Current Practice of Airway Stenting in the Adult Population in Europe: A Survey of the European Association of Bronchology and Interventional Pulmonology (EABIP)

The main purpose of airway stenting (AS) is to restore and maintain luminal patency. Any endoluminal or extrinsic pathology causing more than 50% reduction in the size of the airway lumen can lead to debilitating symptoms such as dyspnoea. These symptoms can be significantly improved by the placement of an airway stent [1,2]. Although many attempts were made to stent the central airway in the past [3,4,5,6,7,8,9,10,11,12,13,14], it was not until the late twentieth century that the commercial era of AS commenced in Europe. A French doctor, Jean Francois Dumon, was the first physician to place a dedicated and specially designed airway silicone stent in 1987 [15]. Subsequently, several companies developed other airway stents using silicone or metallic components. In the last 30 years, numerous reports have been published describing the placement of self-expanding and balloon-expandable metal stents for the treatment of central airway diseases [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33]. However, despite the availability of additional commercial products on the market, the Dumon stent (Tracheobronxane®; Novatech, La Ciotat, France) has remained the most commonly placed stent worldwide and the “gold standard” for the treatment of both benign and malignant airway stenoses over the last 20 years [1,2]. These stents have 2 specific designs: straight and Y-shaped (for disease involving the carina) [34]. Silicone stent placement requires a skill set in rigid bronchoscopy (RB), while metallic stent placement can be performed using flexible bronchoscopes.

The European Association of Bronchology and Interventional Pulmonology (EABIP) was founded in 2002 with the objective to exchange knowledge and experience amongst interventional pulmonologists within Europe. This has been achieved through joint international multicentre research projects, establishing procedural and training standards, and agreeing on a unified terminology to improve communication within the community of European interventional pulmonologists. A European survey was launched through the EABIP executive board to investigate AS practice in the 26 European countries represented by an EABIP national delegate.

A questionnaire was developed by the EABIP board members and sent to all EABIP national delegates representing 26 European countries (Appendix 1). Each national delegate was responsible for obtaining the most precise and objective data regarding AS practice in his/her country.

Statistical analysis of the data was performed using the software package IBM SPSS Statistics 20 (Statistical Package for the Social Sciences). Continuous parameters are presented by means when normally distributed or medians and standard deviations or range. Categorical variables are reported as frequencies and percentages. Univariate analysis involved the use of analysis of variance (ANOVA) for multiple continuous variables. For the analysis of correlation, the Pearson correlation test was used for continuous data and the Spearman test for categorical data. Values were considered statistically significant for a level of p < 0.05.

All 26 European national delegates responded to the questionnaire. AS (Fig. 1) is performed in more than 30 centres in 3 countries (France, Germany, and the UK), in 21-30 centres in 2 countries (Italy and Spain), in 11-20 centres in 2 countries (Belgium and Poland), in 6-10 centres in 5 countries (Austria, Finland, The Netherlands, Portugal, and Switzerland), in 2-5 centres in 11 countries (Bulgaria, Denmark, Estonia, Greece, Hungary, Ireland, Norway, Romania, Slovenia, Sweden, and Turkey), and in a single centre in 2 countries (Croatia and Serbia). In addition, since the close of the survey in February 2016, two additional centres have started performing AS in Serbia. Finally, 1 national delegate reported that AS was not performed (Macedonia).

With regard to specialties performing AS, delegates reported that it is exclusively performed (Table 1) by pulmonologists in 5 countries (Croatia, The Netherlands, Portugal, Romania, and Serbia) and predominately by pulmonologists in 12 countries (Austria, Belgium, Bulgaria, France, Germany, Greece, Hungary, Ireland, Norway, Sweden, Switzerland, and Turkey). A further 3 delegates reported that AS is mainly performed by thoracic surgeons (Estonia, Finland, and Poland). Finally, AS is equally performed by pulmonologists and thoracic surgeons in 4 countries (Italy, Slovenia, Spain, and the UK), and equally performed by thoracic surgeons and ears, nose, and throat (ENT) surgeons in 1 country only (Denmark). In total, ENT surgeons perform AS in 14 countries (Belgium, Bulgaria, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Norway, Poland, Sweden, Switzerland, and the UK). In addition, radiologists perform AS in 4 countries (France, Hungary, Spain, and the UK).

In all countries, AS is predominately performed within the public hospital sector. In only 10 of the 26 countries (Table 1), AS is performed in private hospitals.

General anaesthesia (GA) is almost the exclusive mode of anaesthesia in the majority of countries; indeed, 16 nations reported that the use of GA is exclusive. However, within the UK system, both GA and local anaesthesia are equally utilized. Stents are placed under local anaesthesia in 9 countries (Table 1).

RB is the main technique for AS in 20 countries (Table 1). Among these 20 countries, RB is the exclusive technique in 5 countries (Croatia, Hungary, Italy, Romania, and Slovenia), and 3 countries reported that RB and flexible bronchoscopy (FB) are equally performed (Denmark, Switzerland, and the UK). Conversely, FB is the favoured technique in 2 countries (Finland and Norway).

Table 2 demonstrates the commercially available stents on the market in each country. Overall, the Dumon straight and Y-shaped stents, Polyflex, T-Tube, Ultraflex, Dynamic, and Silmet stents are the most widely available stents. Delegates from 8 countries reported that there were more than 10 commercially available brands available on the market in their country (Austria, France, Germany, The Netherlands, Spain, Sweden, and Turkey). On the other hand, 2 countries have less than 5 commercially available stents available (Norway and Serbia).

Amongst the commercially available stents (Table 2), the Dumon and the Ultraflex stents are by far the most commonly placed stents. The Dumon and Ultraflex stents are almost equally popular - the Dumon stent is ranked within the top 3 stents in 18 countries; while this position belongs to the Ultraflex in 15 countries. After these 2 leading stents, third place is occupied by the Aerstent, which is in the top 3 rankings in 4 countries and the number 1 placed stent in 3 countries. Finally, 5 countries reported that centres also place Silmet and Microtech stents.

In total, 12 countries reported that AS is an economically viable activity, while 10 countries claimed that it is not financially rewarding for their health system (Table 1).

Table 3 reports the data on global net incomes and per capita income per country. This demonstrates that countries with a total number of AS centres between 11 and 20 have the highest average global net income. Countries with 6-10 centres have the highest average per capita income. There is a statistically significant association between the number of centres and the average global net income of that nation (F = 3,453, p = 0.018). In addition, there is a strong statistical correlation between the number of centres per nation and its overall ranking on the global net income list (ρ = 0.822, p = 0.000). Finally, there was a statistical correlation between the number of centres per nation and the overall ranking on the per capita income list (ρ = 0.466, p = 0.016).

The EABIP undertook this survey to assess the current practices of AS in adults within Europe, the birthplace of this technique. According to current geographical and political definitions, Europe represents a total of 51 countries; however, only 26 countries have a national delegate represented within the EABIP. Among these 26 countries, with a total population of 580 million, AS is performed in all but one country (Macedonia).

Of the remaining 25 countries, 3 of the 4 largest nations (in terms of population) have more than 30 centres practicing AS: Germany, the UK, and France. Based on the results of this survey, it appears that more than 200 centres perform AS in Germany. In addition, these 3 nations represent the highest ranked nations within Europe in terms of gross national income. These results show that these countries have 1 AS centre for every 2.3 million inhabitants.

Turkey, which is the third largest country in Europe, based on population (6th in terms of gross national income, 26th in terms of per capita income), has only 2-5 centres performing AS. However, AS is a relatively new procedure available in Turkey and it is possible that training is still required to increase the number of centres offering the technique. The Turkish national delegate stated that:

In Turkey, stent placement should be standardized and we will begin a certificate program which lasts 6 months including theoretical and practical education with the Ministry of Health. Interventional Pulmonology is not a subspecialty in Turkey as it is in the rest of Europe. However, we think that education and interventions have to be strictly standardized to ensure a good and effective clinical approach.

The next two most populated countries, Italy (4th) and Spain (5th), have between 21 and 30 centres. This represents 1 centre for every 1.8-2.6 million inhabitants. These are followed by Poland and Belgium listed 7th and 10th, respectively, in terms of population. These countries have between 11 and 20 centres performing AS, equating to 1 centre for every 1.23-2.24 million inhabitants.

Four other countries, Austria, Finland, Portugal, and Switzerland, listed 15th, 19th, 12th, and 15th, respectively, in terms of population, have between 6 and 10 centres each (i.e., 1 centre for every 0.8-1.3 million inhabitants).

Twelve countries, with a total population of close to 168 million, have between 2 and 5 centres performing AS. Amongst these countries, there is a large heterogeneity in terms of centres per population; for instance, Turkey has 1 centre for approximately 15 million inhabitants, while Estonia has 1 centre for less than 1 million people.

Finally, 2 countries, Croatia and Serbia, report 1 centre performing AS in the country. This represents 1 centre per 6.25 million inhabitants.

Therefore, in summary of the above results, this paper demonstrates that the most populated countries in Europe have more centres than the least populated nations. However, when the data is analysed per population, there is good homogeneity between all countries with roughly 1 centre for 1.3-2.2 million people, with the exception of Turkey, Croatia, and Serbia.

Since the earliest years of interventional pulmonology, AS has been performed by different specialists: pulmonologists, ENT surgeons, thoracic surgeons, and radiologists. For instance, J.F. Dumon, L. Freitag, and Marc Noppen are pulmonologists, while William Montgomery was an ENT surgeon. In addition, numerous thoracic surgeons have been trained in this technique. In many cases, this was a skill set learned by the thoracic surgeon to repair postsurgical anastomotic complications, but the skill was additionally used to manage central airway disease. Our survey demonstrated that AS is exclusively or predominantly performed by pulmonologists in 17 out of the reporting 26 countries and equally performed by both specialties in 3 nations. Furthermore, AS is primarily performed by thoracic surgeons in 3 countries (Estonia, Finland, and Poland). The national delegate from Finland explained this finding by stating that the procedure is only economically viable if performed as a surgical procedure.

Overall, it is difficult to explain the variation in terms of AS operator between the European countries. We suggest that each country should review their AS practices, both current and historical, as this may assist in explaining the differences in national practices. We can make the hypothesis that these variations are due to a number of factors that not only vary from country to country but also from unit to unit within a country, for example skill set/training of the operator, training in RB, accessibility to a dedicated unit, availability and ease of access to GA, tradition, and, most significantly, reimbursement patterns in each health care structure. However, despite these multiple factors, it does appear that AS remains within the domain of pulmonologists in the majority of European countries.

In all reporting European countries, AS is performed primarily within the public hospital sector. As per our previous analysis, it is unclear why this pattern exists, and indeed without a precise and exhaustive analysis of individual health services, which differ significantly from nation to nation within Europe, it is impossible to be certain of this result. However, we hypothesize that only large-volume private institutions can offer the procedure at a frequency high enough to make it financially viable. In addition, most AS services have developed in institutions with on-site thoracic surgery facilities; these are often not available in medium-sized private hospitals. In our opinion, the presence of a thoracic surgery department is mandatory for a safe AS service and, in return, interventional pulmonologists will be referred patients requiring stent placement after surgical interventions. In addition, our surgical colleagues are occasionally needed to assist in the care of patients developing complications after endoscopic procedures. In certain countries, current AS reimbursements are not rewarding enough for private structures to develop these techniques.

In the majority of European countries, AS is performed under GA, and this survey has shown that the procedure is performed exclusively under GA in 16 countries. Nine countries reported that AS can be performed under local anaesthesia. This is most likely explained by physician difficulty in accessing operating room facilities and anaesthetic cover. The lack of RB skills remains an important factor explaining why some centres still perform AS using flexible bronchoscopes [35]. For instance, in the UK, pulmonologists do not have easy access to RB as it is generally performed by thoracic surgeons. The recommendations of the British Thoracic Society guidelines [36] state that “the majority of the published case series regarding outcomes and complications of stent deployment are for deployment by rigid bronchoscopy only. Flexible bronchoscopy is an alternative to rigid bronchoscopy to deploy metallic airway stents.” Although NICE guidelines [37] state that all cancer centres need to provide access to AS, the subsequent British Thoracic Guidelines supported stenting under FB guidance. This is despite these guidelines clearly stating the significant benefits of RB over FB techniques. However, they completed the guideline by stating that most clinicians did not have adequate training or a skill set in RB and therefore flexible procedures were acceptable. The outcome of these statements is that pulmonologists in the UK continue to place metallic stents using a flexible bronchoscope with or without GA, while surgeons are capable of placing both metallic and silicone stents using RB. It is also important to recognize that RB is generally necessary to place stents in patients who have airway obstruction secondary to anything other than routine malignant tracheobronchial disease [37]. RB requires either a state-of-the-art bronchoscopy suite equipped to provide GA or an operating room. This scenario is rarely available to pulmonologists in the UK. In addition, few operators have adequate volume to demand a dedicated session in the operating room. As can be expected, and particularly at the early stage of service development, referred cases can be irregular and erratic, thus leading to uncertainty in procedure scheduling compared to more established and higher-volume surgical procedures. Dedicating one or two half-day lists per week for procedures allows for more consistent scheduling, but it does not eliminate the issue of obtaining regular operating room time [38].

This survey demonstrates that RB is favoured in 20 countries and that RB and FB are equally utilized in 2 other nations. Only 2 countries favour FB. Physicians with adequate RB skills are probably the primary factor for deciding on the type of AS procedure and stent selection. The lack of RB training remains a significant factor, despite the recommendations of respiratory societies. The ACCP guidelines [39] state that “dedicated operators performing airway stenting should have extensive experience in flexible and rigid bronchoscopy and management of central airway lesions.” To maintain competency, dedicated operators should perform at least 10 procedures per year. In order to make the best choice for the individual patient, the dedicated operator should be proficient in the placement of both flexible and silicone stents. The ATS and ERS statement [40] wrote: “Stent insertion should be reserved for bronchoscopists who have had ample experience with rigid/flexible bronchoscopy and endotracheal intubation. In order to maintain competence, 5-10 procedures per year should be performed.”

In these two recommendations, the volume of the procedures is probably not enough to maintain competence, especially if a unit is utilizing multiple stent types. Our questionnaire has shown that there are 14 brands available in Europe. In addition, 3 countries have locally developed stents available. The survey has shown that 8 countries have more than 10 types of stents available for use, while 2 countries have less than 5 stents on the market. Surprisingly, Turkey, which has only 2-5 centres performing AS, has 13 different stent types on the market. There is no doubt that companies have focused on this country as an emerging market for future sales.

The most widely available stents in Europe are the Dumon, Polyflex, T-Tube, Ultraflex, Dynamic, and Silmet stents. Not surprisingly, all of these stents are distributed by the two biggest and historically most active companies in this field: Novatech SA and Boston Scientific. Of the top 3 stents, Dumon (silicone stent) is available in 18 countries and Ultraflex (self-expandable nitinol stent) is available in 15 countries. These stents are clearly the market leaders. Other silicone stents such as the Polyflex and Noppen stents appear to have a limited market share, while the newer brands of fully covered metallic stents such as Aerstent (3rd rank), Silmet (4th rank), and Microtech stents (5th rank) may need more time to establish themselves in this area and ultimately challenge the monopoly enjoyed by the Dumon and Ultraflex stents.

The choice of a stent, as already stated, relies not on evidence-based medicine but primarily on the skills of the operators in both FB and RB, on stent availability, on overall commercial strategies, and on other, multiple subjective factors and expert opinions.

Unfortunately, the growth of AS may be limited by local and national reimbursement strategies rather than patient clinical benefit, which is obvious. Overall, 12 countries stated that the procedure of AS is financially viable. Within these countries, financial viability relies on a combination of factors: commercial stent price, favourable stent, and procedure reimbursement by local national institutions or private insurance companies to ensure that the overall financial position for the institution is favourable.

On the other hand, 10 national delegates stated that AS is not financially worthwhile in their jurisdiction. For instance, in Bulgaria, the national delegate wrote that “Airway stenting is not reimbursed and patients have to pay for the procedure themselves (about 700 Euro for a silicone stent and 1,300 Euro for a metal stent). The National Health Insurance Fund pays about 450 euros for this interventional procedure. Therefore airway stenting is not a profit-earning activity for our institutions.”

The delegate from Croatia stated that “the price for stent placement is less than the cost of the stent itself. By including the price of dilatation and other procedures performed before stent placement, we can reach an amount that is greater than the price of the stent.”

In Hungary, the delegate reported that “stents are reimbursed on a case by case basis, strictly by the cost of the stent, without any further reimbursement. It means that it is not worth doing this kind of service.” In Portugal, “there is no reimbursement for stents and every time we place a stent the cost comes out of the hospital's budget.”

In Romania, AS is not financially viable “because the price of the stent is very high (between 500-1,000 Euro) comparing with the average income of people (200-300 Euro) and the price of the stent is not covered by health insurance. The National Health Insurance scheme does not pay for the interventional procedures and the reimbursement for one bronchoscopy is about 100-150 Euro, no matter how complex the procedure is (the same price for diagnostic and interventional procedures).”

The Serbian delegate stated that “our Medical Authorities do not reimburse stenting anymore so our procedure rate has decreased significantly.”

There is very little published data regarding the economic value of AS. Lund et al. [38] wrote that, in the USA, considering the time necessary for performing advanced therapeutic bronchoscopy, the professional fees are not attractive. The net facility reimbursement largely depends on stent costs and airway stent placement is not reimbursed at competitive rates and may even lead to a net loss for the facility.

The practice management benefits of central airway therapy are probably best obtained by a multidisciplinary airway team within an established cancer centre structure. It is obvious that AS in a pulmonary practice requires expertise with other procedures and a substantial capital investment (e.g., for thermal ablation technology, bronchoscopes, and RB equipment).

The finances of stenting and interventional bronchoscopy differ greatly between a multidisciplinary disease management team and a physician in private practice. Most reimbursement schemes will pay for a single procedure irrespective of the complexity of the intervention. For example, if an interventional bronchoscopy procedure requires the destruction of a tumour followed by a bronchoplasty with stent placement in the bronchus, the reimbursement is substantially lower than that obtained if each procedure was performed individually.

The complexities of stenting require both RB and FB facilities and are dependent on the airway disease and stent type required. Unfortunately, the required skill sets, training, associated risks, and limited pool of technical competency in performing RB are not recognized.

Improved reimbursement for bronchoscopic stent placement is required. These are high-risk, complex procedures and are usually performed in patients with poor physiologic reserve and significant co-morbidities and associated poor performance status. However, current reimbursement is a significant deterrent to AS. Current facility reimbursement rules are a disincentive to developing outpatient procedures and the use of metallic stenting. Currently, it appears that the best business model is a hospital-funded or health system-funded regional centre of excellence using a cost-centre approach to evaluate the real return on the investment.

This survey was performed to assess the current status and practices of AS in Europe. There are, however, a number of limitations in the results. It was not possible to collect precise data with respect to the indications for AS or the total number of stents placed per centre and per country. In some countries (the UK, Poland, and Denmark), the national delegate was unable to provide accurate data on the most popular stents placed in their region. However, the merit of this collaborative work is to provide a snapshot of AS practice in the 26 European members of the EABIP.

It is impossible to draw accurate conclusions, guidelines, or recommendations on AS practice given the limitations of this work and given the heterogeneity in practice and economic variability within countries. The EABIP has no role in the strategic planning of the health services of each country; however, the association can support and develop AS within Europe by developing ongoing training programs and courses and ensuring that skills and knowledge are shared amongst centres to create a greater standardization of practices within the region.

H.D., S.A.H., S.B., P.G.-S., S.G., F.J.F.H., M.M.: EABIP Executive Committee 2014-2016.D.B., A.B., L.D., J.D., C.D., R.E., L.E., M.E. M.F., M.H., S.M., Z.P.-S., M.P., M.R., A. Rosell, A. Rozman, P.L.S., M.S., A. Szlubowski, G.S., A. Sundset, T.U., C.G., B.Z., M.Z., L.Z.: EABIP Board of National Delegates.