Summary of Evidence

Steroid-eluting sinus implants and stents may prove to have a role in the treatment of nasal polyposis; however, further data are needed from higher quality studies to evaluate the efficacy and durability of the results. The evidence is insufficient to determine the effects of the technology on health outcomes.

For individuals who have chronic rhinosinusitis who have undergone endoscopic sinus surgery (ESS) who receive implantable steroid-eluting sinus stents, the evidence includes randomized controlled trials (RCTs). Relevant outcomes are symptoms, change in disease status, morbid events, and treatment-related morbidity. The most direct evidence relating to use of steroid-eluting nasal stents as an adjunct to ESS comes from 4 RCTs comparing steroid-eluting stents with either a non-steroid-eluting stent or medical management. The need for post-operative intervention at 30 days was reduced by 14% to 24%, translating to a number needed to treat of 4.7 or more. Three trials used blinded assessors to evaluate post-implantation sinus changes, an important strength, but the trials had potentials for bias. To evaluate the benefit most accurately from Propel® devices it is important to ensure that the comparison group is not undertreated (ie, receives some form of packing, intranasal steroids, and irrigation). 

For individuals who have recurrent sinonasal polyposis who have undergone ESS who receive steroid-eluting sinus implants, the evidence includes RCTs. Relevant outcomes are symptoms, change in disease status, morbid events, and treatment-related morbidity. Two RCTs were identified evaluating the use of steroid-eluting nasal implants for recurrent or persistent nasal polyposis after ESS, which demonstrated improvements in polyp grade and ethmoid obstruction. Strengths of these trials included use of sham control and adequate power for its primary outcome. However, the trials had a high-risk of bias due to unblinded outcome assessment. Although avoidance of repeat ESS and oral steroids may be relevant outcomes for this indication, it would be more important if decisions about repeat ESS or other treatments were standardized and, in the trial setting, if decisions were prespecified or made by a clinician blinded to treatment group.

Rationale

Chronic rhinosinusitis (CRS) is defined as an inflammatory condition involving the paranasal sinuses and linings of the nasal passages, which persists for 12 weeks or longer. CRS can be divided into three subtypes:

• CRS with nasal polyposis
• CRS without nasal polyposis
• Allergic fungal rhinosinusitis

Symptoms of CRS include nasal obstruction or blockage, thick nasal drainage, facial pressure, and reduction in sense of smell. CRS is divided into CRS with nasal polyps (CRSwNP) and CRS without NP (CRSsNP), which are distinguished by the presence or absence of nasal polyps. Recommended initial treatment includes a combination of intranasal corticosteroids and intranasal saline, rather than either therapy alone or treatment with oral glucocorticoids or antibiotics. Treatment should be continued for at least two months as improvement may be gradual. Even with optimal and consistent use, many patients experience only modest improvement with these initial interventions. For patients with persistent symptoms, there are several options for additional treatments but very few studies to define their relative efficacy. A common practice is to use the combination of an oral glucocorticoid and oral antibiotic for 10 to 14 days, yet data and high-quality evidence to support these treatments specifically for CRS is lacking. For most patients, sinus surgery is considered when there is insufficient response to standard medical management. 

Endoscopic sinus surgery (ESS) is intended to restore physiologic sinus ventilation and drainage, which can facilitate the gradual resolution of mucosal disease. ESS involves the removal of small pieces of bone, polyps, and debridement of tissue within sinus cavities. For all procedures, there is substantial postoperative inflammation and swelling, and postoperative care is therefore a crucial component of ESS. There are a number of postoperative treatment regimens. Options include saline irrigation, nasal packs, topical steroids, systemic steroids, topical decongestants, oral antibiotics, and/or sinus cavity debridement. Implantable sinus stents are another option for postoperative management following ESS. These implants are intended to stabilize the sinus openings and the turbinates, reduce edema, and/or prevent obstruction by adhesions. They can also be infused with medication delivered topically over an extended period of time, and this local delivery of medications may be superior to topical applications in the postoperative setting. Sinus stents are defined as implantable devices specifically designed to improve patency and/or deliver local medication. These devices are inserted under endoscopic guidance and are distinguished from sinus packing and variations on packing devices routinely employed after sinus surgery. Reducing postoperative inflammation and maintaining patency of the sinuses may be important in achieving optimal sinus drainage and may impact recovery from surgery and/or reduce the need for additional surgery.

Randomized controlled trials (RCTs) are important in the evaluation of sinus implants as an adjunct to functional endoscopic sinus surgery (ESS) to adequately compare implantable stents with alternative treatment regimens and to minimize the effects of confounders on outcomes. Case series and trials without control groups offer little in the way of relevant evidence, because improvement in symptoms is expected after ESS and because there are multiple clinical and treatment variables that may confound outcomes. The most relevant comparison for sinus stents is unclear because there is no standardized optimal postoperative treatment regimen. Ideally, the “standard care” comparison group should include some form of packing, intranasal steroids, and irrigation. An important consideration in evaluating controlled trials is that the control arm may not be treated with optimal intensity, thereby leading to a bias in favor of the device. Another concern is comparison of the efficacy of a drug with the efficacy of a drug delivery system. For example, if a steroid-eluting spacer is compared with a control of saline irrigation alone, it will be difficult to separate the efficacy of the drug itself (steroids) from the drug delivery system (stent).

Several implantable sinus devices have been approved by the U.S. Food and Drug Administration (FDA) for use in the ethmoid sinus. In 2011, the Propel® system, a self-expanding, bioabsorbable, steroid-eluting stent was approved by the FDA through the premarket approval process. This device is placed via endoscopic guidance using a plunger. Steroids (mometasone furoate) are embedded in a polyethylene glycol polymer, which allows sustained release of the drug over an approximate duration of 30 days. The device dissolves over several weeks, and therefore does not require removal. A smaller version of the Propel® device, the Propel® mini Sinus Implant, was approved for use in patients older than 18 years of age following ethmoid sinus surgery. In 2017, the Propel® Contour was approved through a premarket approval supplement. The Propel® Contour sinus implant is an adaptable implant that is designed to maximize drug delivery to the frontal and maxillary sinus.

The Sinuva® (mometasone furoate) sinus implant was initially approved by the Food and Drug Administration (FDA) in 1987. In 2017, a new higher dose implant containing 1350 mcg of mometasone furoate was approved through the premarketing approval process (PMA) drug pathway. In contrast, the Propel® devices have been cleared through the PMA as devices and provide 370 mcg of mometasone furoate. All of these products are manufactured by Intersect, Inc. 

The Sinuva® implant has been FDA-approved for the treatment of nasal polyps in patients ≥ 18 years of age who have had ethmoid sinus surgery. The implant is loaded into a delivery system and placed in the ethmoid sinus under endoscopic visualization. The Sinuva® Sinus Implant is made from bioabsorbable polymers designed to gradually soften over time. The implant may be left in the sinus to gradually release the corticosteroid over 90 days. The implant should be removed by 90 days or earlier at the physician’s discretion.

Steroid-Eluting Stents as an Adjunct to ESS 

The most relevant comparison for sinus stents is unclear because there is no standardized optimal postoperative treatment regimen. Ideally, the “standard care” comparison group should include some form of packing, intranasal steroids, and irrigation. An important consideration in evaluating controlled trials is that the control arm may not be treated with optimal intensity, thereby leading to a bias in favor of the device. For example, a study design that compares a steroid-eluting stent with a non-steroid-eluting stent will primarily evaluate the efficacy of steroids when delivered by the device but will not evaluate the efficacy of a stent itself. If the control group does not receive topical or oral steroids postoperatively, then this might constitute undertreatment in the control group and result in a bias favoring the treatment group. Another concern is comparison of the efficacy of a drug with the efficacy of a drug delivery system. For example, if a steroid-eluting spacer is compared with a control of saline irrigation alone, it will be difficult to separate the efficacy of the drug itself (steroids) from the drug delivery system (stent).

A 2015 Cochrane review addressed steroid-eluting sinus stents for improving chronic rhinosinusitis (CRS) symptoms in individuals undergoing ESS. Study eligibility criteria were RCTs that compared the effects of steroid-eluting sinus stents with non-steroid-eluting sinus stents, nasal packing, or no treatment in adults with CRS who underwent ESS. After an initial search, 21 RCTs were identified that tested sinus stents, spacers and packing material for patients with CRS undergoing ESS but none met the inclusion criteria. Reviewers concluded that there is no evidence from high-quality RCTs to demonstrate the benefits of steroid-eluting stents.

A systematic review of early postoperative care following ESS was published in 2011 by Rudmik et al. Reviewers evaluated a number of postoperative regimens, including stents. Reviewers included 1 RCT by Cote et al (2010) and 2 nonrandomized studies. The RCT did not involve a stent but rather compared steroid-impregnated dressings to saline-impregnated dressings. Some devices included in these studies are considered middle meatal spacers and are outside the scope of this rationale document. The overall level of evidence was judged as B (RCT with limitations). Reviewers concluded that topical steroids delivered by the “nonstandard” route required further study and that the results of current studies could not be extrapolated to larger populations. Based on this evidence, reviewers did not recommend use of stents, but considered them an option for postoperative care.

Han et al (2012) performed a meta-analysis of the 2 published RCTs assessing the Propel® implant, both of which compared a steroid-eluting stent with a non-steroid-eluting stent. Trial results were combined at the patient level, with reanalysis of the endoscopy videos by a panel of 3 independent ear, nose, and throat experts. The combined results were that the steroid-eluting device reduced postoperative interventions by 35% (p<0.001), reduced lysis of adhesions by 51% (p<0.001) and reduced the need for oral steroids by 46% (p<0.001). Due to study design, it is not clear whether these benefits were a result of the steroids or the device.

There are 4 RCTs of the Propel®, Propel® Mini, and Propel® Contour steroid-eluting sinus stents, all sponsored by the device manufacturer (Intersect ENT). These trials used an intrapatient control design, with each patient receiving a drug-eluting stent on 1 side and a non-drug-eluting stent or medical treatment on the other via random assignment.

The first RCT of the Propel® sinus implant was published in 2011 by Murr et al. Thirty-eight patients with refractory CRS were included in the efficacy evaluation, and an additional 5 patients were enrolled for a safety evaluation. An intrapatient control design was used, meaning that each patient received a drug-eluting stent on 1 side and a non-drug-eluting stent on the other via random assignment. Patients were not permitted to use topical or oral steroids for 30 days following the procedure. A 14-day course of antibiotics was given to all patients. The primary end point was the degree of inflammation recorded on follow-up endoscopy at day 21 postprocedure, as scored by a 100-mm visual analog scale (VAS). Semiquantitative grading was also performed for polypoid changes, middle turbinate position, and adhesions/synechiae. The clinicians recording the outcomes were the same physicians who treated the patients. One patient withdrew prior to study completion. The difference in inflammation scores at 21 days significantly favored the steroid-eluting group. The estimated difference in scores from graphical representation was approximately 18 units on the 0 to 100 VAS. The percentage of patients having polypoid changes was 18.4% in the steroid-eluting group and 36.8% in the non-steroid-eluting group (p=0.039). Adhesions were also significantly less common in the steroid-eluting group (5.3% vs 21.1%, p=0.03). There were no significant differences in the appearance or position of the middle turbinate. Limitations include the lack of non-stent comparator, lack of physician evaluator blinding, and small study size.

In 2012, Marple et al published results of the ADVANCE II trial, an RCT of the Propel® sinus implant for 105 patients with CRS refractory to medical management. This trial also used an intrapatient control design, with each patient receiving a drug-eluting stent on 1 side and a non-drug-eluting stent on the other via random assignment. Patients were not permitted to use topical or oral steroids for 30 days following the procedure. A 14-day course of antibiotics was given to all patients. The primary efficacy outcome was reduction in the need for postoperative interventions at day 30 post procedure. A panel of 3 independent experts, blinded to treatment assignment and clinical information, viewed the endoscopy results, and determined whether an intervention was indicated. The primary safety end point was the absence of clinically significant increased ocular pressure through day 90. Three (2.9%) patients were lost to follow-up, and 9 (8.6%) patients could not be evaluated because the video of the endoscopy could not be graded. Two patients had the device removed within 30 days of placement. Of the remaining patients, need for postoperative intervention by expert judgment was found in 33.3% of patients in the steroid-eluting arm and in 46.9% in the non-steroid-eluting arm (p=0.028). According to the judgments of the clinical investigators treating the patients, intervention was required in 21.9% of the steroid-eluting group and 31.4% of the non-steroid-eluting group (p=0.068). The reduction in interventions was primarily driven by a 52% reduction in lysis of adhesions (p=0.005). The primary safety hypothesis was met, because there were no cases of clinically significant increases in ocular pressure recorded over the 90-day period post procedure. Again, this study evaluated the benefit of drug delivery via the stent rather than the stent itself. Other limitations include a large amount of missing data due to loss of follow up, poor video quality, and early withdrawal.

The RCTs by Smith et al (2016) and Luong et al (2017), implanted either a Propel® Mini Sinus Implant or a Propel® Contour Sinus Implant in the frontal sinus with a control of surgery alone on the contralateral side. The primary outcome was the need for post-operative intervention (eg, surgery or steroids) determined by an independent blinded physician. Both trials showed a reduction in the need for additional surgical intervention by approximately 22%, with no adverse effects of treatment. The number needed to treat was 4.7 to prevent 1 patient from undergoing postoperative intervention. No stent-related adverse events were noted.

The primary limitations for the studies by Murr et al (2011) and Marple et al (2012) on the Propel® implant in the ethmoid sinus was whether the comparator had received the optimal treatment in terms of packing, intranasal steroids, and irrigation. For the studies by Smith et al (2016) and Luong et al (2017), there was a high percentage of patients who were not able to be evaluated due to video quality.

The largest nonrandomized study identified was reported by Xu et al. (2016). It evaluated post-ESS synechiae formation among 146 patients (252 nasal cavities) treated with a steroid-eluting absorbable spacer and 128 patients (233 nasal cavities) treated with a nonabsorbable spacer. Eligible patients included those who underwent ESS (at minimum, maxillary antrostomy, and anterior ethmoidectomy) for CRS with or without nasal polyps and were treated with a sinus spacer. Rates of synechiae formation at 1 month postoperatively did not differ significantly between groups (5 [2.0%] nasal cavities in the absorbable stent group vs. 13 [5.6%] nasal cavities in the nonabsorbable spacer group).

Steroid-Eluting Stents for Recurrent Polyposis

A relatively small body of literature has addressed outcomes after placement of steroid-eluting absorbable sinus stents in the office setting as a planned procedure post-ESS or due to recurrent or persistent nasal polyposis after ESS. Two RCTs evaluated the use of steroid-eluting nasal implants for recurrent or persistent nasal polyposis after ESS, which demonstrated improvements in polyp grade and ethmoid obstruction. Strengths of the trials included use of sham control and adequate power for the primary outcome. However, the trials had a high risk of bias due to unblinded outcome assessment. Although avoidance of repeat ESS and oral steroids may be relevant outcomes for this indication, it would be more important if decisions about repeat ESS or other treatments were standardized and, in the trial setting, if decisions were prespecified or made by a clinician blinded to treatment group.

In 2014 Han et al published a patient-blind randomized controlled trial comparing the Sinuva® implant with a sham procedure in 100 chronic rhinosinusitis patients with nasal polyps. In this study 53 patients received office-based placement of the Sinuva® implant. The control group (n=43) underwent sham procedure. For patient-reported outcomes, there were no significant differences in change in nasal obstruction/congestion scores between groups. At 90 days follow-up, clinical investigators found a statistically significant decrease in bilateral polyp grade (change from baseline [CFBL] –1.0 versus –0.1; P=0.016); however, in a subsequent publication, an independent panel of 3 surgeons did not find a statistically significant difference between Sinuva® and sham groups at 90 days (CFBL –0.76 versus –0.38; P=0.099). The authors of the Han study reported multiple limitations of the 2014 study. There was not a defined medical treatment regimen prior to enrollment. There was no control over patient prior treatment regimens and compliance. Clinical investigators performing endoscopic grading were not blinded to the treatment (implant vs. placebo); and the study entry criteria required patients to be surgical revision candidates while concurrently allowing for one sinus side to have only grade one polyposis which may have impacted the outcomes and lessened the opportunity of generalizing these outcomes to other patients. Another limitation is the small sample size.

In 2014, Lavigne et al published a prospective multicenter study enrolling 12 patients who had prior endoscopic sinus surgery (ESS) but experienced recurrent polyposis refractory to medical therapy. Implants were placed bilaterally under topical anesthesia in‐office. Follow‐up through 6 months included endoscopic grading, patient‐reported outcomes (22‐item Sino‐Nasal Outcomes Test [SNOT‐22]) and need for revision ESS. Implants were successfully inserted in 21 of 24 (88%) ethmoid sinuses, resulting in 11 evaluable patients. Within 1 month, mean bilateral polyp grade was reduced from 4.5 at baseline to 2.3 (p = 0.008) and sustained through 6 months (2.33; p = 0.008). Mean SNOT‐22 score was significantly improved from 2.19 at baseline to 0.90 within 1 month (p = 0.001) and sustained to 6 months (1.03; p = 0.012). Sixty‐four percent of patients were no longer revision ESS candidates at 6 months. The authors concluded that the study provided initial clinical evidence of the feasibility, safety, and efficacy of in-office steroid-eluting implant placement in CRS patients with recurrent polyposis after ESS and further studies are needed. 

In 2018, Kern et al published the pivotal efficacy study for the FDA-approval of the Sinuva® higher dose steroid implant. This was a randomized controlled trial of 300 adults with refractory chronic rhinosinusitis with nasal polyps who were candidates for repeat surgery. Patients were randomized 2:1 to receive the steroid implant versus a sham. Both procedures were performed bilaterally as in-office procedures. The Sinuva® implants were removed at day 60 following implantation to provide blinded grading of the polyps at 90 days. During the 90-day follow-up both treatment and control groups were required to self-administer mometasone furoate (MF) nasal spray 200 mcg once daily. The 2 co-primary efficacy endpoints were the change from baseline to day 30 in nasal obstruction/congestion score, as determined by patients, and change from baseline to day 90 in bilateral polyp grade. NP grading was performed by a panel of 3 sinus surgeons based on a centralized, independent, blinded review of video endoscopies at baseline and day 90 (co-primary end point) and by unblinded clinical investigators during endoscopy at all time points (secondary endpoints) resulting in a total grade on a scale from 0 to 8. Patients receiving implants demonstrated significant reductions in both nasal obstruction/congestion score (p = 0.0074) and bilateral polyp grade (p = 0.0073) compared to control. Therefore, both co-primary efficacy objectives were met. Author noted limitations of this study included: absence of a defined medical regimen prior to enrollment; clinical investigators performing endoscopic grading and assessment of indication for repeat ESS at day 90 were not blinded to the treatment assignment; and the length of the trial was short at 90 days reflecting the time course of drug release from the implant. 

In December 2019 Hayes Inc, a well-known technology assessment organization, published a health technology assessment (HTA) of the Sinuva® implant. The 2023 annual review of this HTA report resulted in no change to the 2019 published HTA findings, quality of evidence and/or conclusions. Studies that enrolled at least 10 patients and were published in English met inclusion criteria for this analysis. Case reports or conference abstracts were not eligible. Three studies meeting eligibility criteria for the evaluation of this device were identified. Study designs included the 2 randomized controlled trials (RCTs) reported above with outcomes reported in 3 publications (Han et al, 2014; Forwith et al, 2016; Kern et al, 2018) and 1 pretest/posttest study (Lavigne et al, 2014) involving 12 patients also described above. All three studies were funded by the manufacturer. 

The overall quality of the body of evidence for the Sinuva® steroid-releasing sinus implant plus daily MF intranasal spray for the treatment of nasal polyps after ESS was rated as low. The evidence was limited largely by a lack of comparative data for the use of Sinuva® implant alone versus alternative treatments, by limited follow-up, and by individual study limitations. Although 2 of the RCTs reported that all patients were blinded during Sinuva® implantation or sham procedure, it is unclear whether patients remained blinded during stent removal. All eligible studies were funded by the manufacturer. In addition, there was significant heterogeneity in which patient-reported assessments were used and inconsistency across studies in efficacy as evaluated by patient-reported outcomes. Finally, some uncertainty remains regarding the safety and long-term benefits associated with the Sinuva® implant. Limitations of individual studies included limited follow-up, lack of investigator blinding, observational rather than experimental design, small sample size, not tracking patient compliance with intranasal steroid spray, baseline differences between groups, and lack of power analyses. 

The technology assessment concluded that the Sinuva® implant plus daily MF intranasal spray may improve symptoms related to disease severity and endoscopic outcomes in addition to reducing the need for additional sinus surgery. However, uncertainty exists due to a limited evidence base and a lack of long-term follow-up. Additional independent studies are required to further establish the safety and effectiveness of the Sinuva® implant, examine long-term need for treatment, and identify optimal patient selection criteria for its use. 

In 2023, the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) issued a position statement on the use of drug-eluting sinus implants for the management of mucosal inflammation of the paranasal sinuses. This statement was not based on a systematic review of the evidence:

"The AAO-HNS considers drug-eluting implants in the paranasal sinuses as a proven and effective therapeutic option for mucosal inflammation." The recommendation states, "Multiple studies have demonstrated the efficacy and safety of drug-eluting implants in controlling sinonasal inflammation. Clinical evidence regarding the use of drug-eluting implants after sinus surgery has particularly shown enhanced wound healing through the reduction of both scar formation and anatomic obstruction."

In 2023, the American Rhinololgic Society (ARS) issued a position statement on the utilization of drug-eluting implants into the sinus cavities. This position statement was not based on a systematic review of the evidence:

"ARS feels strongly that drug-eluting implants should in no way be considered investigational and should be available to patients, when selected by the physician, in order to maximize outcomes." The recommendation notes, "There continues to be a growing level of high-quality evidence on the safety and efficacy of drug-eluting implants in the paranasal sinuses. These studies have demonstrated cost effectiveness as well as improvement of patient centered outcomes by reducing inflammation, maintaining ostial patency, decreasing scarring, and preventing middle turbinate lateralization while limiting the need for administration of oral steroids."

Reference List

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