BMJ No 7106 Volume 315 Papers Saturday 23 August 1997
A randomised comparison of the EuroQol and Short Form-36 after
stroke
Paul J Dorman, Jim Slattery, Barbara
Farrell, Martin S Dennis, Peter AG Sandercock and
the United Kingdom collaborators in the International Stroke
Trial
The impact of a disease on health related quality of life
is important but difficult to measure. If the instrument used for
measuring this is too complicated some people may not answer some
questions and others may not respond at all. Although incomplete data
may introduce biases, make interpretation difficult, and reduce the
generalisability of the results,(1) papers on selecting
quality of life instruments have ignored response
frequency.(2,3) We postulated that the
brevity and simplicity of the EuroQol questionnaire (six separate
questions and a visual analogue scale) would achieve a better response
in stroke survivors than the SF-36 (34 separate questions) and
performed a randomised controlled trial to test this hypothesis.
Methods and results
We included all patients who had been entered by United
Kingdom centres in the International Stroke Trial between 2 March 1993
and 31 May 1995 who were not known to be dead. We randomised eligible
patients using an allocation code generated by an adaptive
randomisation algorithm (minimisation)(4) to postal follow
up with either the EuroQol or the SF-36 instrument. We incorporated
both instruments into questionnaire booklets which also asked for the
patient's address, type of residence, functional outcome after stroke,
and whether or not the patient completed the form independently. We
posted the booklets with a personalised letter explaining the purpose
of the study and a reply paid envelope. We asked subjects to complete
the questionnaire without help if possible, and, if they could not, to
give it to a relative or carer willing to respond for them. A reminder
letter and questionnaire were sent after two weeks. The primary
measures of outcome for each instrument were: the frequency of response
after the first mailing and the reminder and the number of forms with
"no domains of missing data." The study was powered (power
=0.95=(1-ß), alpha=0.05) to detect an absolute difference in overall
response of 5% - that is, of 50 forms per 1,000 between the two groups,
assuming an overall mean response of 75%.
Of the 4,016 patients in the International Stroke Trial, 2,253 patients
were eligible and randomised. The groups were well matched for age,
sex, and distribution of baseline stroke syndromes. The median time
between the onset of stroke and form completion was 56 weeks (range
17-125) in both groups. Response and "response with no missing
data" were significantly more frequent in patients allocated the
EuroQol instrument (see table). For both instruments about half of all
completed forms were completed by the patients (51% for the EuroQol
and 50% for SF-36) rather than by carers. Respondents to the EuroQol
questionnaire reported dependency in activities of everyday living
significantly more often than patients responding to the SF-36 (58%
v 50%, P=0.00006). Comment
This is the first randomised comparison of two commonly used
health status measures. Patients allocated to the EuroQol were
significantly more likely to respond and to provide complete data. The
observed difference, although modest in absolute terms (about 50
additional forms returned per 1,000 mailed), would translate to a
shortfall of about 1,000 completed forms in a survey of 20,000 subjects
studied by SF-36 rather than the EuroQol. The 11% absolute difference
in forms with no missing data is also important. Use of the EuroQol
could increase the efficiency of the study and reduce the resources
required. Also the better the response, the less the risk of bias by
the empirical use of arbitrary values for missing items of data.
In our study patients who responded with the EuroQol instrument were
more likely to be dependent. Thus, by enabling responses to be obtained
even from patients with poor outcomes, a simple instrument may have
more power to detect differences than a more complex measure with a
lower frequency of response. Simple questionnaires with higher response
frequencies may therefore be preferable to more complex
intruments.
| Table 1 - Comparison of response frequency and
completeness of data for the EuroQol and SF 36. Results are numbers
(and percentages) |
| Measure of performance | Questionnaire
allocated | Absolute difference
(%) | Odds ratio of response (95%
CI) | P |
|---|
| SF-36
(n=1128) | EuroQol
(n=1125)
|
| Response |
| To first
mailing | 679 (60) | 747
(66) | 6 | 1.31 (1.1 to
1.6)‡ | 0.002 |
| After two mailings | 849-
(75) | 905 (80) | 5 | 1.35 (1.1
to 1.6)‡ | 0.003 |
| Complete data
|
| No missing data | 616 (55)* | 747
(66%)† | 11% | 1.64 (1.4 to
1.9)** | < 0.0001 |
*Questionnaires with no missing data (after interpolation of
missing values where possible) for the SF-36.
†Questionnaires with no missing data (for the EuroQol any
missing data resulted in a missing domain).
‡Odds of response, comparing Euroqol with SF-36 (odds g1
indicate EuroQol better).
**Odds of response with no missing data , comparing Euroqol with
the SF-36 (odds g1 indicate EuroQol better). |
Appendix
The International Stroke Trial United Kingdom Collaborators
Hospital coordinators
Dr R Coleman, Aberdeen Royal Infirmary, Aberdeen; Dr S Hamilton, Woodend Hospital,
Aberdeen; Dr P Wilkinson, Ashford Hospital, Ashford; Dr A Colchester, The William Harvey
Hospital, Ashford; Dr A H Al-Hillawi, Stoke Mandeville Hospital, Aylesbury; Dr P G Flanagan,
Antrim/Braid Valley Hospital, Ballymena; Dr J Barrett, Clatterbridge Hospital, Bebington; Dr
AP Passmore, Belfast City Hospital, Belfast; Dr D Gilmore, Royal Victoria Hospital, Belfast;
Dr M T E Heafield, Selly Oak/Queen Elizabeth Hospital, Birmingham; Dr A Mehrzad, General
Hospital, Bishop Auckland; Dr N Roberts, Queens Park Hospital/Royal Infirmary, Blackburn;
Dr M J O'Donnell, Blackpool Victoria Hospital, Blackpool; Dr K R H Adams, Bolton General
Hospital, Bolton; Dr AA Gatnash, Pilgrim Hospital, Boston; Dr J D Fulton, Stracathro Hospital,
Brechin; Dr A Dunn, Bronllys Hospital, Brecon; Dr A Dunn, Builth Hospital, Brecon; Dr S
Nurick, Royal Sussex County Hospital, Brighton; Dr L Dow, Frenchay Hospital, Bristol; Dr S C
Sharma, Burnley General Hospital, Burnley; Dr JICarpenter, Kent and Canterbury Hospital
NHS Trust, Canterbury; Dr A Bayer, Llandough Hospital Nhs Trust, Cardiff; Dr P Chin,
Cumberland Infirmary, Carlisle; Dr P Bannister, Barnes Hospital, Cheadle; Dr W D Fitzroy
Smith, Countess Of Chester Hospital, Chester; Dr A G Arnold, Castle Hill Hospital,
Cottingham; Dr K Muhiddin, Derby City General Hospital, Derby; Dr T M Kemp, Dewsbury
& District Hospital, Dewsbury; Dr D K Chadha, Doncaster Royal/Montague Hospital,
Doncaster; Dr R Williams, Dorset County Hospital, Dorchester; Dr A C F Colchester, Buckland
Hospital, Dover; Dr H A Carmichael, Vale Of Leven District General Hospital, Dumbarton; Dr
I Hay, Dumfries & Galloway Royal Infirmary, Dumfries; Dr M J P Power, The Ulster Hospital,
Dundonald; Dr P Sandercock, Western General Hospital, Edinburgh; Dr B Chapman, Royal
Infirmary, Edinburgh; Dr R G Smith, Royal Victoria Hospital, Edinburgh; Dr S Choudhury,
Ellesmere Port Cottage Hospital, Ellesmere Port; Dr J Kelly, Erne Hospital, Enniskillen; Dr R
Hardie, Royal Devon & Exeter (Wonford), Exeter; Dr R Lenton, Falkirk & District Royal
Infirmary, Falkirk; Dr K R Lees, Western Infirmary, Glasgow; Dr D Macintyre, Victoria
Infirmary, Glasgow; Dr M Barrie, Princess Alexandra Hospital, Harlow; Dr D W Bruce,
General Hospital, Hartlepool; Dr C M James, Withybush General Hospital, Haverfordwest; Dr
P Overstall, Hereford General Hospital, Hereford; Dr C E Clarke, Hull Royal Infirmary, Hull;
Dr M M Steven, Raigmore Hospital NHS Trust, Inverness; Dr S Grimmer, Ipswich Hospital,
Ipswich; Dr JG Howe, Airedale General Hospital, Keighley; Dr J Bamford, St James Hospital,
Leeds; Dr I Pye, Leicester Royal Infirmary, Leicester; Dr A N Khan, Leigh Infirmary, Leigh; Dr
A Sharma, Fazakerley Hospital, Liverpool; Dr D Barer, Royal Liverpool Hospital, Liverpool;
Dr P Humphrey, Walton Centre For Neurology & Neurosurgery, Liverpool; Dr D Farquhar,
St John's Hospital, Livingston; Dr A Dunn, Llandrindod Hospital, Llandrindod; Dr Kafetz,
Whipps Cross, London; Dr B I Hoffbrand, Whittington Hospital, London; Dr M S Ali,
Greenwich District Hospital, London; Dr A Blackburn, King's College Hospital (Dulwich),
London; Dr A C Pereira, St George's Hospital Medical School, London; Dr A Colchester, Guy's
Hospital, London; Dr M Gill, St Andrew's Hospital, London; Dr P Bath, King's College
Hospital, London; Dr A B Lehmann, The Homerton Hospital NHS Trust, London; Dr R Bhatia,
Central Middlesex Hospital, London; Dr P McCaffrey, Craigavon Hospitals Group, Lurgan; Dr
DJ Walker, Macclesfield District General Hospital, Macclesfield; Dr S Musgrave, Trafford
General Hospital, Manchester; Dr J C Sharma, Newark General Hospital, Newark; Dr H
Rodgers, Royal Victoria Infirmary, Newcastle; Prof D Barer, Newcastle General Hospital,
Newcastle; Dr G A Ford, Freeman Hospital, Newcastle; Dr R Curless, Preston Hospital, North
Shields; Dr D Cohen, City Hospital, Nottingham; Dr J Horsley, Ormskirk District General
Hospital, Ormskirk; Dr S Winner, Radcliffe Infirmary, Oxford; Dr R Harries-Jones, Poole
Hospital Nhs Trust, Poole; Dr J Abrams, Whiston Hospital, Prescot; Dr B Bhowmick,
Glanclwyd District General Hospital, Rhyl; Dr E L Rose, Halton General Hospital, Runcorn; Dr
P Tyrrell, Hope Hospital, Salford; Dr J Paterson, Scarborough Hospital, Scarborough; Dr G
Venables, Royal Hallamshire Hospital, Sheffield; Dr D Da Costa, Northern General Hospital,
Sheffield; Dr S R Hill, Royal Shrewsbury Hospital, Shrewsbury; Dr D Smithard, Queen Mary's
Hospital, Sidcup; Dr J Wade, Heatherwood & Wexham Park Hospitals Trust, Slough; Dr T
Cassidy, South Tyneside District Hospital, South Shields; Dr GF Turner, Southampton General
Hospital, Southampton; Dr C McAlpine, Stirling Royal Infirmary, Stirling; Dr B Herd, North
Tees General Hospital, Stockton-On-Tees; Dr A N Hamlyn, Corbett Hospital, Stourbridge; Dr
A Hamlyn, Wordsley Hospital, Stourbridge; Dr P Cleland, Sunderland General Hospital,
Sunderland; Dr K A Sands, The King's Mill Centre, Sutton-In-Ashfield; Dr M Evans, Musgrove
Park & Trinity Hospital, Taunton; Dr R Bland, Treliske Hospital, Truro; Dr L Loizou,
Pinderfields General Hospital, Wakefield; Dr M R Clements, Watford General Hospital,
Watford; Dr J Voke, Queen Elizabeth II Hospital, Welwyn Garden City; Dr R H Hyatt,
Sandwell Healthcare NHS Trust, West Bromwich; Dr H Bhakri, Weston General Hospital,
Weston-Super-Mare; Dr G Sangster, Arrowe Park (Wirral) Hospital, Wirral; Dr R Blandford,
Bassetlaw District General Hospital, Worksop; Dr R Clifford-Jones, Worthing Hospital,
Worthing.
Hospital collaborators
A full list of UK hospital collaborators will be published with the main trial data.
Neurosciences trials unit office
Dr P Dorman, Dr C Counsell, Dr R Lindley, Dr M Dennis, Prof CP Warlow, Dr P Sandercock
(Clinical); B Farrell (Senior Trials Coordinator); A Bowie, D Perry (Computer Programming);
G Moody, H Taylor, L Robertson, K Mowatt, P McClaren, M Livingstone, D Charlton, S
Anderson, L Reynolds, V Scoltock, A Brownlie, I McCrindle, M Kaye, J Boyle (Clerical and
Data); F Waddell (Nursing); J Slattery (Statistics).
Clinical trials service unit
Prof R Peto, Dr R Collins, Dr Z Chen, P Dove.
We thank all the patients, their families, and carers for their
participation.
Funding: PJD is supported by a UK Medical Research Council
clinical training fellowship. JS and and PAGS are support by grants
from the UK Medical Research Council. The International Stroke Trial
was sponsored by the UK Medical Research Council, the European Union,
and the Stroke Association. This study was supported by a grant from
Glaxo Wellcome plc.
Conflict of interest: None.
(Accepted 8 April 1997)
Neurosciences Trials Unit,
University
Department of Clinical Neurosciences,
Western General Hospital,
Edinburgh EH4 2XU
P J Dorman, MRC training
fellow
J Slattery, senior
statistician
B Farrell, senior trial
coordinator
M S Dennis, senior lecturer
in stroke medicine
P A G
Sandercock, reader in
neurology
Correspondence to: Dr
Dorman. pd@skull.dcn.ed.ac.uk
References
1 Fallowfield L. Quality of quality-of-life data.
Lancet 1996;348:421-2.
2 Guyatt G H, Feeny D H, Patrick D L. Measuring health-related
quality of life. Ann Intern Med 1993;118:622-9.
3 Testa M A, Simonson D C. Assessment of quality-of-life outcomes.
N Engl J Med 1996;334:835-40.
4 White S J, Freedman L S. Allocation of patients to treatment
groups in a controlled clinical trial study. Br J Cancer
1978;37:849-57.
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