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Quality of life and needs for care of patients with schizophrenia
Meijer, C.J.
Publication date
2005
Link to publication
Citation for published version (APA):
Meijer, C. J. (2005). Quality of life and needs for care of patients with schizophrenia.
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Qualityy of Life in schizophrenia measured by the
MOSS SF-36
andd the Lancashire Quality of Life Profile:
aa comparison
C.J.. Meijer
A.H.. Schene
M.W.J.. Koeter
Publishedd in Acta Psychiatrica Scandinavica
S u m m a r y y
O b j e c t i v e e
Too compare two Quality of Life (QoL) instruments on reliability, feasibility and conceptual overlapp in a group of outpatients with schizophrenia.
M e t h o d d
Thee Lancashire Quality of Life Profile (LQoLP) and the MOS SF-36 were used to assess the QoLL of 143 schizophrenic outpatients.
3 22 Results
Feasibilityy and reliability for both instruments were satisfying. Second order factor analysis onn ten LQoLP and eight MOS SF-36 scales resulted in three factors: one health related QoL factorr and two general QoL factors: an internal and an external factor.
Conclusion n
QoLL measures in schizophrenia studies are not exchangeable. Validity of a specific QoL instrumentt depends upon the purpose of the study. The LQoLP allows suggestions for spe-cificc improvements in mental health care for long term psychiatric patients. The SF-36 is a goodd choice when comparison with other patient groups on health related QoL is relevant.
2 . 11 I n t r o d u c t i o n
Becausee of their severe and persistent nature disorders like schizophrenia have major consequencess for the general health, functioning, autonomy, subjective well being and life satisfactionn of those who suffer from it ( 1 , 2). To assess these diverse consequences the conceptt Quality of Life (QoL) was introduced, first in general medicine, and from the early eightiess also in psychiatry.
Althoughh QoL proves to be difficult to define quite a number of QoL measures have been developedd to describe populations, to evaluate community programs or to be used as out-comee measures in clinical trials (3-6). These measures differ on the following characteris-tics:: measuring objective or subjective QoL; being administered as interview or self report questionnaire;; being generic or disease specific; focussing on the consequences of disease (healthh related) or on satisfaction with life in general; and finally covering multiple domains orr overall QoL.
Duringg the eighties the subjective domain specific life satisfaction approach became the mostt popular in psychiatry. Examples of widely used instruments developed in that tradition aree the Lehman Quality of Life interview (3) and the Lancashire Quality of Life Profile (7, 8).. More recently however shorter, generic Health Related Quality of Life (HRQoL) question-nairess like the Nottingham Health Profile (9) and the Medical Outcome Study Short Form-366 Health Survey (10) became popular in studies with chronic psychiatric patients. Also diseasee specific HRQoL instruments like the Self-report Quality of Life Measure for people withh Schizophrenia (5) have recently been developed.
Givenn their different background, the choice for a specific QoL instrument may have serious implicationss for outcome. In most studies arguments for the choice of an instrument are nott made explicit however. So far it is not clear to what extent these different approaches measuree a common underlying concept and in what sense QoL is related to functioning inn chronic psychiatric populations. In this study we will compare two frequently used and welll established measures - the SF-36 and the Lancashire Quality of Life Profile - in a populationn of 143 patients with schizophrenia. Comparisons are made on 1. feasibility, 2. reliability,, 3. conceptualisation and 4. relation with overall functioning as rated by a profes-sionall caregiver.
2 . 22 Method Patients s
Inn a two-step procedure 143 patients with schizophrenia (ICD F20) aged 18-65 inclusive weree randomly selected. In the first step an administrative prevalence sample was identified fromm the caseloads from specialist mental health services (in-patient, outpatient and com-munity)) in two regions in the Netherlands: an urban region (Amsterdam SouthEast) and a rurall region (West Friesland). Patients needed to have been in contact with mental health servicess during the three-month period preceding the start of the study.
Amsterdamm subjects were also part of the EPSILON study of schizophrenia in five European countriess (11). We used the same exclusion criteria in both sites: patients receiving exten-dedd in-patient treatment episodes for longer than one year; current residence in pr son; thee presence of coexisting learning disability, primary dementia, another severe organic
disorderr and not speaking the Dutch language. In the second step diagnoses were confirmed byy research staff on the basis of case notes and clinician information using the Item Group Checklistt (IGC) of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) (12).
I n s t r u m e n t s s
TheThe Medical Outcome Study 36 Item Short Form (SF-36)
Thee Medical Outcome Study 36 Item Short Form (SF-36) (10) is a 36-item self report ques-tionnaire.. It addresses eight health domains:
-- physical functioning (PF): e.g. impairment in physical activities like climbing a stairs or carryingg groceries
3 44 - role physical (RP): role limitations because of physical problems, e.g. not able to work becausee of physical problems
-- bodily pain (BP): e.g. suffering from pain, or being restricted by this
-- general health (GH): e.g. the evaluation of general health and expectations about future health h
-- vitality (VT): e.g. a lack of energy or feeling tired
-- social functioning (SF): e.g. being less capable of keeping up contacts with family or friends becausee of emotional or physical problems
-- role-emotional (RE): role limitations because of emotional problems, e.g. being restricted inn achievement or amount of time spent on work or other activities because of emotional problems s
-- mental health (MH): emotional well being, e.g. suffering from depressive mood or sad-ness s
Thee SF-36 represents the 'subjective - self report - generic - multidimensional - health related'' approach to QoL measurement. The SF-36 has been extensively used and tested forr its psychometric properties in many groups of patients with chronic illness and has beenn shown to have good reliability and validity (13). In spite of the fact that patients with schizophreniaa might suffer from cognitive deficits, psychometric properties (test retest re-liabilityy and internal consistency) of the instrument were found to be good in this group as welll (14,15). The eight dimensions of the SF-36 can be visualised as a health profile. Apart fromm these dimensions a Physical Component Summary Scale and a Mental Component Summaryy Scale can also be constructed (16).
TheThe Lancashire quality of Life Profile
Thee Lancashire Quality of Life Profile (LQoLP) is a structured interview especially developed forr people with serious mental illness (7). It focuses on satisfaction with life on different life domainss relevant for this group. It comprises specific domains as well as an overall quality off life score. A person is asked to rate his satisfaction on most items on a 7-point-scale, rangingg from "can't be worse" to "can't be better". In an earlier study we used concept map-pingg to explore the QoL concept in relation to long-term mental illness (17). In this study wee found that some additional domains like autonomy, sense of purpose, inner experience andd intimate relationships were also of great importance from the patient's point of view. For thatt reason the Life Regard Index (18) with the two subscales 'Framework' and 'Fulfilment' coveringg that type of domains was added (6).
Thee extended Dutch version of the LQoLP contains the following subscales: -- satisfaction with health
-- satisfaction with living situation -- satisfaction with family relations -- satisfaction with finances -- satisfaction with safety
-- positive and negative self esteem: the Rosenberg 10-item Self-bsteem Scale ( 1 9 ) , measu-ringg the individual's sense of personal worth
-- framework: part of the Life Regard Index (20, 18), assessing the degree to which an in-dividuall can envision his/her life as having some meaningful perspective
-- fulfilment: idem but assessing whether an individual has derived a set of life-goals from it
Thee LQoLP represents a 'combined subjective and objective interview disease specific -multidimensionall - satisfaction with life in general' approach to the measurement of QoL. Reliabilitiess of the LQoLP domains were found to be moderate to sufficient (6). The extended Dutch versionn of the LQoLP was administered by trained interviewers (three psychologists and three docto-rall students in psychology) and had a mean administration time of 45 minutes (SD=13 minutes).
TheThe Global Assessment of Functioning Scale
Thee Global Assessment of Functioning (21), is a measure of'psychological, social and oc-cupationall functioning' as rated by a professional caregiver. In this study the GAF was rated byy a psychiatrist or community psychiatric nurse who had been in regular contact with the patientt for the last period. One score is given on a scale ranging from 1 to 100, higher scoress indicating better functioning.
Statistics s
Cronbach'ss alphas and average inter-item correlation coefficients were used to assess the reliabilityy of the SF-36 subscales and the LQoLP domains. Cronbach's alpha is a function of bothh mean inter item correlation and the number of items in a subscale. To make reliability estimatess comparable, we used Spearman Brown correction.
Too determine conceptual overlap between the subscales and domains of both instruments, secondd order factor analysis was used (PCA with VARIMAX rotation). Secondary factor ana-lysiss is used to search for underlying dimensions that may explain the correlations between thee subscales of both instruments (the LQoLP and the SF-36). The association of both in-strumentss with GAF-scores was assessed with Pearson's r. One-tailed p-values were used forr significance testing.
-- pp_ = kp/(l*(k-l)p) with p - reliability of scale with hypothetical number of items, p reliability of the actual scalescale and k = n./n with n = hypothetical number of items and n = actual number of items.
2.33 Results
Feasibility y
Thee vast majority of the patients were both able to fill out the SF-36 and to understand andd answer the LQoLP interview questions (see table 2.1). Of all the SF-36 forms filled out byy the patients 123 (86%) were filled out in such a way that we were able to construct a completee QoL profile. A SF-36 subscale score was regarded as missing when more than halff of the items pertaining to this subscale were missing. Of those 20 patients having mis-singg subscale scores, ten had missing scores on only one subscale while eight had missing subscalee scores on seven or more subscales. The SF-36 subscale "general health' was most 3 55 frequently missing.
Thee LQoLP comprises a reliability rating on which the interviewer has to assess on a 4-point scalee whether the interviewee was able to understand the questions and to give consistent andd valid answers. Fifteen of 138 interviews were assessed by the interviewer as either very orr generally unreliable in this respect. Five patients were not able to complete the LQoLP att all. For five patients both the LQoLP and the SF-36 were regarded as either unreliable orr missing.
TableTable 2.1 Feasibility of the 5F-36 and the LQoLP in patients with schizophrenia (N =143)
________ , __ . _ , _ ... ________
Missingg Missing no** IM Cum. % N Cum. %
00 123 86.0 Interviews regarded as reliable 123 86,0 11 10 93.0 Interviews regarded as unreliable IS 96.5 22 1 93.7 Interviews missing 5 100.0 33 1 94,4 44 0 94.4 55 0 94.4 66 0 94.4 77 2 95.8 88 6 100.0
NumberNumber of missing SF-36 scales
Reliability y
Reliabilitiess for the SF-36 subscales ranged from 0.71 ('social functioning') to 0.89 ('physi-call functioning') (see table 2.2). Reliabilities of the LQoLP domain scores ranged from 0.58 ('positivee self esteem') to 0.79 ('leisure and social participation' and 'framework').
Whenn comparing the a values for the different scale scores one has to take into account that aa is both a function of the inter-item correlations and the number of items of a subscale. Too get a more valid comparison amongst the scales the Spearman Brown formula was used too calculate the a values of the different subscales in the hypothetical situation that each subscalee comprises 7 items (table 2.2 last column). In this way reliabilities for the different subscaless and domain scores are more comparable. The results show that after Spearman Brownn correction reliabilities were substantially better for subscales and domains containing feww items, such as the LQoLP domains 'family' and safety'.
TableTable 2.2 Reliabilities of the SF-36 and the LQoLP in patients with schizophrenia (n = 143)
Numberr of items" a" r ' " a c " " "
S F - 3 6 6 PF F RP P BP P GH H VT T SF F RE E MH H LQoLP P Health h
Leisuree and social Living g Family y Finances s Safety y Positivee e s t e e m Negativee e s t e e m Framework k Fulfilment t 10 0 4 4 2 2 5 5 4 4 2 2 3 3 5 5 7 7 6 6 4 4 2 2 4 4 2 2 5 5 5 5 10 0 13 3 00 89 0.85 5 0.83 3 0.76 6 0.76 6 0.71 1 0.83 3 0.81 1 0.69 9 0.79 9 0.74 4 0.59 9 0.61 1 0.64 4 0.58 8 0.61 1 0.79 9 0.76 6 0.45 5 0.59 9 0.72 2 0.39 9 0.45 5 0.55 5 0.52 2 0.46 6 0.24 4 0 . 4 1 1 0.41 1 0.42 2 0.33 3 0.47 7 0 . 2 1 1 0.24 4 0.28 8 0.20 0 0.8G G 0.91 1 0.94 4 0.82 2 0.85 5 0.90 0 0.92 2 0.86 6 0.69 9 0.84 4 0.83 3 0.83 3 0.77 7 0.86 6 0.66 6 0.69 9 0.72 2 0.63 3
NumberNumber of items within the subscales "" * Cronbach 's alpha
Average inter-item correlation
* * * ** Reliabilities after Spearman Brown correction
S F - 3 66 and LQoLP: conceptualisation
AA second order factor analysis (principal components analysis with VARIMAX rotation) on thee 10 LQoLP domains and the 8 SF-36 subscales revealed 3 factors (table 2.3). The first factorr was named health-related QoL with substantial factorloadings for all SF-36 subsca-les.. The LQoLP domain 'health' also loaded high on this factor. The second factor referred too more internal and non-material aspects of QoL, with substantial factorloadings for the LQoLPP domains 'positive self esteem', 'negative self esteem', 'framework', 'fulfilment' and alsoo 'satisfaction with health' and 'satisfaction with leisure and social participation'. The thirdd factor reflected more external and material components of7 QoL. It included subjective
evaluationss of satisfaction with 'living arrangements', 'family', 'finance' and 'safety'.
Factorloadingss suggest that the SF-36 and LQoLP measure distinct aspects of QoL. All SF-36 scaless had highest loadings on the first factor and all LQoLP domains had highest loadings onn the second or the third factor. Some subscales of the SF-36 ('vitality', 'general health' andd 'mental health') also had substantial loadings on the second factor. Only one LQoLP domainn ('health') had a substantial factorloading on the first factor. The SF-36 Physical Componentt and Mental Component Summary Scales had a substantial correlation with the firstt factor ( 0 . 7 1 and 0.72, respectively). Both SF-36 summary scales correlated weakly withh the second factor (0.24 and 0.26, respectively) and the third factor (-0.11 and 0 . 3 1 , respectively). .
AA two-factor solution corroborated this finding (see table 2.3). The subscales of the SF-36 andd the domains of the LQoLP were separated, except for the LQoLP domain 'health', which hadd a higher loading on the first factor.
TableTable 2.3 Second order factor analysis on SF-36 subscales and LQoLP domains: three and two-fac-tortor solutions (N=108) 3 8 8 S F - 3 6 6 PF F RP P BP P GH H VT T SF F RE E MH H L Q o L P P T h r e e e - f a c t o r r s o l u t i o n * * Factor r 0 . 5 6 6 0 . 7 7 7 0 . 6 0 0 0 . 6 3 3 0 . 5 8 8 0 . 7 8 8 0 . 7 7 7 0 . 5 6 6 1 1 Factorr 2 0.37 7 0.14 4 - 0 . 0 5 5 0.44 4 0 . 5 3 3 0 . 2 6 6 0 . 0 6 6 0.45 5 Factorr 3 - 0 . 2 1 1 - 0 . 0 7 7 0.26 6 0.12 2 -0.08 8 0.04 4 0,22 2 0.28 8 T w o - f a c t o r r s o l u t i o n * * * Factorr 1 0 . 6 7 7 0 . 7 8 8 0 . 5 1 1 0 . 7 1 1 0 . 7 2 2 0 . 8 1 1 0 . 7 1 1 0 . 6 2 2 Facto o 0.05 5 - 0 . 0 4 4 0.07 7 0.32 2 0.26 6 0.12 2 0 . 1 1 1 0.45 5 Health h
Leisuree and social Living g Family y Finances s Safety y Positivee e s t e e m N e g a t i v ee esteem F r a m e w o r k k F u l f i l m e n t t 0.47 7 0.28 8 0.06 6 0.09 9 0.00 0 0.07 7 0.28 8 0.08 8 0.06 6 0.24 4 0 . 5 7 7 0 . 6 8 8 0.24 4 0.27 7 0.22 2 - 0 . 0 7 7 0 . 6 9 9 0 . 5 9 9 0 . 8 1 1 0 . 7 7 7 0,19 9 0.36 6 0 . 6 1 1 0 . 3 9 9 0 . 6 2 2 0 . 6 8 8 0.23 3 0.39 9 - 0 . 0 4 4 0.24 4 0 . 5 8 8 0 . 4 1 1 0.03 3 0 . 1 1 1 - 0 . 0 3 3 - 0 . 0 6 6 0.43 3 0.20 0 0.29 9 0.43 3 0.48 8 0 . 7 0 0 0 . 5 8 8 0 . 4 5 5 0 . 5 9 9 0 . 4 1 1 0 . 6 2 2 0 . 6 8 8 0 . 7 2 2 0 . 5 4 4
** Factor loadings of Principal Components Analysis after VARIMAX rotation: three-factor solution
**** Factor loadings of Principal Components Analysis after VARIMAX rotation: two-factor solution boldbold highest loading
Relationn b e t w e e n S F - 3 6 , LQoLP and social functioning
Bothh SF-36 subscales and LQoLP domain scores were only weakly to moderately correlated too overall 'psychological, social and occupational functioning' as measured by the GAF (ta-blee 2.4). The highest correlations with the GAF score were found for the SF-36 subscales 'sociall functioning' and 'mental health' (r = 0.37 and r = 0.38, respectively) and the LQoLP domainss 'health' and 'negative self esteem' (r = 0.33 and r = 0.35). A multiple regression analysiss that was performed to see which SF-36 subscales or LQoLP domains would best predictt the GAF-score showed that only two LQoLP domains predicted GAF score: 'satisfaction withh health' and 'negative self esteem' (F = 12.84 df = 2. 94 p < 0.00, R2 = 0.22).
2 . 44 Discussion
Differentt QoL approaches are used in studies with patients suffering from schizophrenia. This studyy showed that two widely used QoL instruments stemming from different traditions, the LQoLPP and SF-36, can both be reliably used in a sample of (ambulatory treated) patients withh schizophrenia. However, the choice for a particular instrument may have serious im-plicationss for outcome, as the two instruments appear to reflect a distinct underlying QoL construct. .
TableTable 2.4 Correlation coefficients global assessment of functioning (GAF)-scores with 5F-36
subsca-lesles and LQoLP domains
GAF F rr D* SF-36 6 PFF 0.28 0.00 RPP 0.26 0,00 BPP 0.19 0,01 GHH 0.20 0.02 VTT 0.17 0.03 SFF 0.37 0.00 3 9 REE 0.25 0.00 MHH 0.38 0.00 LQoLP P Health h
Leisuree and social participation Living g Family y Finances s Safety y Positivee Esteem Negativee Esteem F r a m e w o r k k F u l f i l l m e n t t 0,33 3 0,18 8 0.04 4 0.12 2 0 . 1 1 1 0.08 8 0.21 1 0.35 5 0.14 4 0.21 1 0.00 0 0.03 3 0.33 3 0.11 1 0.13 3 0.20 0 0,02 2 0.00 0 0.08 8 0.02 2
** p < 0.05; one tailed significance
Sincee the early eighties, at least 10 instruments have been developed to measure QoL in chronicc psychiatric patients (3, 22, 23). Several of these instruments represent a domain-specificc life satisfaction approach, capturing multiple life domains on which people with chronicc psychiatric illness might experience handicaps. The LQoLP is one of the most widely usedd instruments in this tradition.
Inn recent literature however, the 'satisfaction with life in general' approach is questioned (5,, 24, 25). The main problem with this approach is that most of its QoL dimensions are nott necessarily related to mental illness (e.g. 'leisure and social participation', 'living ar-rangements',, 'family relations' and 'financial situation'), but might be influenced by multiple factors.. Further, it was questioned whether these QoL instruments are capable of detecting specificc impairments in functioning and whether they are sensitive to small changes due to (pharmacological)) interventions. Besides most of these instruments are lengthy interviews andd require trained interviewers to administer. Finally some instruments are limited in their psychometricc properties.
Ass a consequence researchers recently started to use 'generic- multi dimensional- health related'' QoL-instruments like the SF-36 (10) in studies with schizophrenic patients ( 5 , 14, 15,, 2 6 - 3 4 ) . The SF-36 has been one of the most widely used of these generic HRQoL-in-strumentss in populations with chronic somatic illness for the last five years. The instrument focusess on aspects of QoL and functioning that are directly related to health.
Consideringg reliability of both instruments in a population of patients with schizophrenia, for thee SF-36 we found satisfactory reliability coefficients comparable to those found by others in
thiss type of population (14, 15). In comparison to results found by Van Nieuwenhuizen et al (6)) with the extended Dutch version of the LQoLP, our reliability coefficients were somewhat lowerr for several domains. The reliability coefficients of the LQoLP in our study are lower forr most domains, except 'leisure and social participation' and 'safety'. An explanation for thesee lower reliabilities might be the more homogeneous character of our group compared too the study of Van Nieuwenhuizen et al. Moderate reliability ratings for the domains 'family relations'' and 'safety' were also found by Van Nieuwenhuizen, who recently started a study inn which the number of items for these domains is extended.
Explorationn of underlying QoL constructs indicated that HRQoL as measured by the SF-36 is 4QQ to be distinguished from life satisfaction as measured by the LQoLP. A distinction between
QoLL components related to mental health and QoL related to physical health was not found orr was less apparent than in somatic groups. A conceptual differentiation between QoL and HRQoLL (or health status) was also brought up by others (35-37). As HRQoL focuses on healthh status and functioning and is expected to be directly influenced by symptoms and disability,, it might be seen as one of the multiple determinants of life satisfaction among otherr factors like personality, social support, environment etc.
Thee distinction between the concepts underlying the two QoL-instruments as we found in thiss study was more pronounced as expected however. The idea that HRQoL measures like thee SF-36 provide an indication of the impact of illness on quality of life assumes that people aree able to make a distinction between health and non-health related components of QoL (38).. In patients with a chronic mental illness this distinction is expected to be more dif-ficultt to make compared to people with chronic somatic illness, because the consequences off schizophrenia often interfere with many life domains and (social) roles. Thus, although ann interconnectedness of HRQoL with other aspects of existence as measured in the LQoLP couldd be expected (such as relationships, income and self-esteem), results indicate that schizophrenicc patients distinguish between health related QoL and life satisfaction. Concep-tuall overlap was found only in domains were some overlap in content was expected, most importantlyy on the QoL domain 'health'.
Twoo alternative explanations might account for the differences found between the instru-ments.. The first alternative explanation for the instruments loading on different factors is methodd variance. The LQoLP is a structured interview and the SF-36 a self report ques-tionnaire.. However, given the fact that the LQoLP does not incorporate an interviewer evaluationn (the scores are patient's evaluation of their QoL) this method effect could only pertainn to the presence of the interviewer itself and possibly a social desirability effect as aa consequence of it.
AA second explanation for the differences found between the instruments might be that life satisfactionn rates tended to be high in this study, irrespective of objective life circumstances. Thiss finding resembles results found in other studies (8, 39, 40). Response shift and active copingg mechanisms as a strategy to re-appraise one's situation and/or deal with changed lifee circumstances are expected to play an important role in the evaluation of one's life sa-tisfactionn (41). HRQoL more often refers to concrete situations or handicaps and therefore iss thought to be less influenced by these processes. HRQoL average scores were found to bee lower for all subscales compared to normal populations. Results of the LQoLP with regard too normal populations will be available within a year from now (P. Huxley: personal c o m m u -nication).. Several studies (using different QoL instruments) have shown however that QoL
scoress of patients suffering from schizophrenia or chronic psychotic disorders are generally higherr than for dysthymia (42) and higher than low income groups of general populations on certainn life domains (43, 44). Larsen and Gerlach (45) found that QoL reported by chronic schizophrenicc patients was almost as high as in the normal American population.
AA three factor solution showed that LQoLP-domains were divided over two factors, distin-guishingg more external and material aspects of QoL (like 'living arrangements' and 'finance') fromm internal and autonomy related aspects of QoL (like 'satisfaction with health', 'self esteem'' and 'fulfilment'). This distinction in part confirms results found by Van Nieuwenhui-zenn (46), who found the 6 life satisfaction domains loading on one factor and the domains selff esteem, framework and fulfilment on another. This means that the distinction between internall versus external and more material QoL-domains appears to be somewhat more pronouncedd in our study.
Thee scales of both instruments correlated only moderately with the Global Assessment of Functioningg Scale, which was confirmed by our multiple regression analysis in which SF-36 andd LQoLP-scales only explained 2 2 % of variance. An explanation might be that a general indicationn of (social) functioning of a patient as given by a clinician is really distinct from and influencedd by other factors than subjective QoL. Another explanation might be that the GAF ass a one-dimensional measure does not give an appropriate indication of social functioning orr that it is not sensible enough to detect aspects of functioning that might influence the lifee quality of patients.
Inn conclusion: this study confirms the importance of a well argumented choice for a particular QoL-instrumentt in groups of patients with chronic mental illness. QoL as measured by the LQoLPP appears to be a concept that is only partly related to health related quality of life as measuredd by the SF-36. Although in many studies arguments for the choice of a particular QoLL operationalisation are not made explicit it is likely that the grounds for such a choice oftenn are more pragmatic than it considers the contents. For example one might prefer a particularr instrument because of its length or feasibility, because it stems from a particular traditionn or because the aim of the study is to compare different populations.
Thee results from this study confirm that apart from the practical grounds for choosing a particularr instrument or operationalisation of QoL, the choice is also one of content. Careful considerationss about what aspects of QoL one aims to capture, and a critical evaluation of thee use of a particular operationalisation in relation to the research questions one wants to answerr deserves careful attention. For example, if one aims at the evaluation of commu-nityy mental health care programs requiring specific recommendations for changes or new developments,, the domain specific life satisfaction approach is more useful. For medical trialss using for instance new anti-psychotic medication on the other hand, one might be moree interested in direct consequences on health and functioning, in which case the SF-36 iss a better choice.
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