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Cost effectiveness and cost utility model of public place defibrillators in improving survival after prehospital cardiopulmonary arrest |
Walker A, Sirel J M, Marsden A K, Cobbe S M, Pell J P |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The provision of defibrillators in major airports, railway stations and bus stations. The comparator was no such provision.
Type of intervention Treatment and secondary prevention.
Economic study type Cost-effectiveness analysis; cost-utility analysis.
Study population The patients studied were those who suffered a cardiac arrest in a major airport, railway or bus station in Scotland between 1991 and 1998.
Setting The setting was primary care (passenger areas in public transport). The economic study was carried out in the UK.
Dates to which data relate The effectiveness evidence and resource evidence related to 1991 to 1998. Effectiveness evidence after 1998 was modelled. The price year used was 2000 - 2001.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The extrapolated costing was based on the same population as that which provided the effectiveness data on the consequences of installing defibrillators.
Study sample The study was an observational study of the prevalence of cardiac arrests and the performance of Scottish ambulance crews over time. All 38 cardiac arrests (5.4 per year) in the time period studied were included.
Study design The study was an observational study of the prevalence of cardiac arrests and performance of Scottish ambulance crews over a period of time.
Analysis of effectiveness All cardiac arrests during the study period were included. The primary health outcome used was the life-years saved.
Effectiveness results The observed survival was 52.9% to arrival at the accident and emergency department, 26.4% to admission and 14.74% to discharge. If public defibrillators were available, the predicted survival figures were 66.7% (arrival), 33.3% (admission) and 16.7% (discharge), respectively.
The mean length of stay after admission was 24 days among those discharged alive, 8 days among those who died and 14 days overall.
Clinical conclusions The marginal increases per year in the numbers surviving were 0.7 (13.8%) at airports, 0.4 (6.9%) at major railway stations and 0.1 (2%) at major bus stations. There would be 0.7 additional patients attending the accident and emergency department and 5.6 additional inpatient days.
Modelling The effects of defibrillators in public places were extrapolated, using information from other sources, to assess the effect on people who suffered cardiac arrest in these places.
Methods used to derive estimates of effectiveness The authors made a key assumption.
Estimates of effectiveness and key assumptions The authors assumed that the availability of defibrillators would have the same effectiveness, in terms of survival to arrival, as the early attendance of ambulance staff.
Measure of benefits used in the economic analysis The life-years gained were derived from the effectiveness results. The quality-adjusted life-years (QALYs) were used to derive a measure of benefit from the effectiveness results. Each QALY was estimated to be 72% of one life-year. The gain in QALYs was discounted at 1.5% and at 0%.
Direct costs The costs were discounted at rate of 6%. Since the perspective of the NHS was taken, only health service costs were estimated. The costs included were per accident and emergency attendance, per day in a coronary care unit, per day in general medicine or cardiology, for buying and maintaining a defibrillator, and for training staff to use a defibrillator. The costs were broken down into prices and quantities. The individual cost components were estimated using published data (Scottish NHS statistics) and personal communications (Scottish ambulance service). The costs of the whole programme were estimated, based on an extrapolation of how the programme would work using data from the Heartstart (Scotland) register, which records data on all resuscitation attempts after cardiopulmonary arrest. The price year was 2000 - 2001.
Statistical analysis of costs No statistical analysis of the costs was carried out.
Indirect Costs No indirect costs were recorded.
Sensitivity analysis A sensitivity analysis was carried out. The variables investigated were the number of cardiopulmonary arrests per year (38 - 50), the utility of survivors (0.72 - 0.92), the discount rate applied to years gained (0 - 6%), the number of defibrillators (21 - 31), and the cost of each defibrillator (1,250 - 2,500). A multi-way sensitivity analysis was performed.
Estimated benefits used in the economic analysis The gain in undiscounted QALYs per survivor was 4.5 (4.1 when discounted at 1.5% per year).
The gain in undiscounted QALYs per year was 0.44.
Cost results The estimated marginal cost of the defibrillator programme was 18,325 per year. Only the costs up to hospital discharge were included.
Synthesis of costs and benefits The cost per life-year gained was 29,625 (years gained not discounted).
The cost per QALY gained was 41,146 (QALYs not discounted).
The authors reported that variation in the cost parameters in the hospital had little effect on the overall result, although they did not give details of the results.
Variation in the benefit parameters had a significant effect on the cost per QALY. The most optimistic assumptions about outcomes coupled with no discounting of future benefits led to a cost per QALY of 23,689. Increasing the rate of discounting to 6% and then decreasing the number of cardiopulmonary arrests led to a cost per QALY of 67,546.
Reducing the cost of the defibrillator component of the programme reduced the cost per QALY to 17,679. When this was combined with the most optimistic assumptions on the benefit side, this led to a cost per QALY of 13,776.
Authors' conclusions The cost per quality-adjusted life-year (QALY) gained showed that this was not the best use for National Health Service (NHS) money to reduce deaths in a public place from cardiopulmonary arrest. The authors pointed out that the cost per QALY from training the police to deal with this condition would result in a cost per QALY of 24,534, and that NICE (National Institute for Clinical Excellence)-recommended technologies should have a cost per QALY of 30,000 or less.
CRD COMMENTARY - Selection of comparators The selection of the comparator, no defibrillators in public transport terminals, was justified as it is current practice in Scotland.
Validity of estimate of measure of effectiveness The effectiveness data were derived from an observational study. The authors assumed that the effectiveness of the availability of defibrillators would be the same as the early attendance of ambulance staff. There is, therefore, a lot of uncertainty surrounding the effect measure. A randomised controlled trial would have been appropriate to determine the effect measure. The analysis of effectiveness was handled credibly.
Validity of estimate of measure of benefit The authors used life-years gained and QALYs gained as a measure of benefit. The benefits were discounted and the discount rate was reported, which aids the generalisability of the results.
Validity of estimate of costs The broad cost categories included were relevant to the NHS perspective adopted. The authors acknowledged that not all of the relevant cost items were included, the costs after hospital discharge were excluded. The costs and the quantities were reported separately and the sources were quoted. No statistical analysis of the quantities was performed. A sensitivity analysis was carried out on the number of defibrillators installed. No statistical analysis of the prices was carried out. It was reported that a sensitivity analysis had been carried out on the hospital costs and on accident and emergency visits, but no details were given.
Other issues The authors made appropriate comparisons of their results with the findings from other studies. The issue of generalisability to other settings was addressed. The general conclusions reflect the scope of the analysis. The authors were aware that an extrapolation of the effects of public provision of defibrillators can never be a substitute for a randomised controlled trial assessing the effects.
Implications of the study The authors concluded that their study should lead to caution about the provision of defibrillators in public transport areas. A randomised controlled trial should be conducted to derive more reliable conclusions about such a policy.
Source of funding Funded by the British Heart Foundation.
Bibliographic details Walker A, Sirel J M, Marsden A K, Cobbe S M, Pell J P. Cost effectiveness and cost utility model of public place defibrillators in improving survival after prehospital cardiopulmonary arrest. BMJ 2003; 327: 1316-1319 Other publications of related interest Pell JP, Sirel JM, Marsden AK, Ford I, Walker N, Cobbe SM. Potential impact of public access defibrillators on overall survival after out of hospital cardiopulmonary arrest: retrospective cohort study. BMJ 2002;325:515-7.
Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Electric Countershock /economics; Emergency Medical Services /economics; Health Care Costs; Heart Arrest /economics /mortality /therapy; Hospital Mortality; Humans; Length of Stay /statistics & Quality of Life; Quality-Adjusted Life Years; Scotland /epidemiology; Survival Analysis; numerical data AccessionNumber 22004008004 Date bibliographic record published 31/07/2004 Date abstract record published 31/07/2004 |
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