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Costs and effectiveness of ultrasonography and limited computed tomography for diagnosing appendicitis in children |
Garcia Pena B M, Taylor G A, Fishman S J, Mandl K D |
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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 A protocol of ultrasonography (USG) followed by computed tomography with rectal contrast (CTRC) was used in the diagnosis of acute appendicitis in children.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised children and adolescents aged between 3 and 21 years with equivocal clinical presentation of acute appendicitis. The patients were excluded if they were pregnant, had undergone an appendectomy, or had a contraindication to rectal contrast.
Setting The setting was an institution. The study was carried out at the Children's Hospital in Boston, MA, USA.
Dates to which data relate The effectiveness and resource data were collected between July 1998 and December 1998. The price year was 1998.
Source of effectiveness data The evidence for the final outcomes was derived from a single study and from the authors' assumptions.
Link between effectiveness and cost data The costing was undertaken prospectively on the same patient sample as that used in the effectiveness study.
Study sample Power calculations to determine the sample size were not reported. One hundred and thirty-nine children had equivocal clinical presentations for appendicitis and were enrolled in the study. The mean age was 11.1 (standard deviation 4.25) years (range: 3 - 20; median 11 years). Two patients were older than 18 years of age. Seventy of the children (50.4%) were male. Fifty children (36%) had pathologically proven appendicitis. Eleven of the 50 patients (22%) had perforated appendicitis and 3 (6%) had a gangrenous appendix. Thirty-one patients were imaged with USG only. One hundred and eight patients underwent CTRC imaging after a negative or equivocal USG.
Study design This was a prospective cohort study carried out in a single centre (Division of Medicine, Children's Hospital, Boston). All patients who did not undergo appendectomy were followed up by telephone, 2 weeks after their visit to the emergency department. The maximum length of follow-up was 6 months.
Analysis of effectiveness The analysis of the clinical study was conducted on an intention to treat basis. The primary health outcome was the change in the patients' management due to the introduction of the USG-CTRC protocol. "Correct changes in the management decisions were defined as those decisions that were necessary and/or benefited the child (i.e., a child with appendicitis who would have been discharged from the hospital or admitted from inpatient observation that went directly to the OR" (operating room). The final correct diagnoses were obtained by pathologic examination of the appendix for patients who underwent appendectomy, and by clinical follow-up for those children treated non-operatively.
Effectiveness results Of the 139 children enrolled, the USG-CTRC protocol resulted in a beneficial change in patient management in 86 children (61.9%), no change in 50 children (36%), and an incorrect change in 3 children (2.1%).
Of the 31 children who underwent USG alone, a beneficial change in management occurred in 12 children (38.7%), an incorrect change in 1 child (3.2%), and no change in 18 children (58.1%).
Of the 108 children who underwent USG followed by CTRC, a beneficial change in management occurred in 74 children (68.5%), an incorrect change in 2 children (1.9%), and no change in 32 children (29.6%).
Clinical conclusions The authors concluded that the use of a protocol of USG followed by CTRC in a cohort of children with equivocal clinical findings for suspected appendicitis, could reduce morbidity. The use of this protocol resulted in a correct change in management in 61.9% of the children. This included preventing the children from being discharged from the hospital or observed in the hospital. In addition, the protocol prevented children without appendicitis from undergoing unnecessary laparotomy.
Methods used to derive estimates of effectiveness The authors made some assumptions used in the analysis.
Estimates of effectiveness and key assumptions The authors assumed a conservative rate of 50% and a rate of 0% for appendiceal perforation in those children with appendicitis who would have been discharged from the hospital. It was also assumed that children with appendicitis would eventually need appendectomy.
Measure of benefits used in the economic analysis No single benefit measure was used in the economic analysis. A cost-consequences analysis was therefore carried out.
Direct costs Discounting was not carried out as the costs were incurred over a period of less than 2 years. The quantities and the costs were reported separately. Although the perspective of the study was not explicitly stated, it appears that the cost/resource boundary of the hospital was adopted. The health service costs considered were for non-perforated appendicitis, perforated appendicitis, an inpatient observation period, USG, and CTRC imaging. The cost of an inpatient hospitalisation day included the daily room, intravenous fluids, laboratory tests, and medications administered. The costs incurred in the emergency division were excluded. It was assumed that the costs of a positive or negative laparotomy were the same.
The quantities were estimated using actual data for the average hospital costs. The quantity of resources was measured from July 1998 to December 1998. The price year was 1998. The cost data were obtained through the hospital's cost database. The cost of pelvic USG and CTRC were calculated from hospital charges with a cost-to-charge ratio of 0.47, and included the costs of radiographic interpretation.
Statistical analysis of costs No statistical analysis of the costs was reported.
Indirect Costs The indirect costs were not considered.
Sensitivity analysis No sensitivity analysis was reported.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The average inpatient observation period cost $1,287 for appendicitis and $1,521 for no appendicitis.
The appendicitis cost $4,794.64 and a perforated appendicitis cost $10,699.54.
The cost of USG was $191.07 and the cost of CTRC was $282.67.
Assuming a 50% perforation rate in those children with appendicitis who would have been discharged from the hospital emergency department before imaging, USG alone saved a total of $20,422.14 (31 children), whereas USG followed by CTRC saved $58,081.85 (108 children). This resulted in an overall net saving of $78,503.99 or $564.78 per child.
Assuming a more conservative 0% perforation rate, USG alone saved $4,373 while USG followed by CTRC saved $52,732. The total net savings were $57,105 or $410.83 per child.
Synthesis of costs and benefits Authors' conclusions A protocol of ultrasonography (USG) followed by computed tomography with rectal contrast (CTRC) in children with negative or equivocal USG examinations, resulted in a high rate of beneficial change in management and in the total cost-savings.
CRD COMMENTARY - Selection of comparators The reason for the selection of the comparator was clear. It was chosen because it represented the current practice for managing children with a clinical presentation for suspected appendicitis. You should consider whether this is a widely used method in your own setting.
Validity of estimate of measure of effectiveness The analysis used a prospective cohort study, which was appropriate for the study. The sample was representative of the study population. However, power calculations were not performed and no details were given on whether the groups were comparable at baseline. In addition, the role of confounding and selection bias cannot be excluded, due to the lack of randomisation.
Validity of estimate of measure of benefit No summary benefit measure was used in the economic analysis, and a cost-consequences analysis was therefore carried out. Consequently, the costs and the benefits were not combined.
Validity of estimate of costs The analysis of the costs appears to have been carried out from the perspective of the hospital. All the relevant categories of cost appear to have been included in the analysis, even if only estimated averages were reported. The costs and the quantities were reported separately. A cost-to-charge ratio was used to assess the true cost of USG and CTRC. No statistical analysis of the quantities was performed, although the authors made some assumptions in terms of the percentage of perforations that could occur. A statistical analysis of the prices was not performed.
Other issues The authors made appropriate comparisons of their findings with those from other studies. However, the issue of the generalisability to other settings was not addressed. The authors did not present their results selectively. The study enrolled children with clinical presentations of appendicitis, and this was reflected in the authors' conclusions. The authors reported a number of limitations to their study. These included the fact that they made certain assumptions that may not have been entirely valid. This was in reference to the percentage of perforations. Also, the analysis only accounted for short-term costs associated with appendicitis.
Implications of the study The authors point out that the analysis supports the use of a protocol of USG followed by CTRC in the diagnosis of acute appendicitis with equivocal presentations in children.
Bibliographic details Garcia Pena B M, Taylor G A, Fishman S J, Mandl K D. Costs and effectiveness of ultrasonography and limited computed tomography for diagnosing appendicitis in children. Pediatrics 2000; 106(4): 672-676 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Appendicitis /radiography /ultrasonography; Child; Child, Preschool; Cohort Studies; Cost Savings; Cost-Benefit Analysis; Female; Hospital Costs /statistics & Humans; Male; Massachusetts; Patient Care Management; Tomography, X-Ray Computed /economics; Ultrasonography /economics; numerical data AccessionNumber 22000001610 Date bibliographic record published 31/12/2002 Date abstract record published 31/12/2002 |
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