2012. Vol.3, No.9, 686-690
Published Online September 2012 in SciRes (http://www.SciRP.org/journal/psych) http://dx.doi.org/10.4236/psych.2012.39104
Copyright © 2012 SciRes.
Agreement between People with Aphasia and Their Proxies on
Health-Related Quality of Life after Stroke, Using the Greek
Maria Ignatiou, Vasiliki Christaki, Evripidis Nicolaos Chelas,
Evangelia Antonia Efstratiadou, Katerina Hilari
Division of Language and Communication Science, City University London, London, UK
Received June 1st, 2012; revised July 2nd, 2012; accepted August 3rd, 2012
Health related quality of life (HRQL) measures are increasingly used to evaluate stroke interventions.
People with severe aphasia after stroke may be unable to self-report on such measures, necessitating the
use of proxy respondents. This study explored the level of agreement between people with aphasia and
their proxies on the Greek Stroke and Aphasia Quality of Life Scale-39 generic version (SAQOL-39g)
and whether this agreement was influenced by proxy levels of depression and carer strain. Methods: Par-
ticipants were people with aphasia (PWA) who were over six months post-stroke and medically stable.
Proxies were nominated by the PWA and had to see them at least twice a week. PWA completed the
Frenchay Aphasia Screening Test and the Greek SAQOL-39g. Proxies completed the Greek SAQOL-39g
proxy version, the General Health Questionnaire-12 and the Caregiver Strain Index. Results: 23 pairs of
people with aphasia and their proxies took part. Proxies rated people with aphasia as more severely af-
fected than they rated themselves. The difference was significant for the overall scale and the physical and
communication domains (p < 0.05); yet the bias introduced by these differences was small to moderate,
with effect sizes ranging from 0.15 to 0.47. The strength of the agreement between people with aphasia
and proxies was excellent for the overall scale and all three domains (ICC = 0.79 - 0.97). The level of
agreement was not associated with carer strain or emotional distress. We conclude that clinicians and re-
searchers can use proxy ratings to evaluate the quality of life of people with severe aphasia but need to be
aware of trends in proxy reporting and take these into account when interpreting data.
Keywords: Proxy; Stroke Outcome; Health-Related Quality of Life; Aphasia; SAQOL-39g
Health-related quality of life (HRQL) is defined as the im-
pact of a health state on a person’s ability to lead a fulfilling life
(Bullinger, Anderson, Cella, & Aaronson, 1993) and generally
incorporates the individual’s subjective evaluation of their phy-
sical, mental/emotional, family and social functioning (Berzon,
Hays & Shumaker, 1993; Hays, Anderson, & Revicki, 1993).
HRQL measures are increasingly used to evaluate healthcare
interventions and they can be particularly useful for people with
chronic conditions (Kartsona & Hilari, 2007). They allow the
clinician to understand and measure the impact of disease on
the patients’ life (Patrick & Erickson, 1993) and to incorporate
the patient’s perspective in clinical decision-making (Mayou &
Bryant, 1993). As a result, clinicians can provide better reha-
bilitation, which can maximize well-being and quality of life
(Royal College of Physicians, 2008).
Stroke is a condition that affects many aspects of HRQL
(Pickard, Johnson, Feeny, Shuaib, Carriere, & Nasser, 2004;
Northcott & Hilari, 2011). Several studies have shown that
people after stroke experience a decline in their quality of life
in terms of depression, physical disabilities, and reduced social
support (Carod-Artal, Egido, González, & Varela de Seijas,
2000). Stroke is the most common cause of aphasia an acquired
language disorder that can affect all language modalities: un-
derstanding what other people say, expressing oneself, and
reading and writing (Chapey, 2008). It is a long-term and life-
changing condition. Aphasia has a profound impact on stroke
survivors’ HRQL (Hilari, 2011). A recent systematic review
reported that emotional distress, reduced level of activities,
increased co-morbidity and severity of communication impair-
ment were predictors of poorer HRQL in people with aphasia
(Hilari, Needle, & Harrison, 2012).
Measures used to evaluate HRQL after stroke should be ac-
cessible to people with aphasia. The most extensively tested
with people with aphasia stroke-specific HRQL scale is the
Stroke and Aphasia Quality of Life scale-39 (Hilari, Byng,
Lamping, & Smith, 2003). The SAQOL-39 is a self-report scale
carried out in an interview format to facilitate people with
aphasia. It covers participants’ perception of how stroke and
aphasia have affected his/her functioning in four domains:
physical, psychosocial, communication and energy. The scale
consists of 39 items each scored on a 5-point scale, with high
scores indicating better HRQL. The SAQOL-39 has also been
evaluated in a generic stroke population, including both people
with and without aphasia, producing the SAQOL-39 generic
version (SAQOL-39g). The SAQOL-39g has exactly the same
items as the SAQOL-39 and it is administered and scored in the
same way, but its items group in three (physical, psychosocial
and communication) rather than four domains (Hilari, Lamping,
Smith, Northcott, Lamb, & Marshall, 2009).
M. IGNATIOU ET AL.
The SAQOL-39g can be used with people with any severity
of expressive language impairment and moderate—mild recap-
tive language impairment (Hilari et al., 2003; Hilari et al.,
2009). Yet, there still are some people with aphasia, those with
severe receptive aphasia who are unable to complete HRQL
scales (Hilari & Byng, 2009). As a result they may be ex-
cluded from stroke-outcomes research, clinical outcome data or
service evaluation (Cruice, Worrall, Hickson, & Murison, 2005).
To prevent this, proxy responders can be used: significant oth-
ers of people with aphasia who complete a HRQL scale as they
think their partner with aphasia would, if they were able to do it
If we are to use proxy respondents to report on the HRQL of
people with such severe aphasia that they cannot report for
themselves, then we need to know how accurate proxies are in
their ratings. Literature on proxy—self-report agreement in
different clinical populations suggests that a) proxy-self report
agreement is better in the longer term because proxies have
been longer exposed to their partners’ symptoms (Pickard et al.,
2004; Sneeuw, Sprangers, & Aaronson, 2002) and b) proxies
tend to report poorer HRQL than the patients report themselves,
but agreement is better for more observable domains (Sneeuw
et al., 2002). Looking at proxy—self-report agreement on
HRQL for people with aphasia, Cruice and colleagues (2005),
used generic HRQL scales and found significant differences.
Still, in line with the generic proxy literature, there was higher
agreement for objective domains (e.g., physical) than subjective
domains (e.g., psychological). Hilari, Owen & Farrelly (2007),
used the SAQOL-39 to address the same question. Although
there were significant differences between people with aphasia
and proxy responses, these differences were small to moderate
(d = 0.2 - 0.5) and correlations between proxy and self-report
scores were high for the overall score and the physical, psy-
chosocial and communication domain (ICC = 0.7 - 0.8). These
findings are important as they suggest that by using a measure
tailored to people with aphasia it is possible for proxy respon-
dents to provide good estimations of the HRQL of their part-
ners with aphasia. However, these findings need to be repli-
cated in different populations.
In terms of factors affecting proxy and self-report agreement
on HRQL post stroke, Knapp and Hewison (1999) unlike other
studies (Williams, Bakas, Brizendine, Plue, Tu, Hendrie, &
Kroenke, 2006) found no effect for patient or proxy mood, but
a significant effect for carer strain, with higher carer strain as-
sociated with discrepancy in assessments. Looking specifically
at people with aphasia, Hilari et al. found no effect for carer
emotional distress or strain (Hilari et al., 2007). The impact of
such variables on proxy and self—report agreement on HRQL
needs further exploration for people with aphasia.
This study aimed to assess proxy—self-report agreement on
the Greek version of the SAQOL-39g (Kartsona & Hilari,
2007). The Greek SAQOL-39g has strong psychometric pro-
perties, with excellent acceptability (minimal missing data; no
floor/ceiling effects), test-retest reliability (ICC = 0.96 scale,
0.83 - 0.99 domains), internal consistency (Cronbach’s alpha
0.96 scale, 0.92 - 0.96 domains), and convergent (r = 0.53 -
0.80 scale; 0.54 - 0.89 domains) and discriminant validity (r =
0.52 scale; 0.04 - 0.48 domains) (Efstratiadou, Chelas, Ignatiou,
Christaki & Hilari, 2012). We expected to replicate the find-
ings of previous research. We hypothesized that proxy ratings
of the HRQL of people with aphasia will correlate highly with
self-report ratings; but proxies will tend to rate people with
aphasia as more severely affected than they rate themselves.
The possible effect of proxies’ high carer strain and emotional
distress on level of agreement was also explored.
Design and Participants
An interview-based survey study was carried out. People
with aphasia were recruited through Speech and Language
Therapy settings in four different cities in Greece and three in
Cyprus. They had to meet the following criteria: a) aphasia due
to a stroke; b) at least 6 months post stroke and medically stable,
c) be able to nominate a significant other to act as a proxy re-
sponder and d) score ≥7/15 on the receptive subtests of the
Frenchay Aphasia Screening Test (FAST) (Enderby, Wood, &
Wade, 1987) which is the cut off score for self-completion of
the SAQOL-39g. The inclusion criteria for the proxies were: a)
see the person with aphasia at least twice a week; b) older than
18 years old and c) no known severe mental health or cognitive
Procedure and Measures
The study obtained ethical approval by the City University
London School of Health Sciences Research Ethics Committee.
Speech and Language Therapy (SLT) in Greece is typically
offered in private settings and, therefore, such settings, known
to provide services to people were aphasia, were approached in
order to find participants. At each site, people with aphasia who
met the eligibility criteria were invited to take part along with
one significant other to act as a proxy. Interviews took place at
the SLT clinic or at the participant’s home. All interviews were
conducted by a Speech and Language Therapist experienced
in working with people with aphasia. First, the receptive sub-
tests of the FAST were completed to ensure participants with
aphasia could self-report on the SAQOL-39g. These subtests
comprise auditory and reading comprehension. Scores range
from 0 - 15 with higher scores suggesting milder aphasia. Then,
the person with aphasia completed the SAQOL-39g in an inter-
view format. As indicated above, scores for each domain and
the overall scale range from 1 to 5 with higher scores indicating
better quality of life. While the person with aphasia was inter-
viewed, proxies completed the following measures by them-
selves: SAQOL-39g proxy version, General Health Question-
naire-12 item (GHQ-12) (Goldberg, 1972) and the Caregiver
Strain Index (CSI) (Robinson, 1983). The GHQ-12 is a measure
of emotional distress. Scores on GHQ-12 range 0 - 12 and
scores ≥ 3 indicate high emotional distress. The CSI is a
13-question tool that measures strain related to care provision.
There is at least one item for each of the following major do-
mains: employment, financial, physical, social and time. Scores
on the CSI range 0 - 13 and positive responses to seven or more
items indicate a greater level of strain.
Descriptive statistics were used to summarize data. Proxy
and self-report agreement was explored by calculating intra-
class correlation coefficients (ICCs). ICC < 0.40 was seen as
indicating poor agreement; 0.40 to 0.75 fair to good agreement,
and 0.76 to 1.00, excellent agreement (Rosner, 2000). Mean
responses of the people with aphasia and their proxies were
Copyright © 2012 SciRes. 687
M. IGNATIOU ET AL.
compared for each domain and the overall SAQOL-39g with
paired-samples t-tests. Effect sizes were calculated by divid-
ing the mean difference scores (proxy minus self-report score)
by the standard deviation of the mean difference scores (Mar-
shall, Hays, & Nicholas, 1994). An effect size of 0.2 was con-
sidered a small bias, 0.5 a moderate bias and 0.8 a large bias
(Cohen, 1998). Independent sample t-tests were used to com-
pare agreement on the SAQOL-39g (mean difference scores) of
those with high versus those with low emotional distress and of
those with high versus those with low carer strain.
Twenty three pairs of people with aphasia and their proxies
took part in the study. Table 1 details their characteristics. The
majority of the people with aphasia were male 19 (83%. They
ranged in age 39 - 81 years, with a mean (SD) = 60.7 (11.2).
Most of them were married/had a partner 20 (87%). Their de-
grees of receptive aphasia on FAST ranged 7 - 15 [mean (SD) =
11 (2.5)]. Most of the proxies were female 20 (87%). They
ranged in age 38 - 75 years, with a mean (SD) = 58.1 (11.8).
The majority 19 (73%) were married/partners of the people
with aphasia. Proxy scores on the CSI ranged 0 - 13 with a
mean (SD) = 7.65 (4.0) and a median of nine. Fifteen (65.2%)
of them were classified as having high carer strain (CSI scores
7 - 13). Scores on the GHQ-12 ranged 0 - 9, with mean (SD) =
4.8 (2.9) and a median of five. Approximately 78% were classi-
fied as having high emotional distress (GHQ-12 scores ≥ 3).
Proxy and Self-Report Agreement
Table 2 presents participants with aphasia (PWA) and prox-
ies mean scores on the SAQOL-39g and its sub-domains, the
difference in mean SAQOL-39g scores (proxy-PWA) and the
agreement statistics (ICC, t tests and effect sizes). The proxy-
PWA difference mean scores were small in all three SAQOL-
39g domains and in the overall scale (–0.08) - (–0.35). How-
ever their standard deviations were comparatively large (0.39 -
0.75). In all three SAQOL-39g domains and the overall scale,
proxies rated PWA as more impaired than PWA rated them-
selves. There was a significant difference between PWA and
proxy reporting for the overall scale (t(22) = –2.31, p < 0.05)
and two of its domains, physical (t(22) = –2.18, p < 0.05) and
communication (t(22) = –2.27, p < 0.05). However, the biases
between PWA and proxies mean scores were small to moderate,
with effect sizes ranging from 0.15 to 0.47.
The strength of the agreement (ICC) between proxies and
PWA was excellent for the overall SAQOL-39g scale (0.96)
and all three domains: physical (0.97), psychosocial (0.89) and
Independent sample t tests were used to evaluate the possible
effect of proxy carer strain and emotional distress on the
agreement. We compared proxy-PWA difference mean scores
on the SAQOL-39g of those with high carer strain (CSI score ≥
7) versus those with low, and of those with high emotional
distress (GHQ score ≥ 3) versus those with low. The results
were not significant.
This study explored the proxy and self-report agreement on
Respondent characteristics: participants with aphasia (n = 23) and their
proxies (n = 23).
Variable PWA n (%) Proxies n (%)
Female 4 (17) 20 (76.9)
Male 19 (83) 3 (11.5)
Mean (SD) 60.7 (11.2) 58.1 (11.8)
Range 39 - 81 38 - 75
Married/had partner 20 (87) 21 (92)
Single 1 (4) 1 (4)
Divorced/widowed 2 (9) 1 (4)
Tim post onset
Mean (SD) 45.7 (35.4) -
Range 9 - 162 -
6 m - 2 y 7 (30) -
2 y - 4 y 8 (35) -
4 y+ 8 (35) -
Relationship to person with aphasia
Spouse - 18 (69.2)
Child - 1 (3.8)
Partner - 1 (3.8)
Other family - 3 (11.5)
GHQ - 12
Mean (SD) - 4.8 (2.9)
Range - 0 - 9
Mean (SD) - 7.7 (4.0)
Range - 0 - 13
FAST: Frenchay Aphasia Screening Test; GHQ-12: General Health Question-
naire-12; CSI: Caregiver Strain Index.
the Greek SAQOL-39g and the possible effect of proxy carer
strain and emotional distress on this agreement. We found no
effect of proxy level of distress or strain on the level of agree-
ment. Proxy scores were significantly lower than the scores of
their partners with aphasia on the overall scale and on two of
the three domains: physical and communication. The standard
deviations of the difference scores were large, showing that
proxy responses may not be a good indicator for self-report
responses at the individual level. At the group level however,
the results were encouraging. Although proxies rated their
partners HRQL consistently lower, the effect sizes were small
to medium (0.15 - 0.47) and they were comparable to those of
other stroke specific HRQL scales, i.e. the Stroke Impact Scale
(SIS) (0.1 - 0.4) (Duncan, Lai, Tyler, Perera, Reker, & Studen-
ski, 2002). Considering that people with aphasia were excluded
from that study and yet comprised the sample in this study,
these results are very positive. They also compare favourably to
Cruice et al.’s findings with people with aphasia and their
Copyright © 2012 SciRes.
M. IGNATIOU ET AL.
Copyright © 2012 SciRes. 689
Comparison of participants’ scores on the stroke and aphasia quality of life scale-39g (SAQOL-39g) (pairs, n = 23).
SAQOL-39g PWA mean (SD) Proxies mean (SD) Proxy-PWA difference mean (SD)ICC t Effect size
Physical 3.38 (1.20) 3.20 (1.22) –0.18 (0.39) 0.97 –2.18* 0.46
Psychosocial 3.28 (0.83) 3.20 (0.88) –0.08 (0.54) 0.89 –0.69 0.15
Communication 3.53 (0.83) 3.18 (0.97) –0.35 (0.75) 0.79 –2.27* 0.46
Overall scale 3.36 (0.77) 3.20 (0.90) –0.16 (0.34) 0.96 –2.31* 0.47
PWA: participants with aphasia; ICC: intra-class correlation coefficient; *p < 0.05.
proxies where effect sizes with the SF-36 (4/8 scores ≥ 0.6 and
up to 1.24) and the Dartmouth COOP Charts (4/9 scores ≥ 0.25
and up to 0.84) were larger (Cruice et al., 2005).
Moreover, proxy and self-report agreement on the Greek
SAQOL-39g as measured by ICCs was excellent (0.79 - 0.97).
These results are promising, given that studies with small sam-
ple sizes (n < 50 pairs) tend to report lower levels of agreement
(Sneeuw et al., 2002). The high agreement in this study could
be attributed to the fact that the SAQOL-39g is a measure spe-
cifically adapted for people with aphasia and thus potentially
more relevant and accessible to them than the scales used in
other studies. It could also be related to the fact that all proxy
raters were relatives of the people with aphasia rather than paid
carers or health care providers. Level of agreement between
patients and health care providers is lower than that between
patients and significant others (Sneeuw et al., 2002). Although
it makes sense to predict that health care providers may be less
aware of patients’ views on their HRQL than family members,
this is not always the case in other clinical groups (Grassi, In-
delli, Maltoni, Falcini, Fabbri, & Indelli, 1996; Sneeuw, Aaron-
son, Sprangers, Detmar, Wever, & Schornagel, 1999). Thus, it
is useful to confirm this effect for people with aphasia. High le-
vels of agreement may be also related to time post-onset. Our
sample comprised people with aphasia who were six months
post-stroke or more. Evidence in the literature suggests that
agreement tends to be higher in long term patients (Pickard et
al., 2004) as their proxies have had longer exposure to their
Of particular note is the high agreement between self-report
and proxy ratings on the Greek SAQOL-39g psychosocial do-
main (ICC = 0.89, difference not significant). Sneeuw et al.’s
systematic review (2002) suggests that median correlations of
proxy-self-report agreement on psychosocial domains tend to
be moderate (0.48 - 0.50). In stroke studies, reported correla-
tions are: for the psychosocial domain of the Sickness Impact
Profile 0.61 (Sneeuw, Aaronson, de Haan & Limburg, 1997),
for emotional functioning on the EuroQol 0.30 (Dorman,
Waddell, Slattery, Dennis, & Sandercock, 1997), for anxiety
and depression on the EQ-5D 0.43 (Pickard et al., 2004), for all
Stroke-Specific Quality of Life scale (SS-QOL) domains 0.30 -
0.59 (Williams et al., 2006) and for the memory, emotion,
communication and social participation domains of the SIS
0.50 - 0.56 (Duncan et al., 2002).
Looking at the level of agreement from a different perspec-
tive we noted that proxy and self-report agreement for the over-
all scale (0.96) was the same as its test-retest reliability (0.96)
(Efstratiadou et al., 2012). This means that for our sample, the
strength of proxy and patient agreement was the same as the
test-retest reliability of the patient on the Greek SAQOL-39g.
As far as the domains are concerned, for the communication
domain scores were different (0.79 for proxy-self-report
agreement and 0.90 for test-retest reliability). However, ICCs
on the proxy and self-report agreement for the physical (0.97)
and the psychosocial domain (0.89) were very similar to those
for test-retest reliability (0.99 and 0.83 respectively) (Efstra-
tiadou et al., in press). These comparisons overall suggest a
good level of proxy-self-report agreement on HRQL using the
Greek SAQOL-39g. Patients’ self-reports are often taken as a
gold standard. However, Sneeuw and colleagues suggest that,
like proxy ratings, patient ratings are not perfectly reliable and
they could be also subject to several forms of bias (Sneeuw et
In our sample, the level of agreement was not associated with
carer strain and emotional distress. These findings are in line
with previous research with the SAQOL-39 with people with
aphasia (Hilari et al., 2007) and, in terms of the effect of carer
mood, with other stroke studies (Knapp & Hewison, 1999).
However, unlike other stroke studies (Williams et al., 2006;
Knapp & Hewison, 1999) we found no effect for carer strain.
This may be due to the overall good levels of agreement in our
sample and also to the fact that our sample were all longer term
Strengths of the study included the use of an accessible and
relevant to people with aphasia measure, the Greek SAQOL-
39g, the use of face to face interviews and the facilitation of the
participants with aphasia by a Speech and Language Therapist.
All this ensured that all people with aphasia who took part in
the study were able to self-report on all the measures used and
there were no missing data.
A limitation of this study was the small sample size. A larger
sample size would have allowed us to explore in more depth the
potential factors that could affect proxy-self-report agreement.
For example, there was not enough variability in our data to
explore potential effects of demographic variables. Yet in other
studies the level of agreement was not related to demographics
variables (Choiniere, Melzack, Girard, Rondeau, & Paquin,
1990; McCusker & Stoddard, 1984; O’Brien & Francis, 1988).
Other factors that could have affected agreement, and could be
explored in future research, include participant with aphasia’s
mood, cognitive status and aphasia severity. Considerations of
respondent burden prevented us from exploring their mood and
cognition. Whether levels of agreement are similar or different
in people with severe aphasia is an important issue. However,
people with very severe receptive aphasia would not be able to
take part in such research as they would not be able to self-
report on the measures used (Hilari & Byng, 2009). Moreover,
in their review, Sneeuw et al. (2002) found that the relationship
between agreement and severity was U-shaped (i.e., agreement
was better for very good or very poor health status and worse
for moderately impaired health status). Larger studies could
M. IGNATIOU ET AL.
also explore factors such as time spent with the person with
aphasia, education and carer levels of social support. Lastly,
future research could explore proxy and self-report agreement
on the Greek SAQOL-39g in a generic stroke sample including
those without aphasia.
Using the Greek SAQOL-39g, proxy raters can provide use-
ful information on the HRQL of people with severe aphasia.
However, the client is the most appropriate source of informa-
tion on their own HRQL and proxy reports should be used only
when people with aphasia are so severely affected that they are
unable to self-report. In addition, clinicians and researchers
need to be aware of trends in proxy reporting and take these
into account when interpreting data.
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