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Título: Validity and reliability of the Spanish EQ-5D-Y Proxy version.

Nº de palabras: 4873.

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Resumen

Antecedentes: recientemente se ha desarrollado la versión del cuestionario EQ-5D-Y

Proxy en español, sin embargo hasta la fecha aún no se han analizado sus propiedades

psicométricas. El objetivo de este estudio es analizar la validez y fiabilidad de la versión

española del EQ-5D-Y Proxy.

Método: Una batería de instrumentos auto-administrados que incluía la versión

española del EQ-5D-Y se administró a un grupo de niños y adolescentes españoles de

población general, De forma similar sus padres recibieron una batería con los mismos

instrumentos en sus versiones proxy. Se realizó un análisis de validez y fiabilidad

mediante test-retest.

Resultados: 620 niños y adolescentes participaron en el estudio junto a sus padres. Una

semana después 158 participantes completaron el cuestionario EQ-5D-Y/EQ-5D-Y

Proxy con el objetivo de realizar un análisis de fiabilidad. El acuerdo entre las

respuestas del test y re-test fue superior al 88% en ambas versiones del EQ-5D-Y. Las

correlaciones con otras medidas de calidad de vida indicaron una validez convergente

similar a la observada en el estudio internacional de validación del EQ-5D-Y. El

acuerdo entre las versiones auto-administradas y proxy osciló entre el 72.9% y 97.1%.

Conclusión: Los resultados obtenidos indican la validez y fiabilidad de la versión proxy

del EQ-5D-Y.

Palabras clave: Adolescentes; Niños; EQ-5D-Y; Medida; Calidad de vida.

ABSTRACT

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Background: The Spanish EQ-5D-Y proxy version has been recently developed but to

date its psychometric properties has not been analysed. The aim of this study is to test

the validity and reliability of the Spanish EQ-5D-Y proxy version.

Methods: A core set of self-reported instruments including the Spanish version of the

EQ-5D-Y was administered to a group of Spanish children and adolescents drawn from

the general population. A similar core set of internationally standardized proxy

instruments including the EQ-5D-Y proxy version were administered to their parents.

Psychometric characteristics of validity and reliability were analysed.

Results: 620 children and adolescents and their parents participated in the study. One

week later, 158 participants completed the EQ-5D-Y/EQ-5D-Y proxy to facilitate

reliability analysis. Agreement between test-retest scores was higher than 88% for EQ-

5D-Y self-reported and proxy version. Correlations with other self-rated health

measures indicated similar convergent validity to that observed in the international EQ-

5D-Y validation study. Agreement between the self-reported and proxy versions ranged

from 72.9% to 97.1%.

Conclusion: The results provide preliminary evidence of the reliability and validity of

the EQ-5D-Y proxy version. They support additional studies using the proxy version as

an alternative to the self-reported EQ-5D-Y.

Keywords: Adolescents; Children; EQ-5D-Y; Measurement; Quality of life; Proxy.

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INTRODUCTION

Public health interest in research designed to evaluate Health Related of Quality of Life

(HRQoL) in children and adolescents has increased over the past decade (U. Ravens-

Sieberer, Erhart, M., Wille, N., Wetzel, R., Nickel, J., & Bullinger, M, 2006).

Physicians, researchers and people responsible for health policies all recognise the

importance of measuring HRQoL. Accurate HRQol assessments can add value to the

results of clinical and physiological evaluations by helping to integrate the traditional

‘biomedical model’ of health science with the ‘social or quality of life model’

(Younossi & Guyatt, 1998). The measurement of HRQoL is very helpful for guiding

health-related decisions, and some HRQoL instruments allow cost-utility analysis of

therapies (Theunissen NC, 1998). In addition, the pharmaceutical industry and the US

Food and Drug Administration (FDA) have recognised the need to assess HRQoL in

paediatric patients to determine the effects of pharmacological treatments on the health

of the child (Matza, Swensen, Flood, Secnik, & Leidy, 2004).

Currently there are some generic tools that measure HRQoL in children and adolescents

who are at least 8 years-of-age; these are based on self-completed questionnaires such

as KIDSCREEN (U. Ravens-Sieberer et al., 2005), PedsQLTM (Varni, Burwinkle, &

Lane, 2005; Varni, Burwinkle, Seid, & Skarr, 2003) or EQ-5D-Y (Wille et al., 2010).

All have been translated, and the Spanish language versions have been validated (Gusi,

Badia, Herdman, & Olivares, 2009; Roizen et al., 2008; Tebe et al., 2008). However the

assessment of HRQoL in children and adolescents with physical or mental problems, as

well as in those who cannot read or write, requires the use of proxy instruments, which

allow necessary information to be obtained from their parents, caregivers, or physician.

Additionally, proxy instruments are also useful for assessing HRQoL in children and

5

adolescents with low socioeconomic status. The children in this population may have a

low level of comprehension; therefore, parental assistance is needed to complete the

HRQoL assessment (Eiser & Morse, 2001; Roizen et al., 2008).

Some of the generic instruments frequently used to assess HRQoL in children and

adolescents already have proxy versions (e.g., KIDSCREEN and PedsQLTM) (Varni,

Limbers, & Burwinkle, 2007). In those instruments, the information provided by parents

has proved both valid and reliable (Robitail et al., 2007; Varni et al., 2007). Information

provided by children, particularly in longitudinal studies, may be less consistent than

that provided by their parents because of changes in attitudes, skills, and priorities

associated with normal development (le Coq, Boeke, Bezemer, Colland, & van Eijk,

2000).

The EQ-5D-Y for children and adolescents has the same characteristics as the original

EQ-5D version for adults. It is short, easy to administer, and provides scores for

different health dimensions as well as an index value that can be used to assess health

status. It is also useful for health economic analysis (U. Ravens-Sieberer et al., 2010).

However, a validated proxy version of this instrument is not yet available in Spanish.

After analysing the expected benefits of a proxy version, a group working with the

EuroQol-Group, which developed the EQ-5D-Y (Wille et al., 2010), developed an

English language EQ-5D-Y proxy version that can be translated and validated in other

languages. The Spanish EQ-5D-Y proxy version has become available recently

(Olivares, Perez-Sousa, Gozalo-Delgado, & Gusi, 2013), and the objective of this study

was to validate it in children and adolescents from 6 to 18 years-of-age in the general

population.

METHODS

Participant recruitment

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Two primary and four secondary schools in the Extremadura region of Spain agreed to

participate in this study. A letter from the investigators explaining the methodology and

purpose of the study was sent to the parents by each of the schools. Signed written

consent was obtained from all participants.

Inclusion criteria

To participate in the study, a student had to give signed written consent and had to

attend school on the day of the test. In addition, the student had to understand Spanish

well enough to fully answer the battery of questionnaires and to return the battery of

questionnaires.

Data collection

First, the school principal and investigators agreed on a date for data collection. In the

classroom, a member of the research team explained the procedure to follow for the

successful completion of the questionnaires. For children 8 years-of-age or younger,

data were obtained orally by face-to-face interview. Data obtained from children older

than 8 years-of-age were obtained by direct administration of the battery of

questionnaires. The duration varied depending of the age of the students: 1 hour for

children 6–8-years-old and half an hour for students 16–17-years-old. One member of

the research team and a teacher were always in the classroom while the children

completed the questionnaires.

To obtain data from the parents or legal representatives, each child was given a consent

form and a battery of questionnaires for their parents along with instructions on how to

complete the survey. After a couple of days, the returned, completed questionnaires

were collected from the schools. A random code was assigned to each participant to

ensure anonymity during data analysis.

Reliability

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For the purpose of evaluating the reliability of the EQ-5D-Y proxy version, a sample of

participants from the schools with the highest level of participation were invited to

complete the EQ-5D-Y and the EQ-5D-Y proxy version again 1 week later.

Instruments and variables

To examine convergent and known group validity for the Spanish EQ-5D-Y proxy

version, a core set of internationally standardized instruments and variables was

administered alongside the EQ-5D-Y proxy version. The English and Spanish

instruments both have self-reported and proxy versions. The present study used the

same core set as the international validation study of the EQ-5D-Y, which allows for

future cross-cultural comparisons (U. Ravens-Sieberer et al., 2010). The core set

included questions regarding basic socio-demographic information (age, gender, level

of education, migration status), measures of HRQoL and subjective health, and

indicators of mental and somatic health problems.

The EQ-5D-Y: The Spanish version of the EQ-5D-Y (Gusi et al., 2009) and the newly

obtained EQ-5D-Y proxy version consisted of a descriptive section that included five

items asking about mobility (‘walking about’), self-care (‘looking after myself’), usual

activities (‘doing usual activities’), pain and discomfort (‘having pain or discomfort’),

and anxiety and depression (‘feeling worried, sad or unhappy’). Each item included

three problem levels (no problems, some problems, or many problems). The EQ-5D-Y

and EQ-5D-Y proxy also included a graduated Visual Analogue Scale (VAS), on which

the respondent rated his/her or his/her child’s overall health status on a scale from 0 to

100, where 0 represented the worst, and 100 the best health status he or she can

imagine.

KIDSCREEN-27: The generic KIDSCREEN-27 (Ulrike Ravens-Sieberer et al., 2007)

and its proxy version (Robitail et al., 2007) were administered as a cross-cultural

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measure to assess HRQoL in children and adolescents. Its five Rasch-scaled dimensions

provided detailed profile information on physical well-being, psychological well-being,

autonomy and parents, peers and social support, and school environment within the last

week. In addition, the KIDSCREEN-10 Index score provided an overall measure of

global HRQoL using 10 of the KIDSCREEN-27 items (U. Ravens-Sieberer & Group,

2006).

Self-rated health: The general health item asks the respondent how he or she would

describe his or her health in general, and was used as a measure of perceived health

status. Response options were ‘excellent’, ‘very good’, ‘good’, ‘fair’ or ‘poor’. This

question has been used in large international health surveys in children and adolescents

and has been shown to be a valid measure of subjective health (Idler & Benyamini,

1997).

Cantril-ladder: The adapted version of Cantril’s ‘life satisfaction ladder’ (Cantril, 1965)

is used in World Health Organisation surveys of children and adolescents and was

included in the children and parent core set to measure general, subjective life

satisfaction. Respondents were presented with a picture of a ladder with steps ranging

from 0 to 10 and asked to indicate where on the ladder they ‘feel they are standing at the

moment.’ The top of the ladder (10) represented the best possible life and the bottom (0)

represented the worst possible life.

Statistical analysis

To analyse the reliability of the EQ-5D-Y and its proxy version, the percentage of

agreement and Cohen’s kappa coefficients (Cohen, 1968) were calculated to estimate

concordance between test and retest responses in each profile domain. Following Landis

and Koch’s guidelines (Landis & Koch, 1977), a kappa coefficient <0.2 was considered

to represent poor agreement, 0.21–0.40 fair agreement, 0.41–0.60 moderate agreement,

9

0.61–0.80 substantial agreement, and >0.81 almost perfect agreement. The Intraclass

Correlation Coefficient (ICC) (Fleiss, 1973) was calculated to estimate the VAS, and an

ICC >0.7 was considered acceptable.

Convergent validity was analysed by determining Spearman’s rank correlation

coefficients for the EQ-5D-Y and its proxy version and between the previously

validated self-reported and proxy versions of the child HRQoL inventories. Following

Cohen et al. (Cohen, 1988), coefficients from 0.1–0.29 were considered to be low, 0.3–

0.49 to be moderate, and 0.5 or above to be high.

Agreement between self-reported and proxy responses was analysed using percentage of

agreement and kappa coefficients for the EQ-5D-Y and its proxy version dimensions.

Agreements between mother-children, father-children, and mother-father responses

were calculated. A two tailed P-value <0.05 was considered statistically significant.

RESULTS

Frequency of reported problems

A total 1328 people participated in this study: 620 children aged 6–17 years (326 boys

and 304 girls) and 708 parents (442 mothers and 266 fathers) (Table 1).

Table 2 shows the frequency of problems reported by children, mothers and fathers. A

low percentage of problems were reported in all dimensions (high ceiling effect).

‘Having pain or discomfort’ and ‘Feeling worried, sad or unhappy’ were the dimensions

with the most reported problems.

Reliability of the EQ-5D-Y proxy version

A total of 158 children (from 6–12 years-of-age) and 114 parents completed the core set

twice within the allowable interval. The test-retest analysis showed a high percentage of

agreement between the children, fathers and mothers (Table 3). The dimensions

‘Having pain or discomfort’ and ‘Feeling worried, sad or unhappy’ showed slightly

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lower agreement in the retest data, but remained higher than 87%. Kappa coefficients

indicated mostly “substantial” or “almost perfect” agreement. ‘Doing usual activities’

was the only dimension with poor agreement in the mothers’ responses according to the

kappa values.

Convergent validity

The correlations between the EQ-5D-Y and its proxy version with KIDSCREEN-10

Index scores, selected KIDSCREEN-27 dimensions, self-rated general health items and

the life satisfaction ladder are shown in Table 4. Correlations between the EQ-5D-Y

dimensions and selected HRQoL scales were similar for children, mothers and fathers.

Because of the high ceiling effect in ‘Mobility’, ‘Looking after myself’ and ‘Doing

usual activities,’ the correlations between those dimensions and the selected HRQoL

scales were low or very low. The correlations for the ‘Having pain or discomfort’

dimension were low. The highest coefficients in this dimension were calculated for the

KIDSCREEN-10 QoL Index (from 0.20–0.24). The ‘Feeling worried, sad or unhappy’

dimension showed a moderate correlation with psychological well-being for children

and fathers responses in the KIDSCREEN-27, and for children, mothers and fathers in

the KIDSCREEN-10 Index. The strongest correlations were observed for the VAS item

especially with KIDSCREEN-10 Index, the self-rated general health item, and the life

satisfaction ladder.

Agreement between self-reported and proxy responses

The percentage agreement between self-reported and proxy responses is shown in Table

5. A high percentage of agreement was observed in all EQ-5D-Y dimensions (from 89.2

to 97.4%). Agreement between children and parents was very good for the ‘Mobility’,

‘Looking after myself’ and ‘Doing usual activities’ dimensions, ranging from 88.0 to

97.4%. Agreement was somewhat lower for the ‘Having pain or discomfort’ and

11

‘Feeling worried, sad or unhappy’ dimensions (from 72.9% to 81.2%). The level of

agreement was confirmed by the kappa coefficients, although the high ceiling effects in

the EQ-5D-Y’s descriptive system did not allow calculation of the coefficients in some

cases.

DISCUSSION

The main study finding was that the Spanish proxy version of the EQ-5D-Y was reliable

and valid for the general population, and that it showed good agreement with the self-

reported EQ-5D-Y. In addition, the reliability and validity of the self-reported EQ-5D-Y

were consistent with the previous international study that validated the EQ-5D-Y (U.

Ravens-Sieberer et al., 2010). This study used the methodology designed by the

EuroQol Youth Task Force and used in the international EQ-5D-Y validity study. Thus,

it has the advantage of allowing cross-cultural comparison with future studies

performed in other countries.

The feasibility of using the EQ-5D-Y proxy version for the parents of children and

adolescents in the general population was very high, as there were no missing or

inappropriate responses. The problems reported in the responses collected by both the

self-reported and proxy instruments were very low for all dimensions. This is typical for

study samples drawn from the general population, and is in agreement with previous

studies (U. Ravens-Sieberer & Group, 2006). A five-level response choice version of

the EQ-5D has recently been developed (Herdman et al., 2011), which might improve

the ability of the EQ-5D to detect moderate impairments in HRQoL in respondents from

the general population. A five-level response option for the EQ-5D-Y would constitute

further improvement. The highest percentage of reported problems in both the self-

reported and proxy instruments occurred in the ‘Having pain or discomfort’ and

‘Feeling worried, sad or unhappy’ dimensions.

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The high ceiling effect impacted negatively on some of the reliability and validity

analyses. Reliability was analysed according to the percentage of agreement and the

kappa coefficients. The results indicated very high reliability for the percentage of

agreement values for the responses in the EQ-5D-Y in children, mothers and fathers

(87.3 to 100%). ‘Having pain or discomfort’ was the dimension with the lowest score

for the percentage of agreement (89.9 in children, 87.3 in mothers and 88.6% in

fathers). The kappa coefficient showed good agreement for most of the dimensions,

with the highest obtained for the fathers’ responses. Reliability could not be calculated

for the mobility dimension because of the high ceiling effect. These results are similar

to those obtained in the EQ-5D-Y validity study performed in Italy and Spain (U.

Ravens-Sieberer et al., 2010).

Regarding convergent validity, the responses of the mothers and fathers in the EQ-5D-Y

proxy version showed a pattern of association similar to that of the children and

adolescent responses in the EQ-5D-Y self-response version. Those responses were

similar to the other validated instruments for measuring HRQoL in children and

adolescents. As noted in the previous EQ-5D-Y validity study (U. Ravens-Sieberer et

al., 2010), the VAS (an overall measure of global health) showed the highest correlation

with the life satisfaction ladder, the KIDSCREEN-10 Index, and the general health item.

Correlations between the EQ-5D-Y proxy version and other validated HRQoL

instruments were low or moderate in all dimensions, and similar to those seen in the

EQ-5D-Y validity results (U. Ravens-Sieberer et al., 2010). As in that study, a high

ceiling effect impacted negatively on the correlation analysis, primarily in the

dimensions of mobility and usual activities. However, the present analysis revealed

some expected associations, such as those between the ‘Feeling worried, sad or

unhappy’ dimension and the Kidscreen-27 psychological well-being, the life

13

satisfaction ladder, and the KIDSCREEN-10 Index; those between the ‘Having pain or

discomfort’ dimension and the Kidscreen-27 physical well-being and the KIDSCREEN-

10 Index; and between ‘Doing usual activities’ and the life satisfaction ladder.

All participants were healthy children who attended school regularly. None suffered

from a serious health problem. To reduce the high ceiling effect and to evaluate the

discriminant validity of this instrument, it will be necessary to analyse the psychometric

proprieties of the EQ-5D-Y proxy version in a sample of mothers and fathers of

children with health problems.

The agreement between the self-reporting and proxy versions of EQ-5D-Y was high in

all dimensions, particularly for the “mobility”, “self-care” and “usual activities”

dimensions. The lowest agreement among responses was found in the “pain/discomfort”

and “anxiety/depression” dimensions; however, that is to be expected, as these

dimensions have a higher psychological component. The agreement between mothers

and fathers was higher than the agreement between mothers or fathers and children in

all dimensions, showing high reliability between different respondents.

This study has some limitations. All participants were children or parents from the

general population. The performance of the EQ-5D-Y proxy version in specific

populations requires further analysis. Moreover, other important properties, such as

sensitivity to change or age appropriateness, need to be examined in future studies.

Additional studies are also needed to determine the reliability and validity of the EQ-

5D-Y proxy version in populations with various health conditions, as well as studies

exploring its use for economic evaluations. The proxy version could be particularly

useful for children younger than 8 years-of-age, or for those who would have difficulty

responding to the questions in the self-reported version.

CONCLUSIONS

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This is the first study to evaluate the validity and reliability of the EQ-5D-Y proxy

version. The results indicate that it is a feasible, reliable, and valid instrument for

measuring HRQoL in children and adolescents using their parents’ responses. However,

further studies are needed to analyse its psychometric properties in clinical populations,

its sensitivity to change, and its use for economic evaluations.

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Table 1. Participants by age and sex (n=620).

Study Age Boys Girls Total Mothers Fathers

Validation n (%) n (%) n (%) n (%) n (%)

6-7 47 (61.8) 29 (38.2) 76 (12.3) 65 (14.7) 32 (12.0)

8-9 72 (53.3) 63 (46.7) 135 (21.8) 108 (24.4) 74 (27.8)10-11 99 (47.6) 109 (52.4) 208 (33.5) 173 (39.1) 98 (36.8)12-13 41 (48.2) 44 (51.8) 85 (13.7) 45 (10.2) 30 (11.3)14-15 32 (48.5) 34 (51.5) 66 (10.6) 29 (6.6) 18 (6.8)16-17 25 (50.0) 25 (50.0) 50 (8.1) 22 (5.0) 14 (5.3)All 316 (51.0) 304 (49.0) 620 (100) 442 (100) 266 (100)

Reliability6-7 37 (62.7) 22 (37.3) 59 (37.3) 10 (12.7) 2 (5.7)8-9 18 (51.4) 17 (48.6) 35 (22.2) 31 (39.2) 14 (40.0)10-11 27 (52.9) 24 (47.1) 51 (32.3) 18 (22.8) 11 (31.4)12-13 7 (53.8) 6 (46.2) 13 (8.2) 20 (25.3) 8 (22.9)All 89 (56.3) 69 (43.7) 158 (100) 79 (100) 35 100

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Table 2. Percentages of reported problems in the EQ-5D-Y Children(n=620)

Mothers(n=442)

Fathers(n=266)

% n % n % nMobility (walking about)No problem 96.8 600 96.8 428 97.7 260Some problem 2.6 16 3.2 14 2.3 6A lot of problem 0.6 4 0.0 0.0 0.0 0.0Missing values 0 0 0 0 0 0Looking after my selfNo problem 96.6 599 95.2 421 96.2 256Some problem 3.1 19 4.8 21 3.8 10A lot of problem 0.3 2 0.0 0.0 0.0 0.0Missing values 0 0 0 0 0 0Doing activities usualNo problem 92.7 575 94.6 418 95.1 253Some problem 6.1 38 5.0 22 4.9 13A lot of problem 1.0 6 0.5 0.3 0.0 0.0Missing values 0 0 0 0 0 0Having pain or discomfortNo problem 84.2 552 81.0 358 85.7 228Some problem 15.0 93 18.8 83 14.3 38A lot of problem 0.8 5 0.2 1 0.0 0.0Missing values 0 0 0 0 0 0Feeling worried, sad or unhappyNo problem 79.8 495 83.7 370 86.8 231A bit 18.9 117 15.8 70 13.2 35Very 1.1 7 0.5 3 0.0 0.0Missing values 0 0 0 0 0 0

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Table 3. Reliability of EQ-5D-Y and EQ-5D-Y ProxyEQ-5D-Y

Children (n=158)EQ-5D-Y ProxyMothers (n=79)

EQ-5D-Y ProxyFathers (n=35)

KappaCoefficient

Agreement(%)

KappaCoefficient

Agreement(%)

KappaCoefficient

Agreement(%)

Mobility (walking about) 0.556* 95.0 0.661* 98.7 # 100

Looking after myself 0.882* 97.5 0.475* 94.9 1.000* 100

Doing usual activities 0.894* 97.5 0.260* 93.7 1.000* 100

Having pain or discomfort 0.679* 89.9 0.626* 87.3 0.643* 88.6Feeling worried. sad orunhappy

0.810* 91.8 0.599* 89.9 0.681* 91.4

VAS 0.855* 0.574* 0.659** p<0.05# Unable to calculateVAS: Visual analogic scale

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Table 4. Convergent validity: Spearman-Rank-Correlation between EQ-5D-Y and EQ-5D-YProxy with KIDSCREEN, general health item and life satisfaction ladder (significantcorrelations are given in bold)

aChildren(n=620)

aMothers(n=442)

aFathers(n=266)

Kidscreen-10 HRQOL-indexMobility (walking about) -.090* -.107* -.056Looking after myself .014 -.036 -.136*Doing usual activities -.139** -.065 -.141*Having pain or discomfort -.239** -.201** -.209**Feeling worried, sad or unhappy -.333** -.303** -.278**VAS .469** .371** .345**

Kidscreen-27 Physical well-beingMobility (walking about) -.043 -.099* -.065Looking after myself .061 -.019 -.107Doing usual activities -.111** -.117* -.080Having pain or discomfort -.155** -.127** -.184**Feeling worried, sad or unhappy -.189** -.133** -.222**VAS .428** .251** .210**

Kidscreen-27-Psichological well-beingMobility (walking about) -.051 -.093 -.062Looking after myself -.016 -.107* -.157*Doing usual activities -.129** -.091 -.117Having pain or discomfort -.195** -.122* -.179**Feeling worried, sad or unhappy -.316** -.234** -.309**VAS .316** .273** .190**

Self-rated general health itemMobility (walking about) -.023 -.086 -.067Looking after myself .017 .040 -.017Doing usual activities .028 -.118* -.065Having pain or discomfort -.050 -.176** -.112Feeling worried, sad or unhappy -.060 -.175** -.090VAS 336** .211** .237**

Life satisfaction ladderMobility (walking about) -.048 -.093 .011Looking after myself -.076 -.011 -.197**Doing usual activities -.132** -.151** -.255**Having pain or discomfort -.170** -.169** -.098Feeling worried, sad or unhappy -.246** -.232** -.236**VAS .433** .351** .396**a Missing values were excluded casewise*<p.05**<p.01

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Table 5. Agreement between self-reported and proxy responses.Children-Mothers

(n=442)Children-Fathers

(n=266)Mothers-Fathers

(n=231)Kappa

coefficientAgreement

(%)Kappa

coefficientAgreement

(%)Kappa

coefficientAgreement

(%)Mobility (walking about) # 95.7 # 97.1 0.558* 97.4Looking after myself # 91.2 # 94.7 0.653* 97.4Doing usual activities # 88.0 # 91.0 0.618* 96.5Having pain ordiscomfort

0.68* 72.9 # 75.1 0.772* 93.5

Feeling worried, sad orunhappy

0.221* 79.0 # 81.2 0.564* 89.2

* p<0.05# Unable to calculate