Ambu aScope4 Broncho for use in unexpected difficult airways

The sponsor identified 3 published economic studies that focused on estimating the cost of the Ambu aScope or the multiple-use fibre optic endoscope. No modelling of the cost consequences of adoption was included in the studies.

The sponsor submitted a de novo cost analysis for Ambu aScope4 Broncho that estimated the costs and consequences associated with the use of the Ambu aScope4 Broncho and multiple-use fibre optic endoscopes. The analysis was from an NHS and personal social services perspective. Full details of all cost evidence and modelling considered by the committee are available in the assessment report overview.

The sponsor submitted a base-case analysis for 3 scenarios: unexpected difficult intubation in the operating theatre units, unexpected difficult intubation in the intensive care unit, and replacing a dislodged tracheostomy tube in the intensive care unit. The model for unexpected difficult airways needing emergency intubation separated patients according to those who had successful intubations and those who had delayed or failed intubations; the latter group were separated further according to those who survived and had no brain injury, and those with brain injury or who died. A separate model was designed for replacing dislodged tracheostomy tubes because this is not managed in the same way as an intubation and is associated with different costs and outcomes. The model for dislodged tracheostomy tubes separated patients into those who were successfully managed, those who had extended intensive care unit stay and those with brain injury or who died. The analysis reported the costs associated with equipment and clinical outcomes, which were delayed or failed intubation and the replacement of dislodged tracheostomy tubes.

The sponsor's base-case analysis included several key assumptions:

• The number of procedures performed per year with multiple-use fibre optic endoscopes was 150.

• The number of multiple-use endoscopes available was 5.

• The multiple-use fibre optic endoscope cost (including weighted costs including stack systems, cameras and so on) was £12,105.

• The Ambu aScope4 Broncho cost per endoscope with monitor was £179 (including VAT).

• The rate of intensive care unit admission or prolongation of stay was 74% for people who have had a failed intubation and 75% for people who have had a dislodged tracheostomy tube replaced.

• The cost of the intensive care unit per day was £1,321.

The model for unexpected difficult intubations had the following assumptions:

• The rate of delayed or failed intubation when using multiple-use fibre optic endoscopes in the operating theatre units was 6.25%.

• The rate of delayed or failed intubation when using multiple-use fibre optic endoscopes in the intensive care unit was 16.6%.

• The average intensive care unit length of stay was 6.2 days.

• The rate of brain injury or death in patients who had difficult intubations and in whom intubation has failed was 28%.

• The reduction in risk of delayed or failed intubation leading to patient harm with the Ambu aScope4 Broncho was 10%.

The model for dislodged tracheostomies had the following assumptions:

• The rate of brain injury or death because of dislodged tracheostomy was 13%.

• The average intensive care unit length of stay was 15.4 days.

• The reduction in risk of dislodged tracheostomy leading to patient harm with Ambu aScope4 Broncho was 10%.

The sponsor's base-case analysis estimated the incremental cost saving of the Ambu aScope4 Broncho compared against multiple-use fibre optic endoscopes to be £30 per intubation for equipment and staff costs only. This was consistent across the 3 settings. If the Ambu aScope4 Broncho was used instead of a multiple-use endoscope and if the equipment and staff costs and the modelled costs associated with hospitalisations were included, then:

• for unexpected and difficult intubation in the operating theatre units there are potential incremental cost savings of £68 per patient

• for unexpected difficult airways in the intensive care unit there are potential incremental cost savings of £130.70 per patient

• for dislodged tracheostomy there are potential incremental cost savings of £1,555.80 per patient.

A deterministic sensitivity analysis explored parameter uncertainty and the effect of these changes on the cost of the Ambu aScope4 Broncho. The parameters included the failure rate of intubation, the reduced risk rates of failed intubation with the Ambu aScope4 Broncho, the length of hospitalisation and the costs associated with multiple-use fibre optic endoscopes. The sensitivity analysis showed that the findings were responsive to the parameter changes in all 3 clinical settings. The Ambu aScope4 Broncho remained cost saving in most scenarios, with the exceptions being long equipment lifetime or a substantially low equipment cost for the multiple-use fibre optic endoscope

The external assessment centre carried out additional analyses to examine the impact of changing the following parameters of the sponsor's base case:

• Rate of delayed intubation in patients with unexpected difficult intubations in the operating theatre units and intensive care units for multiple-use fibre optic endoscopes (10%).

• Rate of harm needing extended hospital stay in patients with difficult intubations when intubation was delayed (50%).

The external assessment centre's base-case analysis in unexpected difficult intubation in an operating theatre unit indicated a cost saving of £401 when using the Ambu aScope4 Broncho. In unexpected difficult intubation in an intensive care unit, the mean cost per patient when using the Ambu aScope4 Broncho was £1,185 and the mean cost of a multiple-use fibre optic endoscope was £1,524. This indicates a cost saving of £339 when using an Ambu aScope4 Broncho in this scenario. The external assessment centre stated that the results were based on clinical expert opinion and the sponsor's assumptions, and the model was subject to uncertainty. After reviewing the sponsor's de novo model (see section 5.21), the committee asked for further information on the cost consequences using a different model structure, assumptions and parameters.

The sponsor's de novo cost analysis modelled a scenario in which multiple-use fibre optic endoscopes were completely replaced by the Ambu aScope4 Broncho. It did not consider the cost consequences of using the Ambu aScope4 Broncho if both multiple-use fibre optic endoscopes and the Ambu aScope4 Broncho were available. The external assessment centre was therefore asked to carry out additional analyses to estimate any potential cost savings of purchasing the Ambu aScope4 Broncho in different settings:

• in small hospital units that do not have access to any multiple-use fibre optic endoscopes for unexpected difficult airway management

• in addition to the existing stock of multiple-use fibre optic endoscopes in operating theatre units and intensive care units for unexpected difficult intubations and displaced tracheostomy tubes.

The external assessment centre modelled costs in 5 clinical settings:

• an isolated hospital unit

• an obstetric unit

• an operating theatre unit

• an intensive care unit

• displaced tracheostomy tubes (in an intensive care unit).
  
  All of the above settings are of indeterminate size. For example, an operating theatre unit is likely to consist of more than 1 operating theatre but the modelling is based on the number of intubations within each unit rather than of the size of the unit. A displaced tracheostomy tube is not a clinical setting and is not specific to an intensive care unit but for the purposes of the cost modelling this procedure has been classed as a clinical setting.
  
  Potential cost savings were considered from purchasing:

• 1 or more Ambu aScope4 Broncho devices for use in managing unexpected difficult intubation in a specified clinical setting with no multiple-use fibre optic endoscopes available

• 1 or more Ambu aScope4 Broncho devices for use in managing unexpected difficult intubation in a specified clinical setting with 1 or more multiple-use fibre optic endoscopes available

• 1 or more Ambu aScope4 Broncho devices for use in managing displaced tracheostomy tubes in an intensive care unit with 1 or more multiple-use fibre optic endoscopes, but where none of these endoscopes may be immediately available.

The economic model was used to evaluate the cost savings of purchasing the Ambu aScope4 Broncho for hospital units that do not have access to multiple-use fibre optic endoscopes. In these hospital units, it was assumed that, if an Ambu aScope4 Broncho was available, it would be used if and only if an unexpected difficult intubation occurred. Unexpected difficult intubations were therefore the entry point into the decision tree. The model was also used to evaluate purchasing the Ambu aScope4 Broncho as an addition for those hospital units that do have access to multiple-use endoscopes. These hospital units are likely to have a high throughput of patients needing intubation (for example, a busy operating theatre) and/or a high probability of expected difficult intubations. For modelling purposes, the number of multiple-use endoscopes was considered fixed for each clinical setting to allow the model to focus on the benefit of purchasing Ambu aScope4 Bronchos as an addition to existing multiple-use endoscopes. The number of unexpectedly difficult intubations arising for which there was no multiple-use endoscope available was modelled as a function of the number of multiple-use endoscopes, numbers of intubations carried out in the unit, and multiple-use endoscope non-availability (which was modelled using a queuing simulation). Difficult intubation events occurred at random intervals according to a Poisson process.

There were uncertainties in several parameters used in the cost modelling, often caused by there being limited or no clinical data to support the assumptions. Cost savings were considered likely in all the clinical settings that were modelled, but these depended on the number of intubations performed and on the number (if any) of existing multiple-use fibre optic endoscopes.

The base-case analysis of all of the clinical settings showed that the potential cost savings from purchasing the Ambu aScope4 Broncho came from using it when multiple-use fibre optic endoscopes were not available, therefore avoiding the consequences of failed intubation such as severe brain injury. It was assumed that an unexpected difficult intubation arises on average 6 times per 1,000 intubations.

The base-case analysis of using the Ambu aScope4 Broncho in an isolated hospital unit assumed 300 intubations per year and that no multiple-use fibre optic endoscopes were available. The cost saving per year was £749 per unit if the cost of the monitor was excluded and £653 if it was included. The number of intubations per year above which purchasing a bundle of 5 Ambu aScope4 Bronchos was cost saving was 95 if the monitor was excluded and 115 if the monitor was included.

Two base-case analyses were performed for using the Ambu aScope4 Broncho in an obstetrics unit: one assumed 400 intubations per year and no multiple-use fibre optic endoscopes, and the second analysis assumed 400 intubations per year and 1 multiple-use endoscope. If there were no multiple-use endoscopes, the cost saving per annum was £1,452 if the cost of the monitor was excluded and £1,356 if it was included. If there were no multiple-use endoscopes, the number of intubations per year above which purchasing a bundle of 5 Ambu aScope4 Bronchos was cost saving was 80. If a multiple-use endoscope was available then the Ambu aScope4 Broncho was estimated to be cost incurring unless a minimum of 500 intubations per year were done in the unit.

The base-case analysis for using the Ambu aScope4 Broncho in operating theatre units assumed that there were 2 multiple-use fibre optic endoscopes and that 1,000 intubations per year were conducted. Based on this, the Ambu aScope4 Broncho was considered to be cost incurring by £203 per unit per year if the cost of the monitor was excluded and £299 if it was included. The number of intubations per year above which purchasing a bundle of 5 Ambu aScope4 Bronchos was cost saving was 1,250 if the monitor was excluded and 1,350 if the monitor was included.

The base-case analysis for using the Ambu aScope4 Broncho in intensive care units assumed that there were 2 multiple-use fibre optic endoscopes and 700 intubations per year. Two assumptions considering the probability of difficult intubation were presented: 20% and 5%. If the probability of difficult intubation was 20%, the cost saving per year was £3,219 if the cost of the monitor was excluded and £3,123 if it was included. If the probability of difficult intubation was 5%, the cost saving per year was £3,128 if the cost of the monitor was excluded and £3,031 if it was included. The number of intubations per year above which purchasing a bundle of 5 Ambu aScope4 Bronchos was cost saving was 50 to 100 with 20% probability and 250 to 300 with 5% probability.

The base-case analysis for using the Ambu aScope4 Broncho to aid the replacement of displaced tracheostomy tubes assumed a displacement rate of 15% per year for an intensive care unit with 2 multiple-use fibre optic endoscopes. For a base case of 200 tracheostomies per year, the cost saving per year was £5,281 per unit if the cost of the monitor was excluded and £5,185 if it was included. The number of tracheostomies per year above which purchasing a bundle of 5 Ambu aScope4 Bronchos was cost saving was 70.

The committee considered the sponsor's economic analysis in which the Ambu aScope4 Broncho completely replaced multiple-use fibre optic endoscopes in operating theatre units and intensive care units. It noted that the sponsor's model did not consider the cost consequences of using the Ambu aScope4 Broncho if both the multiple-use endoscopes and the Ambu aScope4 Broncho are available. The committee received advice from several clinical experts that a multiple-use endoscope would, where available, be preferred by clinicians, and concluded that the sponsor's model was not realistic. The committee also considered that there were too many uncertainties in the sponsor's economic model to use the outcomes as the basis to make recommendations.

The committee requested further modelling, which was carried out by the external assessment centre, to establish any potential cost savings of purchasing the Ambu aScope4 Broncho in 5 clinical settings. This modelling considered the cost consequences for 2 scenarios: using the Ambu aScope4 Broncho where multiple-use endoscopes are not available for use in a clinical setting; and using the Ambu aScope4 Broncho where multiple-use endoscopes are normally available in a clinical setting but for some reason are inaccessible. The committee judged that if the Ambu aScope4 Broncho was available for use, there are likely to be cost savings in all the settings modelled, based on the following assumptions about the number of intubations or tracheostomies performed each year:

• Isolated hospital unit with no multiple-use endoscopes: 95 intubations.

• Obstetrics unit with no multiple-use endoscopes: 80 intubations.

• Obstetrics unit with 1 multiple-use endoscope: 500 intubations.

• Operating theatre unit with 2 multiple-use endoscopes: 1,250 intubations.

• Intensive care units with 2 multiple-use endoscopes: 50 intubations (20% difficult intubation probability) and 250 intubations (5% difficult intubation probability).

• Replacement of displaced tracheostomy tubes (assuming a 15% per year displacement rate) in an intensive care unit with 2 multiple-use endoscopes: 70 tracheostomies.

The committee noted that the analyses showed specific advantages for the Ambu aScope4 Broncho in the replacement of displaced tracheostomy tubes (see section 4.6). The committee accepted expert advice that multiple-use fibre optic endoscopes are often damaged in the intensive care unit when they are used during tracheostomy replacement. The modelling assumed that there were 2 existing multiple-use endoscopes and that the Ambu aScope4 Broncho is used when a multiple-use endoscope is unavailable. Combining the described advantages with its other use in intensive care units, the committee judged that the Ambu aScope4 Broncho has the potential for most cost savings in intensive care units.

The committee recognised uncertainties in a number of the parameters in the external assessment centre's economic model. The committee noted that adverse events are rare but that some of these events, such as hypoxic brain damage, may result in considerable costs. It accepted that the cost modelling provided by the external assessment centre took account of this. The cost modelling was based on overall risks in the NHS and it should be noted that cost consequences may vary between units.

The committee noted that the external assessment centre's economic model was based on assumptions of a certain number of intubations per year. It recognised that most hospitals in England have been designed with several operating theatres adjacent to each other (that is, operating theatre units) with shared availability of multiple-use fibre optic endoscopes. The numbers of intubations performed annually in these operating theatre units typically far exceeds the threshold number determined from the cost modelling. The committee therefore considered that, when this is the case, the cost savings will be greater than those estimated.

The committee was also advised that in certain situations in which a multiple-use fibre optic endoscope is not available, planned operations may be cancelled. This can result in unused operating theatre unit time, and increased length of stay or readmission for patients, leading to additional costs. The committee considered this was an additional reason that the cost savings associated with introducing the Ambu aScope4 Broncho to operating theatre units may have been underestimated.

For the guidance review, the external assessment centre revised the model to reflect 2018 costs. Further details of the cost parameter changes are in the costing review report. The external assessment centre applied the revised cost of the device and other costs to the cost model for settings with no multiple-use fibre optic endoscopes available and reported that net savings doubled to £1,638 (previously £749) with the cost of the monitor included and £1,433 (previously £653) when the cost of the monitor was deducted. This increase in cost savings is because of the increase in the cost of harms. It is also considered plausible that these savings will be achieved at lower thresholds than the 95–115 intubations noted in section 5.16. The external assessment centre also applied the revised costs to an intensive care unit setting. It reported that the cost saving in this setting also doubled to £6,632. [2019]