Does Angioplasty Improve the Quality of Life for Claudicants?: A Prospective Study

Does Angioplasty Improve the Quality of Life for Claudicants?: A Prospective Study Ian C. Chetter, FRCS, J. Ian Spark, FRCS, D. Julian A. Scott, MD, FRCS, and Ralph C. Kester, FRCS, Leeds, UK

This study aims to analyze the impact of percutaneous transluminal angioplasty (PTA) for claudication on patients’ quality of life (QOL). The patients in this study included 108 claudicants, 74 men and 34 women, with a median age of 67 years (range 40-87 years), who were assessed prior to and at 1, 3, and 6 months following PTA. This is the first report to demonstrate that the previously well-documented improvements in the clinical indicators of lower-limb ischemia are accompanied by improvements in individual QOL domains and in overall global QOL. These findings are detectable within a month following PTA and last at least 6 months. The results of this study may go some way to provide proof of efficacy for the procedure and thus help justify the recently questioned widespread use of PTA in clinical practice. (Ann Vasc Surg 1999;13: 93-103.)

INTRODUCTION Intermittent claudication is a common condition affecting 6% of the population over 65 years of age and results in significant impairment of healthrelated quality of life (QOL).1,2 Since its conception over three decades ago and later modification, the utilization of percutaneous transluminal angioplasty (PTA) in the management of intermittent claudication has increased exponentially.3-6 This rapid and widespread acceptance of PTA into clinical practice is supported by its high technical success rates, low complication rates, and acceptable patency rates.7-9 However, in the present climate of evidence-based medicine, these proven benefits are insufficient and we are required to provide proof of efficacy, specifically in terms of patient benefit.10 From the Department of Vascular and Endovascular Surgery, St. James’s and Seacroft University Hospitals, Leeds, UK. Presented at the Twenty-third Annual Meeting of the Peripheral Vascular Surgery Society, San Diego, CA, June 6-7, 1998. Correspondence to: I.C. Chetter, FRCS, Department of Vascular and Endovascular Surgery, St. James and Seacroft University Hospitals, Beckett Street, Leeds LS9 7TF, UK.

The aim of this prospective observational study was to assess the impact of PTA on patient-reported, health-related QOL.

MATERIALS AND METHODS The ethical committee of St. James’s and Seacroft University Hospitals approved this study and all participating patients gave informed written consent. Over a 12-month period, all patients presenting to the unit with intermittent claudication treated with arterial PTA were recruited into the study. Patients with critical ischemia as defined by the European Consensus document were excluded.11 Patients were assessed in the vascular laboratory 1 day prior to PTA and at 1, 3, and 6 months following PTA. Transport was supplied if requested through a local taxi firm or the hospital ambulance service. Assessment of Clinical Indicators of Lower-Limb Ischemia At each assessment, the following were recorded: patient-reported walking distance (PRWD) in meters; maximum treadmill walking distance (MTWD) 93

94

Angioplasty and quality of life

in meters, calculated from the duration walked on a treadmill at a speed of 2.5 km/hr with a 10° incline (the test was stopped if the patient completed 5 min and this was taken as the MTWD); and ankle brachial pressure indices using a hand-held Doppler (8 MHz probe) measured at rest (ABPI R) and following treadmill testing (ABPI PE). In patients unable to tolerate treadmill testing, the recommendations of the International Society for Cardiovascular Surgery (ISCVS) were followed and ABPI PE was simulated by suprasystolic thigh cuff occlusion for 5 min.12 Patency of the PTA site was assessed using color-coded duplex scan if at any of the follow-up appointments recurrent or residual symptoms were reported in the angioplastied limb and there was a 艋0.1 improvement in ABPI R. Isotope limb blood flow (ILBF), a method of analyzing reactive hyperemic limb perfusion via an isotope influx technique, was also assessed prior to PTA and at 3 months following PTA. The description and validation of this technique has been described in detail elsewhere.13 Quality of Life Assessment Short Form 36 (SF 36) and EuroQol (EQ) health assessment questionnaires were posted to patients, with their appointment, 1 week prior to attendance. On arrival at the vascular laboratory, the questionnaire was inspected and the patient was prompted to respond to any omissions; thus fully completed questionnaires were collected on all attending patients. The SF36 was developed from the Medical Outcomes Study General Health Survey instrument. The objectives of the authors of the SF36 were to develop a general health survey instrument that was comprehensive and psychometrically sound, yet short enough to be of practical use in large-scale studies.14 The SF36 contains 36 questions covering eight QOL domains: physical functioning (PF); role limitations due to physical problems (RP); social functioning (SF); role limitations due to emotional problems (RE); mental health (MH); vitality (V); bodily pain (BP), and general health (GH). Question scores for each domain are coded, summed, and transformed onto a scale from 0 (worst possible score) to 100 (best possible score). Thus a profile of health-related QOL is generated but unfortunately, no single index. The attraction of the SF36 is that it is the product of a vast amount of developmental work and psychometric testing in the U.S.A.15,16 In this study, the UK version of the questionnaire was used. This version of the SF36 contains only minor word changes involving 5 of the 36 questions, e.g.,

Annals of Vascular Surgery

Table I. The EuroQol health status questionnaire Mobility I have no problems walking about I have some problems walking about I am confined to bed Self-care I have no problems with self-care I have some problems washing or dressing myself I am unable to wash or dress myself Usual activities I have no problems performing my usual activities (e.g. work, study housework, family or leisure activities) I have some problems with performing my usual activities I am unable to perform my usual activities Pain/discomfort I have no pain or discomfort I have moderate pain or discomfort I have extreme pain or discomfort Anxiety/depression I am not anxious or depressed I am moderately anxious or depressed I am extremely anxious or depressed

1 2 3 1 2 3 1

2 3 1 2 3 1 2 3

A profile of 21221 would thus represent some problems walking about, no problems with self-care, some problems with usual activities, moderate pain or discomfort, and no anxiety/ depression.

Table II. The EuroQol matrix to derive TTO-based global QOL index EuroQol dimension

Level 2

Level 3

Mobility Self-care Usual activity Pain/discomfort Anxiety/depression Constant for any dysfunctional state = 0.081

0.069 0.104 0.036 0.123 0.071

0.314 0.214 0.094 0.386 0.236 Constant for level 3 score in any dimension = 0.269

A profile 21221 would score 1 − 0.081 − 0.069 − 0.036 − 0.123 = 0.691.

replacing ‘‘block’’ as a distance measure with ‘‘half a mile’’ and ‘‘100 yards.’’ It is short and covers a wide range of areas that may be affected by illness. Extensive work with the UK version of the SF36 has revealed high response rates and excellent validity and reliability in both population samples and perhaps more importantly in this specific group of patients.17,18 It is also more sensitive to change than

4 3 = drug controlled 0 8 2 3 = >2 drugs/ uncontrolled 1 3 = juvenile onset

AO, adult onset; AF, atrial fibrillation; CCF, congestive cardiac failure; CVD, cerebrovascular disease; IHD, ischemic heart disease; MI, myocardial infarction.

13

2 = transient or temporary stroke 3 = stroke with permanent deficit 33

2 = stable angina, AF, controlled CCF 3 = unstable angina, symptomatic arrhythmia, poorly controlled CCF, recent MI 55

2 = <20/day/ <1 year abstinence 3 = >20/day 12 3 2 = AO insulin controlled

2 = 2 drug controlled

29 11 1 = AO diet/drug controlled

1 = 1 drug controlled

2

9

21

1 = mild elevation, diet controlled 2 = strict diet control 0 1 = asymptomatic, with bruit 2 1 = remote MI 25

74 0 = normal blood lipids 93 0 = asymptomatic, no bruit 73 0 = asymptomatic/ normal ECG 20

0 = never/ >10 years abstinence 1 = <10 years abstinence 65 93 0 = none

0 = none

Hyperlipidemia n CVD n IHD n Smoking n Hypertension

+3 = markedly improved; symptoms gone or markedly improved, ABPI > 0.9 +2 = moderately improved; still symptomatic but at least single-category improvement, ABPI increased by >0.1 but not normalized +1 = minimally improved; no categorical shift, but >0.1 increase in ABPI or visa versa 0 = no change; no categorical shift and <0.1 change in ABPI −1 = mildly worse; no categorical shift but ABPI decreased >0.1 or visa versa −2 = moderately worse; one category worse or unexpected minor amputation −3 = markedly worse; more than one category worse or unexpected major amputation.

n

ISCVS-suggested standards on outcome criteria for reports dealing with lower extremity ischemia were used to assess outcome:12

Diabetes

Overall Outcome Assessment

Table III. Predisposing factors and comorbidity within this patient group

other commonly used generic questionnaires in this group of patients and British population norms are available.18-20 In addition to ‘‘raw’’ SF36 scores QOL scores, effect sizes were calculated by dividing the difference between the pretreatment and posttreatment median values by the interquartile range of the pretreatment values. Effect sizes have been strongly recommended for interpretation of quality of life changes in health care in order to demonstrate the relative importance of a treatment effect within a study.21 The EQ was developed by a multidisciplinary group of European researchers, whose aims were to develop a standardized generic instrument to describe health-related QOL in a way that reflected the salient features of health as perceived by the general population.22 The instrument was designed to be interview or self-completed. The EQ measures five QOL domains; mobility, self-care, usual activities, pain, and anxiety/depression, each measured on three levels (Table I). The EQ thus generates a possible 243 different profiles of health-related QOL, which can be converted into single indices using a matrix derived from regression analysis of time trade-off (TTO) data (Table II).23 The EQ also incorporates a visual analogue scale (VAS) on which patients are requested to rate their healthrelated QOL on a scale from 0 (worst imaginable) to 100 (best imaginable), thus deriving a second single index. The EQ has been found to be acceptable, valid, and reliable in population studies, among other patient groups, and in claudicants.18,24-26

Chetter et al. 95

n

Vol. 13, No. 1, 1999

96

Angioplasty and quality of life

Statistical Analysis All data were collected on a specifically designed Microsoft Access database and analyzed using Microsoft Excel (Microsoft Ltd, Wharfdale Road, Winnerish Triangle Wokingham, Berks) and Astute Statistics (DDU Software, The Old Medical School, The University of Leeds, Leeds, W Yorks). QOL scores were not normally distributed (KolmogorovSmirnov goodness-of-fit test). The Kruskal Wallis analysis of variance was used to assess change over time of clinical indicators of lower-limb ischemia, SF 36 domains, and EQ indices. The Wilcoxon matched-pairs test was used to analyze the change in ILBF following PTA.

RESULTS The results are analyzed on an intention-to-treat basis. The study group consisted of 108 patients, 74 men and 34 women, with a median age of 67 years (range 40-87 years), who had suffered with intermittent claudication for a median of 2 years (range 0.5-15 years). Four patients suffered grade 1 or mild claudication (can complete 5 min on the treadmill at 2.5 km/hr at a 10° incline, ankle pressure after treadmill testing is >50 mmHg but >25 mmHg below the systolic blood pressure), 82 patients suffered grade 2 or moderate claudication (cannot complete treadmill test but post-treadmill ankle pressure >50 mmHg), and 22 patients suffered grade 3 or severe claudication (cannot complete treadmill test but post-treadmill ankle pressure <50 mmHg). Factors predisposing to peripheral vascular disease and comorbid conditions are summarized in Table III. Prior to PTA, all patients attempted treadmill testing, but 12 patients were unable to tolerate walking on the treadmill and thus recorded a MTWD of zero. Nine patients declined ILBF prior to PTA and thus were excluded from the ILBF results analysis. All patients underwent unilateral PTA of a short-segment arterial stenosis or occlusion. The specific arterial segments undergoing PTA are summarized in Table IV. Thirty three patients (31%) complained of bilateral claudication and underwent angioplasty of an arterial segment in the most symptomatic limb. Twenty-six of the suprainguinal angioplasties were performed on limbs with evidence of significant superficial femoral artery disease at arteriography. There were six technical failures due to the inability to cross the lesion with a wire. Attendance rates were 87%, 89%, and 88% at 1, 3, and 6 months, respectively. Cumulative patency rates were 91%, 81%, and 75% at 1, 3, and 6 months (Fig. 1).

Annals of Vascular Surgery

Table IV. Arterial lesions undergoing PTA Right

Left

Total

Common iliac artery External iliac artery Superficial femoral artery Popliteal artery

23 4 33 1

20 2 23 2

43 6 56 3

Total

61

47

108

Clinical Indicators of Lower Limb Ischemia Angioplasty resulted in a 7-fold increase in PRWD at 1 month, which was maintained at 3 and 6 months (Fig. 2). Following PTA, six patients at 1 month, 6 patients at 3 months, and seven patients at 6 months declined treadmill testing mainly because of comorbid conditions (e.g., previous CVA or angina), thus these patients recorded a MTWD of zero meters. Nevertheless, a 2-fold increase in median MTWD was observed at 1 month post-PTA, which was maintained at 3 and 6 months (Fig. 3). Some improvement of MTWD was demonstrated in approximately 85% of patients at each follow-up period; however, only approximately 20% of patients completed the full 5 min of treadmill testing (Fig. 4). Important causes of premature cessation of treadmill testing in the other 80% of patients included residual/recurrent ipselateral claudication, contralateral limb claudication and comorbidity, i.e., shortness of breath, chest pain, and arthritis (Fig. 5). ABPIs in the leg undergoing PTA demonstrate a significant improvement post-angioplasty, both at rest and following treadmill testing (Fig. 6). However, there would seem to be a downward trend during follow-up of both indices. There is no significant change in the ABPIs in the limb not undergoing PTA at rest or following treadmill testing; however, the median values are persistently <1, with post-exercise values being marginally lower than those at rest (Fig. 7). There is a significant improvement in limb perfusion as indicated by the improvement in the ILBF following PTA (Fig. 8). There is no significant change in the ILBF of the nonangioplastied leg, however, the values are persistently lower than the normal values of 10 mL/ 100 mL/min.13 Quality of Life Results PTA results in significant improvements in SF36measured physical functioning, role physical, pain,

Vol. 13, No. 1, 1999

Chetter et al. 97

Fig. 1. Life-table data. Numbers of PTA sites at risk of restenosis/occlusion at the beginning of each period are indicated. Standard error at each time point <10%.

Fig. 2. Patient reported walking distance (PRWD) results. p < 0.01 by KWANOVA.

vitality, social functioning (p 艋 0.01) and mental health (p 艋 0.05). There does appear, however, to be a downward trend in several of these QOL domains during follow-up (Fig. 9). PTA had no significant impact on the SF36 domains of general health (p = 0.35) or role limitations due to emotional problems (p = 0.75). Effect sizes are presented in Figure 10.

The EQ results are presented in Figure 11. Over the study period, significant improvements in global QOL measured using the EQ VAS and TTO indices were observed (p < 0.01 KWANOVA). Improvements in EQ TTO indices without corresponding improvements in ABPI were observed in 12% of patients at 1 month, and in 11% of patients at 3 and 6 months.

98

Angioplasty and quality of life

Annals of Vascular Surgery

Fig. 3. Maximum treadmill walking distance (MTWD) results p < 0.01 by KWANOVA.

Fig. 4. Changes in maximum treadmill walking distance (MTWD) on treadmill testing.

Overall Outcome Assessment

DISCUSSION

Improvements were observed, according to ISCVSsuggested reporting standards (i.e., an improvement in claudication category or an improvement in ABPI >0.1) in 80% of patients at 1 month, 73% of patients at 3 months, and 71% of patients at 6 months. No change in claudication category and a <0.1 change in ABPI was observed in 13% of patients at 1 month, 18% of patients at 3 months, and 13% of patients at 6 months. Clinical deterioration (a fall in claudication category, development of rest pain or ulceration, or a fall in ABPI >0.1), was observed in 7%, 9%, and 16% of patients at 1, 3, and 6 months, respectively (Fig. 12). No amputations (digital or more proximal) were performed.

The high rates of attendance at follow-up are attributable to the provision of accessible and reliable patient transport. The age range, sex ratio, factors predisposing to peripheral vascular disease, and levels of comorbidity are as expected in a group of patients with claudication. A 6% technical failure rate for PTA is in keeping with other studies. An overall cumulative patency rate of 75% at 6 months was a little disappointing, given that 5-year patency rates of 50-90% for iliac lesions and 43-75% for femoropopliteal lesions have been reported in the literature.27-29 In general, PTA patency rates are inferior to those achieved by bypass surgery; however, procedure-related mortality is substantially lower, as

Vol. 13, No. 1, 1999

Chetter et al. 99

Fig. 5. Outcome after treadmill testing (TT) following PTA for intermittent claudication.

Fig. 6. Variation in ankle brachial pressure index (ABPI) in limb undergoing PTA. p < 0.01 at rest and post-exercise (KWANOVA).

are the procedure costs and length of hospital stay.27 PTA and reconstructive surgery have been demonstrated to have a similar impact on QOL.30 The large discrepancy between reported and measured walking distances may be accounted for by the speed of the treadmill. Many patients reported that the treadmill was much faster than their normal walking speed, thus perhaps this speed underestimates patients’ walking distances, and a slower speed may demonstrate improved correlation. It is interesting that only one-fifth of patients are sufficiently mobile to complete treadmill testing following PTA and a greater number than may be expected are limited by comorbid conditions, contralateral claudication, and residual or recurrent ipselateral claudication. This suggests that with refinements in patient selection, the outcome following PTA could be improved further, and perhaps

certain claudicants (e.g., those with bilateral symptoms or those with cardiorespiratory disease) may be suitable for other interventions prior to or instead of PTA, i.e., a supervised exercise program or optimization of concomitant medical therapy. There is little doubt that PTA improves the clinical indicators of lower-limb ischemia, however, the downward trend of several of these indicators in both the symptomatic and asymptomatic limbs demonstrates the progressive nature of the disease. Therefore it is important to demonstrate that any intervention in claudicants has an immediate and relatively lasting impact on patient-reported QOL. As described by others, intermittent claudication has a serious inhibitory effect on QOL.2 The impact of PTA for claudication on QOL is disputed.31,32 This study demonstrates that PTA results in significant improvement in six of eight SF36-measured QOL

100

Angioplasty and quality of life

Annals of Vascular Surgery

Fig. 7. Variation in ankle brachial pressure index (ABPI) in limb not undergoing PTA. p = 0.47 (rest) and 0.46 (post-exercise) by KWANOVA.

Fig. 8. Isotope limb blood flow (ILBF) results, medians, and interquartile ranges.

Fig. 9. Median SF36 scores. *p < 0.01, **p < 0.05 by KWANOVA.

Vol. 13, No. 1, 1999

Chetter et al. 101

Fig. 10. SF36 effect sizes. Effect size = Post M − Pre M/Pre IQR where Post M = median SF36 domain score post-PTA, Pre M = median SF36 domain score prior to PTA, and Pre IQR = SF36 domain interquartile range prior to PTA.

Fig. 11. EuroQol (EQ) results for visual analogue scale (VAS) index (p < 0.01) and time trade-off (TTO) index (p < 0.01 KWANOVA).

domains. The only SF36 domains not affected by PTA are role limitations due to emotional problems and general health. Most SF36 domains seem sufficiently responsive to detecting QOL changes associated with successful angioplasty. Because all QOL domains except general health perception show a positive effect, it does not seem logical that PTA results in physical, social, and psychological improvements but patients describe their general health as unchanged or deteriorating. This may detract from the face validity of this domain in this specific group of patients. The downward trend in many of the QOL domains during follow-up would seem to reflect progression of peripheral vascular disease and comorbidity. This supports the con-

struct validity of these domains for this in this particular patient group. Significant improvements in both EQ indices are demonstrated following PTA, thus it may be concluded that the procedure improves patients’ overall global QOL. It is recognized that any intervention for claudication will have a placebo effect, and it could be argued that the QOL benefits demonstrated here are largely due to this placebo effect. We would suggest that in fact, the placebo effect due to PTA in this study is minimal, as demonstrated by only modest improvements in the SF36’s psychological domains of vitality and mental health. Indeed, in the SF36’s other psychological domain, role limitations due to emotional problems, no improvement was observed over the

102

Angioplasty and quality of life

Annals of Vascular Surgery

Fig. 12. International Society for Vascular Surgery outcome criteria.

study period. This is further supported by the fact that only a small minority of patients experienced QOL improvements on the EQ TTO index without corresponding improvements in resting ABPI.

CONCLUSION PTA improves patients’ QOL and this helps to justify the recent increase in its use in the management of claudication. However, outcome in this diverse patient group is not as impressive as one may expect, and several QOL domains demonstrate a downward trend during follow-up. Perhaps, then, with improved selection of patients and arterial lesions for PTA and the use of alternate interventions prior to or instead of PTA, it may be possible to focus this precious but expensive resource more costeffectively. Financial support for this work was provided by the Yorkshire Vascular & Surgical Research Fund, and the Northern & Yorkshire Research Fellowship Scheme. This study was presented in abstract form at the Peripheral Vascular Surgical Society, Boston, MA, May 31, 1997. REFERENCES 1. Widmer LK, Greensher A, Kannel WB. Occlusion of the peripheral arteries: a study of 6,400 working subjects. Circulation 1964;30:836-842. 2. Pell JP. Impact of intermittent claudication on quality of life. Eur J Vasc Endovasc Surg 1995;9:469-472. 3. Dotter CT, Judkins MP. Transluminal treatment of arteriosclerotic obstruction. Description of a new technique and a preliminary report of its application. Circulation 1964;30: 654-670. 4. Gruntzig A, Hopff H. Perkutane Rekanalisation chronischer

5.

6.

7.

8.

9.

10. 11.

12.

13.

14.

15.

16.

arterieller Verschlusse mit einem neuen Dilationskatheter. Modifikation der Dotter Technik. Dtsch Med Wochensch 1974;99:2502-2510. Gutteridge B, Torrie P, Galland B. Trends in arterial reconstruction, angioplasty, and amputation. Health Trends 1994; 26:88-91. Pell JP, Whyman MR, Fowkes FGR, Gillespie I, Ruckley CV. Trends in vascular surgery since the introduction of percutaneous transluminal angioplasty. Br J Surg 1994;81:832835. Spence RK, Freiman DB, Gatenby R, et al. Long term results of transluminal angioplasty of the iliac and femoral arteries. Arch Surg 1981;116:1377-1386. Waltman AC, Greenfield AJ, Novelline RA, et al. Long term results of transluminal angioplasty of the iliac and femoropopliteal arteries. Current status. Arch Surg 1982;117:12181221. Zeitler E, Richter EI, Roth FJ, Schoop W. Results of percutaneous transluminal angioplasty. Radiology 1983;146:5760. Porter J. Endovascular arterial intervention: expressions of concern. J Vasc Surg 1995;21:995-997. European Working Group on Chronic Leg Ischaemia. Second European consensus document on chronic critical leg ischaemia. Eur J Vasc Surg 1992;6(Suppl A):1-32. Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery, North American Chapter, International Society for Cardiovascular Surgery. Suggested standards for reports dealing with lower extremity ischaemia. J Vasc Surg 1986;4:80-94. Parkin A, Robinson PJ, Wiggins PA. The measurement of limb blood flow using technetium labelled red blood cells. Br J Radiol 1986;59:493-497. Ware JE, Sherbourne C. The MOS 36 item short form health survey 1: conceptual framework and item selection. Med Care 1992;30:473-483. McHorney CA, Ware JE, Raczek AE. The MOS 36 item short form health survey (SF36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care 1993;31:247-263. Stewart AL, Hays RD, Ware JE. The MOS short form General

Vol. 13, No. 1, 1999

17.

18.

19.

20.

21.

22.

23.

24.

Health Survey: reliability, validity in a patient population. Med Care 1988;26:724-735. Brazier JE, Harper R, Jones NMB, O’Cathain A, Thomas KJ, Usherwood T, Westlake L. Validating the SF36 health survey questionnaire: a new outcome measure for primary care. Br Med J 1992;305:160-164. IC Chetter, Spark JI, Dolan P, Scott DJA, Kester RC. Quality of life analysis in patients with lower limb ischaemia; suggestions for European standardisation. Eur J Vasc Endovasc Surg 1997;13:597-604. Jenkinson C, Coulter A, Wright L. Short form 36 (SF36) health survey questionnaire. Normative data for adults of working age. Br Med J 1993;306:1437-1440. Garratt AM, Ruta DA, Abdalla MI, Buckingham JK, Russell IT. The SF36 health survey questionnaire: an outcome measure suitable for routine use within the NHS?. Br Med J 1993;306:1440-1444. Kazis LE, Anderson JJ, Meenan RF. Effect sizes for interpreting changes in health status. Med Care 1989; 27(suppl):S178-S189. The EuroQol Group. EuroQol: a new facility for measurement of health related quality of life. Health Policy 1990;16: 199-208. Williams A. The measurement and valuation of health: a chronicle. Discussion paper 136 1995, Centre for Health Economics, The University of York, UK. Kind P. Measuring health status in the community: a com-

Chetter et al. 103

25.

26.

27.

28. 29.

30.

31.

32.

parison of methods. J Epidemiol Commun Health 1994;48: 86-91. Brazier J, Jones N, Kind P. Testing the validity of the EuroQol and comparing it with the SF36 health survey questionnaire. Qual Life Res 1993;2:169-179. Dorman PJ, Slattey J, Farrell B, Dennis MS, Sandercock PAG. A randomised comparison of the EuroQol and short form 36 after stroke. Br Med J 1997;315:461. Insall RL, Loose HWC, Chamberlain J. Long term results of double balloon percutaneous translumuinal angioplasty of the aorta and iliac arteries. Eur J Vasc Surg 1993;7:31-36. Ahn SS, Eton D, Moore WS. Endovascular surgery for peripheral arterial occlusive disease. Ann Surg 1992;216:1-16. Van der Heijden FHWM, Eikelboom BC, Banga JD, Mali WPTM. Management of superficial femoral artery occlusive disease. Br J Surg 1993;80:959-963. Currie IC, Wilson YG, Baird RN, Lamont PM. Treatment of intermittent claudication: the impact on quality of life. Eur J Vasc Endovasc Surg 1995;10:356-361. Cooke TA, O’Regan M, Galland RB. Quality of life following percutaneous transluminal angioplasty for claudication. Eur J Vasc Endovasc Surg 1996;11:191-194. Whyman MR, Fowkes FGR, Kerracher EMG, Gillespie IN, Lee AJ, Housley E, Ruckley CV. Randomised controlled trial of percutaneous transluminal angioplasty for intermittent claudication. Eur J Vasc Endovasc Surg 1996;12:167-172.