|
Cost-effectiveness analysis of potential improvements to emergency medical services for victims of out-of-hospital cardiac arrest |
Nichol G, Laupacis A, Stiell I G, O'Rourke K, Anis A, Bolley H, Detsky A S |
|
|
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 Five strategies adopted for the improvement of the emergency medical services (EMS) systems for the management of out-of-hospital cardiac arrest. The five strategies were as follows:
(1)improvement in response time in a one-tier EMS system by addition of more EMS providers in ambulances;
(2)improvement in response time in a two-tier EMS system by the addition of more basic life support BLS/BLS-D (BLS with defibrillation) providers in pump vehicles to the first tier,
(3) improvement in response time in a two-tier EMS system by the addition of more BLS/BLS-D providers in ambulances to the first tier,
(4)change from a one-tier to a two-tier EMS system by the addition of BLS/BLS-D providers in pump vehicles as the first tier,
(5)change from a one-tier to a two-tier EMS system by the addition of BLS/BLS-D providers as the first tier.
Study population Victims of out-of-hospital cardiac arrest.
Setting Out of hospital and hospital. The economic study was carried out in Ontario, Canada.
Dates to which data relate The effectiveness analysis data were taken from a meta-analysis of 41 case series by the authors published in 1996. The data related to the utility of health states were obtained from patients interviewed in 1992 who had taken part in a randomised trial of therapy for cardiac arrest who survived to discharge (also 1992). The date of the resource use data (mainly based on personal communication) was not specified (reported elsewhere). The fiscal year was 1991 (converted to 1993 prices by adjusting for inflation).
Source of effectiveness data Effectiveness data were derived from a synthesis of previously published studies, and a single study.
Modelling A decision tree in Smltree was used in estimating final outcomes and costs for the five strategies assessed
Outcomes assessed in the review The review assessed the survival rate of different types of EMS, response time, the life expectancy conditional on being discharged alive from hospital, and the rate of bystander CPR.
Study designs and other criteria for inclusion in the review Sources searched to identify primary studies The methods used to identify suitable studies were not explicitly reported in this paper although the authors make reference to previous studies (refs. 5 and 6) which provide more details.
Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included 41 case series were included.
Methods of combining primary studies The case series were combined using meta-analysis. Survival rates from admission to discharge from hospital were combined in a geometric mean survival rate, the survival rate to admission being defined as a function of this rate.
Investigation of differences between primary studies Results of the review Survival rate for the one-tier system was 5.2% versus 10.5% in a two-tier system. A 1 minute decrease in mean response improved survival by 0.4% and 0.7%, respectively. The rate of bystander CPR was 17.6%. The life expectancy conditional on being discharged alive from hospital was 5.61 years or, with discounting, 4.38 years. These data were used as input parameters for the decision model.
Measure of benefits used in the economic analysis The benefit outcome measure chosen was quality adjusted life years gained (QALYs). A decision tree was used to estimate the benefit outcome. The valuation of health states was carried out on the basis of descriptors adapted from the Sickness Impact Profile. Patients' values were used to assess the health states and values were obtained by interview. The tool used was a standard gamble technique. It was reported that the average utility of the interviewed survivors was 0.84 (SD, 0.25) which was used in the QALY calculations.
Direct costs Costs were discounted. Quantities and costs were not analysed separately, and only unit costs were reported. Costs measured were cost of operation (treatment before admission and during hospital stay) and overhead costs (only for two-tier systems). The cost boundary adopted was society. The estimation of quantities was based on personal communication. The prices were those prevailing in different regions and organisations across Ontario. The source of costs was mainly the EMS system in Hamilton, Ontario. Among the sources were the Ontario Heart and Stroke Foundation, the Regional Municipality of Ottawa-Carleton, the Hamilton Fire Department and the Ontario Ministry of Health. The price date was 1993. The prices were reflated from 1991 figures using the consumer price index. The authors excluded fixed costs for one-tier systems because they were common to all systems. The treatment cost after discharge was not included in the study.
Currency US dollars ($). A conversion was carried out from Canadian dollars (Can$) using the 1993 annual average exchange rate ($1=Can$1.29).
Sensitivity analysis A one-way sensitivity analysis was carried out focusing on the following parameters: proportion of bystander CPR, response time interval, EMS tier, survival during hospitalisation, long-term survival, utility and cost components.
Estimated benefits used in the economic analysis A 5% discount rate for life expectancy was used. The incremental survival (QALYs) figures for improvement in response time were as follows:
one-tier EMS system by addition of more EMS providers in ambulances, 0.0213;
two-tier EMS system by the addition of more BLS/BLS-D providers in pump vehicles to the first tier, 0.0449;
two-tier EMS system by the addition of more BLS/BLS-D providers in ambulances to the first tier, 0.0449.
The corresponding figures for changing from a one-tier to a two-tier EMS system by the addition of BLS/BLS-D providers as the first tier were as follows: providers being in pump vehicles, 0.1925; providers being in ambulances, 0.1925.
Cost results A 5% discount rate was used. The incremental cost figures for improvement in response time were as follows:
one-tier EMS system by addition of more EMS providers in ambulances, $7,800;
two-tier EMS system by the addition of more BLS/BLS-D providers in pump vehicles to the first tier, $2,400;
two-tier EMS system by the addition of more BLS/BLS-D providers in ambulances to the first tier, $7,100.
The corresponding figures for changing from a one-tier to a two-tier EMS system by the addition of BLS/BLS-D providers as the first tier were as follows: providers being in pump vehicles, $7,700; providers being in ambulances, $18,200. The duration of costs was only until discharge from hospital.
Synthesis of costs and benefits The incremental cost per QALY figures for improvement in response time were as follows:
one-tier EMS system by addition of more EMS providers in ambulances, $368,000;
two-tier EMS system by the addition of more BLS/BLS-D providers in pump vehicles to the first tier, $53,000;
two-tier EMS system by the addition of more BLS/BLS-D providers in ambulances to the first tier, $159,000.
The corresponding figures for changing from a one-tier to a two-tier EMS system by the addition of BLS/BLS-D providers as the first tier were as follows: providers being in pump vehicles, $40,000; providers being in ambulances, $94,000.
It was reported that "the most important sensitivity analyses were those concerning the costs attributed to the BLS/BLS-D providers in pump vehicles". The sensitivity analysis revealed that "the results for changes in EMS systems (from one-tier to two-tier), were susceptible to changes in the effect estimate of unit hours".
Authors' conclusions The most attractive options in terms of incremental cost-effectiveness were improved response time in a two-tier EMS system or change from a one-tier to a two-tier EMS system. Future research should be directed toward identification of the costs of instituting the first tier of a two-tier EMS system and identification of cost-effective methods of improving response time
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparators is clear. The authors examined ways of achieving a reduction in response time intervals and the impact of a two-tier system over a one-tier system. Types of EMS system vary from one region to another which impacts on survival rates for cardiac arrest patients.
Validity of estimate of measure of benefit The estimate of benefit is likely to be internally valid as the authors undertook a systematic review and meta-analysis of studies to determine effectiveness and supplemented this with quality of life interviews using cohorts of survivors. Sensitivity analyses were performed to test the robustness of the results.
Validity of estimate of costs The resource utilisation was not reported separately from the costs, although these data are provided elsewhere as shown in the references. As costing was undertaken retrospectively and integrated into a model some limitations may exist in terms of reliability.
Other issues The authors have noted that "It is likely that the quality of life of those interviewed is better than that of the average survivor of an out-of-hospital cardiac arrest. This may make our cost-utility ratios more favourable than is really the case". The generalisability of the results was not specifically addressed and they may vary according to the EMS services available in a particular country or setting.
Implications of the study Future research should be directed toward identification of the costs of instituting the first tier of a two-tier EMS system and identification of cost-effective methods of improving response time.
Source of funding Supported in part by the Advanced Coronary Treatment Foundation which received funding in part from the Asmund S. Laerdal Foundation for Acute Medicine; and Physio-control Canada. Dr Detsky was supported by a National Health Research Scholar Award from Health and Welfare Canada. Dr Nichol was supported by a Palef Fellowship from Loeb Medical Research Institute, Ottawa Civic Hospital.
Bibliographic details Nichol G, Laupacis A, Stiell I G, O'Rourke K, Anis A, Bolley H, Detsky A S. Cost-effectiveness analysis of potential improvements to emergency medical services for victims of out-of-hospital cardiac arrest. Annals of Emergency Medicine 1996; 27(6): 711-720 Indexing Status Subject indexing assigned by NLM MeSH Cardiopulmonary Resuscitation /education; Cost-Benefit Analysis; Decision Trees; Electric Countershock /economics; Emergency Medical Services /economics; Heart Arrest /mortality /therapy; Humans; Life Support Care /economics; Ontario; Reaction Time AccessionNumber 21996000689 Date bibliographic record published 30/06/1999 Date abstract record published 30/06/1999 |
|
|
|