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Effectiveness of a 'thrombolysis nurse' in shortening delay to thrombolysis in acute myocardial infarction |
Somauroo J D, McCarten P, Appleton B, Amadi A, Rodrigues E |
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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 compares the effectiveness of using a thrombolysis nurse in shortening delay to thrombolysis in acute myocardial infarction (MI) against the use of no thrombolysis nurse.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients presenting with chest pain to the Aintree University Hospital.
Setting The setting was secondary care. The economic study was carried out in a District General Hospital in Aintree, Liverpool, England.
Dates to which data relate The authors did not report the dates during which the effectiveness and resource data were collected, but did state that the data were collected over an 18 month period - 3 months before, and 15 months after the employment of a thrombosis nurse. The price year was not reported.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data Cost data were estimated retrospectively using the same patient sample as that used to generate effectiveness data.
Study sample The authors did not report any calculations to estimate the sample size required to detect statistically significant differences in costs or effects. The study sample comprised 365 patients presenting to the Aintree University Hospital to receive thrombolysis during the 18 month time period of the study. Of the 365 patients, 269 patients presented with clear symptoms of MI with a diagnostic first ECG (definite MI) warranting immediate thrombolysis. During the three month period before the appointment of the thrombolysis nurse 57 patients presented with acute MI, and, of these, 41 had a definite MI. Over the 15 months when the thrombolysis nurse was on duty, 67 patients presented with acute MI, of whom 45 had a definite MI. When the thrombolysis nurse was off duty during these 15 months, 241 patients were treated with thrombolysis for acute MI, of whom 203 had a definite MI.
Study design The study was a single-centred, before and after study using two separate cohorts of patients and was carried out in Aintree University Hospital. The duration of follow-up for each patient was from presentation (at the hospital or at the start of MI pain) until a thrombolytic had been administered. The authors did not report the number of patients lost to follow-up. The authors did not report any procedures to mask investigators to the use of a thrombolysis nurse at the analysis of outcome.
Analysis of effectiveness The analysis was based on treatment completers only. The primary outcomes used in the analysis were: the door-to-needle times of patients with definite MI; pain-to-needle times for definite MI; and door-to-needle times of patients without definite MI on first electrocardiogram (ECG) but who subsequently qualified for thrombolysis.
Effectiveness results The median door-to-needle time for thrombolysis was 66 minutes (interquartile range: 60 - 92) for the standard care group (pre-thrombolysis nurse).
The median door-to-needle time for thrombolysis was 30 minutes for the intervention group (when the thrombolysis nurse was on duty). The authors reported that this difference represented a significant saving of 36 minutes, (p=0.0001).
The median door-to-needle time was 65 (51 - 94) minutes when the thrombolysis nurse was off duty, (p=0.0001 compared to when the nurse was on duty). However, there was no statistical difference between door-to-needle times when the pre-thrombolysis nurse was off duty compared to when the thrombolysis nurse was off duty, (p=0.29).
The median pain-to-needle time was less than 110 minutes (range: 85 - 200) when the thrombolysis nurse was on duty and 205 minutes (range: 135 - 380) when she was off duty. There was a highly significant saving of 95 minutes in the median pain-to-needle time, (p=0.0001).
Analysis of those patients with delays due to non-diagnostic first ECG at presentation revealed that, once the ECG became diagnostic for acute MI, the median time to thrombolysis was 61.5 (range: 47 - 99) minutes during the three months before the appointment thrombolysis nurse. This delay decreased to 25.5 (range: 19 - 41) minutes when the thrombolysis nurse was on duty, a statistically significant saving of 36 minutes, (p=0.02).
Clinical conclusions The authors concluded that the thrombolysis nurse produced a considerable improvement in the median door-to-needle and pain-to-needle times in patients presenting with definite MI, in addition to considerably improving the door-to-needle times for patients presenting with a non-diagnostic first ECG who subsequently qualified for thrombolysis.
Measure of benefits used in the economic analysis The authors used the number of lives saved as the summary measure of health benefit in the economic analysis. The authors reported that they extrapolated the number of lives saved from the saving of median door-to-needle time using information from the Grampian Region Early Anistreplase Trial (GREAT).
Direct costs Resource use and costs were not reported separately. The only direct cost included in the analysis was the cost of employing the thrombolysis nurse at a salary of 22,500 per annum for a 37-hour week. The annual salary cost would rise to 100,800 per annum if thrombolysis nurse cover were extended to 24 hours. The unit cost data were taken from the hospital at which the thrombolysis nurse was based. The price year was not reported and discounting was not undertaken.
Statistical analysis of costs No statistical analysis of costs was conducted.
Indirect Costs No indirect costs were included in the analysis.
Currency UK pounds sterling (). No currency conversions were reported.
Sensitivity analysis The authors did not conduct a sensitivity analysis.
Estimated benefits used in the economic analysis The authors reported that the introduction of a thrombolysis nurse resulted in a saving of 36 minutes in median door-to-needle time and that this would lead to 41 additional lives saved per 1,000 patients treated. The authors estimated that, if thrombolysis nurse cover were extended to 24 hours, 8 additional lives would be saved at 30 months.
Cost results The annual cost of the thrombolysis nurse was 22,500. No further cost results were reported.
Synthesis of costs and benefits The authors conducted a synthesis of costs and benefits by calculating the cost per additional life saved. The authors estimated that the introduction of 24-hour thrombolysis nurse cover would save 8 additional lives at 30 months at a cost of 12,300 per additional life saved.
Authors' conclusions The authors concluded that the introduction of the thrombolysis nurse produced a considerable improvement in median door-to-needle and pain-to-needle times in patients presenting with definite MI. The authors stated that this would lead to an additional 41 lives saved at 30 months per 1,000 patients treated. The authors estimated that, with 24-hour thrombolysis nurse cover, this would lead to 8 additional lives at 30 months at a cost of 12,300 each. Furthermore, the authors also stated that there was a considerable improvement in door-to-needle times for patients with a non-diagnostic first ECG who subsequently qualified for thrombolysis.
CRD COMMENTARY - Selection of comparators A justification was given for the choice of comparator used, namely that it represented standard practice in the authors setting. You, as the user of the database, should decide if this is a widely used health technology in your own setting.
Validity of estimate of measure of effectiveness The analysis was based on a before and after study design using two separate cohorts of patients. A more appropriate design for evaluating the effectiveness of a thrombolysis nurse would have been a randomised, controlled trial in which patients were randomly allocated to the thrombolysis nurse or standard practice. This would have removed the problems of selection bias inherent in the current study design. The study sample was representative of the study population, but the authors did not state whether the patient groups were comparable at analysis. The study did not report a power calculation but there was still a statistical difference between the intervention group (use of a thrombolysis nurse) and comparator group (standard practice), which implies that the sample size was large enough to detect a statistically significant difference.
Validity of estimate of measure of benefit The estimation of benefits was obtained directly from the effectiveness analysis. The choice of estimate was justified by making reference to a published study. The authors did not describe clearly the approach used to derive the measure of benefit, life years saved, from the effectiveness measure, median door-to-needle time.
Validity of estimate of costs The only direct costs reported by the authors were the cost of employing the thrombolysis nurse. The implicit study perspective was that of the NHS. No other costs relating to the management of patients requiring thrombolytic therapy were identified or quantified. Thus, it seems that not all the costs relevant to the study perspective were included in the analysis. The analysis did not include the cost of other members of staff who would have undertaken the work of the thrombolysis nurse if she were not in post or the cost of drugs and consumables used during the administration of thrombolytic therapy. Thus, the analysis would not have correctly estimated the additional cost of providing a thrombolysis nurse compared to standard practice. Costs and quantities were not reported separately. No statistical analysis of costs was undertaken. Furthermore, no sensitivity analysis was reported by the authors, which limits the generalisability of the study's findings. The price year was not reported. No currency conversions were reported and discounting was not undertaken even though the authors reported the costs for a 30-month time period.
Other issues The authors made appropriate comparisons of their findings with those from other studies but due to the omission of a sensitivity analysis did not fully address the issue of generalisability to other settings. The authors do not appear to have presented their results selectively. The study enrolled patients with definite MI, which is reflected in their conclusions. The authors added that a limitation of their study was that the cost-effectiveness calculations did not consider the potential benefits and life saved in patients without definite MI. The authors stated that the thrombolysis nurse improved the median times to thrombolysis in patients presenting with a non-diagnostic first ECG, who subsequently qualified for thrombolysis. Furthermore the authors reported that there were also non-quantifiable benefits of having a specialist cardiac nurse offering advice on other cardiac emergencies but did not elaborate on what these benefits might be.
Implications of the study The authors concluded that a thrombolysis nurse significantly shortens delay to thrombolysis, and thus reduces anticipated mortality in these patients. The authors reported that this appears to be a cost-effective way of maximising health gain from the use of thrombolytic therapy in acute MI. Consequently the authors proposed that such a strategy should be applicable to most district general hospitals in the UK.
Source of funding Sponsored by Boehringer Ingelheim.
Bibliographic details Somauroo J D, McCarten P, Appleton B, Amadi A, Rodrigues E. Effectiveness of a 'thrombolysis nurse' in shortening delay to thrombolysis in acute myocardial infarction. Journal of the Royal College of Physicians of London 1999; 33(1): 46-50 Other publications of related interest Comments: Journal of the Royal College of Physicians of London 1999;33(1):6-7.
Comments: Journal of the Royal College of Physicians of London 1999;33(4):400.
Comments: Journal of the Royal College of Physicians of London 1999;33(3):284-5.
Indexing Status Subject indexing assigned by NLM MeSH Emergency Service, Hospital /standards; England; Evaluation Studies as Topic; Hospitals, District; Hospitals, General; Humans; Myocardial Infarction /drug therapy; Nursing Staff, Hospital; Thrombolytic Therapy /utilization; Time Management; Treatment Outcome AccessionNumber 21999000457 Date bibliographic record published 30/11/2002 Date abstract record published 30/11/2002 |
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