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Cost-effectiveness analysis of weekday and weeknight or weekend shifts for assessment of appendicitis |
Doria A S, Amernic H, Dick P, Babyn P, Chait P, Langer J, Coyte P C, Ungar W J |
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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 examined diagnostic assessment of paediatric appendicitis during two different periods of activity in a hospital. The weeknight or weekend shift (after-hours period, AHP) was compared with the weekday shift (standard-hours period, SHP). The SHP was defined as the work shift occurring between 8 a.m. and 5 p.m. from Monday to Friday, encompassing 45 hours per week. The AHP was defined as the work shift occurring between 5:01 p.m. and 7:59 a.m. from Monday to Friday (weeknight shift) and between 5:01 p.m. on Fridays or the first day of a long weekend and 7:59 a.m. on Mondays or the first working day after a long weekend (weekend shift), encompassing 123 hours per week.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised children with ages ranging from the neonatal period to 17 years, who were admitted for suspected appendicitis.
Setting The setting was tertiary care. The economic study was carried out in Canada.
Dates to which data relate The effectiveness and resource use data were gathered between April 2001 and March 2002. The price year was 2004.
Source of effectiveness data The effectiveness evidence was derived from a single study.
Link between effectiveness and cost data The costing was carried out retrospectively on the same sample of patients as that used in the effectiveness analysis.
Study sample Power calculations, if performed, were not reported. Among the 122 children who underwent imaging during the time interval of the study and who were potentially eligible cases, 46 were excluded. Patients were excluded if they were admitted directly to the operating room without any investigation by imaging (n=21), if they underwent an interval appendectomy (n=7), if they had a laparoscopic procedure (n=13), or if their histologic assessment indicated a normal appendix (n=5). Finally, a cohort of 76 consecutive children was included in the analysis. There were 41 children (48.8% girls) in the AHP group and 35 (34.3% girls) in the SHP group. The mean age of the children was 9.8 (+/- 3.9) years in the AHP group and 10.6 (+/- 3.3) years in the SHP group.
Study design This was a retrospective cohort study that was carried out at a single tertiary centre, the Hospital for Sick Children in Toronto (Ontario). The patients were followed from the time of their registration at the emergency department until their discharge from hospital after the surgical procedure. No patient was lost to the follow-up assessment. Blinding was not performed.
Analysis of effectiveness All of the patients included in the initial study sample were accounted for in the analysis of effectiveness. The primary outcome measure was the rate of perforation. Other outcomes such as true-positive cases (with ultrasound or computed tomography) and the mean length of stay for the two groups were also reported. At baseline, demographics, diagnostic test results (against laparotomy that was considered the 'gold' standard), and time intervals from registration to surgery were comparable between groups. However, the baseline degree of severity of appendicitis, as measured by histopathologic scores, was greater for patients in the AHP group.
Effectiveness results The perforation rate was 32% in the AHP and 17% in the SHP. The authors pointed out that this result is likely to reflect the longer duration of symptoms (>/=48 hours) for patients in the AHP (38%) group in comparison with patients in the SHP (18%) group.
Thirty-one per cent of patients who had their diagnostic examinations performed in the SHP and 10% of those who had the diagnostic assessment carried out in the AHP underwent scanning within the first 2 hours of the corresponding work shifts.
The mean length of stay was 4.9 days (range: 1 to 29) for the AHP group and 4.5 days (range: 1 to 14) for the SHP group.
The rate of true-positive cases was similar between the two groups.
Clinical conclusions The effectiveness analysis showed that the perforation rate was higher among patients treated during the AHP than those treated during the SHP. However, at baseline, children in the AHP group had more severe appendicitis.
Measure of benefits used in the economic analysis The summary benefit measure was the perforation rate. This was derived directly from the effectiveness analysis.
Direct costs The analysis of the costs was carried out from the perspective of the third-party payer (provincial Ministry of Health and Long-Term Care). It included the costs associated with emergency, diagnostic imaging, surgery, ward, transport and pathology. The unit costs were not presented separately from the quantities of resources used. Resource use was estimated on the basis of hospital records for patients included in the effectiveness analysis. The costs were estimated using two approaches. One was a salary-based payment schedule at the authors' institution, while the other was a fee-for-service schedule (i.e. the Ontario Health Insurance Plan). Discounting was not relevant as costs were incurred during a short time. The price year was 2004.
Statistical analysis of costs Statistical analyses of the costs were not performed.
Indirect Costs The indirect costs were not included in the economic evaluation.
Currency Canadian dollars (CAD). These were converted to US dollars ($). Note that the conversion considered not only the exchange rate (0.75) but also the growth factor (7%) from 2001 to 2004.
Sensitivity analysis A sensitivity analysis was carried out to investigate the impact of using different diagnostic costs for ultrasound and computed tomography, which were used separately. A secondary analysis was performed by matching patients with a similar appendicitis score in the two groups.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results Using salary-based costs, the average cost per patient was $4,970 with the AHP and $4,860 with the SHP. The average total costs per patient were $3,715 with the AHP and $4,521 with the SHP in patients with non-perforated appendicitis, and $7,688 (AHP) and $6,472 (SHP), respectively, in patients with perforated appendicitis.
Using fee-for-service costs, the average cost per patient was $3,901 with the AHP and $3,774 with the SHP. The average total costs per patient were $2,871 with the AHP and $3,521 with the SHP in patients with non-perforated appendicitis, and $6,128 (AHP) and $4,952 (SHP), respectively, in patients with perforated appendicitis.
Synthesis of costs and benefits The costs and benefits should have been combined using incremental cost-effectiveness ratios (ICERs; i.e. the incremental cost per perforation avoided). However, the incremental analysis revealed that SHP dominated AHP, which was both less effective (higher perforation rate) and more expensive (higher cost per patient).
In a secondary analysis, in which the ICER was calculated by matching patients with a similar histological score for appendicitis in both work shifts, the ICER with SHP (which was more effective but also more expensive than AHP) was $3,067 with salary-based costs and $2,587 with fee-for-service costs.
The sensitivity analysis confirmed the base-case results in that the use of alternative costs associated with computed tomography or ultrasound for the assessment of children with clinically suspected appendicitis did not alter the ICER.
Authors' conclusions The standard-hours period (SHP) was dominant for the diagnosis and treatment of appendicitis in the population considered in the study, regardless of the staff payment system. However, it was pointed out that the results were due only to the fact that the most severe cases attended the after-hours period (AHP) and not to other factors that the authors had considered, such as increased costs associated with premium fees for staff, longer delays between patient's registration and surgery, or lower diagnostic performance. Overall, the diagnostic imaging did not have a great impact on the total costs.
CRD COMMENTARY - Selection of comparators The comparison between SHP and AHP was appropriate given the objective of the study. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The clinical outcome used in the analysis was based on a cohort study. The retrospective nature of the study represents a limitation of the analysis, as does the lack of random allocation of patients to the study groups. Thus, selection bias and confounding factors might have affected the results of the analysis. The authors described the sample selection process and reported the reasons for excluding some of the patients. The study groups were not well matched at baseline and the authors did not control for the potential impact of co-morbidities using statistical analyses. Instead, a secondary analysis was carried out in which only matched patients were used, although this substantially reduced the size of the patient sample. The authors noted that, ideally, patients should have been followed after hospital discharge, but the preliminary nature of the study precluded a more accurate analysis. The evidence came from a single centre, which limits the representativeness of the patient sample. No formal justification for the size of the sample was provided, and power calculations were not reported. These issues tend to limit the internal validity of the analysis.
Validity of estimate of measure of benefit The summary benefit measure was specific to the disease considered in the study. It would not be comparable with the benefits of other health care interventions. The impact of the intervention on quality of life was not investigated.
Validity of estimate of costs The perspective adopted in the study was appropriate. All the relevant categories of costs appear to have been included in the analysis. Details on the unit costs and quantities of resources used were not presented. This will limit the possibility of replicating the analysis in other settings. The source of the costs was reported for all items. No statistical analyses of the costs were carried out. A sensitivity analysis was carried out to deal with potential variations in the costs in other settings. The price year was reported, which enhances the possibility of carrying out reflation exercises in other time periods. Charges were used to derive costs, but two alternative sources of costs were used.
Other issues The authors did not make extensive comparisons of their findings with those from other studies. In terms of the generalisability of the study results to other settings, the authors stated that, given the peculiarities of the Canadian health system, caution will be required when extrapolating the results of the analysis to other countries. It was also noted that patients assessed in a teaching hospital might, in general, have more severe appendicitis than patients admitted to community hospitals.
Implications of the study The study results suggested that the more severe cases attended the AHP, thus the SHP was more effective and less expensive. The authors stated that further studies should investigate the cost-savings associated with not operating on patients whose imaging findings show no evidence of appendicitis, as opposed to operating on patients who were not previously imaged.
Bibliographic details Doria A S, Amernic H, Dick P, Babyn P, Chait P, Langer J, Coyte P C, Ungar W J. Cost-effectiveness analysis of weekday and weeknight or weekend shifts for assessment of appendicitis. Pediatric Radiology 2005; 35(12): 1186-1195 Other publications of related interest Barnett MJ, Kaboli PJ, Sirio CA, et al. Day of the week of intensive care admission and patient outcomes. Med Care 2002;40:530-9.
Bell CM, Redelmeier DA. Mortality among patinets admitted to hospitals on weekends as compared with weekdays. N Engl J Med 2001;345:663-8.
Moore JD. Hospital saves by working weekends. Mod Health 1996;26:82-4.
Indexing Status Subject indexing assigned by NLM MeSH Adolescent; After-Hours Care /economics; Appendicitis /economics /pathology /radiography /ultrasonography; Canada; Child; Child, Preschool; Circadian Rhythm; Cost-Benefit Analysis; Fee-for-Service Plans /economics; Female; Humans; Infant; Length of Stay /economics; Male; Retrospective Studies; Sensitivity and Specificity; Severity of Illness Index; Time Factors; Tomography, X-Ray Computed /economics; Ultrasonography, Interventional /economics; United States; Work Schedule Tolerance AccessionNumber 22006000059 Date bibliographic record published 31/10/2006 Date abstract record published 31/10/2006 |
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