Quality of Life Enjoyment and Satisfaction Questionnaire

Quality of Life Enjoyment and SatisfactionQuestionnaire short form for quality of lifeassessments in clinical practice: a psychometric studyD . S T E VA N O V I C m d

Department of Psychiatry, General Hospital Sombor, Sombor, Serbia

Keywords: mental illness, quality of

life, reliability, responsiveness, validity

Correspondence:

D. Stevanovic

Department of Psychiatry

General Hospital Sombor

Apatinski put 38, 25000 Sombor

Serbia

E-mail: [email protected]

Accepted for publication: 26 March

2011

doi: 10.1111/j.1365-2850.2011.01735.x

Accessible summary

The measurement characteristics of the Quality of Life Enjoyment and SatisfactionQuestionnaire (Q-LES-Q) for quality of life (QOL) assessments in the clinicalsettings were evaluated.

The Q-LES-Q SF showed sound internal consistency, testretest reliability, andconvergent and criterion validity, with 80% sensitivity and 100% specificity.

The Q-LES-Q SF could produce reliable, valid and sensitive assessments of QOLin routine psychiatric practice.

Abstract

The Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) and its shortform (Q-LES-Q SF) are among the most frequently used outcome measures inpsychiatry research. The aim of this study was to analyse the measurement propertiesof the Q-LES-Q SF for quality of life assessments in the clinical settings. Fifty-sevenadults with a psychiatric diagnosis participated. Psychometric evaluation includeddescriptive analysis, internal consistency, testretest reliability, validity, sensitivityand responsiveness analysis. The amount of missing data was 5.3%, while no floor orceiling effects were observed. The internal consistency and testretest coefficients were0.9 and 0.93, respectfully. Almost all items significantly correlated to the total scoreand other measures used in the study, with the correlations ranging 0.410.81. Finally,the responsiveness parameters indicated the Q-LES-Q SF is 80% sensitive and 100%specific measure. This preliminary analysis of the Q-LES-Q SF demonstrated that itcould produce reliable and valid clinical assessments of quality of life.

Introduction

Quality of life (QOL), as one of the most importantpatient-reported outcome, represents how an individualperceives the impacts of a health condition and its treat-ment on his or her daily living. It has become an essentialpart in research and recognized as an important end pointin the clinical settings. The purpose of measuring QOL inresearch is to compare groups of patients (usually overrelatively short periods) with the focus on the assessmentsof their performance. Such situations are different fromclinical practice, where the purpose of measurement is toassess change in individual patients, sometimes for many

years. Rapidly, QOL entered many researches, mainlybecause we have reached some consensus on its measure-ment in clinical trials, but there are very limited reportsabout its routine use in clinical practice (Acquadro et al.2003, Szende et al. 2005).

In a review from 1999, the authors evaluated someconceptual and methodological issues related to QOLassessment in mental health research. Among other find-ings, they observed that more research is required as relatedto QOL instruments in order to use them as clinicallyappropriate assessment procedures (Gladis et al. 1999).This implies that clinically useful QOL instruments need tobe feasible, reliable, valid and sensitive to change.

Journal of Psychiatric and Mental Health Nursing, 2011, 18, 744750

744 2011 Blackwell Publishing

The Quality of Life Enjoyment and Satisfaction Ques-tionnaire (Q-LES-Q) is among the most frequently usedoutcome measures in psychiatry research (Endicott et al.1993). It is a generic, self-reported QOL measure assessingthe physical health, subjective feelings, leisure activities,social relationships, general activities, satisfaction withmedications and life satisfaction domains. The Quality ofLife Enjoyment and Satisfaction Questionnaire Shortform (Q-LES-Q SF) was developed from the original,long form, fully representing its concept. The Q-LES-Q SF produced psychometrically sound QOL assessments indifferent groups of people with psychiatric illnesses, interms of good reliability, validity and sensitivity to change(Endicott et al. 1993, 2007, Mllerov et al. 2001, Ritsneret al. 2002, Rucci et al. 2007, Mick et al. 2008, Hope et al.2009, Wyrwich et al. 2009).

This study was organized with the aims to analyse themeasurement properties of the Q-LES-Q SF and toexamine its ability to measure QOL in the clinical settingsusing a Serbian sample. It was assumed that the measureshould possess appropriate measurement properties of anevaluative measure to be used for assessing change inindividual patients (Fayers & Machin 2007).

Methods

Q-LES-Q SF

The Q-LES-Q SF is a self-reported questionnaire, with 16items, derived from the general activities scale of the origi-nal 93-item form (Endicott et al. 1993). It evaluates overallenjoyment and satisfaction with physical health, mood,work, household and leisure activities, social and familyrelationships, daily functioning, sexual life, economicstatus, overall well-being and medications. Responses arescored on a 5-point scale (not at all or never to frequentlyor all the time), where higher scores indicate better enjoy-ment and satisfaction with life (possible range 1470).Fourteen summated items create the total Q-LES-Q SFscore. Two last items, about medications and overall lifesatisfaction, are considered independently.

The MAPI Research Trust Institute developed the Serbianversion provided to the author by the developer J. Endicott,PhD. The version was pre-tested in a small group of psychi-atric patients prior this study to test the cultural appropri-ateness and content validity (Fayers & Machin 2007).

Subjects and assessments

All adults admitted to daily hospital for some psychiatrictreatment between December 2008 and January 2009 wereeligible. Exclusion criteria were the presence of any other

major medical problem (e.g. chronic illness, impairment),inability to read or write and living in an institution. Allpatients were diagnosed according to the InternationalClassification of Diseases (ICD 10) [World HealthOrganization (WHO) 1993] and to all was initiatedsome kind of treatment, medications, social therapy and/orpsychotherapy.

Fifty-seven subjects who accepted to participate andprovided a written consent were assessed independently(Table 1). However, each analysis below included only sub-jects who provided all data.

First assessmentOn the admission, each participant was evaluated on theClinical Global Impression severity scale (CGIs) rated by aclinician and the Patient-reported Global Impression sever-ity scale (PGIs) rated by a participant, both as a 7-pointscale, from 1 extremely ill to 7 not ill at all (Endicottet al. 1993). The Q-LES-Q SF was completed afterwards.

Second assessmentOn the second appointment, 7 days later, the subjects wereevaluated again and those who remained stable over thisperiod completed the Q-LES-Q SF. A stable subject isone whose health status has not changed in any domainsince the previous assessment.

Third assessmentAt the follow-up assessment, 4 weeks later, beside the CGIs,PGIs and the Q-LES-Q SF, the Clinical Global Impressionimprovement scale (CGIi) was completed by a clinician,from 0 state unchanged to 6 ideal improvement

Table 1Demographic characteristics of 57 subjects

Age, years (M, SD) 47.16, 9.22

Gender, n (%) 38 (66.7) M, 19 (33.3) FMarital status,n (%)

25 (43.87) married/live with a partner,22 (38.59) never married,10 (17.54) separated/divorced/a

partner diedEducational level,n (%)

11 (19.29) primary school,39 (68.43) secondary school,7 (12.28) high school/university degree

Occupational status,n (%)

21 (36.84) full- or part-time work,16 (28.07) retired,19 (33.33) not employed,1 (1.75) college student

Psychiatric diagnosisaccording to theICD-10 categories(WHO, 1993), n (%)

20 (35.08) Schizophrenia, schizotypal anddelusional disorders (F20-F29),

16 (28.07) Mood disorders (F30-F39),11 (19.29) Anxiety, stress-related and

somatoform disorders F40-F48,10 (17.56) Disorders of adult personality

and behaviour (F60-F62)

Q-LES-Q SF in clinical practice

2011 Blackwell Publishing 745

(Endicott et al. 1993). The three indexes, CGIs, PGIs andCGIi, were the external criteria of change (anchors) andeach should significantly correlate with the Q-LES-Q SF(Fayers & Machin 2007). Thus, any change in the Q-LES-Q SF would be observed in the external criteria of change.

After the final assessment, all participants were assignedto two groups. The unchanged group (n = 22) includedsubjects without changes in mental health status from thefirst assessment and the changed group (n = 14) includedthose subjects who improved over the study period (theimprovement was measured as change in scores in two ormore of the anchors used). During the follow-up period, twosubjects worsened significantly, four were acutely diseased(a viral infection), five were discharged earlier (as a result offinancial problems) and 10 refused to participate this time.

After the approval from the Psychiatric Board about theinvolvement of all patients in the study activities, the EthicsComity of the authors institution (General HospitalSombor) approved the study.

Psychometric analysis

Descriptive analysisThe number and distribution of missing data were exam-ined to assess the acceptability of the questionnaire assum-ing that this value should not be more than one-third ofunanswered items for an individual (Fayers & Machin2007, Terwee et al. 2007). The distribution of responses foreach item was assessed visually. Further, the mean, stan-dard deviation, skewness and kurtosis for responses toevery item were calculated (Ware & Gandek 1998). Finally,the percentage of responses on anchor points was exam-ined to detect floor or ceiling effects, which should notexceed 15% (Terwee et al. 2007).

Analysis of validityThree assumptions were considered for validity. All itemsshould be correlated minimally 0.4 to the total score cor-rected for overlap using Spearmans correlation. These cor-relations should not be substantially different between theitems, indicating that the amount of information to the totalconcept being measured is similar for each item (Ware &Gandek 1998). Finally, the Q-LES-Q SF should be signifi-cantly correlated with the CGIs, PGIs and CGIi (P < 0.05,Spearmans correlation) as the means of criterion validity.

Analysis of internal consistency reliability, testretestreliability, sensitivity and responsivenessIt was assumed that the questionnaire should have appro-priate internally consistency reliability and it should bestable in stable subjects (testretest reliability, reproducibil-ity), it should be sensitive to detect differences in QOL

between different people (sensitivity), and it should be ableto detect QOL changes in unstable subjects (responsive-ness) (Fayers & Machin 2007).

Internal consistency reliability was assessed by Cron-bachs alpha and it should exceed 0.7. Testretest reliabilitywas analysed using the intraclass correlation coefficient(the two-way random method of absolute agreement) toderive the reliability coefficient (Streiner & Norman 2008).The retest took place 7 days later considering the 1-weektime frame of the Q-LES-Q SF. Testretest reliabilityshould be at least 0.9 in order to evaluate the ability of thequestionnaire in detecting changes important for individualcomparisons (Fayers & Machin 2007).

Eventually, the responsiveness was evaluated as the fol-lowing. First, the standard error of measurement (SEM)was derived from the standard deviation of the sample,from which was assessed the reliability, multiplied bysquare root of (1 the reliability) (Sprangers et al. 2002,Crosby et al. 2004). For the SEM, 90% confidence inter-vals (90% CI) were calculated around individual patientscores, reflecting the questionnaires accuracy for indi-vidual assessments and clinical decision making (Williams& Naylor 1992). Further, the SEM was converted into thesmallest detectable change (SDC) reflecting the smallestwithin-individual change in score that could be interpretedas a real change, above measurement error in one indi-vidual (Terwee et al. 2007). The SDC was calculated bymultiplying the z-score corresponding to the level of sig-nificance, the square root of 2 and the SEM. A z-score of1.64 was chosen to reflect an acceptable 90% CI for clini-cal application to individual patients (Schmitt & Di Fabio2004). Finally, the minimal important difference (MID;also known as minimal clinically important difference),defined as the smallest difference in score perceived asbeneficial, was determined using mean change scores forpatients with small but meaningful change according tosome external criteria (Schmitt & Di Fabio 2004).

Change over the 4-week interval was analysed usingthree responsiveness indices at the individual patient level.Only data from all followed-up patients were used (de Vet2001, Schmitt & Di Fabio 2004). Reliable change propor-tion the proportion of the sample with change scoresexceeding the SDC, which is also sensitivity to change;MID proportion the proportion of the sample withchange scores exceeding the MID, and specificity to change the proportion of those who claimed perceiving nochange and their scores did not exceed the SDC.

Results

From the pre-testing, it was accepted that the Q-LES-Q SF possesses culturally appropriate items with sufficient

D. Stevanovic


content validity. Only item that measures satisfaction witheconomic status possesses insufficient characteristics forevaluative purposes.

The amount of missing data was 5.3% and none of thesubjects left more than one-third of unanswered items.The data are particularly missing for the third item (sat-isfaction with work), whereas the majority of the sub-jects were unemployed or retired. On the other hand, thegroup considered all possible responses and there were nobiased patterns in responding. The differences betweenthe distribution measures are roughly equivalent, exceptbetween Item no. 3 (satisfaction with work) and theothers, while no floor or ceiling effects were observed forthe total and they were below 15% for all items. InTable 2 were given the distributional data of the Q-LES-Q SF items.

Validity

All items, except Item no. 3 (r = 0.18), were significantlycorrelated to the total score and the correlations rangedbetween 0.41 and 0.81. Two last, uncommitted items aboutmedications and overall life satisfaction, were correlated tothe total 0.66 and 0.83, respectfully. Finally, the Q-LES-Q SF score was significantly correlated with the CGIs, PGIsand CGIi, 0.89, 0.43 and 0.47 respectfully.

Internal consistency reliability, testretest reliability,sensitivity and responsiveness

The internal consistency reliability of the questionnairewas 0.90, while testretest reliability was 0.93. Fifty-foursubjects were retested, as the subjects whose health status

has not changed in any domain since the first assessment,while three subjects had not appeared to the testing. Testretest reliability of Item no. 15 was 0.75 and 0.80 of Itemno. 16.

In Table 3 were given the descriptive data of the changeand unchanged group and in Table 4 the responsivenessparameters. The SDC of the measure is almost 6.5, whilethe MID almost nine. The Q-LES-Q SF is able to detectchanges in QOL in nearly 80% (sensitivity to change) ofthose who claimed that there was change during the followup, while it detects 100% the absence of QOL changewhen there was no real change (specificity to change).

Table 2Distributional data of the Q-LES-Q SF items (n = 57)

Items M SD

Skewness Kurtosis

Statistic Standard error Statistic Standard error

1. physical health 3.07 1.24 -0.37 0.316 -0.94 0.622. mood 2.86 1.11 -0.36 0.316 -0.98 0.623. work 2.13 0.51 0.45 0.316 3.79 0.624. household activities 3.16 1.01 -0.01 0.316 -0.63 0.625. social relationships 2.73 1.16 0.19 0.316 -0.73 0.626. family relationships 3.25 1.18 -0.44 0.316 -0.66 0.627. leisure time activities 2.96 1.05 -0.31 0.316 -0.65 0.628. ability to function in daily life 2.91 1.23 0.11 0.316 -1.07 0.629. sexual drive. interest and/or performance 2.75 1.18 -0.25 0.316 -1.2 0.62

10. economic status 2.34 1.15 0.51 0.316 -0.67 0.6211. living/housing situation 3.17 1.23 -0.51 0.316 -0.73 0.6212. ability to get around physically without feeling dizzy or falling 3.18 1.23 -0.23 0.316 -0.93 0.6213. your vision in terms of ability to do work or hobbies 2.88 1.17 0.18 0.316 -0.91 0.6214. overall sense of well-being 2.80 1.02 0.12 0.316 -0.7 0.62Row total (114 item) 37.27 9.28 -0.67 0.316 0.53 0.6215. medication 3.55 0.94 -0.33 0.316 -0.63 0.6216. overall life satisfaction and contentment 3.04 1.08 0.14 0.267 -0.82 0.53

Q-LES-Q SF, The Quality of Life Enjoyment and Satisfaction Questionnaire Short form.

Table 3Total Q-LES-Q SF score at baseline and the 4-week follow up ofthe groups

GroupBaseline scoreM (SD)

Follow-up scoreM (SD)

Changed, n = 14 33.57 (6.24) 42.52 (8.48)Unchanged, n = 22 45.02 (10.92) 44.76 (11.5)

Q-LES-Q SF, The Quality of Life Enjoyment and SatisfactionQuestionnaire Short form.

Table 4Responsiveness parameters for the Q-LES-Q SF

Parameter Value

Standard error of measurement (SEM) 2.74, 90% CI = 4.49Smallest detectable change (SDC) 6.34Minimal important difference (MID) 8.95Sensitivity to change 78.57%MID proportion 71.43%Specificity to change 100%

Q-LES-Q SF, The Quality of Life Enjoyment and SatisfactionQuestionnaire Short form.



Discussion

This psychometric study of the Q-LES-Q SF examined itsmeasurement properties in a small sample of people withpsychiatric illnesses in Serbia. The study demonstratedthat, as a generic QOL questionnaire, the Q-LES-Q SFpossesses appropriate measurement properties of an evalu-ative measure for assessing QOL changes in individualpatients.

In the entire questionnaire, the response rate was highand the amount of missing data was small. The meanvalues were roughly equivalent, as if the standard devia-tions, and no floor or ceiling effects were observed. Thedistribution of the data has a negative skewness in a major-ity of the items, although not significant, and a negativekurtosis, both indicating the observations clustered less.Together, the results revealed the Q-LES-Q SF is a feasiblemeasure, with good acceptability of the concept measured,i.e. life enjoyment and satisfaction, but it would ratherdetect positive states within the concept. Nevertheless, itemno. 3 (satisfaction with work) significantly differed fromthe others, which was possible to explain by a high rate ofthe group unemployment. This item is suspected of havinglesser importance for clinical, routine evaluations, whichwill be explored with the future use of the measure.

The multivariable analysis showed the questionnairepossesses appropriate convergent and criterion validity, aswell as internal consistency reliability, for a measure to beused in the clinical settings, but these parameters deservemore explorations. First, except Item no. 3 (satisfactionwith work), all items correlated significantly to the totalscore, but the correlations are substantially different amongthe items, showing the amount of information providedto the total score is different for each item (Williams &Naylor 1992). This indicates that some items are morerelevant or superior in reporting QOL than others are,which is best possible to examine using factor analysis.Factor analysis could identify the underlying constructs ofthe items, to sort them in subscales and to equalize theimportance (Ware & Gandek 1998, Fayers & Machin2007).

Second, the correlations with the Global Clinical Indexindicate the Q-LES-Q SF is valuable for evaluating illnessseverity, but its value shall be explore in depth for peoplewith different psychiatric conditions (Endicott et al. 1993).Finally, the internal consistency reliability of the Q-LES-Q SF is high, 0.90, what pictures high homogeneity amongthe items in measuring the intended concept, consistency ingiving a response across the items, but also might indicateredundancy among the items (Streiner & Norman 2008).The internal consistency should be also evaluated usingfactor analysis.

The analysis of testretest reliability, sensitivity andresponsiveness confirmed the appropriateness of theQ-LES-Q SF for evaluative purposes (Fayers & Machin2007). First, the Q-LES-Q SF testretest reliability is high,0.93, and this is appropriate for individual comparisons,implying its stability in repeated assessments (Streiner &Norman 2008). Second, the approach used here to evaluatethe sensitivity and responsiveness to change is suitable formeasures used in clinical practice (Wyrwich et al. 1999, deVet 2001, Schmitt & Di Fabio 2004). When the SEM isconsidered for an instrument, clinicians will be aware ofthe amount of the measurement error, while the SDC willguide them how much an individual has to change to bejudged as having really changed. Appling this to theQ-LES-Q SF, the SEM is 2.74 points of the total (with4.49 in 90% confidence interval), while the SDC is 6.34,meaning that a clinician should consider the individualscore to be true score 4.49 and that individual has tochange at least 6.34 points on the total, to be judged ashaving really changed. On the same note, whereas the MIDas the smallest difference in the score perceived as beneficialis 8.95, an individual has to change nearly 9 points on theQ-LES-Q SF to be considered as having clinicallymeaningful change. Finally, considering the three respon-siveness indexes, reliable change proportion or sensitivityto change, MID proportion and specificity to change, theQ-LES-Q SF is highly sensitive and specific. Based on thedata, the questionnaire could detect in 80% of the casesthose who have really changed in their QOL according tothe external criteria, and could in 100% exclude those whohave not really changed.

Nevertheless, we should be aware that the above param-eters, although robust and trustworthy, do not necessarygeneralize to all situations and they were observed in asmall group of patients (Wyrwich et al. 1999, Schmitt & DiFabio 2004). Specially, other external criteria that willserve as anchors of change might be used for MID orclinicians might set a priori the MID of the Q-LES-Q SF(Wyrwich et al. 2009). Additionally, if someone intends touse the measure for group comparisons, he or she musttake into account the group effect, SDCgroup (Terwee et al.2007).

Finally, the measurement characteristics of item no. 15and no. 16, medications and overall life satisfaction, areworth mentioning. The distribution data were satisfactoryand they were highly correlated with the total Q-LES-Q SF, but both possess inappropriate reliability for individualcomparisons. Therefore, the responsiveness was not evalu-ated and these items shall be used with precautions.

Comparing these findings with other validation studiesof the Q-LES-Q, the following was observed. The internalconsistency reliability coefficients of this version or the

D. Stevanovic


general activities scale, an equivalent to the short form, aresimilar between the original (0.90) (Endicott et al. 1993),Czech (0.90) (Mllerov et al. 2001), Hebrew (0.95)(Ritsner et al. 2002), Italian (0.92) (Rucci et al. 2007) andthe Serbian version (0.9). However, the testretest reliabil-ity coefficient is highest for the Serbian Q-LES-Q SF(0.93). Finally, the authors that validated the Q-LES-Q SFfor attention deficit hyperactivity disorder reported thatthe minimally important difference anchored by clinicalratings is 3 points on the raw score, what equals the SEMobserved in this study (Mick et al. 2008). In two studieswith bipolar disorder and generalized anxiety disorder, theminimum clinically important Q-LES-Q (SF) score changewas identified to be 11.89 and 6.80 points, respectfully(Endicott et al. 2007, Wyrwich et al. 2009). These findingsindicate that for measures such as the Q-LES-Q (SF) themagnitude of the MID may vary depending on the specificpopulation of interest and as well as of the purpose ofassessment.

There are several limitations of the study. First, theheterogeneity of the sample (gender, age and diagnoses)could explain high reliability coefficients. Second, a smallnumber of participants did not allowed to study changesin mental health in those who deteriorated duringthe study period. Third, other aspects of validity, like

construct and predictive, were not evaluated and it werenot including other QOL measures, whereas such areunavailable in Serbian. Finally, the sample in overall wassmall and this limit the generalizability of the study toother settings.

In summary, this preliminary analysis of the Q-LES-Q SF demonstrated that it is appropriate QOL questionnairefor routine, clinical assessments of individuals with psychi-atric illnesses. It showed that the measure could producereliable, valid and sensitive assessments of the individualsQOL. However, with awareness of the limitations of thepresent study and the questionnaire itself, further investi-gations will be needed. Future research will be directed toevaluate its measurement properties in samples that aremore homogeneous, with different groups of patients. Inparticular, the issues arose during the study will be alsoanalysed. In this way, the Q-LES-Q SF will evolve into agold standard for QOL evaluations in routine psychiatricpractice, as it is in research.

Acknowledgments and disclosures

I would like to thank Professor Jean Endicott and to allpeople with psychiatric illness included in the study. Theauthor has no competing interests.

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D. Stevanovic


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