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Is physician anesthesia cost-effective |
Abenstein J P, Long K H, McGlinch B P, Dietz N M |
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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 provision of anaesthesia care by physicians specialising in anaesthesiology (anaesthesiologists) versus non-medically-directed nurses with graduate-level education in anaesthesia (nurse anaesthetists) was examined.
Type of intervention Other: Anaesthesia care supportive to treatment.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients receiving anaesthesia care during surgical procedures.
Setting The setting was secondary care. The economic study was conducted in the USA.
Dates to which data relate The effectiveness data were derived from a study published in 2000. The resource use data were derived from literature published between 1996 and 2002. Prices relating to 2002 were used.
Source of effectiveness data The effectiveness data were derived from a non-systematic review or synthesis of completed studies.
Modelling An ad hoc model was developed to estimate the cost-effectiveness of physician-directed anaesthesia relative to a non-medically-directed nurse anaesthesia model of care. Two reference cases were modelled. The first reference case analysis examined the provision of anaesthesia care to a 50-year-old privately insured patient. The second one assumed the provision of anaesthesia care to a 75-year-old Medicare (public) insured patient.
Outcomes assessed in the review The outcomes assessed were the effectiveness of physician versus nurse anaesthesia (expressed as 30-day mortality), and failure to rescue after the provision of anaesthesia.
Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Nine primary studies were included in the review.
Methods of combining primary studies It was unclear whether the results of the primary studies were combined. The outcomes were reported using a narrative method, however, data from the individual studies may have been used in isolation.
Investigation of differences between primary studies The authors discussed the differences between the primary studies reviewed. For example, insufficient sample sizes, differing methods of attributing mortality to anaesthesia care, and different lengths of follow-up, which resulted in differences in the effectiveness rates reported.
Results of the review For undirected nurse anaesthetists, the 30-day mortality rate was 4.54%, the complication rate was 47.9%, and the failure to rescue rate was 9.32%.
The corresponding rates for nurse anaesthetists medically directed by anaesthesiologists were 3.41% (30-day mortality), 41.2% (complications) and 8.18% (failure to rescue), respectively.
These findings were statistically significant, (p=0.0001).
When the data were adjusted for patient and hospital characteristics, the adjusted odds ratio for 30-day mortality and failure to rescue were larger when care was not directed by physicians (1.08, p<0.04 and 1.10, p<0.01 respectively).
Measure of benefits used in the economic analysis The measure of benefit used was the number of life-years saved (LYS) with physician anaesthesia versus nurse anaesthesia.
Direct costs It was stated that the perspective of the payer, both private and public (Medicare), was adopted in the study. The costs comprised anaesthesia provider costs, as well as potential cost-savings associated with reduced perioperative morbidity and mortality under the physician anaesthesia care model. The unit costs and the quantities were reported separately for the anaesthesia provider costs. Anaesthesia resource use was estimated from literature published between 1996 and 2002. The unit costs (professional fees) for the private payer perspective were derived from an electronic survey that collected data from 173 relevant responders in the USA (e.g. health practitioners, managers, members of the ASA association). The unit costs for the public payer perspective were based on Medicare fee schedules. The average cost associated with perioperative death was based on the assumption that this was equal to the average cost of preventable perioperative events and approximately half the cost of death after cardiac surgery. The cost estimates for these conditions were derived from literature published between 1996 and 1999. Discounting was not necessary since the costs were incurred during less than one year. Prices relating to 2002 were used.
Statistical analysis of costs The costs were treated deterministically (i.e. no statistical analysis of the costs was undertaken).
Indirect Costs The indirect costs were not included in the analysis.
Sensitivity analysis A sensitivity analysis was undertaken to determine how robust the results were to changing variable estimates. All the parameters included in the analysis, such as professional unit costs, estimated cost-savings due to reduced mortality, and the difference in 30-day mortality rates between physician and nurse anaesthesia care, were varied in one-way sensitivity analyses. The ranges for professional unit costs were derived by increasing or decreasing the baseline costs by two standard deviations (SDs). Other ranges were based on assumptions (e.g. the difference in effectiveness was assumed to be 25 times worse than that used in the base-case analysis).
A multi-way sensitivity analysis, in which the robustness of the results in a worst-case scenario was investigated, was also performed. Finally, threshold analyses were undertaken to determine the magnitude of difference in outcomes between physician-directed and nurse anaesthesia that would be required for physician anaesthesia to be considered cost-effective according to accepted cost-effectiveness standards in the USA.
Estimated benefits used in the economic analysis It was estimated that, for every 400 patients anaesthetised, one additional patient would die within 30 days if non-medically-directed nurses, compared with medically-directed models of care, provided anaesthesia. Two reference case analyses were conducted. In reference case 1, an additional 50-year-old patient was assumed to survive due to physician-directed anaesthesia versus nurse anaesthesia, and was estimated to gain 30 life-years (or 20.19 life-years when the benefits were discounted at 3%). In reference case 2, an additional 75-year-old patient was assumed to survive when physician-directed anaesthesia was performed, and the estimated discounted life expectancy was 9.75 years (discount rate 3%).
Cost results The incremental, professional cost per case of physician anaesthesia for a privately insured patient was $23.79. In the case of a Medicare patient, this cost was zero. The incremental cost-saving associated with reduced perioperative mortality under the physician anaesthesia care model was $43,000 per patient life saved.
Synthesis of costs and benefits The costs and benefits were combined in the form of an incremental cost-effectiveness ratio (ICER). This ratio expressed the incremental cost per LYS associated with physician anaesthesia compared with the nurse anaesthetist model of care. Besides differences in professional fees, the incremental cost used in the ratio also included the cost-saving associated with reduced perioperative mortality under the physician anaesthesia care model. The ICER for a 50-year-old privately insured patient (reference case 1) was -$2,601 per LYS (savings favouring physician care). The ICER for a 75-year-old Medicare patient (reference case 2) was -$4,410 per LYS.
The results from the private payer perspective, referring to a 50-year-old patient, were most sensitive to assumptions about differences in reimbursement between physicians and nurses, as well as the assumed mortality gains with physician-directed anaesthesia. When the difference in professional unit costs was maximised (physician fees were increased by 2 SDs and nurse fees were decreased by 2 SDs), then the ICER became +$13,481 per LYS. Under the conservative assumption of one life saved per 10,000 cases by physician care, the ICER increased to +$9,653 per LYS. Under the worst-case scenario, the ICER rose to +$38,778 per LYS. The threshold analysis suggested that physician-directed anaesthesia needed an improved outcome of one death avoided per 1,287 anaesthetics relative to non-medically-directed nurse anaesthesia for physician anaesthesia to be considered cost-effective according to accepted US cost-effectiveness threshold standards of $50,000 to $80,000 per life-year gained.
Results from the public payer perspective, referring to a 75-year-old patient, were robust to alternative physician reimbursement patterns (since the differences in physician and nurse fees were very low in the public payer model), cost-savings due to reduced mortality, and differences in outcome. Under the worst-case scenario, the ICER increased to +$1,541 per LYS. The threshold analysis showed that physician-directed anaesthesia needed an improved outcome of one death avoided per 24,600 anaesthetics relative to non-medically-directed nurse anaesthesia for physician anaesthesia to be considered cost-effective according to the accepted US cost-effective threshold standards.
Authors' conclusions Physician-directed anaesthesia was both more effective and more cost-effective than non-medically-directed nurse anaesthesia. Even under conservative assumptions least favourable to physician anaesthesia, the cost-effectiveness of physician anaesthesia still compared favourably with cost-effectiveness estimates of other medical interventions.
CRD COMMENTARY - Selection of comparators The selection of the comparators was justified by the fact that both interventions represented alternative accepted models of anaesthesia care in the USA. You should decide whether any of these models of care represent widely used practice in your own setting.
Validity of estimate of measure of effectiveness It was not stated that a systematic review of the literature had been undertaken. In addition, no details about the methods of identifying the included studies were reported. The effectiveness data were outlined using narrative methods, though it was unclear whether any synthesis took place. The impact of differences between the primary studies on the effectiveness estimates was discussed. However, the justification for the choice of the estimates used was unclear. Overall, given the quality of reporting, the validity of the effectiveness estimates was difficult to assess.
Validity of estimate of measure of benefit The estimation of benefits was modelled. The method used to derive the measure of health benefit was age-specific and did not allow the results to be generalised to the entire study population.
Validity of estimate of costs The perspective of the study was reported to be that of both the private and public payer. All the relevant categories of costs were included in the analysis. The costs and the quantities were reported separately for anaesthesia provider costs, which increases the generalisability of the results. However, the remaining costs in the analysis, associated with savings due to reduced mortality following physician care, were presented as one cost estimate based on assumptions. It was unclear what this estimate might include. A sensitivity analysis of this cost-saving, and of unit anaesthesia provider costs, was conducted. The ranges used for the cost-saving were based on further assumptions, while those for the unit anaesthesia provider costs appear to have been appropriate. Reimbursement rates for anaesthetics were used to proxy prices. Therefore, it was likely that the costs did not reflect resource use. Discounting was unnecessary since the costs were incurred during less than one year and, appropriately, was not undertaken. The year to which the prices referred was reported, which aids the replication of the study in other settings.
Other issues The authors did not compare their results with findings of other studies. The issue of the generalisability of the results to other settings was not discussed. The authors reported that their study considered only the impact of physician anaesthesia on the costs and outcomes of the operative practice. Other forms of anaesthesia care, such as intensive care, preoperative evaluation and pain management, were not considered in the analysis. The results of the analysis were adequately reported. A limitation of the study that hinders the generalisability of the results is the fact that it examined two reference cases, each characterised by one type of payer (private or public) and, simultaneously, by a specific age of the patient (thus affecting the calculated life expectancy). Consequently, it is not clear which of the two factors contributed more substantially to the results. Therefore, the results for each reference case cannot be generalised to a private or public payer perspective, or an age-specific patient group, but only to the combination of the two. This limitation was not reflected in the authors' conclusions.
Implications of the study It was stated that the study offers economic evidence in support of maintaining current practice in anaesthetics in the USA, which, at the time of the study, was physician-directed at a percentage over 90%. However, the authors stated that this suggestion does not mean that nurse anaesthesia should be discontinued, rather, that it should be medically directed. Nevertheless, in medical environments where physician anaesthesia is unavailable, nurse anaesthetists might be the only choice for emergency surgical treatment. The authors suggested that additional research on anaesthesia outcomes is needed to determine whether the difference in outcomes adopted in this study persist across a variety of surgical populations. Moreover, they suggested that further research should investigate the clinical and economic impact of the non-operative practice of anaesthesiologists for a complete assessment of the incremental cost-effectiveness of medically-directed versus non-medically-directed anaesthesia care models.
Bibliographic details Abenstein J P, Long K H, McGlinch B P, Dietz N M. Is physician anesthesia cost-effective. Anesthesia and Analgesia 2004; 98(3): 750-757 Indexing Status Subject indexing assigned by NLM MeSH Age Factors; Aged; Algorithms; Anesthesia /economics /mortality /standards; Cost Savings; Cost-Benefit Analysis; Data Collection; Humans; Insurance, Health, Reimbursement /economics; Middle Aged; Models, Economic; Nurse Anesthetists /economics; Physicians /economics; Treatment Outcome AccessionNumber 22004000415 Date bibliographic record published 30/11/2004 Date abstract record published 30/11/2004 |
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