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Excising the reexcision: stereotactic core-needle biopsy decreases need for reexcision of breast cancer |
Kaufman C S, Delbecq R, Jacobson 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 Stereotactic core-needle biopsy (SCNB) was compared to wire-localised breast biopsy (WLBB) for the diagnosis of breast cancer in patients with mammography detected suspicious or highly suspicious lesions.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised women with suspicious or highly suspicious lesions detected by mammography. The authors did not report other characteristics of this population. They reported details of the study sample, but not whether this group comprised all the women diagnosed with suspicious or highly suspicious lesions during this time period (study population). The characteristics of the study sample in the two groups were:
average age 62 years (WLBB), 64 years (SCNB);
frequency of invasive cancer 57% (WLBB), 61% (SCNB);
frequency of ductal carcinoma in situ 43% (WLBB), 39% (SCNB);
tumour size 16mm (WLBB), 15mm (SCNB);
frequency of mammographic calcifications 48% (WLBB), 42% (SCNB); and
masses 52% (WLBB), 58% (SCNB).
Setting The setting for this study was secondary care. The study was conducted in one institution in Washington, USA.
Dates to which data relate The data on effectiveness and resource use were collected between 1994 and 1996. The price year for the unit cost data was not reported.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data Cost and effectiveness data were collected retrospectively for the same sample of patients.
Study sample No power calculations were reported. The study retrospectively reviewed 113 consecutive patients who had mammography-detected non-palpable breast cancer before and after the use of SCNB. Of these, 47 patients were in the WLBB group and the next 66 consecutive patients with this diagnosis were evaluated by SCNB. The authors did not report whether this sample included all women with suspicious or highly suspicious lesions detected by mammography, or the reasons for excluding patients.
Study design The study was a single-centre, before and after study. The duration of follow-up, numbers lost to follow-up and method used to mask the investigators to diagnostic method when reviewing case notes were not reported.
Analysis of effectiveness The authors did not report whether an intention to treat or treatment completers only analysis was planned. The authors did not define primary outcomes for the analysis. The measures included in the analysis were:
the number of negative margins;
the proportion of patients who required re-excision;
the proportion of patients who had multiple operations;
the proportion of patients who had one stage surgery;
the volume of the initial wide excision.
The margins were defined as negative when there was at least 1mm of normal tissue beyond the inked margin. The authors did not provide a description of 'inked margin'. Indications for re-excision were not standardised among the surgeons. Some patients who had focal microscopic involvement of margins did not have re-excision when irradiation was considered to be adequate treatment by the attending physician. The authors compared the measurements of the greatest maximal length and total volume of the breast specimen from the first surgical procedure. Specimen volume was calculated from pathology reports by multiplying the measured height, width, and length of single specimens. Volumes for multiple pieces of the first surgical specimen were added. The two groups, WLBB and SCNB, were statistically comparable in terms of the patient characteristics reported and no adjustments were made for confounding factors.
Effectiveness results The proportion of negative margins was: 38% WLBB, and 77% SCNB, (p<0.001).
The proportion of patients who required reexcision was: 68% WLBB, and 21% SCNB, (p<0.001).
The proportion of patients who had multiple operations was: 79% WLBB, and 21% SCNB, (p<0.001).
The maximal length of the initial wide excision specimens were: 5.2cm WLBB, and 6.8cm SCNB, (p=0.19).
The volumes of the initial wide excision specimens were: 37.3cc WLBB, and 97.3cc SCNB, (p<0.002).
Clinical conclusions The authors concluded that the use of SCNB was associated with breast excisions of larger volume, a higher rate of negative margins achieved during surgery, decreased need for re-excision and a higher rate of single surgical procedures.
Measure of benefits used in the economic analysis The outcomes were reported in a disaggregated fashion and no summary measure of benefit was derived. The analysis was therefore of cost-consequences design.
Direct costs The authors reported the direct medical costs of hospital services. The costs included in the analysis were: surgeons' fees, hospital and outpatient charges, and charges for pathology, radiology, pharmacy and laboratory. The estimation of the quantities and costs was based on actual data taken from a retrospective review of the number of procedures in each of the two groups (SCNB and WLBB). Quantities of resource use and costs were not reported separately. The unit cost data were the all-inclusive estimates of charges from the hospital perspective. For the baseline analysis these were: SCNB $1,000, lumpectomy $2,500, lumpectomy with axillary dissection $6,000, axillary dissection $4,000 and mastectomy $8,000. The price year was not reported. The time horizon for the study was not reported. Discounting was not carried out, although it was not clear whether this would have been relevant as the time horizon for the study was not reported.
Statistical analysis of costs No statistical analysis of costs was carried out.
Indirect Costs Indirect costs were not included in this study and, as the study perspective was not reported, it is not clear if their omission was appropriate.
Currency US dollars ($). No conversion rate was reported.
Sensitivity analysis The authors used threshold analysis to determine the break-even charge for SCNB where the costs of both groups were equivalent.
Estimated benefits used in the economic analysis The reader is referred to the effectiveness results reported previously.
Cost results The mean cost per patient diagnosed in the WLBB group was $7,810, and the mean cost per patient in the SCNB group was $6,870. This included the cost of the diagnostic procedure and the subsequent surgical procedures measured in the study. The authors reported that the charges for the SCNB group would equal the WLBB group when the charge for an SCNB procedure was $1,900 rather than $1,000, (the charge used in the baseline analysis).
Synthesis of costs and benefits The estimated benefits and costs were not combined and no incremental analysis was performed.
Authors' conclusions The authors' concluded that, when SCNB is used to diagnose breast cancer, a single surgical procedure is possible four times as often with WLBB localisation. Before the use of SCNB the authors reported that 50% more operations were needed for patients undergoing breast cancer treatment, which resulted in a cost saving of 12% for those who have SCNB.
CRD COMMENTARY - Selection of comparators The authors justified the comparison of SCNB and WLBB by reference to published debate about the added value of SCNB in women with suspicious or highly suspicious lesions detected by mammography. The authors also reported that SCNB was the standard method of diagnosis in their institution at the time the study was conducted, and that it was not feasible prospectively to allocate patients to WLBB. The authors did not report whether alternative diagnostic methods are available or relevant to the study question. You, as a user of this database, should consider whether the comparators used in this study are relevant to clinical practice in your own setting.
Validity of estimate of measure of effectiveness The authors noted that a prospective randomised study design was desirable, but not feasible, and the retrospective before and after study was the next best alternative in their setting. The authors indicated that there was no change in care providers and management skills during the time period studied. Whilst this would help to minimise the impact of external variables on the values of the effectiveness measures, the internal validity of the study design may still have been compromised by changes in external factors such as the population at risk, care provided outside the institution, quality and completeness of retrospective data and review and interpretation of retrospective data by the investigators. The authors did not explicitly report whether the study group was a sample or all of the women in the population of interest. It is not possible to assess whether the study sample was representative of the study population. The authors noted in the discussion that only women with a confirmed diagnosis of non palpable breast cancer were included in the study. If this means that women with suspicious or highly suspicious lesions and no confirmed diagnosis of non palpable breast cancer were excluded, then the study could have over-estimated the effect of one or both of the alternatives evaluated. This would depend on whether the diagnostic performance is higher or lower in women with non palpable breast cancer than in women who do not have the disease.
The patients in each group were comparable in terms of the characteristics reported. The authors compared the clinical measures using appropriate statistical analysis for differences between groups but did not report any adjustments or additional analyses to control for the impact of potential confounding factors due to the study design.
Validity of estimate of measure of benefit The authors evaluated a number of clinical measures. However, these did not include mortality, or measures of health status of the patients over a specified time frame. The authors listed the benefits of SCNB to patients, surgeons and insurers in the USA. From the patients' perspective these included complete preoperative discussion, clearer definitive surgical choice and fewer trips to the operating room. Long term health status was not included in this list. The analysis did not measure patients' preferences and values for the listed benefits.
Validity of estimate of costs Limited information on the types of costs and sources for the cost data included in this study was reported. The authors did not provide details about the quantities or unit costs of resources used to provide the diagnostic interventions or subsequent surgical procedures. The sensitivity analysis was limited to a threshold analysis of the charge for SCNB. The time frame to which the cost data related or whether discounting was relevant was not reported.
Other issues Assessment of the validity, robustness and generalisability of the results of the study is limited by the fact that necessary information about the study population, study sample, power calculations, perspective, time horizon, patient health outcomes and benefits, costing methods or sensitivity analysis was not reported.
Implications of the study The authors suggested that SCNB rather than WLBB diagnosis should be used in patients with mammographically-detected breast cancer before the first surgical procedure because it improves patient convenience and generates cost savings. No recommendations for future research were made. You, as a user of this database, need to consider these conclusions given the problems of limited information outlined above, and in terms of current practice in your own setting.
Bibliographic details Kaufman C S, Delbecq R, Jacobson L. Excising the reexcision: stereotactic core-needle biopsy decreases need for reexcision of breast cancer. World Journal of Surgery 1998; 22(10): 1023-1027 Other publications of related interest Comment in: World J Surg 1999;23(9):981.
Indexing Status Subject indexing assigned by NLM MeSH Biopsy, Needle /economics /methods; Breast Neoplasms /economics /pathology /radiography /surgery; Carcinoma /economics /pathology /radiography /surgery; Carcinoma in Situ /economics /pathology /radiography /surgery; Carcinoma, Ductal, Breast /economics /pathology /radiography /surgery; Cost Savings; Fees, Medical; Female; Hospital Charges; Humans; Lymph Node Excision /economics; Mammography /methods; Mastectomy /economics; Mastectomy, Segmental /economics; Middle Aged; Neoplasm Invasiveness; Reoperation; Retrospective Studies; Stereotaxic Techniques /economics AccessionNumber 21998001382 Date bibliographic record published 31/12/2001 Date abstract record published 31/12/2001 |
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