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Prospective assessment of integrating the existing emergency medical system with automated external defibrillators fully operated by volunteers and laypersons for out-of-hospital cardiac arrest: the Brescia Early Defibrillation Study (BEDS) |
Cappato R, Curnis A, Marzollo P, Mascioli G, Bordonali T, Beretti S, Scalfi F, Bontempi L, Carolei A, Bardy G, De Ambroggi L, Dei Cas L |
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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 study examined the use of automated external defibrillators (AEDs) by volunteers and laypersons for the treatment of out-of-hospital cardiac arrest (CA). The programme involved 2,186 volunteers and laypersons, as well as 152 paramedics from emergency departments in various hospitals. The training programme was conducted by 14 qualified instructors during 5 hours of theory and practical instruction, including training in basic life support.
Study population The study population comprised patients who, outside of the county hospitals, had been unconscious and unresponsive either suddenly or after a brief prodrome, had no palpable pulse and no spontaneous respiration. Patients who, in spite of signs of arrest, were under 9 years of age, had trauma, drug overdose, poisoning, drowning, exsanguination, electrocution or asphyxia, were excluded.
Setting The setting was the community. The economic study was carried out in Italy.
Dates to which data relate The effectiveness and resource use data were gathered from June 1997 to May 1999 for the conventional care group and from July 2000 to June 2002 for the intervention group. The price year was not explicitly reported, although most unit costs were taken from 1997 databases.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was carried out on the same sample of patients as that used in the effectiveness analysis. The costing was performed retrospectively in the control group and prospectively in the intervention group.
Study sample Power calculations were performed in the preliminary phase of the study on the basis of data obtained in the retrospective phase of the study. These showed that a sample of at least 478 patients was required to detect a statistically significant difference in the primary clinical measure, with a beta error of 0.10 and a level of significance of 0.05. A total of 112 patients per group were added to limit the influence of secular trends and unknown cointerventions due to the historical cohort. Patients were identified at the authors' institution during the two study periods. There were 692 patients (62.9% male) in the historical cohort and 702 patients (65.1% male) in the prospective cohort. The mean age was 67.2 (+/- 14.9) years in the historical cohort and 69.4 (+/- 14.1) years in the prospective cohort.
Study design This was a prospective cohort study with an historical control, which was carried out in the county of Brescia in Italy. The allocation of patients to study groups depended on the period during which they experienced a CA. The length of follow-up was 58 (+/- 11) months (median 52) in the historical cohort and 18 (+/- 13) months (median 16) in the prospective cohort. No patient was lost to follow-up. Blinding was not performed.
Analysis of effectiveness All patients included in the initial study sample were considered in the analysis of effectiveness. The primary outcome measure was 1-year survival free of neurological impairment. Other clinical end points were survival to admission to a hospital department, survival to discharge from hospital, and survival to discharge from hospital free of neurological impairment. Specific analyses were carried out to assess the difference in clinical outcomes depending on the urban versus rural context and, in the prospective cohort, survival free of neurological impairment at 1-year follow-up between CA victims receiving defibrillation option within 8 minutes and those receiving defibrillation option after 8 minutes from witnessed collapse. Clinical data pertaining only to the prospective cohort were also gathered and reported.
The study groups were comparable at baseline in terms of demographic and clinical factors such as gender, proportion of outdoor events, witnessed events, and events in which basic life support was performed by the occasional witness. However, patients in the prospective cohort were significantly older than those in the historical cohort.
Effectiveness results The rate of 1-year survival free of neurological impairment was 0.9% (95% confidence interval, CI: 0.4 to 1.8) in the historical cohort and 3.0% (95% CI: 1.7 to 4.3) in the prospective cohort, (p=0.0015).
Survival to admission to a hospital department was 5.5% in the historical cohort and 8.1% in the prospective cohort, (p=0.03).
Survival to discharge from hospital was 1.4% in the historical cohort and 4.4% in the prospective cohort, (p=0.04).
Survival to discharge from hospital free of neurological impairment was 1.4% in the historical cohort and 4.1% in the prospective cohort, (p=0.04).
Increase in survival was noted in both the urban territory (from 1.4%, 95% CI: 0.4 to 3.4, to 4.0%, 95% CI: 2.0 to 6.9; p=0.024) and rural territory (from 0.5%, 95% CI: 0.1 to 1.6, to 2.5%, 95% CI: 1.3 to 4.2; p=0.013).
Throughout the duration of the study, the yearly incidence of dispatched CAs was more than three times as high in the urban territory (0.7 per 1,000 inhabitants) than in the rural territory (0.2 per 1,000 inhabitants).
A significantly lower sudden death rate difference between the two environments was observed (0.8 per 1,000 per year and 0.6 per 1,000 per year, respectively; p<0.001 versus dispatched arrests).
The number of additional survivors was 1.5 per 100,000 in the urban territory and 0.5 per 100,000 in the rural territory.
Of the victims of a witnessed CA surviving free of neurological impairment at discharge in the prospective cohort, 46.1% received defibrillation later than 8 minutes from collapse (mean 13.1 +/- 4.3 minutes). One-year survival in this group was 1.7% (95% CI: 0.8 to 3.4) compared with 12.5% (95% CI: 10.1 to 16.0) in patients receiving defibrillation within 8 minutes from collapse, (p<0.001).
Survivors in the group of patients receiving defibrillation after 8 minutes from collapse accounted for 30.6% of all survivors free of neurological impairment at the 1-year follow-up.
In the prospective cohort, the total response time was 17.6 (+/- 14.7) minutes.
No complications relating to the use of AEDs were reported.
Five (16.1%) of the survivors in the prospective cohort had been treated with AEDs in public access locations.
In patients with ventricular fibrillation at the time of electrocardiogram recording, the 1-year survival free of neurological impairment was 10.0%.
Clinical conclusions The effectiveness analysis showed that the programme under examination was more effective than the conventional approach for the treatment of out-of-hospital CAs.
Measure of benefits used in the economic analysis The summary benefit measure used was the expected number of quality-adjusted life-years (QALYs). These are usually calculated as the expected survival adjusted by a quality of life factor. However, an estimation of the quality of life factor was not explicitly reported. Discounting future benefits to a present value was not performed.
Direct costs The analysis of the costs was carried out from the viewpoint of the third-party payer. The categories of costs included were purchase and updating of AEDs, costs of trainings, diagnostic procedures, cardiac surgical procedures, implantable cardioverter defibrillators, outpatient visits, rehabilitation and re-hospitalisations. The initial costs were calculated during the first year of the study (start-up phase), whereas the costs of maintenance were calculated during each subsequent year (steady-state phase). The unit costs were generally presented separately from the quantities of resources used, although not for all items. Resource use was estimated using data derived from the sample of patients included in the effectiveness analysis. The costs were derived from official data derived from the Italian Department of Health in 1997. Hospitalisation costs where based on Diagnosis-Related Groups. Discounting could have been relevant for costs incurred after the first year, but it does not appear to have been applied. The price year was not explicitly reported.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The indirect costs were not included in the economic analysis.
Sensitivity analysis Sensitivity analyses were not performed.
Estimated benefits used in the economic analysis The expected QALYs were not reported.
Cost results The additional total costs associated with the new defibrillation system were EUR 1,017,514 in the start-up phase and EUR 681,766 in the steady phase.
Synthesis of costs and benefits Incremental cost-utility ratios were calculated in order to combine the costs and benefits of the alternative strategies.
The incremental cost per additional QALY gained with the new programme over the conventional approach was EUR 39,388 (95% CI: 16,731 to 49,329) during the start-up phase of the study and EUR 23,661 (95% CI: 10,327 to 35,528) during the steady phase.
Authors' conclusions The use of automated external defibrillators (AEDs) operated by volunteers and laypersons for the treatment of out-of-hospital cardiac arrests (CAs), to augment the current emergency medical system in Italy, was safe. In addition, it improved survival of CA victims and it was cost-effective from the perspective of the third-party payer.
CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparators was clear. The new programme was compared with conventional care for patients experiencing an out-of-hospital CA. Details of the operational plan, training and equipment for the intervention and the comparator were given. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The effectiveness data were estimated through a comparison of a prospective group and an historical control group. Such a design was necessary because the new intervention and the comparators were implemented in two different time periods. Since the two groups of patients were not assessed concurrently, factors other than the study interventions might have affected the results of the analysis. The authors acknowledged that the use of a simultaneous comparison would have been more appropriate. Further, given the design of the study, the two cohorts could not be fully compared since some end points were not available in the historical group of patients. Age was statistically different between the groups at baseline, but, despite the fact that advanced age could be associated with a worse prognosis, prospective patients had better survival than slightly younger historical patients. However, the authors did not attempt to control for this different demographic factor. These aspects of the analysis might limit its validity. The size of the sample was defined on the basis of statistical tests and all patients initially included in the study sample were taken into consideration. Moreover, subgroup analyses were performed. These issues strengthen the robustness of the comparison.
Validity of estimate of measure of benefit The use of QALYs as the summary benefit measure was appropriate, not only because QALYs capture the impact of the interventions on survival and quality of life, which represent two relevant dimensions of health for patients experiencing a CA, but also because QALYs can be readily compared with the benefits of other health care interventions. However, details on the calculation of QALYs were not provided, nor was there any information on the quality of life adjustment. The authors did not report the methods used to convert clinical values to utility weights, thus it is not possible to judge the appropriateness of this approach.
Validity of estimate of costs The analysis of the costs was consistent with the perspective adopted. Some information on the unit costs and quantities of resources used was provided, which will facilitate replication exercises in other settings. The source of the data was stated. The cost estimates were specific to the study setting, and the impact of using alternative economic estimates was not investigated. The price year was not given, thus limiting the possibility of reflating the costs in different time periods. Statistical analyses of the costs were not performed. Discounting could have been relevant for costs incurred from the second year of the project implementation, but it was not performed.
Other issues The authors stated that their clinical results were comparable with those observed in other published studies. No comparisons were made on the cost-effectiveness of the new intervention. In terms of the generalisability of the study results to other settings, it was pointed out that current findings could be applicable to other territories similar to that examined in the study where there are legislative, logistic, or budget constraints around the widespread use of AEDs. However, the use of alternative clinical and economic data was not investigated since sensitivity analyses were not carried out. This limits the external validity of the study. In general, the issue of the uncertainty around key clinical and economic items was not investigated, which could be seen as an important limitation of the analysis. Finally, the study was not sufficiently transparent in terms of describing the methods used to derive quality of life weights from clinical results.
Implications of the study The study results appear to support the use of AEDs operated by volunteers and laypersons for the treatment of out-of-hospital CAs.
Bibliographic details Cappato R, Curnis A, Marzollo P, Mascioli G, Bordonali T, Beretti S, Scalfi F, Bontempi L, Carolei A, Bardy G, De Ambroggi L, Dei Cas L. Prospective assessment of integrating the existing emergency medical system with automated external defibrillators fully operated by volunteers and laypersons for out-of-hospital cardiac arrest: the Brescia Early Defibrillation Study (BEDS) European Heart Journal 2006; 27(5): 553-561 Other publications of related interest Nichol G, Valenzuela T, Roe D, et al. Cost-effectiveness of defibrillation by targeted responders in public settings. Circulation 2003;108:697-703.
The Public Access Defibrillation Trial Investigators. Public-access defibrillation and survival after out-of-hospital cardiac arrest. N Engl J Med 2004;351:637-46.
Caffrey SL, Willoughby PJ, Pepe PE, Becker LB. Public use of automated external defibrillators. N Engl J Med 2002;347:1242-7.
Indexing Status Subject indexing assigned by NLM MeSH Automation; Electric Countershock /instrumentation /standards; Emergencies; Emergency Medical Services /standards; Emergency Treatment /instrumentation /standards; Female; Heart Arrest /therapy; Humans; Italy; Male; Middle Aged; Prospective Studies; Survival Analysis; Volunteers AccessionNumber 22006006536 Date bibliographic record published 31/01/2007 Date abstract record published 31/01/2007 |
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