A decision analytic model was constructed to assess the potential costs and effects associated with VivaSight-DL compared with a cDLT in a cost-effectiveness analysis (Fig. 1). Costs of reusable bronchoscopes, including capital costs and costs associated with reprocessing, personnel, maintenance, and repair, were obtained using a 10-year time horizon. Costs related to VivaSight-DL were obtained using a 24-h time horizon. All costs are presented in $US, and adjusted to year 2018 values, with a discount rate of 3.5% regarding capital expenditures. The effectiveness measure for the cost-effectiveness analysis (CEA) was the number of times that fiberoptic confirmation of the tube placement during intubation or surgery was unnecessary and thus avoided. Effect data were obtained from a randomized controlled trial (RCT) and used to inform the decision model. The analysis was conducted from a healthcare sector perspective in Denmark, and the decision analytic model was constructed using the software TeeAgePro 2018 (TreeAge Software, Inc, Massachusetts, USA) (Fig. 1).
In the RCT, 50 patients were randomly assigned to two groups using a computer-generated random number list (http://www.randomizer.org). The intervention group was assigned to undergo intubation using VivaSight-DL, and the control group was assigned to undergo intubation using a cDLT (Shiley™ Medtronic, Minnesota, USA). Dropouts in both groups meant it was necessary to randomly assign 20 additional subjects to reach a total minimum number of 50 fully evaluable patients.
Patients were eligible for inclusion if they were admitted to Unit BTY, Department V, Odense University Hospital (OUH), Denmark, and if they were evaluated as being eligible for an OLV with the use of a left-sided DLT. Patients were excluded if they had known tracheobronchial anatomic anomalies or tracheal pathology, had anticipated difficult airways, were aged < 18 years, were undergoing an emergency procedure, required rapid sequence induction or right-sided DLT, had a prior systematic infection or suspected tuberculosis, or were unsuited for intubation with a DLT (VivaSight-DL or cDLT). Lastly, patients who needed surgeries in which the use of other lung isolation devices or techniques was likely to be warranted (tracheostomy, nasal intubation, etc.) were excluded. Physicians were eligible for participation if they had experience with DLT-associated intubations involving fewer than 50 patients, had completed the simulation training course, and had experience with at least ten cDLT placements and three VivaSight-DL placements involving a training manikin. Novice physicians were included to reflect real-world clinical settings, as the RCT was conducted at a university hospital.
Resource Use and Costs
Data on the utilization of resources and unit costs related to the cDLT and reusable bronchoscopes were obtained from OUH. All costs occurring before 2018 were adjusted using the average consumer price index for the year the cost occurred . Finally, all costs were converted to $US (exchange rate $US1 = DKK6.55; 7 February 2019).
A micro-costing analysis was carried out to obtain cost inputs for the CEA. The micro-costing approach was chosen because it allows for precise assessment of economic costs . The purpose of the analysis was to determine the cost per use of a cDLT with a reusable bronchoscope compared with the cost per use of VivaSight-DL. Regarding the VivaSight-DL group, in cases in which bronchoscopy was required, both a single-use bronchoscope (aScope™ 4 Broncho, Ambu A/S) and reusable bronchoscopes were considered in the analysis.
Therefore, several procedures involving bronchoscopy and the reprocessing procedure were observed in detail. All capital costs related to the cleaning equipment, including the automated endoscope reprocessor (AER) and the drying cabinets, were amortized over an 8-year period. The 8-year amortization period was based on the average age of the drying cabinets and AER. A discount rate of 3.5% was used to calculate the present value of capital expenditures. Reusable bronchoscopes were amortized over a 6-year period, which was selected based on the average age of the six bronchoscopes currently available at OUH [26, 27]. The micro-costing analysis was carried out in regards to capital costs, reprocessing costs, and repair and maintenance costs.
Additionally, the total intubation time, number of intubation attempts, number of times the tube needed to be repositioned during surgery, and time spent by the backup anesthesiologist assisting the novice physician were accurately assessed during the RCT. The intubation time was defined as the time from introduction of the laryngoscope blade into the patient’s mouth until correct tracheal cuff placement confirmed by capnography. All clinical data were measured and obtained by the physicians and other personnel themselves. Lastly, a total of ten bronchoscopy procedures were monitored by the investigator to estimate the average time spent on bronchoscopy involving a fiberoptic or video-enabled bronchoscope.
Reprocessing and Repair Costs
Cost estimates related to reprocessing and repair of the reusable bronchoscopes were based on the six bronchoscopes available at Unit BTY, Department V, OUH. This analysis involved the mean annual number of bronchoscopy procedures (n = 600), mean reprocessing time, and mean annual cost of repairs. Maintenance of the reprocessing equipment was managed by medical engineers at OUH, and no records were kept of previous repairs or services, so these costs were based on the literature adjusted by − 20% to avoid overestimation . Materials related to reprocessing such as consumables were accounted for. Reprocessing costs were divided into costs for reprocessing equipment, manual precleaning, drying, and AER running costs. A detailed description of the reprocessing materials and costs is provided in Table 1. The hourly wage of cleaning personnel was calculated based on 2018 wages and an estimate of 1500 productive working hours annually. Costs related to the training and education of cleaning personnel were not included, as these data were not available at OUH. Purification of the water used by the AER was centralized in the basement of the hospital and thus a water disinfector was not required. Therefore, it was not possible to calculate the costs of purifying the water.
The number of times that fiberoptic confirmation of the tube placement during intubation or surgery was unnecessary and thus avoided was chosen as the effectiveness measure. The effectiveness measure was chosen due to the assumption that fiberoptic confirmation using a bronchoscope is both time consuming and costly. Although intubation time is an indicator of the relative ease of correct tube placement, it is not a sufficient effectiveness measure, as it reflects physician competences and varies greatly between patients because of differences in airway anatomy and health status.
A number of one-way analyses were conducted to assess the impact on the incremental cost-effectiveness ratio (ICER) of varying the percentage of VivaSight-DL cases in which fiberoptic confirmation with a single-use bronchoscope (aScope™ 4 Broncho) was needed (5%, 10%, and 15%) and by increasing the annual number of bronchoscopy procedures (800, 1000, and 1200). When increasing the annual number of bronchoscopy procedures, the annual repair and maintenance costs were proportionally increased, and the amount of detergent used for the AER was increased. Furthermore, the maintenance cost was decreased by an additional 10%, 20%, and 30%, respectively, as the maintenance cost was based on the literature  and may be slightly overestimated compared with current clinical settings at OUH (i.e., the baseline cost was based on the literature and adjusted by − 20%). Lastly, the capital cost of the VivaSight-DL device was decreased by 10%, 20%, and 30% to account for differences between countries.
A two-way sensitivity analysis was conducted to assess the impact of cost levels regarding VivaSight-DL and cDLTs with reusable bronchoscopes. The analysis included all costs directly related to the use of cDLTs with reusable bronchoscopes. Moreover, a probabilistic sensitivity analysis (PSA) was conducted to simultaneously test the impact of the different variables and to assess the robustness of the result (Table 2). A second-order Monte Carlo simulation with 10,000 simulations was used for the PSA. Gamma distributions were applied to all cost variables, as this distribution allows for right skewness and because the cost variables can only take a positive value. Beta distributions were applied to the probability variables, as the probabilities can only lie between zero and one.
All non-cost data obtained from the RCT were stored and managed using Smart-Trial (http://www.smart-trial.com) and exported to and analyzed using Microsoft Excel 2016. All cost data were stored and analyzed in Excel. For both the intervention and control groups, means and standard deviations (SDs) were determined for the baseline patient characteristics, comprising age, weight, height, and body mass index. Two-sided Fisher’s exact tests were used to test for statistically significant differences between sex and number of patients who had a tube repositioning in the intervention and control groups. Furthermore, a two-sided Wilcoxon rank sum test was used to determine whether there was a statistically significant difference in age, height, weight, intubation attempts, intubation time, Cormack-L classification (classification used to describe laryngeal view during direct laryngoscopy ), use of fiberoptic bronchoscopy, prevention of repositioning, repositioning time, and time spent by responsible anesthesiologists to assist repositioning between the two groups. A statistical significance level of 0.05 was applied.