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Increased efficiency and cost-effectiveness in the evaluation of the blunt abdominal trauma patient with the use of ultrasound |
Arrillaga A, Graham R, York J W, Miller R S |
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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 Ultrasound (US) used to evaluate patients suspected of having blunt abdominal trauma. US evaluation was performed during the resuscitation by certified radiology technicians and interpreted immediately by a radiologist at the time of the test. Three areas were evaluated for the presence of intraperitoneal fluid: the right upper quadrant, the left upper quadrant, and the pelvis with a full bladder.
Economic study type Cost-effectiveness analysis.
Study population Patients suspected of having blunt abdominal trauma.
Setting Hospital (a community-based, Level I trauma centre). The economic analysis was carried out in the USA.
Dates to which data relate Source of effectiveness data The evidence for the final outcomes was based on a single study.
Link between effectiveness and cost data Costing was conducted on the same patient sample as that used in the effectiveness analysis. The resource use data appear to have been collected prospectively.
Study sample Power calculations were not used to determine the sample size. The study sample consisted of 331 patients. During the 9-month study period, 223 CTs and 15 DPLs were performed on patients in the standard group. Within this group 2 patients had both a CT and a DPL. The US (test) group consisted of 104 patients including 8 patients who had both a US and a CT examination, 2 who had a US and DPL, and 1 patient who had all three tests. Because it might be argued that it would not be fair to compare the time it takes to complete ultrasound during the day versus the time it takes to complete CTs and/or DPLs during the evenings or weekends, charts for the 9 months before the study were analysed and the time to disposition was determined for CTs and/or DPLs performed from 8am to 5pm, Monday to Friday.
Study design This was a prospective cohort study (or non-randomized study with both concurrent and historical controls), carried out in a single centre. The duration of the follow-up appears to have been until operation or autopsy. The number of patients who were lost to follow-up was not reported.
The US protocol was as follows:
hemodynamically stable patients with a positive US for three sites were taken to the operating room (OR);
hemodynamically stable patients with positive US in fewer than three sites were taken to CT;
if at any time the patient (in either group) became hemodynamically unstable, s/he received a DPL.
Analysis of effectiveness The principle (intention to treat or treatment completers only) used in the analysis of effectiveness was not stated. The primary outcome measure of the study was time to disposition: the time that elapsed between patient presentation and the completion of the selected procedures, at which point a decision could be made about the status of the patient's abdomen. The sensitivity, specificity, and accuracy of the tests were reported as well as morbidity and mortality. The confirmation or otherwise of the US results was based on operation, autopsy, or other tests. The study groups were comparable in terms of age, sex, and Injury Severity Score.
Effectiveness results A significant difference did exist between groups in time to disposition. Both of the CT/DPL groups (8am to 5pm group and the group from the nights and weekends) had significantly longer disposition times than the US group, (p<0.0001). The median time to disposition for the CT/DPL group during weekdays was 80 minutes, and for the week nights and weekends group it was 92 minutes. The median time to disposition for the US group was 20 minutes. The sensitivity, specificity, and accuracy of the confirmed results are shown below.
US: sensitivity, 92%; specificity, 100%; and accuracy, 99%.
CT: sensitivity, 100%; specificity, 99%; and accuracy, 99%.
DPL: sensitivity, 100%; specificity, 100%; and accuracy, 100%.
There was no significant difference between the two groups with respect to morbidity (18.6% for the US group and 13.3% for the CT/DPL group) or mortality (8.8% US and 5.9% CT/DPL).
Clinical conclusions This study shows that differences in disposition time are significantly less in the US group than in the standard group. Patients who were evaluated with US were diagnosed faster than those with CT/DPL, thus increasing the efficiency of care.
Measure of benefits used in the economic analysis The time taken to decide the status of the abdomen (cleared, laparotomy required, or nonoperative management) was the benefit measure adopted.
Direct costs Costs were not discounted due to the short time frame of the cost analysis. Resource use quantities were only reported in terms of mean (SD) length of stay and ICU days. Charges and costs were reported separately. The cost analysis covered the costs of CT scan of abdomen (CT scan, nonionic contrast, injector syringe), abdominal US (US, US stat charge, portable charge), and DPL (peritoneal tap supplies). The source of cost data was the department cost manager through the use of a fully integrated computer software system designed for hospital cost accounting and budgeting. The cost calculation system took into account all supplies, labour, and other costs and combined them to determine a cost for each procedure. The perspective adopted in the cost analysis appears to have been that of the patient and the hospital. The price year was not specified.
Indirect Costs Indirect costs were not considered.
Sensitivity analysis No sensitivity analysis was conducted.
Estimated benefits used in the economic analysis A significant difference did exist between groups in time to disposition. Both of the CT/DPL groups had significantly longer disposition times than the US group, (p<0.0001). The median time to disposition for the CT/DPL group during weekdays was 80 minutes, and for the weeknights and weekends group it was 92 minutes. The median time to disposition for the US group was 20 minutes.
Cost results The charge per patient in the CT/DPL group was $1,304, compared to $250 for the US group. The cost per patient was $526 for the CT/DPL group and $186 for the US group. The total procedure costs for the CT/DPL group, throughout the study period, were 2.8 times greater than those of the US group.
Synthesis of costs and benefits The incremental cost-effectiveness ratio was calculated in terms of cost per minute saved by performing US instead of CT/DPL, which amounted to $5 per minute saved.
Authors' conclusions Ultrasound is not only effective in diagnosing blunt abdominal trauma, but it is also more efficient and cost-effective than CT/DPL.
CRD COMMENTARY - Selection of comparators A justification was given for the choice of the comparator. The strategy of using CT/DPL had been the gold standard in the USA since the 1970s. You, as a database user, should consider whether this is a widely used health technology in your own setting.
Validity of estimate of measure of effectiveness The internal validity of the effectiveness results can not be assured owing to the non-randomised nature of the study design and the lack of power calculations to justify the sample size. Furthermore, it was not explicitly stated whether the effectiveness analysis was based on intention to treat or on treatment completers only. However, it was deemed that the lack of significant differences in the demographics of the two groups tended to uphold the study findings. The study sample appears to have been representative of a broad range of patients suspected of having blunt abdominal trauma from a community-based Level I trauma centre.
Validity of estimate of measure of benefit The estimate of benefit measure was directly obtained from the effectiveness analysis. No justification was provided for why other benefit measures, which may have helped to incorporate the subjective assessment of the patients and staff, were not adopted in the economic study. This is particularly relevant given that the invasiveness or non-invasiveness of the tests was discussed as a factor determining the final utility of the procedures.
Validity of estimate of costs Positive aspects of the cost analysis which are likely to have enhanced its validity, were that some resource use quantities were reported separately from the costs, cost and charge categories were reported separately and a distinction was made between true costs and charges and both were reported. However, the price year was not reported, the effects of alternative procedures on indirect costs were not addressed and statistical analyses were not performed on cost data. It is not clear how the incremental cost-effectiveness ratio was calculated. It was reported that US was both more time efficient and less costly, which methodologically does not require incremental cost-effectiveness analysis. Cost results may not be generalisable outside the study setting.
Other issues Given the limitations of the study design, and the lack of sensitivity analysis and statistical analysis of the costs, the study results may need to be treated with some degree of caution. The issue of generalisability to other settings or countries was not addressed. Some comparisons were made with other studies. The degree to which the study sample was representative of the study population was not discussed in the authors' comments.
Implications of the study The results of this study convinced the study institution's administration to purchase a US machine dedicated solely for use in the trauma bays. It was reported that after instituting a US machine in the trauma bays 24 hours a day, 7 days a week, the costs to perform an US were reduced from $186.16 to $62.04 because there was no longer a stat charge or a portable charge.
Bibliographic details Arrillaga A, Graham R, York J W, Miller R S. Increased efficiency and cost-effectiveness in the evaluation of the blunt abdominal trauma patient with the use of ultrasound. American Surgeon 1999; 65(1): 31-35 Indexing Status Subject indexing assigned by NLM MeSH Abdominal Injuries /ultrasonography; Adult; Clinical Protocols; Cost-Benefit Analysis; Evaluation Studies as Topic; Female; Humans; Male; Peritoneal Lavage /economics; Prospective Studies; Sensitivity and Specificity; Tomography, X-Ray Computed /economics; Ultrasonography /economics; Wounds, Nonpenetrating /ultrasonography AccessionNumber 21999000223 Date bibliographic record published 31/07/2001 Date abstract record published 31/07/2001 |
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