b.A Quality of Life Research 10: 165-173, 2001 165Jl_[ © 2001 Kluwer Academic Publishers, Printed in the Netherlands.

Comparison of German language versions of the QWB-SA and SF-36evaluating outcomes for patients with prostate disease

D. Frosch 1'2, F. Porzsolt 3, R. Heicappell 4, K. Kleinschmidt 5, M. Schatz 6, S. Weinknecht 7 & R.M. Kaplan 11Department of Family and Preventive Medicine, University of California, San Diego, USA," 2SDSU/UCSDJoint Doctoral Program in Clinical Psychology," 3p_Tchotherapie und Psychosomatische Medizin, UniversitdtUlm; 4Department of Urology, Benjamin Franklin University; 5Department of Urology, University HospitalUlm; 6Department of General Surgery, University Hospital Ulm; 7Department of Urology, Urban Hospital,Berlin, Germany

Accepted in revised form 5 April 2001

Abstract

Background: The quality of well-being scale (QWB) and the Medical Outcome Study 36-item short form(SF-36) are alternative methods for measuring general health outcomes. Few studies compare these ap-proaches against one another and no studies have compared German language versions. Method: AGerman language version of the self-administered quality of well-being scale (QWB-SA) was developedusing forward and back translation methods. The German QWB-SA and a German language version of theSF-36 were administered to clinical population groups with current diagnoses of prostate cancer, benignhyperplasia of the prostate, colon cancer, and rectal cancer. Data were obtained from four German clinics.

In addition to the quality of life measures, data on cancer stage and disease state were obtained. Results:The QWB-SA and SF-36 were highly correlated. The QWB-SA was systematically related to disease state.Those with no symptomatic evidence had the highest scores followed by those who were stable with nometastatic disease and those with metastatic progression. Similar patterns were found for most SF-36 scalesalthough the SF-36 failed to discriminate between those with no evidence of disease and those with stable

disease without metastasis. Conclusions: Both the QWB-SA and SF-36 perform as expected using Germanlanguage translations. Although both measures differentiate patients with metastasis from those withoutsymptoms, the QWB-SA better differentiated those with no evidence of disease from those with stabledisease without metastasis.

Key words: Prostate cancer, Quality of life, Quality of well-being scale, SF-36

Introduction guages. Two examples are the quality of well-beingscale (QWB) [4] and the Medical Outcomes Study

A variety of different methods are available to (MOS) 36-item short form (SF-36) [5]. Valid ad-measure health-related quality of life [1, 2]. Many aptations of quality of life measures allow inves-of these measures are specific to particular illnesses tigators to directly compare samples from differentor diseases. However, there is a continuing need countries, thereby increasing overall sample sizes,

for general or generic measures that can be used and providing the opportunity to examine possiblefor population monitoring, evaluation research, cultural factors in disease processes and treatmentindividual clinical decisions, or as outcome mea- outcomes [6, 7].sures in randomized clinical trials [3]. Some of There are two major approaches to quality ofthese methods are now available in different lan- life assessment: Psychometric and decision theory.

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health. The measure has been given to literally ported a mother tongue other than German. There

hundreds of thousands of respondents and has an were no differences in education between groups.excellent record of reliability and validity [17]. The The majority of the sample completed high schoolraw scoring direction on the scales vary, with (65.0%) and 31.8% reported having completedhigher responses reflecting more favorable health some college. There were significant differenceson some and low score reflecting more favorable between groups in age and time since diagnosishealth on others. The raw score on each scale is of the primary disease. Patients with BPH weretransformed to a percentage-like expression on a oldest (Mean = 68.5 years, SD ---9.0), followed0 100 scale, with higher scores always being 'bet- by prostate cancer patients (Mean = 66.8 years,ter'. No single overall score may be computed, SD = 7.5), and colo-rectal cancer patientsmaking the SF-36 a 'profile' health measure. (Mean=64.9 years, SD=8.7; F(3,272)=2.91,However, summary measures for physical and p < 0.05). Prostate cancer showed the longest timemental health can be computed. The SF-36 is a since diagnosis (Mean = 856.4 days, SD -- 954.5),morbidity-only (live person) measure and unlike followed by colo-rectal cancer patients (Mean--the QWB cannot account for mortality. 802.4, SD = 592.9), and BPH patients (Mean ---

In this paper, we compare the validity of Ger- 379.9, SD = 34.6; F(3,269) = 30.24, p < 0.001).man language versions of the QWB and SF-36 for However, there was no correlation between timeevaluating outcomes of prostate cancer, since diagnosis and scores on the self-administered

version of the QWB (QWB-SA) and all SF-36scales. There was a modest correlation between

Methods days since diagnosis and age (r = 0.17, p < 0.05)suggesting that time since diagnosis was slightly

Participants longer for older patients. There was also a modestcorrelation indicating that time since diagnosis was

In order to examine the psychometric properties of slightly longer for less educated patientsthe German versions of the QWB and the SF-36, (r = -0.20, p < 0.05).the measure was given to four groups of patients.These were: Men previously diagnosed with pros- Measures - quality of well-being scaletate cancer (n = 104), men previously diagnosedwith benign prostatic hyperplasia (n = 90), men This study used the QWB-SA [16]. The QWB-SApreviously diagnosed with colon cancer (n = 41), format is similar to the interviewer version. The

and men previously diagnosed with rectal cancer primary differences are the mode of administration(n = 42). No women were included in this study, and an increased number of mental health itemsParticipants were recruited through four hospital- in the symptom/problem subscale. Initial studies

based clinics in Germany. Urology patients were have demonstrated good psychometric propertiesrecruited from two clinics in Berlin, and one clinic of the QWB-SA [3]. Basic demographic informa-in the city of Ulm in Southern Germany. Patients tion was also obtained.with a history of colon and rectal cancer were re-cruited from a separate clinic in Ulm. The project Translationwas approved by the institutional ethics board atthe University of Ulm. The original English language QWB-SA was

A total of 479 patients were contacted for pur- adapted according to steps outlined by Guillemin,pose of this study. The cumulative response was Bombardier, and Beaton [18]. In the first phase the62.8%. One hundred and fifty-seven prostate measure was translated by four bilingual individ-cancer patients were contacted resulting in a re- uals. All were native German speakers with ex-sponse of 66.2%. One hundred and fifty-five BPH cellent proficiency in English. Two translatorspatients were contacted resulting in a response of were based in the US, and two in Germany. One58.1%. One hundred and twenty-nine colon or individual was a German academic based in therectal cancer patients were contacted resulting in a US. Two individuals were graduate students, oneresponse of 77.3%. Nine participants (3.3%) re- in the US, and the other in Germany. The fourth

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Correlations between Total QWB Scores and SF-36 Subscales

0.8

0.7

0.6

0.5

rv

0.4

O.

0,3

0,2

0.1 a :

PF RP BP GH VT SF RE MH

SF-36 Subscales

Figure 1. Correlations between the QWB-SA and SF-36 subscales.

Among prostate cancer patients the three most (n = 85). These patients are further broken downfrequently endorsed items were 'reduced sexual into those with no symptomatic evidence of dis-interest or performance', 'loss of bladder control, ease (n = 48), those who were stable disease

frequent urination at night, or difficulty urinating', without metastases (n = 24) and those with stableand 'pain, stiffness, cramping, weakness, or metastasis (n = 3) or with disease progressionnumbness in joints or muscles of hands, feet, arms (n = 10). For these analyses the last two groups

or legs', Among BPH and colo-rectal cancer pa- with metastases were combined. There was a sta-tients the most frequently endorsed items were tisticaUy significant linear contrast confirming the'difficulties falling or staying asleep', 'reduced predicted rank order (F(1,82) = 4.18, p < 0.05).sexual interest or performance', and 'taking reed- Figure 3 summarizes SF-36 data by diseaseication, including over-the-counter medication', status. For all SF-36 scales with the exception of

role physical (RP), the group with metastasic or

Psychometric analysis progressed disease scored lower than the other twogroups. However, the SF-36 did not discriminate

The QWB-SA was significantly correlated with between those with no evidence of disease andeach SF-36 subscale. Correlations ranged from those with stable disease without metastasis. Lin-0.28 for General Health Perceptions (GH) to ear contrasts were non-significant for all SF-36

0.67 for Physical Functioning (see Figure l). As subscales.expected, SF-36 subscales were highly intercorre- Typically the QWB-SA analysis uses only thelated, symptom or problem with the lowest weight.

Figure 2 compares QWB-SA scores among pa- However, considerably more symptom data aretients diagnosed with prostate cancer and for collected and are rarely analyzed. In order towhom data on disease progression were available take advantage of the symptom data, we used

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0.10 between prostate cancer and rectal cancer inD

ProstateCancer comparison to BPH and colon cancer. Table 1

summarizes the means for the groups and showse- 0.05- comparisons for the three specific hypotheses.

HypothesisI wasbest supportedfor the GHa) scale of the SF-36. Hypothesis II was not sup-

0.00 '_ ported by the QWB or any of the subscales of the"_ BPI-,,., SF-36.The strongestfindingswerein relationtoC

hypothesisIII. For the RP, VT, and SF scales-0.05 prostate cancer and rectal cancer patients weretl

colorecta_Canoer significantly lower than patients with BPH andthose with colon cancer.

-0.10 . j • , , • , , , .-0.6 -0.4 -0.2 0.0 0.2 0,4 0.6

UrologicalDiscussion

Figure 4. Group eentroids in the space created by the two

discriminatefunctions. The SF-36 and the QWB-SA are alternative

methods for evaluating health-related quality ofLastly, for each quality of life scale, four groups life in patients with cancer. Evidence from this

were compared: prostate cancer (n = 104), BPH study suggests that both the QWB-SA and SF-36(n = 88), colon cancer (n = 41), and rectal cancer perform as expected when using German language(n = 42). These groups were compared on the translations. Some evidence suggests that theQWB-SA and the eight SF-36 scales. The four scales can discriminate among patients with dif-groups yielded three degrees of freedom for corn- ferent types of cancer or benign hyperplasia of theparison. These degrees of freedom were used to prostate. However, the QWB-SA differentiatestest three specific hypotheses. Hypothesis I sug- levels of prostate cancer severity. The SF-36 alsogested that there would be a difference between performs appropriately, although differences be-prostate disease and colon or rectal disease. The tween patients with no evidence of disease andtest compared the prostate cancer and BPH groups stable disease are more difficult to detect.against the colon and rectal cancer groups. The Our results also suggest that the QWB-SAsecond hypothesis considered whether prostate symptom scales can provide valuable information.cancer was different from the other three condi- Discriminant function studies suggest that pros-tions. The third hypothesis evaluated differences tate cancer and colo-rectal cancer patients are

Table 1. Comparison of groups for QWB and SF-36

Variable Prostate cancer BPH Colon cancer Rectal cancer Hypothesis

(n = 104) (n = 88) (n = 41) (n = 42)I II III

Age* 66.81 (7.52) 68.48 (8.97) 66.20 (8.31) 63.55 (8.97) N/A N/A N/A

QWB-SA 0.61 (0.15) 0.63 (0.15) 0.66 (0.14) 0.61 (0.16) 0.37 0.17 0.08

PF 72.I7 (25.67) 73.27 (26.43) 73.83 (23.83) 65.79 (26.27) 0.40 0.72 0.19

RE 70.20(39.86) 80.49(36.65) 82.46(20.91) 73.68(43.26) 0.61 0.09 0.07

RP 55.81 (41.78) 70.73 (40.60) 65.63 (41.48) 41.44 (43.21) 0.09 0.53 0.01

SF 76.68 (26.36) 81.32 (24.92) 82.32 (20.91) 73.8l (26.88) 0.78 0.44 0.05

VT 54.40 (19.19) 58.59 (22.67) 56.80 (20.60) 49.33 (20.53) 0.22 0.85 0.04

BP 62.35 (38.53) 65.08 (36.69) 69.07 (37.67) 57.91 (40.52) 0.96 0.73 0.17

GH 53.80 (10.19) 53.54 (9.38) 51.35 (11.41) 50.62 (10.45) 0.05 0.14 0.86

MH 69.69(21.42) 75.22(18.70) 73.74(20.22) 72.33(17.54) 0.83 0.12 0.20

*p < 0.05.

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