SNOT-22 subdomain outcomes following treatment for sinonasal malignancy: A prospective, multicenter study.

BACKGROUND: Patients with sinonasal malignancy (SNM) present with significant sinonasal quality of life (QOL) impairment. Global sinonasal QOL as measured by the 22-item Sinonasal Outcomes Test (SNOT-22) has been shown to improve with treatment. This study aims to characterize SNOT-22 subdomain outcomes in SNM. METHODS: Patients diagnosed with SNM were prospectively enrolled in a multi-center patient registry. SNOT-22 scores were collected at the time of diagnosis and through the post-treatment period for up to 5 years. Multivariable regression analysis was used to identify drivers of variation in SNOT-22 subdomains. RESULTS: Note that 234 patients were reviewed, with a mean follow-up of 22 months (3 months-64 months). Rhinologic, psychological, and sleep subdomains significantly improved versus baseline (all p < 0.05). Subanalysis of 40 patients with follow-up at all timepoints showed statistically significant improvement in rhinologic, extra-nasal, psychological, and sleep subdomains, with minimal clinically important difference met between 2 and 5 years in sleep and psychological subdomains. Adjuvant chemoradiation was associated with worse outcomes in rhinologic (adjusted odds ratio (5.22 [1.69-8.66])), extra-nasal (2.21 [0.22-4.17]) and ear/facial (5.53 [2.10-8.91]) subdomains. Pterygopalatine fossa involvement was associated with worse outcomes in rhinologic (3.22 [0.54-5.93]) and ear/facial (2.97 [0.32-5.65]) subdomains. Positive margins (5.74 [2.17-9.29]) and surgical approach-combined versus endoscopic (3.41 [0.78-6.05])-were associated with worse psychological outcomes. Adjuvant radiation (2.28 [0.18-4.40]) was associated with worse sleep outcomes. CONCLUSIONS: Sinonasal QOL improvements associated with treatment of SNM are driven by rhinologic, extra-nasal, psychological, and sleep subdomains.

Does Extended Reality Simulation Improve Surgical/Procedural Learning and Patient Outcomes When Compared With Standard Training Methods?: A Systematic Review.

INTRODUCTION: The use of extended reality (XR) technologies, including virtual, augmented, and mixed reality, has increased within surgical and procedural training programs. Few studies have assessed experiential learning- and patient-based outcomes using XR compared with standard training methods. METHODS: As a working group for the Society for Simulation in Healthcare, we used Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and a PICO strategy to perform a systematic review of 4238 articles to assess the effectiveness of XR technologies compared with standard training methods. Outcomes were grouped into knowledge, time-to-completion, technical proficiency, reactions, and patient outcomes. Because of study heterogeneity, a meta-analysis was not feasible. RESULTS: Thirty-two studies met eligibility criteria: 18 randomized controlled trials, 7 comparative studies, and 7 systematic reviews. Outcomes of most studies included Kirkpatrick levels of evidence I-III (reactions, knowledge, and behavior), while few reported level IV outcomes (patient). The overall risk of bias was low. With few exceptions, included studies showed XR technology to be more effective than standard training methods in improving objective skills and performance, shortening procedure time, and receiving more positive learner ratings. However, XR use did not show significant differences in gained knowledge. CONCLUSIONS: Surgical or procedural XR training may improve technical skill development among trainees and is generally favored over standard training methods. However, there should be an additional focus on how skill development translates to clinically relevant outcomes. We recommend longitudinal studies to examine retention and transfer of training to clinical settings, methods to improve timely, adaptive feedback for deliberate practice, and cost analyses.

Predictive factors for decreased baseline quality of life in patients with sinonasal malignancies.

BACKGROUND: The impact of sinonasal malignancies (SNMs) on quality of life (QOL) at presentation is poorly understood. The Sinonasal Outcome Test (SNOT-22) and University of Washington Quality of Life (UWQOL) are validated QOL instruments with distinctive subdomains. This study aims to identify factors impacting pretreatment QOL in SNM patients to personalize multidisciplinary management and counseling. METHODS: Patients with previously untreated SNMs were prospectively enrolled (2015-2022) in a multicenter observational study. Baseline pretreatment QOL instruments (SNOT-22, UWQOL) were obtained along with demographics, comorbidities, histopathology/staging, tumor involvement, and symptoms. Multivariable regression models identified factors associated with reduced baseline QOL. RESULTS: Among 204 patients, presenting baseline QOL was significantly reduced. Multivariable regression showed worse total SNOT-22 QOL in patients with skull base erosion (p = 0.02). SNOT-rhinologic QOL was worse in women (p = 0.009), patients with epistaxis (p = 0.036), and industrial exposure (p = 0.005). SNOT extranasal QOL was worse in patients with industrial exposure (p = 0.016); worse SNOT ear/facial QOL if perineural invasion (PNI) (p = 0.027). Squamous cell carcinoma pathology (p = 0.037), palate involvement (p = 0.012), and pain (p = 0.017) were associated with worse SNOT sleep QOL scores. SNOT psychological subdomain scores were significantly worse in patients with palate lesions (p = 0.022), skull base erosion (p = 0.025), and T1 staging (p = 0.023). Low QOL was more likely in the presence of PNI on UW health (p = 0.019) and orbital erosion on UW overall (p = 0.03). UW social QOL was worse if palatal involvement (p = 0.023) or PNI (p = 0.005). CONCLUSIONS: Our findings demonstrate a negative impact on baseline QOL in patients with SNMs and suggest sex-specific and symptom-related lower QOL scores, with minimal histopathology association. Anatomical tumor involvement may be more reflective of QOL than T-staging, as orbital and skull base erosion, PNI, and palate lesions are significantly associated with reduced baseline QOL.

Viral infections and chronic rhinosinusitis.

Viral infections are the most common cause of upper respiratory infections; they frequently infect adults once or twice and children 6 to 8 times annually. In most cases, these infections are self-limiting and resolve. However, many patients with chronic rhinosinusitis (CRS) relay that their initiating event began with an upper respiratory infection that progressed in both symptom severity and duration. Viruses bind to sinonasal epithelia through specific receptors, thereby entering cells and replicating within them. Viral infections stimulate interferon-mediated innate immune responses. Recent studies suggest that viral infections may also induce type 2 immune responses and stimulate the aberrant production of cytokines that can result in loss of barrier function, which is a hallmark in CRS. The main purpose of this review will be to highlight common viruses and their associated binding receptors and highlight pathophysiologic mechanisms associated with alterations in mucociliary clearance, epithelial barrier function, and dysfunctional immune responses that might lead to a further understanding of the pathogenesis of CRS.

Recurrence patterns among patients with sinonasal mucosal melanoma: A multi-institutional study.

OBJECTIVE: To evaluate recurrence patterns and survival after recurrence among patients with sinonasal mucosal melanoma (SNMM). METHODS: This was a multi-institutional retrospective review from seven U.S. institutions of patients with SNMM from 1991 to 2022. Recurrence was categorized as local, regional, distant, or multifocal. Kaplan-Meier tests were used to evaluate disease-free survival (DFS), overall survival (OS), and post-recurrence survival (PRS) reported with standard errors (SE) and log-rank testing used for comparison. Cox-regression was further used, with hazard ratios (HR) and 95% confidence intervals (CI) reported. RESULTS: Among 196 patients with SNMM, there were 146 patients with recurrence (74.5%). Among all patients, 60-month DFS (SE) was 15.5% (2.9%), 60-month OS (SE) was 44.7% (3.7%), mean age ± standard deviation at diagnosis was 69.7 ± 12.5 years, and 54.6% were female. In 26 patients who underwent primary treatment of the neck, 60-month DFS did not differ from no treatment (p > 0.05). Isolated distant recurrence was most common (42.8%), followed by local (28.3%), multifocal (20.7%), and regional recurrence (8.3%). Among patients with regional recurrence in the neck, there was no 60-month PRS benefit for patients undergoing salvage neck dissection or radiation (p > 0.05). Among patients with distant recurrence, only immunotherapy was associated with improved 12-month PRS (HR = 0.32, 95% CI = 0.11-0.92, p = 0.034), and no treatment group was associated with improved 24- or 60-month PRS (p > 0.05). CONCLUSION: SNMM is associated with a high recurrence rate and poor survival. Primary treatment of the neck was not associated with reduced recurrence, and immunotherapy for treatment of distant recurrence was associated with increased 12-month PRS.

Long-term quality of life after treatment in sinonasal malignancy: A prospective, multicenter study.

BACKGROUND: Quality of life (QOL) for individuals with sinonasal malignancy (SNM) is significantly under-studied, yet it is critical for counseling and may impact treatment. In this study we evaluated how patient, treatment, and disease factors impact sinonasal-specific and generalized QOL using validated metrics in a large cohort over a 5-year posttreatment time frame. METHODS: Patients with SNM who underwent definitive treatment with curative intent were enrolled in a prospective, multisite, longitudinal observational study. QOL was assessed using the 22-item Sino-Nasal Outcome Test (SNOT-22) and University of Washington Quality of Life Questionnaire (UWQOL) instruments at pretreatment baseline and multiple follow-ups through 5 years posttreatment. Multivariable modeling was used to determine demographic, disease, and treatment factors associated with disease-specific and generalized physical and social/emotional function QOL. RESULTS: One hundred ninety-four patients with SNM were analyzed. All QOL indices were impaired at pretreatment baseline and improved after treatment. SNOT-22 scores improved 3 months and UWQOL scores improved 6 to 9 months posttreatment. Patients who underwent open compared with endoscopic tumor resection had worse generalized QOL (p < 0.001), adjusted for factors including T stage. Pterygopalatine fossa (PPF) involvement was associated with worse QOL (SNOT-22, p < 0.001; UWQOL Physical dimension, p = 0.02). Adjuvant radiation was associated with worse disease-specific QOL (p = 0.03). Neck dissection was associated with worse generalized physical function QOL (p = 0.01). Positive margins were associated with worse generalized social/emotional function QOL (p = 0.01). CONCLUSION: Disease-specific and generalized QOL is impaired at baseline in patients with SNM and improves after treatment. Endoscopic resection is associated with better QOL. PPF involvement, adjuvant radiation, neck dissection, and positive margins were associated with worse QOL posttreatment.

The Role of Viruses in the Inception of Chronic Rhinosinusitis.

Chronic rhinosinusitis (CRS) is a complex inflammatory disorder that affects between 2% and 16% of adults in the United States, with estimated healthcare costs between 4 and 12 million USD. Viruses are a common etiologic factor for URIs, are frequently identified in the sinuses of patients with CRS, and trigger CRS exacerbations. Therefore, investigating the role of viruses provides an opportunity to identify their role in the pathogenesis of CRS. In this review, we identified the viruses frequently isolated in patients with CRS, as well as their associated immunologic responses and contributions to inflammation. Rhinovirus, parainfluenza virus, influenza virus, and respiratory syncytial virus are the viruses commonly found in patients with CRS. This information allows us to target pathways early in the pathogenesis of CRS, thereby playing a significant role in slowing the progression of this chronic disease.

Epithelial cell responses to rhinovirus identify an early-life-onset asthma phenotype in adults.

BACKGROUND: The study of pathogenic mechanisms in adult asthma is often marred by a lack of precise information about the natural history of the disease. Children who have persistent wheezing (PW) during the first 6 years of life and whose symptoms start before age 3 years (PW+) are much more likely to have wheezing illnesses due to rhinovirus (RV) in infancy and to have asthma into adult life than are those who do not have PW (PW-). OBJECTIVE: Our aim was to determine whether nasal epithelial cells from PW+ asthmatic adults as compared with cells from PW- asthmatic adults show distinct biomechanistic processes activated by RV exposure. METHODS: Air-liquid interface cultures derived from nasal epithelial cells of 36-year old participants with active asthma with and without a history of PW in childhood (10 PW+ participants and 20 PW- participants) from the Tucson Children's Respiratory Study were challenged with a human RV-A strain (RV-A16) or control, and their RNA was sequenced. RESULTS: A total of 35 differentially expressed genes involved in extracellular remodeling and angiogenesis distinguished the PW+ group from the PW- group at baseline and after RV-A stimulation. Notably, 22 transcriptomic pathways showed PW-by-RV interactions; the pathways were invariably overactivated in PW+ patients, and were involved in Toll-like receptor- and cytokine-mediated responses, remodeling, and angiogenic processes. CONCLUSIONS: Asthmatic adults with a history of persistent wheeze in the first 6 years of life have specific biomolecular alterations in response to RV-A that are not present in patients without such a history. Targeting these mechanisms may slow the progression of asthma in these patients.

The GSDMB rs7216389 SNP is associated with chronic rhinosinusitis in a multi-institutional cohort.

BACKGROUND: Chronic rhinosinusitis (CRS) is a multifactorial disease with a high co-occurrence with asthma. In this multicohort study, we tested whether single nucleotide polymorphisms (SNPs) associated with childhood asthma and rhinovirus (RV)-associated disease are related to an increased susceptibility to adult CRS in a multicohort retrospective case-control study. METHODS: Participants at two tertiary academic rhinology centers, University of Arizona (UofA) and University of Pennsylvania (UPenn) were recruited. Cases were defined as those with physician diagnosed CRS (UofA, n = 149; UPenn, n = 250), and healthy controls were those without CRS (UofA, n = 66; UPenn, n = 275). Genomic DNA was screened for the GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP. Gene dosage, or the number of combined risk alleles in a single subject was calculated. Meta-analysis of the association between GSDMB or CDHR3 genotypes and CRS was performed and additive gene dosage effect for each population calculated using p for trend. RESULTS: A meta-analysis revealed a combined increased risk for CRS in subjects with the GSDMB rs7216389 SNP (odds ratio [OR] 1.40; 95% confidence interval [CI], 1.16-1.76; p = 0.004). Both the UofA (OR 1.73; 95% CI, 1.23-2.43; p = 0.002) and UPenn (OR 1.27; 95% CI, 1.02-1.58; p = 0.035) populations showed a significant positive association between the number of combined risk alleles of GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP and risk for CRS. CONCLUSION: Carriers of the GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP are at increased susceptibility for CRS. These data suggest that therapeutic approaches to target aberrant responses to RV infection may play a role in the treatment of unified airway disease.

Surgical approach is associated with complication rate in sinonasal malignancy: A multicenter study.

BACKGROUND: Management of sinonasal malignancy (SNM) often includes surgical resection as part of the multimodality treatment. Treatment-related surgical morbidity can occur, yet risk factors associated with complications in this population have not been sufficiently investigated. METHODS: Adult patients with histologically confirmed SNM whose primary treatment included surgical resection were prospectively enrolled into an observational, multi-institutional cohort study from 2015 to 2020. Sociodemographic, disease, and treatment data were collected. Complications assessed included cerebrospinal fluid leak, orbital injury, intracranial injury, diplopia, meningitis, osteoradionecrosis, hospitalization for neutropenia, and subsequent chronic rhinosinusitis. The surgical approach was categorized as endoscopic resection (ER) or open/combined resection (O/CR). Associations between factors and complications were analyzed using Student's t test, Fisher's exact test, and logistic regression modeling. RESULTS: Overall, 142 patients met the inclusion criteria. Twenty-three subjects had at least 1 complication (16.2%). On unadjusted analysis, adjuvant radiation therapy was associated with developing a complication (91.3% vs 65.5%, p = 0.013). Compared with the ER group (n = 98), the O/CR group (n = 44) had a greater percentage of higher T-stage lesions (p = 0.004) and more frequently received adjuvant radiation (84.1% vs 64.4%, p = 0.017) and chemotherapy (50.0% vs 30.6%, p = 0.038). Complication rates were similar between the ER and O/CR groups without controlling for other factors. Regression analysis that retained certain factors showed O/CR was associated with increased odds of experiencing a complication (odds ratio, 3.34; 95% confidence interval, 1.06-11.19). CONCLUSIONS: Prospective, multicenter evaluation of SNM treatment outcomes is feasible. Undergoing O/CR was associated with increased odds of developing a complication after accounting for radiation therapy. Further studies are warranted to build upon these findings.

Development of a self-directed sinonasal surgical anatomy video curriculum: Phase 1 validation.

BACKGROUND: Sinusitis is a common outpatient diagnosis made by physicians and is a reason for referral to otolaryngologists. A foundation in basic sinonasal anatomy is critical in understanding sinus pathophysiology and avoiding complications. Our objective in this study was to develop and to validate a self-directed surgical anatomy video for medical students. METHODS: Two multimedia videos were developed highlighting sinonasal anatomy. In Video 1 we included audio narration and radiologic imaging. Video 2 incorporated highlighted images from a sinus surgery video. An assessment was developed to test sinonasal anatomy landmarks, spatial recognition of structures, and their clinical relevance. An expert panel of rhinologists scored face and content validity of the curriculum videos and assessment. Factor analysis was used to separate questions into face and content validity domains, and a one-sample t test was performed. RESULTS: The panel scored face validity (Videos 1 and 2: 4.4/5) and content validity (Video 1: 4.5/5, 0.83; Video 2: 4.3/5, 0.75) significantly higher than a neutral response. There were no statistical differences for face or content validity between videos. The assessment was rated suitable (29%) or very suitable (57%) for testing basic sinonasal surgical anatomy, and the majority (71%) of respondents agreed (14%) or strongly agreed (57%) that the assessment thoroughly covered the sinus anatomy content with which medical students should be familiar. CONCLUSION: We have developed two videos and an assessment that highlight and test sinonasal anatomy. Future studies will aim to identify whether the use of a self-directed video curriculum improves sinonasal anatomy awareness and whether incorporation of surgical endoscopic videos augments training.

International consensus statement on allergy and rhinology: rhinosinusitis 2021.

I. EXECUTIVE SUMMARY: BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document. METHODS: ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. RESULTS: ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided. CONCLUSION: This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

MUC1 contributes to goblet cell metaplasia and MUC5AC expression in response to cigarette smoke in vivo.

Goblet cell metaplasia (GCM) and mucin overproduction are a hallmark of chronic rhinosinusitis (CRS) and chronic obstructive pulmonary disease (COPD). In the airways, cigarette smoke (CS) induces activation of the epidermal growth factor receptor (EGFR) leading to GCM and overexpression of the gel-forming mucin MUC5AC. Although previous studies have demonstrated that a membrane-bound mucin, MUC1, modulates the activation of CS-induced EGFR, the role of MUC1 in CS-induced GCM and mucin overproduction has not been explored. In response to CS exposure, wild-type (WT) rats displayed Muc1 translocation from the apical surface of airway epithelium to the intracellular compartment of hyperplastic intermediate cells, EGFR phosphorylation, GCM, and Muc5ac overproduction. Similarly, human CRS sinonasal tissues demonstrated hyperplasia of intermediate cells enriched with MUC1 in the intracellular compartment, which was accompanied by GCM and increased MUC5AC expression. To further evaluate the role of Muc1 in vivo, a Muc1 knockout (KO) rat (MUC in humans and Muc in animals) was developed. In contrast to WT littermates, Muc1-KO rats exhibited no activation of EGFR, and were protected from GCM and Muc5ac overproduction. Genetic knockdown of MUC1 in human lung or Muc1 knockout in primary rat airway epithelial cells led to significantly diminished EGF-induced MUC5AC production. Together, these findings suggest that MUC1-dependent EGFR activation mediates CS-induced GCM and mucin overproduction. Strategies designed to suppress MUC1-dependent EGFR activation may provide a novel therapeutic approach for treating mucin hypersecretion in CRS and COPD.

Virtual coach: the next tool in functional endoscopic sinus surgery education.

BACKGOUND: Functional endoscopic sinus surgery (FESS) can be challenging as novices become accustomed to handling endoscopes and instruments while navigating complex sinonasal anatomy. Experts demonstrate fluid and efficient motions when addressing pathology. The training process from novice to expert relies on hands-on experience in cadaveric laboratories and preceptorship models that require significant time and expense. This study aims to validate the use of a virtual coach to guide users step-by-step through a basic FESS. METHODS: Seventeen surgeons were grouped into novice (n = 10) and expert (n = 7) based on self-reported levels of surgical experience. Users were trained using the maxillary antrostomy module in the Neurorhinological Surgery (NRS) simulator combining the physical craniofacial model with virtual reality (VR)-tracked surgical instruments in the VR operating room. The virtual coach guided the user using surgical videos, auditory, and visual cues. The coach recorded data for each subject including the number of times borders of the nasal cavity were encountered and time to completion. Users graded the usefulness of the virtual coach on a Likert questionnaire. RESULTS: Face validity of our NRS simulator was replicated by user questionnaires, and construct validity replicated by differentiation between novice and expert level surgeons (p < 0.01). Novices contacted a significantly higher number of anatomic borders (n = 17) and had a longer operative time (t = 370 seconds). All users reported high scores on the benefit and usefulness of the virtual coach. CONCLUSION: The virtual coach provides a useful tool to enhance FESS education by providing objective real-time data in a novel mixed-reality surgical environment.

High-Efficiency, Selection-free Gene Repair in Airway Stem Cells from Cystic Fibrosis Patients Rescues CFTR Function in Differentiated Epithelia.

Cystic fibrosis (CF) is a monogenic disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. Mortality in CF patients is mostly due to respiratory sequelae. Challenges with gene delivery have limited attempts to treat CF using in vivo gene therapy, and low correction levels have hindered ex vivo gene therapy efforts. We have used Cas9 and adeno-associated virus 6 to correct the ΔF508 mutation in readily accessible upper-airway basal stem cells (UABCs) obtained from CF patients. On average, we achieved 30%-50% allelic correction in UABCs and bronchial epithelial cells (HBECs) from 10 CF patients and observed 20%-50% CFTR function relative to non-CF controls in differentiated epithelia. Furthermore, we successfully embedded the corrected UABCs on an FDA-approved porcine small intestinal submucosal membrane (pSIS), and they retained differentiation capacity. This study supports further development of genetically corrected autologous airway stem cell transplant as a treatment for CF.

Are rhinoviruses implicated in the pathogenesis of sinusitis and chronic rhinosinusitis exacerbations? A comprehensive review.

BACKGROUND: Rhinovirus (RV) infections are the most common cause of viral upper respiratory infections (URIs), and in the majority of persons they are self-limiting. However, in others, viral URIs can progress to bacterial sinusitis and induce chronic rhinosinusitis (CRS) exacerbations. METHODS: We conducted a comprehensive Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) review through April 2018 based on MEDLINE, EMBASE, Web of Science-Science Citation Index (SCI), and Conference Proceedings Citation Index- Science (CPCI-S) using keywords: RV, respiratory virus, sinusitis, and airway epithelial cells. The goal of this systematic review was to: (1) determine the prevalence between RV and CRS, (2) study the changes that occur after experimental RV inoculation, (3) investigate the pathophysiologic mechanisms by which RV induces sinonasal inflammation, and (4) explore the treatment options available for RV-associated sinusitis. Data regarding study design, research question, intervention, subjects, outcomes, and biases was extracted. RESULTS: The initial search yielded 2395 unique abstracts, of which 614 were selected for full-text review; 147 were included in the final review. We determined that (1) the prevalence of RV infections is increased in those with CRS, (2) humans challenged in vivo with RV secrete local inflammatory mediators with radiographic mucosal thickening, (3) RV species RV-A and RV-C challenges in vitro to sinonasal epithelia produce robust cytokine responses and differential gene changes, and (4) no current therapies have produced consistent and significant resolution of disease. CONCLUSION: RV infections are common in persons with CRS, and incite inflammatory reactions that may result in CRS exacerbations and progression of disease. Further studies assessing RV species, and the host-virome response are required to develop new strategies targeting RV-induced CRS.