Measuring outcomes of importance to women with stress urinary incontinence.
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ABSTRACT: Quality of life has been defined as "the extent to which our hopes and ambitions are matched by experience." To improve a patient's quality of life through medical care would be to "narrow the gap between a patient's hopes and expectations and what actually happens." Using the above definition as a conceptual basis, we produced a self-administered, Patient-Generated Index (PGI) of quality of life. The PGI was completed by 359 patients presenting with low back pain. The validity of the measure was assessed by correlating patients' PGI scores with a well-validated health profile, the Short-Form 36-item Health Survey (SF-36), and with their scores on a clinical back pain questionnaire. Stepwise multiple regression was then used to model the relationship between the PGI score and the SF-36. Patients' PGI scores showed a high correlation with SF-36 scales measuring pain, social functioning, and role limitations attributable to physical problems, and with the clinical questionnaire. Together with whether a person was retired or not, these health variables were able to explain 25% of the variance in PGI scores. Patient generated index scores were significantly lower in patients referred to hospital compared with those managed solely in general practice and tended to reflect the general practitioner's assessment of symptom severity. We conclude that it is possible to construct a questionnaire that quantifies the effect of a medical condition on patients' quality of life in a way that has meaning and relevance in the context of their daily lives. The PGI has considerable potential for routine use in a wide range of clinical conditions for which the measurement of outcome has hitherto proved very difficult.Medical Care 12/1994; 32(11):1109-26. · 3.23 Impact Factor
This is the author's version of the work. It is posted here for personal use, not for
redistribution. The definitive version was published in British Journal of
Obsterics and Gynaecology 2009;116(5):719-25, http://dx.doi.org/10.1111/j.1471-
Measuring outcomes of importance to women with stress urinary incontinence
Laura Ternent1,2 Luke Vale1,2, Brian Buckley3, Charis Glazener2
1Health Economics Research Unit, University of Aberdeen, UK
2Health Services Research Unit, University of Aberdeen, UK
3Primary Care, Department of General Practice, National University of Ireland,
Address for correspondence:
Health Services Research Unit, Institute of Applied Health Sciences, University of
Aberdeen, AB25 2ZD.
Tel: 01224 554687
Fax: 01224 550926
Objective: To provide evidence on outcomes of importance to women who have
stress urinary incontinence (SUI). The secondary aim was to identify additional
outcomes that ought to be collected in future primary studies or in systematic reviews
of the literature.
Design: Questionnaire survey of a cohort of women with SUI.
Sample: 188 women with SUI.
Methods: Areas of importance to women who suffer from SUI were assessed using a
patient generated index (PGI). In addition to the PGI, the questionnaire included the
King’s Health Questionnaire (KHQ) and the EuroQol- 5D (EQ-5D).
Main Outcome Measures: PGI, EQ-5D, and the King’s Health Questionnaire.
Results: In total, 38 different areas were reported by respondents on the PGI. PGI
and EQ-5D scores were positively correlated and significant. Correlations between
the seven domains of the KHQ and PGI were all negative but only two were
statistically significant: personal relationships and severity measures.
Conclusion: The PGI succeeded in capturing a diverse range of outcomes of
importance to women suffering with SUI. Given the limited correlation between the
KHQ domains and the PGI and, in addition, that the areas mentioned in the PGI were
not found to map well to the EQ-5D, the PGI in this instance may be capturing
concerns of women who suffer from SUI which are not captured by quality of life
measures such as the EQ-5D.
Stress urinary incontinence (SUI) is the most common type of incontinence,
especially in middle aged-women. It is defined as involuntary leak or loss of urine
caused by sneezing, exercising, lifting or physical activity (Abrams et al 2002).
Studies investigating the prevalence of SUI in women are hampered by differing
definitions of SUI, and social factors such as the limited recourse to health care due to
embarrassment. Indeed, only 15% of women identified as suffering from SUI consult
a health professional (Shaw et al, 2006; 2001), suggesting that those presenting for
help represent the ‘tip of the iceberg’ of a common condition. Embarrassment
associated with urinary incontinence may cause withdrawal from social situations and
reduces quality of life (Hunskaar and Vinsnes 1991). Many women with SUI show
symptoms of depression and introverted behaviour, together with dysfunctional
interpersonal relationships (Norton et al, 1988). Furthermore, SUI may lead to
withdrawal from regular physical activities and thus impair women’s general health
(Nygaard et al 1990).
The aim of this survey was to provide evidence on outcomes of importance to women
who have SUI. Much of the available literature focuses on clinical outcomes which as
a result may have limited relevance to women with SUI. The purpose of this work
was to prospectively survey women with SUI to provide information on outcomes of
importance to them; a secondary aim was to identify additional outcomes that ought to
be collected in future primary studies or define relevant outcomes for systematic
reviews of the literature.
In order to assess the areas of importance to women who suffer from SUI, a
questionnaire was designed. A patient generated index (PGI) (Ruta et al, 1994) was
employed to allow respondents to state and evaluate the areas of their life affected by
SUI. In addition to the PGI, the questionnaire included the Kings Health
Questionnaire (KHQ) (Kelleher et al, 1997), the EQ-5D and questions relating to
socioeconomic and demographic information.
The PGI is an individualised patient-reported health instrument which allows the
respondent to select, weight, and rate the importance of a particular health outcome
(Martin et al, 2006). The PGI was designed with the aim of producing a valid
measure of outcome that reflected areas of importance to patients’ lives (Ruta et al
1994). The PGI involves the respondent deciding what factors are important to them.
Examples of the types of factors that may be important are included to provide
guidance. The aim of the PGI is therefore to capture the diverse range of concerns or
priorities of respondents. Using the PGI, respondents can vary the weight they attach
to these concerns or priorities, which provide researchers with an insight into the
respondent’s viewpoint. An overall score for the PGI for each respondent can then be
calculated by multiplying the rating for each health area by the proportion of points
allocated to that particular area.
The PGI is completed in three stages: in the first stage respondents are asked to
identify up to five areas of their life that are affected by their SUI. Respondents are
given a list of outcomes to act as prompts to help them think about which areas of
their life are affected by their condition. Respondents can then choose from these
options or provide their own examples. In addition to the five boxes, there is a sixth
box which enables respondents to rate all other areas of their life affected by their
SUI. Possible examples of the factors to include on the PGI were drawn from three
sources. The first of these was the King’s Health Questionnaire, which was used to
generate a list of outcomes under the broad headings of: Role limitations; Physical
limitations; Social limitations; Personal relationships and Emotions. These outcomes
were supplemented from Cochrane reviews of non-surgical treatments (Hay-Smith
and Dumoulin 2006; Brazzelli et al 2007; Mariappan et al 2007; Bezerra et al 2007).
Finally, a general literature search was also conducted although this did not provide
further additions to the 17 different outcomes identified from the KHQ and the
Cochrane reviews. These outcomes were then narrowed down to those considered
most relevant by members of the project team.
In stage two of the PGI, respondents were asked to score each area listed in stage one
of the PGI on a scale ranging from 0 to 6. The score given in stage two was intended
to reflect how the individual was affected by their SUI in the past month. A score of 0
would signify that the effect on their life was as bad as it could possibly be and a
score of 6 would correspond to an effect that was as good as it could possibly be.
Finally, in stage 3, respondents were asked to ‘spend’ 10 points to indicate the relative
importance of each of the areas mentioned in stage one. Respondents were requested
to spend more points on areas that were the most important to them.
As noted above, in addition to the PGI, the questionnaire also contained the Kings
Health Questionnaire (KHQ) and the EQ-5D. The KHQ is a condition specific
questionnaire which aims to assess the impact of urinary incontinence on an
individual’s quality of life. It contains questions set in nine domains relating to:
general health perception, incontinence impact, role limitations, physical limitations,
social limitations, personal relationships, emotions, sleep and energy, and severity.
With the exception of the final part of the questionnaire (severity measures) scores
can be calculated for each domain (0 – 100). The higher the score the worse off an
individual feels they are and the lower they perceive their quality of life to be.
The EQ-5D is a standardised instrument for use as a measure of health outcome.
Applicable to a wide range of health conditions and treatments, it provides a simple
descriptive profile and a single index value for health status
(http://www.euroqol.org/.) The EQ-5D has five dimensions (mobility, self-care, usual
activities, pain/discomfort and anxiety/depression) that can be converted into a utility
The Bladder & Bowel Foundation (formerly InContact and the Continence
Foundation) is a national charity that provides information and support to people with
bladder and bowel problems, representing the interests of people with continence
problems with the aim of ensuring they have access to the latest information and
services available (http://www.bladderandbowelfoundation.org/). In 2006 a survey
conducted by InContact was completed by 755 people affected by bladder and bowel
problems (Buckley, Wagg, Winder 2007). Of these, 188 women with SUI gave
consent for future contact about relevant research and formed the sample for the
current study. In July 2007 these women were sent questionnaires for the current
study by InContact. Given that this is a self slecctedselected sample of women
suffering from SUI and not a random sample of the population, it is not known how
representative this sample is of the wider population.
The 2006 survey in which the participants were originally identified was a service
evaluation in which InContact surveyed people who had previously been in touch
with the charity and as such no ethical approval was necessary. The 2006 survey
materials contained an explicit assurance that confidentiality would be maintained and
that identifiable data would not be passed on to third parties. Respondents were asked
if they were willing to be contacted in the future for research purposes. For this study
questionnaires were sent in July 2007 to 188 women with SUI who gave their consent
for further contact relating to research. The questionnaires were returned directly to
the charity and after screening only anonymous data were subsequently forwarded to
the authors in accordance with the Medical Research Council’s guidance on the use of
personal information in medical research and the Data Protection Act 1998 (HMSO,
1998; Medical Research Council, 2000).
In total, 105 out of 188 respondents (55.9%) completed and returned the
questionnaire. Table 1 shows the areas of an individual’s life that they reported to be
affected by their SUI and the frequency that the area was mentioned within the sample
as a whole. Thirty-eight different areas were reported by respondents.
Out of 105 respondents, 73 answered the PGI correctly, 9 respondents made mistakes
in the PGI and 23 respondents did not fully complete it (Table 2). Of the 73
respondents who correctly completed the questionnaire, 61 answered the PGI with no
mistakes (all sections were completed satisfactorily), the remaining 12 respondents
made a small error in completion of the PGI. This small error always occurred in
section three of the PGI, where respondents had to spent 10 points, these respondents
did in fact spend ten points, however they missed out spending points in area 6 (all
other areas of their life affected by SUI) and totalled to ten in box 6. An example of
the PGI used can be seen in aAppendix 1.
Table 3 shows the demographic information of the sample as a whole and for those
individuals who correctly completed and incorrectly completed the PGI. The mean
age for the sample as a whole was 57 (range 28 to 89). As can be seen in Table 3,
those respondents who correctly completed the PGI were on average younger than
those who incorrectly completed the PGI. In addition, those who correctly completed
the PGI appear to be better educated and in higher income groups.
In addition to listing the outcomes of importance to women who suffer from SUI, the
PGI can also be calculated into a score of overall quality of life. The score ranges
from 0 to 6, with 0 reflecting a very low quality of life (“it’s as bad as it could
possibly be”) and 6 reflecting a very high quality of life (“it’s as high as it could
possibly be”) An example of the PGI and the method used to calculate the score is
given in Table 4. For the respondents who successfully completed the PGI the mean
score was 2.4 (SD 1.4, range 0-6). 101 of 105 returned questionnaires had a fully
completed EQ-5D. Scores on the EQ-5D ranged from -0.17 to 1. The mean EQ-5D
score was 0.598 (SD 0.339). Correlation between the mean PGI score and the mean
EQ-5D was, as expected, positive and significant.
Scores (out of 100) for each domain in the KHQ can be seen in Table 5. The higher
the score, the worse off an individual feels. In addition to the domains of the KHQ, it
also contains a section detailing the respondent’s bladder problems and how much
they affect the individual’s life.
Correlations of the PGI and seven domains of the KHQ were also performed. We
would expect to find a negative correlation between the PGI and KHQ. All
correlations were negative, however only two were significant: personal relationships
(P=0.004) and severity measures (P=0.003).
In addition, correlations of the EQ-5D score and the domains of the KHQ were also
performed. We found all seven of the KHQ domains to be significantly (negatively)
correlated with the EQ-5D. This result is to be expected since many of the EQ-5D
and KHQ domains are similar.
The PGI has been used to quantify the effect of SUI on the quality of patients’ lives
for the first time. The respondents are a self-selected sample of women who had
previously been in touch with a patient support charity and who may be considered to
be active help-seekers. However, there is no reason to suspect that their experience of
SUI and the relative perceived impact of SUI on various aspects of their lives are
different from the wider population of women affected. Nearly 70% of respondents
successfully completed the questionnaire, a further 9% attempted the PGI but made
mistakes in its completion, and 22% failed to fully complete the PGI; the majority of
these respondents completed stage 1 of the PGI but failed to complete stage 2 or 3.
Those respondents who successfully completed the questionnaire were found to be
younger, in higher income groups and have a higher level of education. For the PGI to
be used as a valid and reliable measure of outcomes of importance to women with
SUI and to be able to accurately quantify the effect of SUI on their lives the response
rate and successful completion of the PGI would need to be improved. Of the
respondents, 31% of respondents had difficulty in completing the questionnaire and
there was also a low response rate to the survey in general (55.9%).
In order to improve this response rate and successful completion alterations could be
made to the layout of the PGI to make it more user-friendly. An alternative would be
to use the questionnaire as the basis for setting a patient’s goals for treatment in a
clinical or research setting: achieving those goals could then be used as a measure of
In stage 1 of the PGI, 38 different areas of an individual’s life affected by SUI were
reported. The most frequently mentioned areas were going out or socialising, with
14% of all respondents listing this as one of the areas of their life affected by their
condition. Thirteen percent of respondents mentioned personal hygiene and 11%
mentioned the effect their condition has on their sleep. Shopping (8%), depression
(8%), physical activity (6%), work (6%), anxiety (6%), travel (4%), household tasks
(2%), personal (1%) and sexual relationships (2%) were all also listed as areas of their
life affected by SUI.
The PGI, or instruments like it, have been criticised in the past, with some authors
questioning whether they reflect the patient’s view point or, conversely, whether they
are simply reflecting the views of the researchers who designed the questionnaire
(Tully and Cantrill, 2000). In this survey, whilst we did find a varied response in the
number of outcomes listed by respondents, the majority of these did in fact come from
the prompt list provided in the PGI. Of the 10 most mentioned areas, eight of these
were from the prompt list. Other studies have found similar associations between the
prompt list and final outcomes listed by respondents. However, it is unclear whether
this association is due to the most relevant examples being selected from the prompt
list, or due to respondents being unwilling or unable to think of their own examples
because the prompt list is already comprehensive (Russell and Macduff, 1998).
We correlated the mean PGI score and the mean EQ-5D scores. This correlation was,
as expected, found to be positive and significant. In addition to this, correlations of
the KHQ and the PGI were performed. Although all correlations of the PGI and KHQ
were of the expected sign (negative), only two were found to be statistically
significant. Given that the PGI outcomes and the domains of the KHQ do not
correlate well, and that many of the aspects respondents mentioned in the PGI list of
outcomes do not map very well on to the dimensions of the EQ-5D this might suggest
that generic measures, like the EQ-5D, may not be a very good reflection of the
preferences of people with incontinence. The PGI in this instance may therefore be
capturing concerns of women who suffer from SUI which are not adequately captured
by generic instruments such as the EQ-5D. This is of particular interest in the context
of health technology appraisals, where EQ-5D has become the accepted standard for
calculation of Quality Adjusted Life Year indices for use in determination of cost
effectiveness (NICE 2008).
Much of the available literature on SUI focuses on doctor-selected clinical outcomes.
Given the undoubted social and personal impact of SUI, these outcomes may as a
result have limited relevance to the women who suffer this condition. The aim of this
survey was therefore to provide evidence on outcomes of importance to women who
have SUI. This is the first attempt to use the PGI in this area. In total, 48 different
areas of an individual’s life affected by SUI were mentioned, the most common of
these being: going out or socialising; personal hygiene; sleep disruption; the effect on
daily activities such as shopping; depression; physical activity; work; anxiety; travel;
household tasks; and personal and sexual relationships. The PGI succeeded in
capturing a diverse range of outcomes of importance to women suffering from SUI.
However, it must be noted that some respondents did have difficulty in completing the
Finally, the PGI was not found to correlate well with the domains of the KHQ, in
addition, many of the aspects respondents mentioned in the PGI list of outcomes were
not found to map well on to the dimensions of the EQ-5D suggesting that generic
measures, like the EQ-5D, may not be a very good reflection of the preferences of
people with incontinence. We conclude that the PGI in this instance may therefore be
capturing concerns of women who suffer from SUI which are not adequately captured
by generic instruments such as the EQ-5D.
Acknowledgements: We would like to thank the women who responded to our
questionnaire. We would also like to thank Mari Imamura for comments on previous
drafts of the paper. The Health Services Research Unit and Health Economics
Research Unit are supported by the Chief Scientist Office of the Scottish Government
Funding declaration: The project was funded by a grant from the NIHR Health
Technology Assessment Programme. The Health Economics Research Unit and the
Health Services Research Unit are funded by the Chief Scientists Office of the
Scottish Government's Health Directorates.
Ethics approval: No ethical approval was necessary. The sample was surveyed by a
charity to whom they had already given consent to be contacted for research purposes.
Questionnaires were returned to the charity. Only anonymous data were supplied to
the authors by the charity. Ethical approval for the study was provided by InContact.
The 2006 survey in which the participants were originally identified was a service
evaluation in which InContact surveyed people who had previously been in touch
with the charity and as such no ethical approval was necessary.
Disclosure of Interests: Brian Buckley is a Cochrane Fellow at the Department of
General Practice, National University of Ireland, Galway, and is the Chair of the
Board of Trustees of the Bladder & Bowel Foundation.
Contribution to Authorship: All authors contributed to the design of the study,
interpretation of data and writing of the manuscript.
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