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Original ArticleEconomic Evaluation of a Randomised Trial of EarlyReturn to Normal Activities Versus CardiacRehabilitation After Acute Myocardial Infarction

Jane P. Hall, PhD, Virginia L. Wiseman, Grad. Dip. (Health Economics) ,I Madeleine T. King, Grad. Dip. (MedicalStatistics), David L. Ross,MB, FRACP,* Pramesh Kovoor, PhD, FRACP,* Robert I?. Zecchin, MN (Cardiac),* FionaM. Moir, BN* and A. Robert Denniss, MD, FRACP*

Centrefor Health Econ omics Research and Evaluation (CHERE ), Sydney and *Cardiology Unit, W estmead Hospital , Sydney,New South Wales, Austral ia

Background: Although there have been a number of economic evaluations of cardiac rehabilita-tion after acute myocard ial infarction (AMI), none has considered only low- risk patients orcontrol groups with no rehabilitation at all.Methods: An economic evaluation was included in a randomised controlled trial of patientsfollowing uncomplicated AMI. Eligible patients were randomised to return to normal activ itiesafter 6 weeks of standard rehabilitation (REHAB, n = 701 or to early return to normal activ ities2 weeks after AM1 with no formal rehabilitation (ERNA, II = 721. Outcomes were assessedweekly for 6 weeks, then 3, 6 and 12 months post-AMI. Outcomes included four qua lity of life(QOL) measures (physical abilities, distress, usual/social activities, self-care) and four measuresof return to normal activ ities (paid and unpaid return to any work and to pre-AM1 level ofwork). Statistical analysis included repeated-measures regression (QOL outcomes) and survivalanalysis (work outcomes).Results: There were no statistica lly significant differences between the two groups in any of theoutcomes measured or in the use of other health services. The net cost that could be saved by thehealth service by targeting rehabilitation to high-risk patients was approximate ly $300 (Aus tral-ian, 19991 per low- risk patient.ConcZusions: Early return to normal activities without formal rehabilitation is cost-effective forlow- risk patients. (Heart, Lung and Circulation 2002; 11: 10-18)Key words: cardiac rehabilitation, cost-effectiveness analysis.

Rhabilitation after acute myocard ial infarction(AMI) is accepted as an integral part of treatment

that enhances physical and psycho logical recov-ery. Some authorities consider that cardiac rehabilitationreduces mortaliv5 but this is not unive rsally acceptedand probably not applicable to low risk groups of patients.Although some studies have shown improvements in1 See related Editorial 1Correspondence: Jane Hall , Centre for Heal th Economics Researchand Evaluation, Level 6, Building F, 88 Mallett Street, Camperdown,New South Wales 2060, Australia. Email: janeh@chere.usyd.edu.au

quality of life2r6r7overall there is probably little effect inmeasurable quality of life outcomes.3,4Restricted health budgets mean that not only mustrehabilitation be shown to be effective, it must also becost-effect ive to compete for scarce resources. There havebeen few economic evaluations of cardiac rehabilitation.There are a number of studies that show lower total costsin patients undergoing rehabilitation. Oldridge et al .*conducted a large, randomised study of cardiac rehabili-tation for low- risk post-AM1 patients with m ild to mod-erate anxiety or depression. Patients randomised to therehabilitation group incurred lower total health service

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costs over 12 months, and a gain in quality-adjusted lifeyears. However, the control group used rehabilitationserv ices provided in the community. Indeed, the costsavings were attributable to the difference in communityrehabilitation visi ts, with no significant differences in therates of rehospitalisa tion or any other serv ices. Levinet ~1.~ report a 5-year follow up of two groups of sur-vivo rs of AMI, one from a hospital that provided a3-month high-intensity rehabilitation program, andanother that referred patients back to primary care. Theyfound total costs to be lower in the former group, withthe rehabilitation costs of the former group being morethan offset by costs of rehospitalisa tion in the lattergroup. Although there was a signif icantly higher rate ofreturn to work in the rehabilitation group, none hadreturned to work by 4months post-AMI. Ades et a2.*Oshowed that the costs of a 3-month rehabilitationprogram were offset by reduced rehospitalisation. How-ever, this was an unrandomised study that combinedAM1 and coronary artery bypass grafting outcomes. In ameta-analysis, Ades et al . l1 found that cardiac rehabilita-tion was more cost-effec tive than thrombo lytic therapies,coronary bypass surgery and cholestero l-lowering drugs,although less cost-effect ive than smoking cessation.However, these findings are subject to three caveats.First, there was no analysis by level of cardiac risk.Second, costs of rehabilitation were assumed to be offsetby lower hospitalisation rates, on which the evidence ismixed (as cited above). Third, the surv ival data aredrawn from cl inical studies that predate some of thetherapies which have been shown to improve surviva l.12A more recent study compared exercise rates and cardio-vascular outcomes in low- to moderate -risk patients ran-domised to a traditional or a less intensive rehabilitationprogram. l3 Although the modified program was lesscost ly and as effective as traditional cardiac rehabilita-tion, both programs included an initial 4 weeks of thrice-weekly supervised exercise with continuous electro-cardiogram (ECG) monitoring.

Rates of return to employment after AM1 of 62-92%have been recorded.14 Return to work is more frequentand earlier in patients who have undergone cardiac rehab-ilitation.4,6,9,15,16Schille r and Baker17 showed in an Aus-tralian study that 80/96 (83%) of rehabilitation patientsand 70/94 (74%) of controls returned to work. Notreturning to paid employment has been associated with alower quality of life;18*19 and return to paid work hasbeen used as an outcome measure in the evaluation ofrehabilitation programs. 16,17 n a study of low-risk post-AM1 patients, Picard et ~1.~~ andomised patients to anoccupational work evaluation. Patients in the interven-tion group returned to work at a median of 7 weeks post-AM1 (part-time and full-time), and patients in the control

group returned to work at a median of 7 weeks (part-time) and 11 weeks (full-time). The intervention grouphad significantly lower medical costs (primarily due tofewer rehospitalisa tions) in the 6 months after AMI.However, the lower hosp ital costs did not fully offset thecost of the rehabilitation program. When the productiongains from increased employment were included, cardiacrehabilitation delivered net economic gains.While the inclusion of production gains (also calledindirect costs/benef its) seems attractive, there are someproblems. First, it is not clear that there is a real neteconomic gain. Second, there are many factors associatedwith returning to work, including employment history,the labour market, insurance benefits, and the physicaldemands of the job. 9J4 Therefore, return to employmentas the only measure of success of rehabilitation is aninadequate measure. 21 It seems that executives and pro-fessionals wil l go back to work anyway; and many otherssimp ly do not wish to.

Overa ll, there are a limited number of economic eval-uations of cardiac rehabilitation and these often rely onnon-randomised designs. There is substantial variationfrom country to country in the patterns of care, costs ofhealth services , and in return to paid employment. Fur-ther, the issue is not just whether cardiac rehabilitation iscost-effect ive, but for whom. Grines et ~1.~~ howed earlydischarge to be safe (and cost saving) for low-riskpatients. Many patients, part icularly those at low risk ,will recover anyways and social and economic factorsinfluence the return to work.The present study was designed to evaluate whetherearly return to normal activities is safe for low-riskpatients. Early return to normal activities (ERNA) wascompared with a conventional rehabilitation programinvolv ing exercise and counselling four times per weekover the 6 weeks following the AMI. As patients who donot receive rehabilitation may have poorer outcomes ormay use more health services, the evaluation includedboth the costs of rehabilitation and any other healthservice costs including readmission to hospital. Healthoutcomes included four health-related quality of lifedomains (physical abilities, distress, usual activities andself-care) and four measures of return to normal activi-ties (two lev els of work - any work and pre-AM1 work-load; and two types of activ ity - paid employment andnormal unpaid activ ities such as household duties).

MethodsStudy DesignAl l patients admitted between Apr il 1994 and December1996 to Westmead and Blacktown Hospitals with a diagnosis

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of AM1 were screened for elig ibility. AM1 patients aged< 75 years were s tratified into high- and low-risk groupsprior to discharge from hospital. Low-risk patients weredefined by the following:1 Negative exercise stress test (< 2 mm ST segmentchange) with at least seven Metabolic Equiva lents

achieved at the initial exercise test or, in manual work-ers, a workload commensurate with leve ls achieved atwork prior to AMI.2 Left ventricu lar ejection fraction 2 40%.3 No inducible ventricu lar tachycardia in patients withleft ventricu lar ejection fraction < 40%.4 No unstable angina post infarction.5 No severe cardiac failure.The study received approval from the WesternSydney Area Eth ics Committee. Consent for participa-tion in the trial was obtained from participating patientsand physicians. E ligib le patients were randomised eitherto: return to normal activ ities after rehabilitation about6-12 weeks after infarction (REHAB); or to return tonormal activ ities at 2 weeks after infarction withoutformal rehabiltation (ERNA). REHAB patients partici-pated up to 4 days a week for 6 weeks in an outpatientcardiac rehabilitation program at Westmead Hospita l.The REHAB program included a low-level training pro-gram, together with counselling on group behaviouraland risk factor management. Both groups were giveneducation about heart disease risk factors, counsellingand a home walking program. Non-English-speakingpatients were interviewed with an interpreter at home orat Westmead Hospital in the cardiac rehabilitationcentre. Clin ical follow up of both groups involved amaximal exercise test and risk modification question-naires at 6 weeks and 6 months, and radionuclide ven-tricula r function at 6 months, and preliminary resultshave been reported elsewhere.23,24Economic EvaluationEconom ic evaluation of the program involved a compari-son between the REH AB and ERN A groups of theimpact on resources, changes in health-related quality oflife, and leve ls of paid employment and unpaid activ ities(e.g. household chores). A questionnaire was posted topatients for completion at nine time points follow ingrecruitment: every week for 6 weeks, then at 12 weeks,6 months and 1 year post in farction. The questionnairecontained three components: quality of life, resource useand work (paid and unpaid). The first questionnaire(week 1) contained additional questions about patientcharacteristics and pre-AM1 activities. Patients whosequestionnaires were 3-5 days overdue were remindedonce by telephone.

Return to normal activi ties. In the first questionnaire(week l), patients were asked what they did prior to theirheart attack (i.e. unemployed, retired, in full-time work,part-time or casual work, student, other) and the averagehours of paid work and/or unpaid activ ities they per-formed per week prior to their infarction. In that ques-tionnaire and all subsequent questionnaires, patientswere asked about the hours of paid work and unpaidactiv ities they had performed in the previous week.There were four measures of return to normal activ itiesfor each follow-up time point: returned to any hours ofpaid work, returned to pre-AM1 hours of paid work;returned to any hours of unpaid activit ies, returned topre-AM1 hours of unpaid activi ties.Health-related quality of life. Patient perceived health-related quality of life was assessed using a cardiovascu-lar extension of the Health Measurement Question-naire.25 The test-retest reliab ility, construct va lidity andresponsiveness of this version of the questionnaire havebeen established in a sample of cardiac patientsF5 Thequestionnaire contains 28 items that are aggregated intofour dimension scales. The physical ability scale containsfour items with a 4-point Likert scale: mobility, climbingstairs, walking 500 m and vigorous activities. The social/usual activities scale contains five items with a $-pointLikert scale: usual daily activities, leisure/hobby activi-ties, seeing friends/relatives, sex life, and social life. Theself-care scale contains four items with a 3-point Likertscale: washing, dressing, eating, using the toilet. Thedistress scale contains 15 items with an ll-point ratingscale: breathlessness, difficu lty sleeping, lack of energy,pain, depression, anxiety, weight/appearance, uncer-tainty, anger, loneliness, loss of self-confidence, feelingdependent, feeling sick, muscle aches/pains, difficu ltyconcentrating and other problems. The cardiac-specificquestions included the four usual activ ities items andsome of the symptom items (shortness of breath, d iffi-culty sleeping, lack of energy, muscle aches and ability toconcentrate). Each dimension score was derived as fol-lows. If half or more of the questions in a dimensionwere missing, the dimension score was considered to bemissing. Otherw ise, the dimension score was the averageof the non-missing item responses, linear ly transformedto a scale with a range of O-100 where a 0 denotes nodistress/problems and 100 denotes the highest possiblelevel of distress/problems.Costs. The two patient groups were assumed to have hadthe same m-hospital treatment (same resource require-ments) for the initia l treatment of AMI. The cost of therehabilitation program was estimated as follows, usingunit cost data provided by Westmead Hospital. Staff

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time was costed using full-time equivalent hourly ratesfor each position and adjusting for on-costs. Hospitaloverheads were attributed on the basis of the physicalarea occupied by the rehabilitation clin ic; capital equip-ment by converting the replacement cost to an annualequipment cost over the estimated useful life; buildingby annual equivalent cost; and consumables at currentmarket rates. These were then expressed as costs per visitand cost per patient. Trave l costs incurred by patientswere also estimated. Patients trave lled to the hospital forexercise by bus, train or car. For those travelling by tramor bus, exact fares were used. Car travel costs wereestimated to be $0.32 per kilometre, which includesvehicle depreciation. Distance travelled by car was esti-mated using local area maps.

Patient covar iates were gender, age, marital status, pre-AM1 health sta tus and pre-AM1 hours of paid employ-ment.The four return-to-work variables were treated assurv ival outcomes, with patients lost to follow upconsidered as right-censored. SA S procedure Lifeteprovided non-parametric estimates of the surv ival dis tri-bution for each intervention group. Two tests of thesignificance of the effect of the intervention were used:the Wilcoxon test (which places more weight on short-term outcomes, i.e. return to normal activ ities in the firstweeks post-AMI) and the log-rank test (which placesmore weight on long-term outcomes).

Post-discharge differences in the use of health-careservices were also assessed. These included physicianvisits (general practitioner and specialist), visits to otherhealth professiona ls (dietitian, physiotherapist, socia lworker, naturopath), diagnostic tests and hospitalreadmissions. Use of four non-hospital services (visits toa rehabilitation clinic, GP/local doctor, specialist doctor,and other health p rofessional) were collected as part ofthe same self-administe red questionnaire as the qualityof life and work outcomes. Information on use of hospi-tal services, including readmiss ions, and telephone con-sultations with rehabilitation staff was collected by thestudy team using medical records. Costs were includedfor each type of service for which there was a statisticallysignificant difference in usage between the REH AB andERNA groups. All costs are expressed in 1999 Australiandollars.

The four quality of life outcome variables were anal-ysed with a repeated measures analysis of variancemodel to test for the effect of intervention (two leve ls:ERNA, RE HAB), time (nine levels : week 1,2,3,4,5,6,12,26 and 52), and the interaction of time and intervention.SA S procedure Mixedz6, which uses maximum likelihoodestimation, was used because the data were unbalanceddue to some missing data. As the patients tended to bequite well , the distributions of the quality of life scoreswas skewed towards the healthy end of the scale. A log-transformation was used to normalise the distribut ionsprior to analysis. For graphical presentation of quality oflife results, confidence intervals were calculated usingthe estimates of group means and standard errors fromthe repeated measures ANOVA, and then antilogged suchthat the graphs are on the original quality of life scale.

ResultsDifferences in the distributions of covariates between thetwo intervention groups (ERNA, RE HAB) were tested forstatis tical significance with the two sample t-test (forcontinuous variables) or the x2 test (for discrete variables)using S AS procedures t-test and Freq, respectively.26

Statistical Analysis SampleOf 1201 AM1 patients under 75 years admitted betweenApr il 1994 and December 1996,187 were eligib le for thisstudy (Table 1). Of the 45 patients who refused consent,49% wished to return to paid work immediate ly and 30%wished to attend the rehabilitation program. The 142

Table 1. Reasons or ineligibilityReasonOngoing anginaCardiac failureExercise stress test (< 7 MET)Unable to exercise (arthritis, peripheral vascular disease)Left bundle branch blockExercise stress test (2 2 mm ST depression)Inducible ventricular tachycardiaOther (deceased, live outside Sydney, self-discharge, mental disorders)

+Totaln = 1014.

Frequency+4111206773261145198

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recruit s were randomised within 1 week of AM1 to usualcardiac rehabilitation (n = 70) or ERNA (n = 72). How-ever, 13 of the 142 recruits (9%) did not complete anyquestionnaires. Thus the effective sample was 129 of 187eligib le patients (69%). As shown in Table 2, the onlystatistically significant difference in patient characteris-tics between the groups at the baseline questionnaire wasthat more patients in the REH AB group li ved alone;nevertheless more than 80% of patients in each grouplived with at least one other person. In each group, twopatients were non-Eng lish speaking.Questionnaire completion and follow-up rates aresummarised in Table 3. For each of the nine follow-uptimes, patients who returned a questionnaire at that timewere noted as completed, patients who did not return aquestionnaire at that time but returned subsequent ques-tionnaires were noted as miss ed and patients whofailed to complete that questionnaire and all subsequentquestionnaires were described as lost to follow up. Thecompletion and drop-out rates were simi lar in the twogroups. Follow-up rates were 76% (98/129) at 3 months,78% (101/129) at 6months and 59% (76/129) at12 months.Table 2. Baseline characteristics

Return to normal activities. The effective sample size foreach of the four measures of return to normal activ itiesdiffered for the following reasons. For the measure ofreturn to any work, the sample s ize was 76, as 60% ofpatients were in paid employment prior to their heartattack. Of these, 65 (86%) patients provided informationon hours of paid work pre-AMI. Thus the effectivesample size for return to pre-AM1 leve ls of paid workwas 65. The sample size for the measure of return to anyunpaid normal activ ities was 119 (i.e. those patients whoprovided information about hours of unpaid act ivitie sduring follow up). This represents 92% of the sample of129 recruits who completed at least one questionnaire. Ofthese, 110 patients provided information on hours ofunpaid activities pre-AMI. Thus the effective sample sizefor return to pre-AM1 leve ls of unpaid activ ities was 110(85% of 129). Most of these patients returned to normalactiv ities prior to being lost from follow up. Censoringrates were low, and approximately the same in eachgroup: 3/76 (4%), 21/65 (32%), l/119 (1%) and 23/110(21%) for the four measures, respec tively.The proportion of respondents returning to the fourclasses of normal activities during the year of follow up is

Characteristic ERNA (n = 62+) REHA B (n = 65+) P valueMale (%) 56 59 0.55Mean (years)ge 56 56 0.93In paid employment at time of AM1 (%) 65 55 0.29Hours week of paid work pre-AM1er 38 35 0.78Hours week of unpaid activ ities pre-AMIer 16 14 0.21Live with at least one other (%)erson 97 84 0.02

+127 of the 129 recruits completed the first questionnaire (the source of information on baseline charac teristics), two recru itsmissed the first questionnaire but completed subsequent questionnaires. AMI, acute myocardial infa rction.

Table 3. Number of patients who completed questionnaires, missed questionnaires or were lost to follow upERNA recruits (n = 72) REHAB recruits (n = 70)Complete Missed Lost to follow up Complete Missed Lost to follow up

Week 1 62 2 8 65 0 5Week 2 63 1 0 57 6 2Week 3 57 2 5 60 2 1Week 4 54 4 1 53 8 1Week 5 52 6 0 51 8 2Week 6 47 10 1 51 8 012 weeks 49 8 0 49 6 46 months 51 2 4 50 3 212 months 39 0 15 37 0 16ERNA, early return to normal activities 2 weeks after AMI with no formal rehabilitation; REHAB , return to normal activitiesafter 6 weeks of standard rehabilitation.

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shown in Fig. 1. The only statistically significant resultwas return to any paid work, with ERNA patients return-ing earlier (Panel A, P = 0.007 for Wilcoxon test; P = 0.04for log-rank test). In the first 6 weeks post-AMI, rates ofreturn to any paid work and pre-AM1 levels of paid workwere higher in the ERNA group than in the REH ABgroup, confirming that patients tended to comply w iththe main study requirement. Nevertheless, a considerableproportion of REH AB patients returned to at least somepaid work within a few weeks of their AMI. By 12 weekspost-AMI, there was little difference between the twogroups in the rate of return to paid work.Health-related qualify of life. For the 947 questionnairesthat were returned the completion rates for the quality oflife questions were high: missing data rates for the qualityof life scales were 2% for the physical, psychological andself-care scales and 4% for the usual activities scale.

The quality of life results are presented in Fig. 2 as themean scores (with 95% confidence intervals, on O-100scale) for the ERNA and REHAB groups. (The confidenceinterva ls are non-symmetrical because they were based onlog-transformed estimates from the analysis of variance. )The results for self-care are not presented because mostpatients had no problems with taking care of themselves(a)00;0 HFE 1 2 3 4 5 6 122652; Cc)

p 100 r UHF1 2 3 4 5 6 122652

(b)1001

0 w HH -1 2 3 4 5 6 122652Cd)

OI,rML1 2 3 4 5 6 122652

WeeksFigure 1. Cumulative proportion of respondents thatreturned to the four class esof normal act ivities during the yearof follow up, in the group of patients who returned to normalactivities 2 weeks after acute myocardial infarction (AMI) withno formal rehabilitation (ERN A, a) and in the group whoreturned to normal ac tivities after 6 weeks of standard rehabi li-tation (REHAB, n ). Respondents were returning to (a) anypaid work (Pwilcoxon 0.007; P,og-rank 0.038), (b ) pre-AMIlevel of work (Pwi,coxon 0.11; P,og-,.ank 0.23), ( c) any unpaidwork @wilcoxon 0.67; P+ rQnk = 0.79) and (d) pre-AMI unpaidlevel of work (PW ilcoxon 0.43; P **- ank 0.83).

and the mean values were consequently all close to zerowith very small standard errors. For the remaining threedimensions, the mean scores were low (considering thescale maximum is loo), indicating good quality of life inthis patient group. For each dimension, the changes inquality of life over time were simila r in both groups, asFig. 2 illustrates. In both groups, the deleterious impactof the infarct on quality of life was apparent in the firstfew weeks post-AMI, and diminished thereafter. Therewere no stat istically significant diffe rences between thegroups in any of the dimensions of quality of life (physi -cal P = 0.72, distress P = 0.33, usual activities P = 0.60).There was a significant effect of time for each dimension(P c 0.001 for each dimension), and a significant interac-tion of time and group for distress (P = 0.007) and usualactivities (P = 0.004).Costs. The costs of the rehabilitation program, includingassessment, counselling and education, were $21.57per patient per exercise session . On average, patientsattended 14 exercise sessions each, giving an estimate fordirect costs (those costs which vary with patient work-load) of $301.91 per patient treated (Table 4). This

(a)14-

(b)

01HH. 0-HHL123456 122652 1 2 3 4 5 6 12 26 52Weeks

1 2 3 4 5 6 12 26 52Weeks

Figure 2. Qualify of life (QOL) mean scores with 95% con-fidence intervals, on O-l 00 scale ) or the patients who returnedto normal activ ities 2 weeks after acute myocardial infarction(AMI) with no formal rehabilitation (ERNA, A) and for thepatients who returned to normal activit ies after 6 weeks ofstandard rehabilitation (REH AB; W. QOL was assessedaccording to (a) dis tress (PcroUp 0.33; PTime 0.0001;Po xT = 0.0067), fb) physical abilit ies @orour, 0.72;PTime 0.0001; P, xT = 0.17) and (c) usual activitiesKhql = 0.60; PT ime 0.0001; P, xT = 0.0043). PGroup, iffer-ence n QOL between ERNA and REHAB groups; Prime,differ-ence n QOL over time; Po xT, group-by-time interactions.

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amount represents the value of resources that would befreed up for alternative uses, should the REH AB patientload be reduced. The full costs of the rehabilitationprogram should include an attribution for hospital over-heads. Hospital overheads include hospital supportservices such as cleaning, power, communications,administration and represent se rvices that are providedacross the hospital and would not be reduced in the shortterm, should the REH AB patient load be reduced. This isalso shown in Table 4, and added $91.70 to the cost perpatient treated, g iving a total hospital cost per patient ofapproximately $400.

In terms of health services resource use, during12-month follow-up period, there was no stat isticallysignificant difference between the two groups in thenumber of: phone calls (P = 0.10); hospital admissions(P = 0.11); gated heart pool scan (P = 0.50); exercise stresstest (P = 0.72); other diagnostics (P = 0.37); or visits to ageneral practitioner (P = 0.61); a specialist doctor(P = 0.35); or any other health professional (P = 0.31).Therefore, as there was no difference in the health servicecosts incurred, the rehabilitation program represents anet cost to the health system compared to ERNA ofaround $400 per patient.

DiscussionThe purpose of this study was to assess the difference incosts and outcomes between the ERNA and REHA Bgroups. The patients in the study were at low r isk forfurther cardiac events and were a relatively small pro-portion of all cardiac patients. Not surpris ingly, thisstudy found no significant differences in clin ical out-comes. However, we hypothesised that there may be adifference in health-related quality of life between thetwo groups; and this difference could have been in eitherdirection. ERNA patients may have had a more positiveperception of their health-related quality of life in theearly weeks post-AM1 due to their improved confidencein their functional capacity. Alterna tively, the impact of

rehabilitation and the sharing of experience with otherAM1 patients may have reduced anxietyF7 No statisti-cal ly significant difference between the groups in health-related quality of life was observed at any time. It ispossible that the quality of life measures used were notsensit ive to subtle differences in the experience of thetwo groups. However, the measures used coveredseveral aspects of quality of life and we found no differ-ences in any of these. This is consistent with other f ind-ings reported in the literature.3,4 In addition, this is alow-risk population with quality of life scores indicatinga good quality of life in the early weeks post-AMI, andtherefore a quick and uncomplicated recovery fromAM1 should not be surprising.No statistica lly significant difference in the use ofhealth-care serv ices was found between the two groups.This is not consistent with several other studies thathave found that the cost of rehabilitation is fully orpartially offset by savings primarily in rehospitalisa-tions.8-10 There are severa l explanations for this. Savingsdue to lower rehospitalisations have been demonstratedin non-randomised studies and therefore it seems thatsome selection effect is likely. The studies were con-ducted before the use of beta-blockers and antiplatelettherapies became common. Other than Carlson eta1.13these studies have not been restricted to low riskpatients. Carlson et al. demonstrated that a reduced cost-modified program was as effective as traditional rehabil i-tation; however, even the modified program involved4 weeks of intensive, supervised exercise.Most ERNA patients d id follow the medical advice toreturn to their normal leve ls of activ ity but there was nolong-term effect in paid workforce participation orunpaid activi ties. In this study, return to paid work wassubstan tially earlier in both groups than reported inother studies ; even in the study by Picard etal. mostpatients recommended to return to work early were notback at work in under 7 weeks post-AMI?O

The present study has some weaknesses. We did notassess patient compliance w ith medication, and therefore

Table 4. Total direct costsCost componentStaffBuildingEquipmentConsumablesSubtotal: direct costsPlus overheadsTotal hospital costs

Estimated cos t per patient per Estimated total cost per patientexercise session ($AUD) treated ($AUD)13.96 195.440.48 6.724.70 65.802.43 34.0221.57 301.986.55 91.7028.12 393.68

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cannot say whether rehabilitation affected this. We fol-lowed patients up to 12 months post-AMI, but the loss of46% of the sample to follow up at 12 months limits ourability to generalise about effects at that time. We cannotcomment on effects beyond the first year, such as patientcompliance with medication and lifes tyle changes in thelong term. If there are undetected benefits beyond12 months, the question then is whether a 6-week programpost-AM1 is the most cost-effective way to achieve this.The power of the present study to detect importanteffects deserves some discussion. We recruited 142patients. Retention rates at 6 months were good (70%). Ateach time point up to 6 months, the study had at least70% power to detect a lo-point difference on the health-related quality of life scales. An effect of this size is likelyto be clin ical ly important. 28 At each time point up to6 months, the study had at least 60% power to detect a20% difference in return to normal activ ities (also aclin ica lly important difference). The power of the analy-ses reported in this paper is higher than this, due to theuse of appropriate statis tical methods fo r analysing lon-gitudinal data. As the study had sufficient power todetect clinically important effects, our conclusions thatthere were no differences are robust.The strengths of the present study are the randomiseddesign, the repeated assessment of outcomes over time to12 months post-AMI, high retention rates up to 6 months(about 20% lost to follow up), and a comprehensiveassessment of quality of life and use of health servic es.This is important in an area where there are few ran-domised studies, and only two that incorporated aneconomic evaluation in the study design.13,29 However,in both these studies the modified intervention sti llinvolved extensive rehabilitation services. Our findingsshow that cardiac rehabilitation does not facilitateimproved quality of life or early return to normal activi-ties in low-risk AM1 patients. This suggests rehabilitationis not necessary for low-risk patients, a finding that hasgreat signif icance. It has the potential to change the post-AM1 management of low- risk patients, and free up reha-bilitation resources better directed to higher r isk patients.

merit: the Epidemiologically Based Needs Assessment Reviews.Radclif fe Medic al Press, Oxford, 1994; 341-78.

2. Lavie CJ, Milani RV. Effects of cardiac rehabilitation programson exercise capacity, coronary risk factors, behavioral character-istics, and quality of life in a large elderly cohort. Am. 1. Cardiol.1995; 76: 177-9.

3. Pashkow FJ. Issues in contemporary cardiac reh abilita tion: ahistorical perspective. 1. Am. Cull. Cardiol. 1993; 21: 822-34.

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