Quality of life measurement: bibliographic study of patient assessed health outcome measures
BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7351.1417 (Published 15 June 2002) Cite this as: BMJ 2002;324:1417All rapid responses
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Published bibliographic study again did show that extensive promotion
of QOL instruments is precocious, as well as substitution of mortality and
disease-specific outcomes in discussions of health care.
"The primary aim of treatment for cancer is to improve the QOL of
patients" are the first words of recent editorial (BMJ v.323, p 1144).
Clinical Evidence statement says: we focus "on outcomes that matter to
patients, meaning those that patients themselves are ware of, such as
symptom severity, QOL"(#6, p. XVI). Such formulation of treatment's aims
have become very popular nowadays.
I try to find out is the expanding use of QOL concept substitute mortality and
disease-specific outcomes in medical research by QOL.
First I searched Medline for QOL-related publications since 1966 to 2001.
All articles of NEJM and BMJ found in this search in years 1994 and 2000
were checked for details of how QOL concept was used.
I found that proportion of human-related articles using concept of QOL
steadily increased during 30 years from 0.1% to 1.58%. 47 items were
published in two target journals (17 from NEJM, 15 in 1994).
Of 32 articles (reports of studies, reviews, cases):
- 20 do not mention QOL-related concepts/instruments in background
section,
- 9 do not mention any QOL-related outcome or measurement instrument in
Methods section,
- only 23 describe evaluation of QOL-related outcome or use of QOL
measurement instrument,
- only 7 of these 23 articles use QOL as primary outcome;
- in Results section 12 do not report any QOL data, only 5 extensively
report data of QOL measurement;
- in Discussion section 7 reports do not mention QOL-related
outcomes/results, and only 8 specifically discuss QOL variables as major
result of study.
It appears that despite aggressive use of QOL concept/wording in journal
editorials/comments, the majority of research reports use QOL as outcome
secondary to mortality and disease-specific outcomes, and in significant
number of reports QOL appears like placing of study results in context, if
not masquerading to being more welcomed.
Competing interests: No competing interests
QOL scale recommendations aren't that simple
As someone who is guilty of adding the large number of disease specific quality of life (QOL) scales, let me add note of caution to Garratt et al.'s1, plea for guidance and recommendations for the users of QOL scales - however understandable that plea is. QOL scales are not like thermometers or spirometers, where the reading is independent of the type of patient. Imagine a thermometer where the reading of the scale depends on the disease the patient has. That is rather what happens with QOL scales.
A QOL scale is just a shopping bag of experiences (or questions) which are put together to form a scale - rather like the retail price index. . The retail price index is a shopping bag of goods for an 'average' shopper, even though most people aren't that average shopper any more than most people have the average height. The scale value obtained from a QOL scale depends on the overlap between the items in a scale and the patient's own experience of disease. So, for example, if there is generic QOL scale and there are lots of pain items but no items on sleep disturbance, then arthritis patients will come out worse than asthma patients.
That is the nature of this type of measurement. The same logic applies to disease specific scales. If there is question about sport, and most patients are elderly, then not surprisingly, you don't get many complaining about how their health has effected their sporting life
The consequence of nature of QOL assessment is that 'best' scale is always 'best' for a particular purpose, where purpose is defined in terms of the population (including the disease and demographic features of the population) as well as the treatment. An example will show how this works. We originally developed a scale to measure QOL in chronic obstructive pulmonary disease (COPD), and which was subsequently used to assess outcome in rehabilitation2. However, some of the items measuring COPD severity didn't change - but we realised that they couldn't possibly improve in rehabilitation, because they were simultaneously measures of disease severity but also encouraged by rehabilitaion (e.g., propping up with pillows at night, eating regular but smaller meals, using oxygen). Consequently we developed a short scale for measuring outcome by selecting item that which did change after rehabilitation3. In other words, we selected the items from our big trolley to make a smaller basket that measured what we wanted.
So, in looking for recommendations, any recommendations should be disease, purpose and population specific. But there is one other problem. QOL researchers always recommend their own scales. It is a personal thing - to the author, the scale is a bit like his or her child. The more 'successful' scales tend to be those whose authors are better promoters at what is fundamentally a historico-social activity, rather than science. The SF-36 is a perfectly reasonable scale, but it popularity has been helped by the fact that it was developed using US government money (which confers respectability) and it has been effectively marketed including an international translation programme. Naturally, the authors of the EuroQol of WhoQol might feel their scales are better! With the proliferation of QOL scales, there are now many authors, but the last person you should come to for a recommendation about QOL scales is someone who is an author - including myself.
1. Garratt A, Schmedit L, Mackintosh A, Fitzpatrick. Quality of life measurement: bibliographic study of patient assessed health outcome measures. BMJ 2002;324:1417-9
2. Hyland ME, Bott J, Singh S, Kenyon CA P. Domains, constructs, and the development of the breathing problems questionnaire. Quality of Life Research 1994; 3:245-256.
3. Hyland ME, Singh SJ, Sodergren SC, Morgan MDL. Development of a shortened version of the Breathing Problems Questionnaire suitable for use in a pulmonary rehabilitation clinic: a purpose-specific, disease-specific questionnaire. Quality of Life Research 1998;7:227-233.
Competing interests: No competing interests