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Background: Pouchitis occurs in up to 80% of patients after total proctocolectomy (TPC) with ileal pouch-anal anastomosis (IPAA) and has been associated with microbial and host-related immunological factors. We hypothesized that a more robust immune response at the time of colectomy, manifested by acute severe ulcerative colitis (ASUC), may be associated with subsequent acute pouchitis., Methods: This was a retrospective cohort analysis of all patients with UC or indeterminate colitis complicated by medically refractory disease or dysplasia who underwent TPC with IPAA at Mount Sinai Hospital between 2008 and 2017 and at least 1 subsequent pouchoscopy. Acute pouchitis was defined according to the Pouchitis Disease Activity Index. Cox regression was used to assess unadjusted relationships between hypothesized risk factors and acute pouchitis., Results: A total of 416 patients met inclusion criteria. Of the 165 (39.7%) patients who underwent urgent colectomy, 77 (46.7%) were admitted with ASUC. Acute pouchitis occurred in 228 (54.8%) patients a median of 1.3 (interquartile range, 0.6-3.1) years after the final surgical stage. On multivariable analysis, ASUC (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.04-2.17) and a greater number of biologics precolectomy (HR, 1.57; 95% CI, 1.06-2.31) were associated with an increased probability of acute pouchitis, while older age at colectomy (HR, 0.98; 95% CI, 0.97-0.99) was associated with a decreased probability. Time to pouchitis was significantly less in patients admitted with ASUC compared with those not (P = .002)., Conclusion: A severe UC disease phenotype at the time of colectomy was associated with an increased probability of acute pouchitis., (© The Author(s) 2023. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Micronutrient deficiencies may occur after restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis (UC), largely due to malabsorption and/or pouch inflammation., Objectives: The objective of this study was to report the frequency of iron deficiency in patients with UC who underwent RPC with IPAA and identify associated risk factors., Methods: We conducted a retrospective chart review of patients with UC or IBD-unclassified who underwent RPC with IPAA at Mount Sinai Hospital between 2008 and 2017. Patients younger than 18 years of age at the time of colectomy were excluded. Descriptive statistics were used to analyze baseline characteristics. Medians with interquartile range (IQR) were reported for continuous variables, and proportions were reported for categorical variables. Iron deficiency was defined by ferritin <30 ng/mL. Logistic regression was used to analyze unadjusted relationships between hypothesized risk factors and the outcome of iron deficiency., Results: A total of 143 patients had iron studies a median of 3.0 (IQR 1.7-5.6) years after final surgical stage, of whom 73 (51.0%) were men. The median age was 33.5 (IQR 22.7-44.3) years. Iron deficiency was diagnosed in 80 (55.9%) patients with a median hemoglobin of 12.4 g/dL (IQR 10.9-13.3), ferritin of 14 ng/mL (IQR 9.0-23.3), and iron value of 44 μg/dL (IQR 26.0-68.8). Of these, 29 (36.3%) had a pouchoscopy performed within 3 months of iron deficiency diagnosis. Pouchitis and cuffitis were separately noted in 4 (13.8%) and 13 (44.8%) patients, respectively, and concomitant pouchitis-cuffitis was noted in 9 (31.0%) patients. Age, sex, anastomosis type, pouch duration, and history of pouchitis and/or cuffitis were not associated with iron deficiency., Conclusion: Iron deficiency is common after RPC with IPAA in patients with UC. Cuffitis is seen in the majority of patients with iron deficiency; however, iron deficiency may occur even in the absence of inflammation., Competing Interests: The authors have no conflicts of interest to declare., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Background: Despite the initial diagnosis of ulcerative colitis (UC), approximately 10% to 20% of patients develop Crohn's disease-like pouch inflammation (CDLPI) after restorative proctocolectomy (RPC) with ileal pouch anal anastomosis (IPAA). The aim of this study was to evaluate whether early pouchitis, defined as pouchitis within the first year after IPAA, is a predictor of CDLPI., Methods: This was a retrospective cohort analysis of patients with UC or IBD unclassified (IBDU) who underwent RPC with IPAA at Mount Sinai Hospital between January 2008 and December 2017. The primary outcome was development of CDLPI. Predictors of CDLPI were analyzed via univariable and multivariable Cox regression models., Results: The analytic cohort comprised 412 patients who underwent at least 1 pouchoscopy procedure between 2009 and 2018. Crohn's disease-like pouch inflammation developed in 57 (13.8%) patients a median interval of 2.1 (interquartile range, 1.1-4.3) years after surgery. On univariable analysis, older age at colectomy (hazard ratio [HR], 0.97; 95% CI, 0.95-0.99) was associated with a reduced risk of CDLPI; although early pouchitis (HR, 2.43; 95% CI, 1.32-4.45) and a greater number of pouchitis episodes (HR, 1.38; 95% CI, 1.17-1.63) were associated with an increased risk. On multivariable analysis, early pouchitis (HR, 2.35; 95% CI, 1.27-4.34) was significantly associated with CDLPI. Time to CDLPI was significantly less in patients who developed early pouchitis compared with those who did not (P = .003)., Conclusion: Early pouchitis is significantly associated with subsequent CDLPI development and may be the first indication of enhanced mucosal immune activation in the pouch., (© The Author(s) 2022. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Anastomotic leaks remain a dreaded complication after ileal pouch anal anastomosis (IPAA). Their impacts can be devastating, ranging from an acute leak leading to postoperative sepsis to chronic leaks and sinus tracts resulting in long-term pouch dysfunction and subsequent pouch failure. The management of acute leaks is intricate. Initial management is important to resolve acute sepsis, but the type of acute intervention impacts long-term pouch function. Aggressive management in the postoperative period, including the use of IV fluids, broad-spectrum antibiotics, and operative interventions may be necessary to preserve pouch structure and function. Early identification and knowledge of the most common areas of leak, such as at the IPAA anastomosis, are important for guiding management. Long-term complications, such as pouch sinuses, pouch-vaginal fistulas, and diminished IPAA function complicate the overall survival and functionality of the pouch. Knowledge and awareness of the identification and management of leaks is crucial for optimizing IPAA success., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Background: The risk of neoplasia of the pouch or residual rectum in patients with ulcerative colitis (UC) who undergo total proctocolectomy (TPC) with ileal pouch anal anastomosis (IPAA) is incompletely investigated. Thiopurine use is associated with a reduced risk of colorectal neoplasia in patients with UC. We tested the hypothesis that thiopurine use prior to TPC may be associated with a reduced risk of primary neoplasia after IPAA., Methods: We conducted a retrospective cohort analysis of patients from a tertiary referral center from January 2008 to December 2017. Eligible patients with UC or IC underwent TPC with IPAA and had at least two pouchoscopies with biopsies ≥ 6 months after surgery. Propensity score analysis was conducted to match thiopurine exposed vs unexposed groups based on clinical covariates. Multivariable Cox regression analysis estimated the risk of neoplasia., Results: A total of 284 patients with UC or IC (57.4% male, median age 35.6 years) were analyzed. Ninety-seven patients (34.2%) were confirmed to have thiopurine exposure ≥ 12 weeks immediately prior to TPC ("exposed") and 187 (65.8%) were confirmed to have no thiopurine exposure for at least 365 days prior to TPC ("non-exposed"). Compared to non-exposed patients, patients with thiopurine exposure less often had dysplasia (7.2% vs 23.0%, p = 0.001) and had lower grades of dysplasia before colectomy. After IPAA, patients with neoplasia were older (44.0 vs 34.8 years, p = 0.03), more likely to have had dysplasia as colectomy indication (44.4% vs 15.4%, p = 0.007), and more likely to require pouch excision (55.6% vs 10.2%, p < 0.0001), compared to patients without neoplasia. On propensity-matched cohort analysis, no factors were significantly associated with risk of primary neoplasia., Conclusion: Thiopurine exposure for at least the 12 weeks prior to TPC in patients with UC or IC does not appear to be independently associated with risk of primary neoplasia following IPAA., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Despite improvements in medical management, 10%-15% of patients with ulcerative colitis (UC) require total proctocolectomy (TPC) with ileal pouch anal anastomosis (IPAA) for refractory disease. 1 Acute pouchitis is the most common post-IPAA inflammatory condition, with cumulative incidence of 45% at 5 years. 2 Up to 20%-30% of patients develop chronic pouch inflammation (CPI), categorized as antibiotic responsive, antibiotic refractory, or Crohn's disease-like (CDL). 3 ., (Copyright © 2021 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Aim: The purpose of this study is to shed light on a rare complication following ileostomy closure after 3-stage IPAA for further study and discussion., Methods: Our department IPAA database was queried for all patients who underwent 3-stage IPAA creation from 2011 through 2018. Data was reviewed and analyzed using the SPSS application. Chi-square test and Fisher's exact test were used for categorical variables. t test or ANOVA was used for continuous variables. Significance was set at p < 0.05., Results: Three hundred seventy-eight charts were queried. Sixty-eight complications (18.0%) were identified after ileostomy closure. Thirty-seven were small bowel obstruction or partial small bowel obstruction (SBO or pSBO, 9.79%), 5 cases of leak from ileoileostomy anastomosis (7.4%), and 4 cases of leak from pouch (5.9%). There was no significant difference in time between restorative proctocolectomy with IPAA and loop ileostomy closure with cases where a complication occurred and where one did not (p = 0.28). Eight patients developed a SIRS response in the first 5 days after surgery without an identified intraabdominal source after extensive work-up. Of these patients, 87.5% also had negative re-explorations (both open and laparoscopic). None required re-diversion, and all recovered well., Conclusions: While SBO remains the most common complication following ileostomy closure, a surprisingly large number of presents present with a SIRS response with no identifiable source. All of these patients recovered with supportive care, and none required further intervention or diversion. This is a poorly understood phenomenon which is unique to ileostomy closure after IPAA, and further study is required.

Background: Total proctocolectomy (TPC) with ileal pouch anal anastomosis (IPAA) is the gold standard surgery for ulcerative colitis (UC) patients with medically refractory disease. The aim of this study was to report the rates and risk factors of inflammatory pouch conditions., Methods: This was a retrospective review of UC or IBD unspecified (IBDU) patients who underwent TPC with IPAA for refractory disease or dysplasia between 2008 and 2017. Pouchoscopy data were used to calculate rates of inflammatory pouch conditions. Factors associated with outcomes in univariable analysis were investigated in multivariable analysis., Results: Of the 621 patients more than 18 years of age who underwent TPC with IPAA between January 2008 and December 2017, pouchoscopy data were available for 386 patients during a median follow-up period of 4 years. Acute pouchitis occurred in 205 patients (53%), 60 of whom (30%) progressed to chronic pouchitis. Cuffitis and Crohn's disease-like condition (CDLC) of the pouch occurred in 119 (30%) patients and 46 (12%) patients, respectively. In multivariable analysis, female sex was associated with a decreased risk of acute pouchitis, and pre-operative steroid use and medically refractory disease were associated with an increased risk; IBDU was associated with chronic pouchitis; rectal cuff length ≥2 cm and medically refractory disease were associated with cuffitis; age 45-54 at colectomy was associated with CDLC. Rates of pouch failure were similar in chronic pouchitis and CDLC patients treated with biologics and those who were not., Conclusions: Inflammatory pouch conditions are common. Biologic use for chronic pouchitis and CDLC does not impact the rate of pouch failure., (© 2019 Crohn's & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: The true incidence of Clostridioides difficile infection (CDI) in patients with an ileal pouch is unknown, and there is little published on its associated risk factors., Objective: We aimed to evaluate the rate and risk factors of CDI in pouch patients., Methods: This was a retrospective review conducted at a single tertiary care inflammatory bowel disease (IBD) center. All ulcerative colitis or IBD-unspecified (IBD-U) patients who underwent total proctocolectomy with ileal pouch anal anastomosis for medically refractory disease or dysplasia between 2008 and 2017 were identified. Symptomatic patients tested for CDI were included. Demographic, disease, and surgical characteristics were collected. Nonparametric methods were used to compare continuous outcomes, and χ 2 and Fisher's exact tests were used to compare patients with and without CDI as appropriate., Results: A total of 154 pouch patients had postoperative C. difficile stool testing for symptoms of fever, urgency, increased stool frequency, hematochezia, incontinence, and abdominal and/or pelvic pain. CDI was diagnosed in 11 (7.1%) patients a median of 139 days (IQR 34-1,170) after the final surgical stage. Ten patients (90.9%) received oral vancomycin for 10 days and 1 patient (9.1%) received oral metronidazole for 2 weeks. Ten patients (90.9%) reported improvement in symptoms at completion of therapy. Nine patients (81.8%) were retested for CDI for recurrent symptoms and found to be negative. No patient had CDI recurrence. There was no significant difference in demographic and surgical characteristics, previous antibiotic or proton pump inhibitor use, or previous hospital admission among the patients with and without CDI., Conclusions: CDI is a rare cause of infectious pouchitis and treatment with oral vancomycin improves symptoms., Competing Interests: The authors have no relevant conflicts of interest or disclosures., (Copyright © 2020 by S. Karger AG, Basel.)

Background: Ulcerative colitis frequently requires surgery as a definitive management strategy. The colonic specimen can be extracted from various sites including a midline incision, the stoma site, or a Pfannenstiel incision. It is unclear if one extraction site offers improved outcomes and fewer complications., Methods: A retrospective review of charts obtained of colorectal surgery patients was conducted for all patients with ulcerative colitis who underwent a subtotal colectomy between 2008 and 2016 at a single tertiary care institution. Demographic data and outcomes data including parastomal and incisional hernias, advanced wound/ostomy certified nurse referrals, surgical site infections, reoperations, and readmissions were collected. Univariate and multivariate analyses were completed to detect any significant differences in outcomes between groups based on extraction site (midline incision, stoma site, or Pfannenstiel incision)., Results: Univariate analysis did not show any statistical differences between groups in regard to outcomes. Stoma site extraction did not statistically differ from midline extraction in regard to hernias, advanced ostomy referrals, infections, or reoperations, but midline incision extraction did have a lower risk of readmission (OR = 0.56, p = 0.0066). Pfannenstiel extraction had lower risk of incisional hernias (OR = 0.25, p = 0.0002), advanced ostomy referrals (OR = 0.45, p = 0.0164) and readmission (OR = 0.26, p < 0.0001) as compared to stoma site extraction., Conclusions: While stoma site extraction can be successfully performed for most patients requiring subtotal colectomy for ulcerative colitis, Pfannenstiel extraction leads to the fewest number of complications and provides the most consistent results.

Background: Portomesenteric venous thrombosis (PMVT) is an under-recognized complication of colorectal surgery. The aim of this study was to describe the rate and risk factors for PMVT in patients undergoing surgery for medically refractory ulcerative colitis (UC)., Methods: A retrospective review of medically refractory UC patients who underwent surgery between January 2010 and December 2016 at a single tertiary care center was conducted. PMVT was defined as thrombus within the portal, splenic, superior, or inferior mesenteric vein on postoperative abdominal computed tomography scans. Factors associated with PMVT on univariable analysis were tested in multivariable analysis. Clinical relevance of risk factors was examined with receiver operating characteristic curves and Kaplan-Meier curves., Results: A total of 434 patients were identified. Postoperative venous thromboembolism (VTE) prophylaxis was administered to 428 (98.5%) inpatients for a mean duration of 7.7 ± 0.17 days. PMVT developed in 36 (8.3%) patients a mean interval of 55.3 ± 10.8 days after index surgery. The majority of PMVT occurred after subtotal colectomy, and the most common initial symptom was abdominal pain. Preoperative C-reactive protein (CRP) was associated with PMVT (odds ratio, 1.01; 95% confidence interval, 1.00-1.02; P = 0.01), and the optimal predictive CRP threshold was 45 mg/L. The rate of PMVT development was greater for patients with CRP >45 mg/L (P = 0.01)., Conclusions: PMVT can present as abdominal pain and occur multiple weeks after discharge. Further studies are needed to identify the appropriate postoperative outpatient thrombosis prophylaxis regimen for at-risk patients., (© 2019 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The significance of endoscopic activity in asymptomatic ulcerative colitis (UC) patients with an ileal pouch is unknown., Aim: To investigate the association of endoscopic pouch activity in asymptomatic patients with the subsequent development of pouchitis., Methods: We analyzed a retrospective cohort of patients with UC or IBD-unspecified who underwent a total proctocolectomy with ileal pouch anal anastomosis (IPAA). Asymptomatic patients with a Pouchitis Disease Activity Index (PDAI) symptom sub-score of zero who underwent an index surveillance pouchoscopy were included. Endoscopic pouch body activity was graded as 0: normal, 1: mucosal inflammation, or 2: mucosal breaks (ulcers and/or erosions). The primary outcome was primary acute idiopathic pouchitis defined as PDAI score ≥ 7 with symptoms lasting less than four weeks and responsive to standard antibiotics, not otherwise meeting criteria for secondary pouchitis. The secondary outcome was chronic idiopathic pouchitis defined as PDAI score ≥ 7 with symptoms lasting greater than four weeks despite standard antibiotics. Predictors of pouchitis were analyzed using Kaplan-Meier and Cox regression methods with hazard ratios (HR) and 95% confidence intervals (CI) reported., Results: 143 asymptomatic pouch patients were included. Index endoscopic pouch body activity was 0 in 86 (60.1%) patients, 1 in 26 (18.2%) and 2 in 31 (21.7%). The median length of follow-up after index surveillance pouchoscopy was 3.03 [IQR 1.24-4.60] years. Primary acute idiopathic pouchitis occurred in 44 (31%) patients and chronic idiopathic pouchitis in 12 (8.4%). Grade 2 endoscopic pouch activity was associated with the development of acute pouchitis (HR 2.39, 95% CI 1.23-4.67), although not chronic pouchitis (HR 1.76, 95% CI 0.53-5.87). Histologic inflammation in endoscopically normal pouch mucosa was not associated with acute or chronic pouchitis., Conclusions: Mucosal breaks are present in nearly a quarter of asymptomatic patients with IPAA and are associated with an increased risk of acute pouchitis., (© 2019 John Wiley & Sons Ltd.)

Background: Surgical treatment of ileosigmoid fistulas in Crohn's disease is poorly characterized., Objective: The purpose of this study was to identify differences in patient postoperative outcomes for isolated ileosigmoid fistulas by surgical approach (laparoscopic versus open) and sigmoid colon repair type (sigmoid resection versus primary repair)., Design: Using a prospectively collected database, we gathered perioperative data from chart reviews to calculate differences and associations between treatment groups., Settings: The study was conducted at a single tertiary care center., Patients: Patients with Crohn's disease who underwent surgery for isolated ileosigmoid fistulas between July 1, 2010, and June 30, 2016 were included., Results: We identified 84 patients, with an average age of 37 years. A total of 51 were men and 33 were women; 34 underwent a sigmoid resection, whereas 50 had a primary repair of the sigmoid. All of the patients underwent an ileocolic resection. A total of 67 surgeries were initially attempted laparoscopically, of which 17 (25.4%) were converted to open, with 50 (59.5%) completed laparoscopically. There were no significant differences in length of stay or incidence of postoperative complications by surgical approach (laparoscopic versus open). For patients who underwent a primary sigmoid repair versus a sigmoid resection, there were no significant differences in postoperative complications, but there was a significant difference in the length of stay (6.36 vs 9.56 d for primary repair versus resection; multivariate p value of 0.022)., Main Outcome Measures: Postoperative complications and length of stay were measured., Limitations: The study was limited by its small sample size, cross-sectional nature of the data, and limited information about preoperative outpatient medical treatment., Conclusions: Laparoscopic surgery for isolated ileosigmoid fistulas in Crohn's disease is safe and does not result in a different length of stay or incidence of postoperative complications. Primary repair (rather than resection) of the sigmoid colon in these cases, when feasible, appears to be safe and is likely to be cost-effective given the reduced length of stay. See Video Abstract at http://links.lww.com/DCR/A993. TÉCNICAS QUIRÚRGICAS Y DIFERENCIAS EN LOS RESULTADOS POSTOPERATORIOS PARA LOS PACIENTES CON ENFERMEDAD DE CROHN CON FÍSTULAS ILEO-SIGMOIDEAS: UNA EXPERIENCIA EN UNA SOLA INSTITUCIÓN, 2010-2016: El tratamiento quirúrgico de las fístulas ileo-sigmoideas en la enfermedad de Crohn está mal caracterizado., Objetivo: Identificar las diferencias en los resultados postoperatorios de los pacientes para las fístulas ileo-sigmoideas aisladas por abordaje quirúrgico (laparoscópica versus abierta) y tipo de reparación de colon sigmoide (resección sigmoidea versus reparación primaria). DISEÑO:: Utilizando una base de datos recopilada de forma prospectiva, se recopilaron datos perioperatorios de las revisiones de los gráficos para calcular las diferencias y las asociaciones entre los grupos de tratamiento., Ajuste: Un solo centro de atención terciaria., Pacientes: Pacientes con enfermedad de Crohn que se sometieron a una cirugía para fístulas ileo-sigmoideas aisladas entre el 1 de julio de 2010 y el 30 de junio de 2016., Resultados: Se identificaron 84 pacientes, con una edad promedio de 37 años. Un total de 51 eran hombres y 33 mujeres; 34 se sometieron a una resección sigmoidea, mientras que 50 tuvieron una reparación primaria del sigmoide. Todos los pacientes fueron sometidos a resección ileocólica. Inicialmente, un total de 67 círugias se intentaron por vía laparoscópica, de las cuales 17 (25,4%) se convirtieron en cirugías abiertas, y 50 (59,5%) se completaron por vía laparoscópica. No hubo diferencias significativas en la duración de la estancia o la incidencia de complicaciones postoperatorias por abordaje quirúrgico (laparoscópica versus abierta). Para los pacientes que se sometieron a una reparación sigmoidea primaria versus una resección sigmoidea, no hubo diferencias significativas en las complicaciones postoperatorias, pero sí hubo una diferencia significativa en la duración de la estancia hospitalaria (6,36 versus a 9,56 días para la reparación primaria frente a la resección; p multivariable -valor de 0.022)., Principales Medidas De Resultados: Complicaciones postoperatorias y duración de la estancia., Limitaciones: Tamaño de muestra pequeño, naturaleza transversal de los datos e información limitada sobre el tratamiento médico ambulatorio preoperatorio del paciente., Conclusiones: La cirugía laparoscópica para fístulas ileo-sigmoideas aisladas en la enfermedad de Crohn es segura y no ocasiona una duración diferente de la estancia hospitalaria ni una incidencia diferente de complicaciones postoperatorias. La reparación primaria (en lugar de la resección) del colon sigmoide en estos casos, cuando es posible, parece ser segura y es probable que sea rentable, dada la duración reducida de la estancia. Vea el Resumen del Video en http://links.lww.com/DCR/A993.

Rationale: Obstructive sleep apnea (OSA) is associated with recurrent obstruction, subepithelial edema, and airway inflammation. The resultant inflammation may influence or be influenced by the nasal microbiome., Objectives: To evaluate whether the composition of the nasal microbiota is associated with obstructive sleep apnea and inflammatory biomarkers., Methods: Two large cohorts were used: 1) a discovery cohort of 472 subjects from the WTCSNORE (Seated, Supine and Post-Decongestion Nasal Resistance in World Trade Center Rescue and Recovery Workers) cohort, and 2) a validation cohort of 93 subjects rom the Zaragoza Sleep cohort. Sleep apnea was diagnosed using home sleep tests. Nasal lavages were obtained from cohort subjects to measure: 1) microbiome composition (based on 16S rRNA gene sequencing), and 2) biomarkers for inflammation (inflammatory cells, IL-8, and IL-6). Longitudinal 3-month samples were obtained in the validation cohort, including after continuous positive airway pressure treatment when indicated., Measurements and Main Results: In both cohorts, we identified that: 1) severity of OSA correlated with differences in microbiome diversity and composition; 2) the nasal microbiome of subjects with severe OSA were enriched with Streptococcus, Prevotella, and Veillonella; and 3) the nasal microbiome differences were associated with inflammatory biomarkers. Network analysis identified clusters of cooccurring microbes that defined communities. Several common oral commensals (e.g., Streptococcus, Rothia, Veillonella, and Fusobacterium) correlated with apnea-hypopnea index. Three months of treatment with continuous positive airway pressure did not change the composition of the nasal microbiota., Conclusions: We demonstrate that the presence of an altered microbiome in severe OSA is associated with inflammatory markers. Further experimental approaches to explore causal links are needed.