four scales.

The questions asked are:

1. How do people with epilepsy and mild intellectual dis-abilities in residential care evaluate their overall QOLand their satisfaction with daily life?

2. How do they evaluate their epilepsy-related QOL?3. Are overall QOL, satisfaction with daily life, and epilep-

sy-related QOL related?4. Which variables are the predominant predictors of these

different QOL domains?

2. Methods

2.1. Sample

One hundred eleven people with epilepsy from residential units of theBethel Institute took part in the study. Participants were volunteers repre-senting nearly all of three units for patients with epilepsy. Four clients didnot participate either for personal reasons or because of insufficient verbalcompetency. The sample consisted of 44 female (39.6%) and 67 male(60.4%) clients, with a mean age of 38.9 (SD = 14.2, range = 19–74).

The clients’ disabilities were a combination of (1) difficult-to-treat-ep-ilepsy, (2) mild intellectual disabilities, and (3) psychosocial disturbances.Information on these three areas of diagnosis was based on the Institute’sclinical files:

1. The mean number of different seizure types was 2.4 (SD = 1.1,range = 1–5). The most frequently documented type of seizure wasgeneralized tonic–clonic, followed by complex partial, simple partial,absence, and tonic. During the 6 months prior to data collection, 74residents (66.7%) had seizures; the remainder of the sample were sei-zure-free. Mean age at onset of epilepsy for the sample was 7.1

(SD = 5.9, range = 0–24), and mean duration of epilepsy was 31.9years (SD = 16.1, range = 4–68). On average, clients were being treat-ed with 2.1 (SD = 1.0, range = 1–5) antiepileptic drugs (AEDs). Val-proate was most frequently prescribed, followed by lamotrigine andcarbamazepine.

2. All participants were able to communicate verbally. Current IQscores were not available. Physicians had rated 78 residents(70.3%) in the sample as having learning disabilities or mild mentalretardation. The majority of 89 residents (80.2%) held employmentin sheltered workshops of the Bethel Institute; the others eitherwere retired or did not work for other reasons at the time ofthe study.

3. Current psychiatric diagnoses based on ICD-10 or DSM-IV were alsonot available. Information from the residential files indicated past orchronic psychiatric symptoms in a majority of 81 participants(73.0%). This large proportion resulted from the classification of allpatients whom physicians had diagnosed with psychological or behav-ior problems as psychiatric cases. Prescriptions of psychotropic medi-cation were judged as additional information on current psychiatricsymptomatology: Thirty-nine people with epilepsy (35.1%) were takingpsychotropic medication in addition to AEDs.

2.2. Measures

2.2.1. Overall QOL and satisfaction with daily life

The single item overall QOL had to be rated on an 11-point scale(0 = ‘‘It could not be worse,’’ 10 = ‘‘It could not be better’’). This one-di-mensional overall QOL measurement has frequently been used in socialscientific studies [16]. The item was also included in the Quality of Lifein Epilepsy Inventory (QOLIE), a widely used questionnaire on epilep-sy-related QOL [17].

Satisfaction with various aspects of daily life and social interactionwas evaluated using eight questions regarding (1) personal indepen-dence, (2) home, (3) caregiving, (4) neighbors, (5) friends/partnership,(6) relationship to relatives, (7) social support in personal problems,and (8) work. The items were selected with respect to the particularliving conditions—residential care. The scale resembled other life satis-faction questionnaires that have, since Cummins, proved their utility inpeople with intellectual disabilities when certain cognitive basic require-ments are met [18]. Each item had to be answered on a 5-point scale(0–4), ranging from ‘‘not at all satisfied’’ to ‘‘extremely satisfied.’’ Rawscores were converted to scores ranging from 0 to 100, with 100 rep-resenting highest satisfaction. A composite score was calculated bydividing the sum of the item scores by the number of items.

2.2.2. Epilepsy-related QOL

Epilepsy-related QOL was measured using four subscales of thePESOS questionnaire (PESOS = performance, sociodemographicaspects, subjective estimation). The PESOS questionnaire is a self-rat-ing tool developed in the Epilepsy Centre Bethel and psychometricallyevaluated with samples from German tertiary care epilepsy centers[19,20]. For use in residential care, some inappropriate items dealingwith work/education or driving cars/motorcycles were eliminated,and a 5-point scale was chosen to score all subscales to prevent con-fusion [21]. The 11 items of the resulting subscale Restrictions in DailyLife (‘‘During the past 6 months, have you felt restricted by epilepsyin the following domains?’’) encompass functional, social, physical, andpsychological dimensions that are generally stressed as central aspectsof health-related QOL in generic questionnaires [22]. Three other epi-lepsy-related PESOS subscales deal with psychosocial aspects, theimportance of which for people with epilepsy is discussed extensivelyelsewhere [23]. Since the 1990s, these aspects have sometimes beenregarded as epilepsy-related QOL components [24]: 12 items refer toepilepsy-related fear (e.g., ‘‘Are you afraid of seizures while goingout?’’), 3 Items refer to [felt] stigma (e.g., ‘‘Do others withdrawbecause of your epilepsy?’’), and 6 items refer to emotional adaptationto epilepsy (e.g., ‘‘Do you think things go wrong in your life becauseof your epilepsy?’’). PESOS raw scores were analogous to scores on

M. Endermann / Epilepsy & Behavior 8 (2006) 703–712 705

the life satisfaction scale converted to a range between 0 and 100, withhigher scores reflecting more epilepsy-related problems, thus indicatinga lower epilepsy-related QOL.

2.2.3. Other psychosocial variables

Based on PESOS items, which are not directly related to epilepsy,two more self-rating scales were developed: One comprised 21 itemsof a questionnaire on activities of daily living (ADL) and coveredimportant aspects of self-sufficiency, mobility, leisure, and social activity(e.g., ‘‘Do you take your meals regularly?’’ ‘‘Do you leave your homeon your own?’’ and ‘‘How often do you have dates with friends?’’).The other scale comprised 10 items of a questionnaire on problemsat work dealing with aspects of achievement and social integration(e.g., ‘‘Do you have memory difficulties at work?’’ ‘‘Do you have con-flicts with your supervisor?’’). Scoring, coding, and conversion of thesetwo scales were done in accordance with the PESOS scales on epilepsy-related QOL.

Finally, emotional distress was measured with the German version ofthe Brief Symptom Inventory (BSI) [25]. The BSI is a standardized self-rat-ing and internationally recognized screening tool for detecting clinicalsymptoms. Its utility has already been demonstrated for people with mildintellectual disabilities, including those with epilepsy [26,27]. Fifty-threequestions on symptoms are answered on a 5-point scale (0–4), ranging from‘‘not at all’’ to ‘‘extremely.’’ The items define a broad spectrum of perceivedrestrictions due to physical and psychological symptoms occurring in thepreceding week. As a measure of global distress, only the Global SeverityIndex (GSI), the composite score of the BSI, was used in this study. Basedon the German normative sample, BSI raw scores were converted to T

scores with respect to gender.

2.2.4. Epilepsy variables

As previously mentioned (see Section 2.1), information on seizure con-trol, that is, information on occurrence of seizures during the 6 monthsprior to data collection, was gathered from the residential files. In addi-tion, clients were asked about the tolerability of their AED treatment(from ‘‘very good’’ or ‘‘good’’ to ‘‘indifferent’’ to ‘‘dissatisfying,’’ the lastmeaning the adverse effects were not tolerable).

2.3. Data collection

Because of the possible reading, attentional, and motivational prob-lems of the clients in residential care, all questionnaires were adminis-tered in face-to-face-interviews. They were read aloud to eachindividual by a member of the Psychological Service of the Bethel Insti-tute. Most of the clients were able to understand the questionnaires andthe 5-point scoring of the items, but in some cases the PESOS scales onepilepsy-related QOL caused problems: The term restriction and othermore abstract words such as self-esteem were sometimes not under-stood. If more detailed explanations using more concrete examplesdid not make a phrase fully comprehensible, the scores of these scaleswere rejected from further data analysis. This factor accounts for amaximum of only 106 cases in the statistical procedures on epilepsy-re-lated QOL.

2.4. Data analysis

SPSS for Windows (Version 8.0) was used for data analysis. As a mea-sure of the scales’ internal consistency, Cronbach’s a was calculated. Rela-tions between scales were analyzed using Spearman’s rank correlationcoefficients due to skewed distribution of scores. Two-tailed t tests wereperformed to look for group differences. As the data analysis was heuristicin nature, no a error correction was conducted despite multiple groupcomparisons. Finally, stepwise regression analyses were performed to lookfor the percentage of variance explanations by different groups ofvariables. The only variables entered as possible predictors were those thathad demonstrated a significant relationship (P < 0.05) with QOL criteriain the preceding univariate data analyses.

3. Results

3.1. Overall QOL and life satisfaction: Distribution of

scores, internal consistency, and gender differences

Taking into account the differences in score scaling, thatis, 0–10 versus 0–100, the overall QOL item was rated low-er than the items on the life satisfaction scale (Table 1). Per-centiles and floor and ceiling effects on the satisfaction scalerefer to a skewed score distribution with an especially highfrequency of ceiling effect on items dealing with satisfactionwith friends/partnership and satisfaction with work. Theinternal consistency of the satisfaction with daily life scalewas 0.67 according to Cronbach’s a.

Although items on the satisfaction with daily life scalecorrelated moderately with the scale’s composite score, cor-relation coefficients between the items on the scale were rel-atively low (Table 2). Among these low coefficients, scoreson satisfaction with self-sufficiency, with home, and withwork were still the most highly correlated with all otheraspects. Comparable values were also computed betweenthe scale’s items and the overall QOL item. Scores on sat-isfaction with different social groups of relevance werepartly more independent: There were substantial relation-ships between satisfaction with friends and satisfactionwith neighbors, as well as between satisfaction with socialsupport, satisfaction with caregiving, and satisfaction withrelatives, but satisfaction with neighbors, satisfaction withrelatives, and satisfaction with friends were, for example,not related to satisfaction with caregiving. Satisfaction withrelatives did not correlate with satisfaction with friends orsatisfaction with neighbors. Female and male clients didnot differ significantly on the overall QOL item and onthe composite score for satisfaction with daily life.

3.2. Epilepsy-related QOL: Distribution of scores, internal

consistency, and gender differences

As has been already demonstrated in more detail [21],the distribution of PESOS scores on epilepsy-relatedQOL differed markedly between the residential populationand epilepsy patients from German tertiary care centers(Table 1): In residents of the Bethel Institute, a floor effectwas observed much more frequently, indicating fewer epi-lepsy-related problems. On all four measures, 27% of cli-ents had, on average, zero scores.

The internal consistency of the four PESOS scales on epi-lepsy-related QOL consistently exceeded Cronbach’s a of0.75 in residential care. Female clients scored significantlyhigher (P < 0.05) on the scale Restrictions due to Epilepsy;they also tended to manifest more problems (P < 0.10) withrespect to the scale Emotional Adaptation to Epilepsy.

3.3. Relations between measures of subjective QOL

A moderate correlation coefficient was computedbetween the overall QOL item and the composite score

Table 1Satisfaction with daily life, overall QOL, and epilepsy-related QOL: Floor and ceiling effects, mean values, and percentiles

Floor % Ceiling % Mean SD 10% 25% 50% 75% 90%

Items on satisfaction with daily lifea (N = 111):Satisfaction with

personal independence 2.7 24.5 71.14 23.51 50.00 50.00 75.00 81.25 100.00... Home 6.3 28.8 68.47 28.55 25.00 50.00 75.00 100.00 100.00... Caregiving 5.4 25.2 66.89 27.83 25.00 50.00 75.00 100.00 100.00... Neighbors 4.5 44.1 72.30 29.84 25.00 50.00 75.00 100.00 100.00... Friends/partnership 1.8 59.1 81.82 26.43 27.50 75.00 100.00 100.00 100.00... Relationship to relatives 8.2 39.1 70.00 31.73 25.00 50.00 75.00 100.00 100.00... Social support in case of personal problems 3.8 37.5 74.76 26.42 37.50 56.25 75.00 100.00 100.00... Work 5.7 40.0 75.95 27.50 25.00 75.00 75.00 100.00 100.00Satisfaction with daily life (composite score) 0 3.6 72.66 15.29 54.13 62.50 75.00 84.38 92.90Overall QOL (single item)b 2.7 13.6 6.25 2.36 3.00 5.00 6.00 8.00 10.00PESOS-scales on epilepsy-related QOL (N = 106)c:

Restrictions in daily life 32.1 0.0 12 14 0 0 7 21 30(6.5) (0.2) (34) (24) (4) (15) (31) (48) (70)

Epilepsy-related fear 21.7 0.0 18 20 0 2 13 28 48(1.9) (0.8) (49) (24) (18) (30) (50) (67) (82)

Stigma 36.8 0.0 23 26 0 0 17 42 67(38.2) (1.3) (24) (28) (0) (0) (13) (43) (69)

Emotional adaptation to epilepsy 17.9 1.9 26 25 0 8 21 34 55(2.8) (5.5) (54) (27) (15) (30) (55) (75) (90)

a Range of items and scale: 0–100 (higher scores = more satisfaction).b Range of the item: 0–10 (higher scores = more satisfaction).c Range of PESOS scales: 0–100; higher scores indicate more problems, i.e., worser QOL. Data in parentheses are for epilepsy patients from German

tertiary care centers (N > 800) according to May et al. [19].

Table 2Correlation coefficients within the scale on satisfaction with daily life and correlations between satisfaction items and the item on overall QOL (Spearmancorrelation coefficients)

Items of the scale onsatisfaction withdaily life

Overall QOL(single item)

Scale on satisfaction withdaily life (composite score)

Items of the scale on satisfaction with daily life (= satisfaction with):

Personalindependence

Home Caregiving Neighbors Friends Relatives Socialsupport

Personal independence 0.35a 0.57a

Home 0.35a 0.65a 0.28a

Caregiving 0.19 0.53a 0.36a 0.39a

Neighbors 0.23b 0.51a 0.28a 0.31a 0.13Friends 0.13 0.48a 0.19b 0.22b 0.06 0.35a

Relatives 0.23b 0.47a 0.20b 0.19b 0.08 �0.03 0.06Social support 0.27a 0.51a 0.27a 0.17 0.29a 0.09 0.08 0.28a

Work 0.42a 0.64a 0.37a 0.38a 0.40a 0.20b 0.24b 0.24b 0.19c

a P < 0.01 (two-tailed).b P < 0.05 (two-tailed).c P < 0.10 (two-tailed).

706 M. Endermann / Epilepsy & Behavior 8 (2006) 703–712

on the satisfaction with daily life scale. Correlation coef-ficients between the four PESOS scales on epilepsy-relat-ed QOL turned out to be somewhat higher, with a meanq of 0.49. Coefficients of correlation between epilepsy-re-lated QOL and the more generic QOL parameters, thatis, overall QOL and life satisfaction, were very low:The mean coefficient between the four PESOS scales onepilepsy-related problems and the overall QOL itemwas q = �0.18; the mean coefficient between thesePESOS scales and the satisfaction with daily life scalewas q = �0.23. Among the PESOS scales, EmotionalAdaptation to Epilepsy was correlated most highlywith overall QOL and satisfaction with daily life(Table 3).

3.4. Relations between QOL measures and other

psychosocial parameters as well as epilepsy variables

Table 3 also refers to the relationship between sub-jective QOL and other variables: The highest mean cor-relation coefficient, q = 0.45, was that between theQOL measures and the BSI composite score indicatinggeneral emotional distress. BSI scores significantly cor-related with all QOL measures. All of the QOL mea-sures also correlated significantly with the problems atwork scale, but coefficients were somewhat lower.Scores on the ADL scale were related only to overallQOL, satisfaction with life, and the Restrictions dueto Epilepsy scale from the domain of epilepsy-related

Table 3Relations between different QOL-domains, between QOL domains and other psychosocial variables, and between QOL domains and epilepsy variables(Spearman correlation coefficients and t tests)

Subjective QOL Epilepsy-related QOL

Overall QOL (item) Satisfaction with daily life Restrictionsa Feara Stigmaa Adaptationa

QOL dimensionsSatisfaction with daily life 0.40e

Restrictionsa �0.10 �0.21f

Feara �0.16g �0.25f 0.45e

Stigmaa �0.17g �0.17g 0.28e 0.54e

Adaptationa �0.28e �0.30e 0.45e 0.58e 0.61e

Other psychosocial variablesADL scaleb 0.20f 0.36e �0.21f 0.09 �0.13 �0.12Problems at workb �0.24f �0.38e 0.35e 0.48e 0.32e 0.44e

BSIc �0.43e �0.48e 0.31e 0.52e 0.46e 0.49e

Epilepsy variablesSeizure controld e e g f

AED tolerabilityd e e

a PESOS scales on epilepsy-related QOL .b Self-constructed scales based on other PESOS-scales. ADL, activities of daily life.c Composite-score GSI of the Brief Symptom Inventory (T score).d Groups without seizure control and low AED tolerability scored higher on PESOS scales, i.e., had lower epilepsy-related QOL.e P < 0.01 (two-tailed).f P < 0.05 (two-tailed).g P < 0.10 (two-tailed).

M. Endermann / Epilepsy & Behavior 8 (2006) 703–712 707

QOL. The reliability of the ADL and problems atwork scales had previously been confirmed as satisfac-tory, with Cronbach a scores > 0.70. Finally, it canbe seen that only measures of epilepsy-related QOLreflected differences on the epilepsy variables seizurecontrol and AED tolerability: Clients with epileptic sei-zures during the 6 months prior to data collection indi-cated significantly (P < 0.05) more problems on all fourepilepsy-related QOL scales; clients with lower AEDtolerability indicated significantly (P < 0.05) more prob-lems on the Restrictions due to Epilepsy and Emotion-al Adaptation to Epilepsy scales.

3.5. Prediction of QOL measures

In addition to the univariate results, stepwise regressionanalyses were performed to predict the six QOL variables

Table 4Regression models to predict QOL parameters

Subjective QOL

OverallQOL (item)

Satisfactionwith daily life

Prediction of QOL parameters fromI. Other QOL parameters

Regression model (always P = 0.000) F(103/2) = 19.91 F(104/1) = 32.2Variance explanation (corrected R2) .27 .23

II. Psychosocial variablesRegression model (always P = 0.000) F(101/2) = 12.96 F(102/2) = 27.5Variance explanation (corrected R2) .19 .34

III. Epilepsy variablesRegression model (always P < 0.05)Variance explanation (corrected R2)

a PESOS scales on epilepsy-related QOL.

(overall QOL, satisfaction with daily life, and four mea-sures of epilepsy-related QOL) from different sets of inde-pendent variables. With respect to single predictors,results of these analyses largely resembled the univariateanalyses already discussed. Therefore, Table 4 outlinesonly the amount of variance explained by different groupsof variables: Generally, most of the variance in QOLparameters can be explained by the remaining QOL param-eters; a smaller proportion of the variance, by the otherpsychosocial parameters. Epilepsy parameters explainedonly epilepsy-related QOL variance. It is worth mentioningthat for overall QOL and satisfaction with life, the almostequal proportions of variance were explained by theremaining QOL parameters and by psychosocial variables.With respect to epilepsy-related QOL parameters, an espe-cially large part of the variance was explained by theremaining variables for epilepsy-related QOL. But findings

Epilepsy-related QOL

Restrictionsa Feara Stigmaa Adaptationa

4 F(103/2) = 17.09 F(103/2) = 58.15 F(103/2) = 63.39 F(102/3) = 59.52.24 .52 .54 .63

8 F(100/2) = 10.48 F(100/2) = 31.31 F(101/1) = 31.20 F(100/2) = 32.17.16 .37 .23 .28

F(103/2) = 24.36 F(104/1) = 8.94 F(104/1) = 4.13 F(103/2) = 7.40.31 .08 .03 .11

708 M. Endermann / Epilepsy & Behavior 8 (2006) 703–712

on the PESOS scale Restrictions due to Epilepsycontradicted this pattern: The largest part of the variancewas explained by epilepsy variables; the other QOLvariables and the psychosocial variables had less influence.

4. Discussion

The four questions asked at the beginning of this articlecan now be answered:

1. Clients with epilepsy and mild intellectual disabilities inresidential care scored relatively high on satisfactionwith daily life: 72.7 on a scale ranging from 0 to 100.They scored lower on overall QOL: 6.3 on a scale rang-ing from 0 to10.

2. Clients in residential care also scored relatively high onepilepsy-related QOL. This conclusion is drawn fromthe low PESOS scores on epilepsy-related problems.

3. Covariation between satisfaction with daily life andoverall QOL was moderate. Covariation within epilep-sy-related QOL, that is, between measures of epilepsy-related QOL, was also moderate. But life satisfactionand overall QOL were only slightly, if at all, correlatedwith measures of epilepsy-related QOL. Consequently,the data collected in this study do not strongly supportthe notion that subjective QOL is a homogeneous theo-retical construct.

4. If the influence of QOL parameters on each other is nottaken into account, BSI scores as indicators of emotion-al distress were the variables in this study that were mosthighly correlated with all of the subjective QOL param-eters. Epilepsy variables were connected only to epilep-sy-related QOL, especially to the scale Restrictions dueto Epilepsy.

4.1. Question 1

From the distribution of scores on the life satisfactionscale, we infer that most of the clients in residential careat the Bethel Institute seemed to have accepted their livingconditions. Their scores were similar to those obtained onsurveys on life satisfaction conducted in different samplesof the general population in Western nations: Cumminsconcluded that a population standard for life satisfactioncan be expressed as 75% (SD = 2.5) of the measurementscale maximum score [2].

Satisfaction scales developed for the general populationusually consist of more items than does this scale on satis-faction with daily life [28]. Here, as part of an assessmenttool, relatively few items were chosen because of possibledeficits in concentration of clients in residential care.Usually, the risk involved in using a smaller number ofitems is diminished reliability of the scale, and the scale’sinternal consistency did indeed not reach the statisticalconvention of a Cronbach a > 0.70. Nevertheless, the scalewas accepted for use as a heuristic questionnaire. Reliabil-ity scores between 0.60 and 0.70 have already been reported

for other QOL scales specially designed for people withmild intellectual disabilities [29]. The only moderate reli-ability of this scale and the somewhat low correlation coef-ficients between the items provide an idea of the domainspecificity of the clients’ evaluations and of content validi-ty: Satisfaction with different social reference groups, suchas neighbors and relatives or relatives and friends, wasevaluated independently, whereas satisfaction with neigh-bors did correlate with satisfaction with friends; these aretwo groups that overlap to a great degree, especially in res-idential care. Satisfaction with social support was correlat-ed to satisfaction with caregiving, as well as satisfactionwith relatives, that is, people who can be considered natu-ral or requested sources of support. Friends did not play arole in the context of social support, a situation, again,most likely reflecting living conditions specific to residentialcare. The relatively consistent correlation between satisfac-tion with personal independence, with home, and withwork and all of the other items on the scale seems to indi-cate that satisfaction with one’s own abilities tends to gen-eralize and have positive effects in many areas.

Clients scored an overall QOL 6.3 on a scale rangingfrom 0 to 10, obviously lower than their life satisfactionscore on more concrete items of daily and social life. Thisfinding is interesting, as Cummins [2], in his overview,reported a large conformity of total scores on subjectiveQOL to single items on overall QOL. In contrast to dataon satisfaction with daily life, data from this study on over-all QOL were not in accordance with the ‘‘gold standard’’of 75% (SD = 2.5) of the measurement’s maximum scorementioned before. But the low overall QOL score in thisstudy is less unusual with respect to special subpopulations:Whereas Cummins [2] detected no difference in satisfactionwith life between the general population and people withintellectual disabilities, he reported lower QOL scores forpersons with chronic disease, whose mean satisfaction withlife score was 4 SD below that of the normative sampleand, thus, more like the overall QOL score for the patientswith epilepsy in residential care in the present study. Eval-uation of overall QOL with a single item allows approxi-mate comparisons with other studies of patients withepilepsy: Two items of the QOLIE, for example, ask forestimates of overall QOL, which form the basis of a sum-mary score on overall QOL ranging from 0 to 100. Thisscore, as well as other overall QOL estimates, differ greatlyin different studies and seem, at least partly, to reflect notonly seizure frequency, but the severity of epilepsy: Patientswhose epilepsy treatment was in the process of being mod-ified had low scores (maximum = 64) [30,31]. Patientstreated in tertiary care centers had better scores (67 or72) [17,32]. However, German patients on monotherapywho were not being treated by specialists had the highestscores; in conformity with the general population they ratedtheir overall QOL 7.7 on a scale ranging from 0 to 10 [22].

Together, the data from the present study are conflict-ing: Scores on overall QOL are in line with life satisfac-tion scores of people with chronic disease, scores on

M. Endermann / Epilepsy & Behavior 8 (2006) 703–712 709

satisfaction with daily life correspond to those of thegeneral population, including people with intellectual dis-abilities. One possible reason for this contradiction couldbe that overall QOL evaluations reflect an entire life,whereas evaluations of satisfaction with daily life reflectthe current state, and unlike comparable scales [28],questions did not at all touch generic aspects of physicaland psychological health. The low score on overall QOLcould therefore be a manifestation of an identity as adisabled person resulting from cumulative frustrationsover the life span.

4.2. Question 2

In this sample, the internal consistency of the PESOSscales on epilepsy-related QOL had to be regarded as satis-factory, and correlation with seizure frequency and AEDtolerability was viewed as an important clue to validity.On the other hand, the distribution of the PESOS scoresclearly differed from those of clinical epilepsy samples[19]: Epilepsy-related problems were noted less often bythe clients in residential care. As indicated elsewhere [21],this difference could only be attributed partly to the higherseizure frequency of patients in tertiary care, and therefore,the influence of other factors must be taken into account:First, in residents with multiple disabilities, the uniqueimpact of the epilepsy may have been reduced. Second, liv-ing conditions in residential care may have been better suit-ed to the everyday needs of people with epilepsy, for whichthe particularly low scores on the restrictions subscaleargue. [3] Finally, living together with other people withepilepsy may have promoted coping skills and adaptationto epilepsy.

In total, the low scores on epilepsy-related PESOSscales, indicating only a few problems, are in line withthe relatively high scores on the satisfaction with daily lifescale.

Within the epilepsy-related QOL scales, it was againstriking that more general items, as on the subscales Stigmaand Emotional Adaptation to Epilepsy, tended to elicithigher scores than more concrete items such as those onthe scale Restrictions due to Epilepsy. Similar to the argu-ments on overall QOL, it seems reasonable to assume thatmore general items evoke an evaluation of earlier and over-all experience with chronic disease or disability.

Gender differences on epilepsy-related QOL in residen-tial care may result predominantly from the fact that sei-zure control and gender were confounded: Only 10(22.7%) female clients, compared with 27 (40.3%) male cli-ents, had been free of seizures during the 6 months prior todata collection.

One could cast doubt on the interpretation of thePESOS scores by arguing that the low scores indicatingfewer problems, especially the floor effect, may haveresulted from a lack of understanding or a generallylow IQ of the subjects. Yet this explanation does notseem very likely: First, with respect to all the scales

used in this study, the clients generally tended not toneglect problems; they had, for instance, a high ‘‘case’’rate according to BSI scores that are discussed later.Second, there was no evidence of acquiescence; evalua-tion of overall QOL, for example, did not reach theexpected 75% of the measurement’s maximum scoreas discussed by Cummins [2]. Third, the distributionsof the PESOS scales differed. Extreme scores resultingfrom a lack of understanding should have beenobtained on more abstract items, but, in fact, theopposite occurred: A particularly large floor effectwas observed on the subscale Restrictions due to Epi-lepsy, where interviewers from the Psychological Servicefailed to recognize problems in understanding. Thefloor effect was smaller on the subscale EmotionalAdaptation to Epilepsy with more abstract items. Thefloor effect on the scale Stigma also appeared not toaccount for problems with understanding, as the per-centage was similar to that of the clinical referencesample.

4.3. Question 3

Interestingly, data from this study demonstrated only alow correlation of epilepsy-related QOL with overall QOLand life satisfaction. This finding seems to be based onlypartly on the selected measures: The overall QOL itemhas been used in social science for decades, and the satisfac-tion with daily life scale resembles other scales on life sat-isfaction [18,22,28]. The validity of the epilepsy-relatedPESOS scales was proven, among others, by the significantrelationship to QOLIE scores for patients from tertiarycare epilepsy centers: In these patients, contradictory tothe results of this study, QOLIE items on overall QOL alsocorrelated with PESOS scales: r = �0.55 for Restrictionsdue to Epilepsy and with r = �0.45 for Epilepsy-RelatedFear [31].

The low covariation of epilepsy-related QOL with over-all QOL and life satisfaction probably is due to residentialcare: Epilepsy may lose its overwhelming meaning when itis no longer experienced as the most influential factor in lifeplanning. Satisfaction with daily life refers to living underconditions in which support is available. Overall QOL,probably more than other aspects of QOL, reflects possiblediscrepancies between actual life and previous or currentlonging for a ‘‘normal’’ life or changes in the living situa-tion. These elements together could result in a more frag-mentary or less homogeneous evaluation of QOLdomains, being more than a methodical artifact resultingfrom this scale on life satisfaction without health-relateditems.

4.4. Question 4

It seems reasonable to stress at the beginning of this sec-tion that two major findings of previous health-related QOLresearch were replicated. On the one hand, many investiga-

710 M. Endermann / Epilepsy & Behavior 8 (2006) 703–712

tions with different epilepsy samples have already shownthat seizure activity negatively influences epilepsy-relatedQOL, whereas seizure freedom is associated with higherQOL [33–36]. On the other hand, the association betweenBSI scores and QOL is in line with many studies providedthat emotional distress or negative affect is the latent con-struct of all self-rating scales on clinical psychologicalsymptoms [37]: In patients with epilepsy, epilepsy-relatedQOL correlated with neuroticism [38,39] or depression[40,41]; neuroticism has also been found to correlate withnon-health-related subjective QOL in nonclinical popula-tions [42,43]. Other aspects that have been less emphasizedor have only recently gained attention are: (1) the influenceof other variables on QOL; (2) the either specific or globalinfluence of variables on QOL dimensions; and (3) the rela-tive importance of predictors. It is also not yet clear (4)which conclusions are to be drawn from the associationbetween QOL and psychological distress.

1. In this study univariate analyses revealed more vari-ables, such as AED tolerability and problems at work,to be associated with QOL dimensions. Nevertheless,explanation of QOL variance by all of the variables thatwere not included as QOL dimensions was only moder-ate. Considering the relative heterogeneity of QOLdimensions, the construct validity of QOL may be ques-tioned. But results of the regression analyses indicatethat the QOL construct alternatively cannot simply bereduced to medical or other psychological concepts.

2. Some variables were more specifically related to QOLdimensions, others more generally, but together theserelationships argue for plausibility and underline contentvalidity. On the one hand, specific relationships stressedthe content specifics of the QOL evaluations: The ADLscale corresponded predominantly to overall QOL andsatisfaction with daily life. Here, epilepsy variables suchas seizure control and AED tolerability correspondedonly to epilepsy-related QOL, whereas other studieshave yielded contrasting results, with an influence of sei-zure frequency on overall QOL [31,44]. On the otherhand, variables such as problems at work and BSI scoreswere universally related to all of the subjective QOLevaluations, with comparatively the highest correlationcoefficients on BSI scores indicating emotional distress.

3. It must be noted that most subscales on epilepsy-relatedQOL were also moderated to a higher degree by BSIscores than by epilepsy variables. The scale Restrictionsdue to Epilepsy was the only exception: Therefore, itmay prove worthwhile to investigate whether this scaleis reacting with special sensitivity to epilepsy treatmentsand, also, if the remaining PESOS scales on epilepsy-re-lated QOL have a higher potential for detecting psycho-therapeutic, emotionally stabilizing effects on patients.

4. As already outlined at the beginning of this section,the association between QOL and BSI scores refersto the results of many other investigations. But whatdoes this association indicate? Does psychological dis-

tress affect QOL? Does low QOL cause psychologicalsymptoms? Is the relationship reciprocal? Based on acorrelational study design, negative affect was consid-ered a factor underlying QOL. But even within theframework of this assumption, it is yet unclearwhether QOL is grounded more on largely time-stableand uncontrollable personality dimensions such asneuroticism or is moderated by more variable affectivedisorders that may be treated effectively. In this con-text, the BSI scores of the residential sample are,unfortunately, anything but clear: They have alreadybeen demonstrated to be sensitive to change and toreflect psychotherapeutic treatments, for example [45],but their relative time stability has already been docu-mented as well [46].

Additionally, it seems important to consider the distri-bution of BSI scores presented in this study: The total scorewas slightly above the average of the normative sample,and following the cutoff criterion (T score P 63), 25.5%of the sample was either prone to developing or actuallyhad a psychological disorder. When this finding is takeninto consideration, the relatively positive QOL evaluationshave to be restricted: Most of the clients in residential careat the Bethel Institute seemed to be satisfied with their cur-rent living situation, although a large percentage had psy-chological problems.

4.5. Consequences

In addition to the questions asked at the beginning ofthis article, data from this study on patients with epilepsyin residential care suggest that:

• QOL was rated with a clear content specificity, but emo-tional distress is the common component in all QOLdimensions.

• The use of QOL composite scores as aggregations ofdata from different QOL dimensions should be discour-aged, as important information may be lost.

• QOL scores may easily obscure emotional problems,including psychological disorders, if comparative dataon QOL of other samples or additional data on emo-tional distress are not taken into account.

• Evaluations of the current living situation paint an alto-gether more optimistic picture than more general andabstract evaluations, which may include the entire lifespan.

• Central epilepsy variables such as seizure control pertainonly to epilepsy-related QOL among nonclinicalpatients with longstanding, chronic epilepsy and mildintellectual disabilities.

As the results of this investigation may, in part, be sam-ple-specific artifacts, the relationship between overall QOL,satisfaction with daily life, and health-related QOL requiresfurther clarification. The only weak covariation of these

M. Endermann / Epilepsy & Behavior 8 (2006) 703–712 711

aspects of QOL is in line with the assumption of QOL asmerely a meta-concept with subdimensions, which mayhave some form of hierarchical structure or causalsequence [47]. Therefore, it seems necessary for QOLresearchers to develop and test models that integrate differ-ent QOL dimensions [48]. Longitudinal observations alsoprovide solid clues to causal relationships between emo-tional variables and life evaluations.

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