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Minimal incision aortic surgery (MIAS) |
Turnipseed W D, Carr S C, Hoch J R, Cohen J R |
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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 use of minimally invasive aortic surgery (MIAS) as an elective treatment for patients with infrarenal aortic aneurysms (AAA) and/or aortoiliac occlusive disease (AIOD). The MIAS procedure involves a small midline periumbilical incision less than 10 cm, intracavitary retraction of the small bowel, and traditional hand-sewn vascular anastomoses.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients who were candidates for standard open aortic surgery, MIAS or endograft repair of abdominal aneurysms. Patients were excluded if they had acutely ruptured aneurysms, suprarenal aneurysms, or if they required concomitant renal, mesenteric or infrainguinal vascular reconstruction.
Setting The setting was secondary care. The economic study was conducted in Wisconsin and in Long Island (NY), USA.
Dates to which data relate The effectiveness, resource use and cost data related to June 1999 to June 2000.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was undertaken prospectively alongside the effectiveness study.
Study sample The sample size was not determined using power calculations. Consecutive patients eligible for the study procedures were allowed to select their preferred procedure, with advice from a surgeon. The authors reported that the majority of patients deferred to the surgeon's preference. The authors made no attempt to select patients on the basis of risk category, body size, aneurysm size, or surgical history. The study sample consisted of 160 patients, 80 who elected to undergo MIAS and 80 who elected to undergo standard open repair. The authors did not report whether any patients refused to participate, or the number excluded.
Study design The study was a non-randomised trial with concurrent controls. The study was conducted in two centres. The length of follow-up was unclear, although it might have been the duration of the episode of care. No loss to follow-up was reported.
Analysis of effectiveness All the patients included in the study were accounted for in the analysis. The primary health outcomes included:
intraoperative operating room time,
intraoperative fluid resuscitation,
transfusion requirement,
intensive care unit stay,
time to general dietary feeding,
hospital length of stay (LOS), and
morbidity and mortality within 30 days of the procedure.
At analysis, the two groups were shown to be similar in terms of age, gender, aneurysm size, body weight and selected co-morbid risk factors, (Fisher's exact test, p>=0.130).
Effectiveness results Only statistically significant results are presented in this abstract.
The average time to general dietary feeding was significantly lower in the MIAS group (3.4 +/- 1.2 days) than in the standard open repair group (5.4 +/- 4.7 days), (p<0.001).
The average total LOS was significantly lower in the MIAS group (4.8 +/- 1.4 days) than in the standard open repair group (7.7 +/- 3.4 days), (p<0.001).
Clinical conclusions The authors concluded that the use of MIAS may shorten the LOS and recovery time for patients requiring surgical repair of aneurysms, without increasing morbidity or mortality, compared with more invasive traditional procedures.
Measure of benefits used in the economic analysis No summary measure of health benefit was used in the economic analysis. In effect, a cost-consequences analysis was performed.
Direct costs The study included costs incurred by the hospital. These included any billable item received by patients during their stay, such as the costs of staff, medical supplies, administration and the facility. The cost data were provided by a national agency that provides cost-related data to major university health care providers in the USA, and were also estimated from charge data. Resource use was incurred during less than one year, therefore discounting was not relevant. Some resource use quantities, such as LOS, were reported separately from the costs. The study reported the average costs. The data related to June 1999 to June 2000.
Statistical analysis of costs The costs were compared statistically, but the test used was unclear. It might have been a two-sided Student's t-test. The authors reported the mean costs and an estimate of the range, although whether this estimate represented standard error, standard deviation or some other statistic was unclear. The total average standard costs were compared using a statistical test. No power calculation was performed for differences in the costs.
Indirect Costs The indirect costs were not included in the analysis.
Sensitivity analysis Sensitivity analyses were not required since sampled data were available.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The average total hospital cost for the MIAS group at the University of Wisconsin was $12,585. The average total hospital charges for this group at Long Island Jewish Hospital were $22,692. The corresponding figures for the standard open repair group were $18,445 (Wisconsin) and $23,501 (Long Island), respectively. A p-value was reported, but it was unclear to which comparison it applied.
The side effects of treatment were included in the analysis if they occurred within 30 days of procedure. Discounting was not relevant.
Synthesis of costs and benefits Authors' conclusions Minimally invasive aortic surgery (MIAS) may be a cost-saving alternative to the standard open repair of aneurysms as it is associated with reduced costs and recovery time, without increased mortality or morbidity.
CRD COMMENTARY - Selection of comparators Standard open repair was chosen as the comparator to represent traditional practice in the treatment of AAA and or AIOD. You should consider whether this represents current practice in your own setting.
Validity of estimate of measure of effectiveness The non-randomised design of the trial introduces the possibility of bias into the results. In particular, as the patients selected their own preferred treatment, predominately at the suggestion of their surgeon, there is potential for selection bias. The failure to find significant differences between patients in terms of baseline demographics and selected risk factors may be somewhat reassuring. Although the groups were shown to be comparable at analysis, a regression-type analysis that included baseline characteristics as covariates would have been more appropriate than a simple comparison of the mean health outcomes. The simple comparison of the mean outcomes did not account for any differences between the two groups which, in a non-randomised trial, cannot be assumed to be unimportant simply because they are not significant.
Validity of estimate of measure of benefit The authors did not derive a measure of health benefit. The analysis was therefore categorised as a cost-consequences study.
Validity of estimate of costs All the costs relevant to the perspective adopted were included in the analysis within a particular timeframe. If patients had been followed up beyond the episode of care, there may have been further costs associated with complications that appeared postdischarge. These costs are important in an analysis where the main benefit of a procedure is to reduce the LOS, because they can rule out the possibility that the intervention is shifting costs into a second episode of care. Some quantities were reported separately from the costs, but not all, which may affect the generalisability of the results.
A statistical analysis of the costs was performed, but the results were unclear. Student's t-test was used for the statistical analysis. However, since this test assumes the data are normally distributed, it may not be appropriate for cost data, which must be positive and which, typically, have a skewed distribution. The sample size might have been sufficient to overcome distributional limitations arising from the use of this test. The costs were obtained from hospital charge data and a national agency in the study setting. The study data related to June 1999 to June 2000.
Other issues The authors made appropriate comparisons of their results with other studies. The issue of generalisability to other settings was not addressed. The authors do not appear to have presented their results selectively. The authors' conclusions did not reflect the scope for selection bias in this non-randomised trial. The authors acknowledged that the procedures varied between the two study centres.
Implications of the study The authors recommended that MIAS be considered for the treatment of patients with aortic disease, as it is safe and cost-efficient.
Bibliographic details Turnipseed W D, Carr S C, Hoch J R, Cohen J R. Minimal incision aortic surgery (MIAS) Annals of Vascular Surgery 2003; 17(2): 180-184 Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Aorta /surgery; Aortic Aneurysm, Abdominal /surgery; Arterial Occlusive Diseases /surgery; Costs and Cost Analysis; Female; Humans; Iliac Artery /surgery; Male; Middle Aged; Minimally Invasive Surgical Procedures /economics /methods; Prospective Studies; Vascular Surgical Procedures /economics /methods AccessionNumber 22003000767 Date bibliographic record published 31/03/2005 Date abstract record published 31/03/2005 |
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