Chronic rhinosinusitis (CRS) is a common, heterogeneous inflammatory disorder of the sinonasal mucosa characterized by persistent symptoms lasting for more than 12 weeks, including nasal obstruction, nasal discharge, facial pressure, and reduction or loss of smell. It represents a significant global health burden due to its chronic nature, impact on quality of life (QoL), reduced productivity, and substantial healthcare utilization. CRS is broadly classified into chronic rhinosinusitis without nasal polyps (CRSsNP) and chronic rhinosinusitis with nasal polyps (CRSwNP), although current concepts recognize CRS as a spectrum of inflammatory endotypes influenced by immune pathways, environmental factors, microbial interactions, and host susceptibility [1]. The European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS 2020) emphasized the importance of individualized assessment and integrated management strategies because CRS demonstrates considerable variation in clinical presentation, disease severity, and treatment response among affected

individuals [2].

The initial management of CRS primarily involves optimized medical therapy, including saline irrigation, intranasal corticosteroids, short courses of systemic corticosteroids in selected patients, and management of associated allergic or inflammatory conditions. However, a considerable proportion of patients remain symptomatic despite adequate medical treatment and subsequently require surgical intervention [2]. Functional Endoscopic Sinus Surgery (FESS) has become the preferred surgical approach for medically refractory CRS because of its minimally invasive nature, preservation of normal anatomy, and ability to restore sinus ventilation and drainage pathways. The fundamental objective of FESS is not complete removal of sinus mucosa but rather correction of anatomical obstruction, improvement of mucociliary clearance, and enhancement of topical medication delivery to diseased areas [3].

Although FESS provides significant symptomatic improvement and improved disease-specific quality of life in most patients, postoperative outcomes remain variable. Some patients experience substantial and sustained improvement, whereas others develop persistent symptoms, recurrent disease, or require revision surgery. Previous studies have demonstrated that patient-reported outcomes measured using validated instruments such as the 22-item Sino-Nasal Outcome Test (SNOT-22) significantly improve after endoscopic sinus surgery; however, the magnitude of improvement differs considerably among individuals [4]. This variability highlights the importance of identifying predictive factors that may influence surgical success and assist clinicians in patient selection, preoperative counselling, and development of personalized treatment strategies.

Several demographic, clinical, radiological, inflammatory, and surgical factors have been proposed as potential predictors of FESS outcomes. Disease phenotype, particularly the presence of nasal polyps, has been associated with differences in postoperative recovery and recurrence patterns. Patients with CRSwNP often demonstrate a higher inflammatory burden, increased eosinophilic activity, and greater likelihood of recurrence compared with patients without polyps [5]. Similarly, comorbid asthma, aspirin-exacerbated respiratory disease (AERD), allergic rhinitis, and systemic inflammatory conditions may negatively influence long-term outcomes due to persistent inflammatory mechanisms affecting sinonasal mucosa [6].

Preoperative disease severity assessed through symptom scores, nasal endoscopy, and computed tomography (CT) findings has also been investigated as a determinant of postoperative improvement. The Lund–Mackay CT scoring system remains widely used for evaluating radiological disease extent, although the relationship between CT severity and patient-perceived improvement is not always consistent [7]. Some studies suggest that patients with severe baseline symptoms may achieve greater absolute improvement after surgery, while others indicate that extensive radiological disease and mucosal inflammation may predict poorer outcomes and increased recurrence risk [8].

Surgical factors may also significantly influence functional outcomes following FESS. The extent of surgery, preservation of mucosal function, management of anatomical variations, surgeon experience, and postoperative care protocols contribute to long-term success. Advances in image-guided surgery, improved instrumentation, and structured postoperative debridement and topical therapy have enhanced surgical precision and may reduce complications and recurrence rates [9]. Nevertheless, excessive surgical intervention without consideration of disease phenotype may not provide additional benefit and emphasizes the need for evidence-based individualized surgical planning.

Despite extensive research on FESS outcomes, predicting which patients will achieve optimal postoperative improvement remains challenging because CRS represents a complex interaction between anatomical abnormalities and chronic inflammatory processes. Most existing studies have focused on isolated predictors, whereas comprehensive longitudinal evaluation integrating demographic characteristics, clinical severity, radiological findings, inflammatory markers, surgical variables, and patient-reported outcomes remains limited.

Therefore, the present prospective longitudinal study aims to evaluate predictive factors influencing outcomes of Functional Endoscopic Sinus Surgery in patients with chronic rhinosinusitis. By assessing preoperative characteristics, surgical parameters, and postoperative functional outcomes over follow-up, this study seeks to identify factors associated with successful recovery and persistent disease. Understanding these predictors may facilitate improved patient counselling, optimized surgical decision-making, and development of personalized management approaches for individuals undergoing FESS for chronic rhinosinusitis.

Study Design and Study Setting A prospective longitudinal observational study was conducted to evaluate the predictive factors influencing postoperative outcomes of Functional Endoscopic Sinus Surgery (FESS) among patients with chronic rhinosinusitis (CRS). The study was conducted in the Department of Otorhinolaryngology at ________ Hospital/Institute, ________ over a period of 18 months (January 2024 to June 2025). The study was designed to assess the association between preoperative clinical characteristics, radiological findings, disease phenotype, surgical parameters, and postoperative functional outcomes following FESS. A prospective design was selected to enable systematic assessment of baseline disease characteristics and longitudinal evaluation of postoperative recovery, recurrence, and quality-of-life improvement. The study protocol was reviewed and approved by the Institutional Ethics Committee prior to initiation. All procedures were performed in accordance with the ethical principles outlined in the Declaration of Helsinki. Written informed consent was obtained from all participants after explaining the objectives, surgical procedure, potential risks, follow-up requirements, and confidentiality measures. Study Population and Sample Size A total of 90 patients diagnosed with chronic rhinosinusitis requiring Functional Endoscopic Sinus Surgery were enrolled in the study. The sample size was determined based on feasibility, expected patient availability during the study period, and previous clinical studies evaluating surgical outcomes following FESS. Patients were recruited consecutively from the outpatient department after confirmation of diagnosis according to established clinical and endoscopic criteria. All participants underwent standardized preoperative assessment, FESS, and scheduled postoperative follow-up evaluation. Inclusion Criteria Patients fulfilling the following criteria were included: • Patients aged 18 years or older. • Patients diagnosed with chronic rhinosinusitis according to established clinical guidelines, with symptoms persisting for more than 12 weeks. • Patients with persistent symptoms despite optimized medical therapy, including intranasal corticosteroids, saline irrigation, and appropriate pharmacological management. • Patients undergoing primary Functional Endoscopic Sinus Surgery. • Patients willing to provide informed consent and comply with postoperative follow-up visits. Exclusion Criteria Patients were excluded if they had: • Previous sinonasal surgery or revision FESS. • Acute bacterial rhinosinusitis at the time of surgery. • Sinonasal malignancy or granulomatous disease. • Significant sinonasal trauma or congenital craniofacial abnormalities. • Patients unwilling to participate or lost to follow-up before completion of postoperative assessment. • Patients with incomplete clinical, radiological, or postoperative outcome data. Preoperative Assessment All enrolled patients underwent detailed clinical evaluation, including demographic assessment, symptom analysis, disease duration, comorbidities, and previous medical treatment history. The following baseline parameters were recorded: • Age and sex • Duration of symptoms • Smoking status • History of allergy • Presence of asthma • Previous medical treatment • Disease phenotype (CRSsNP or CRSwNP) • Presence and grade of nasal polyps • Olfactory dysfunction • Associated comorbidities The severity of sinonasal symptoms was evaluated using the validated 22-item Sino-Nasal Outcome Test (SNOT-22) questionnaire. The SNOT-22 score was recorded preoperatively and compared with postoperative scores to determine improvement in disease-specific quality of life. Nasal Endoscopic Evaluation All patients underwent diagnostic nasal endoscopy before surgery using a rigid endoscope. Endoscopic findings were documented, including: • Nasal polyps • Mucosal edema • Purulent discharge • Crusting • Middle turbinate abnormalities • Osteomeatal complex obstruction Endoscopic disease severity was graded using the Lund–Kennedy endoscopic scoring system, which evaluates polyps, discharge, and mucosal edema. Higher scores indicated greater disease severity. Radiological Assessment All patients underwent preoperative high-resolution computed tomography (HRCT) of the paranasal sinuses. CT findings were evaluated using the, which provides standardized assessment of sinus opacification and disease extent. The following radiological parameters were recorded: • Maxillary sinus involvement • Ethmoid sinus involvement • Frontal sinus involvement • Sphenoid sinus involvement • Osteomeatal complex involvement • Total Lund–Mackay score The relationship between preoperative radiological severity and postoperative functional improvement was assessed. Surgical Procedure All patients underwent Functional Endoscopic Sinus Surgery under general anaesthesia. The surgical procedure was performed using standard endoscopic techniques with preservation of normal mucosa wherever possible. The extent of surgery was individualized according to disease involvement and included: • Uncinectomy • Middle meatalantrostomy • Anterior and/or posterior ethmoidectomy • Frontal sinusotomy • Sphenoidotomy • Endoscopic polypectomy when indicated Intraoperative findings, extent of disease, surgical duration, intraoperative complications, and additional procedures were recorded. All patients received standardized postoperative care, including saline nasal irrigation, topical intranasal corticosteroids, and scheduled endoscopic cleaning when required. Postoperative Follow-up and Outcome Assessment Patients were followed prospectively for 12 months after surgery. Follow-up assessments were performed at: • 1 month • 3 months • 6 months • 12 months At each visit, patients underwent: 1. Clinical symptom evaluation. 2. Nasal endoscopic examination. 3. Assessment of postoperative complications. 4. SNOT-22 quality-of-life evaluation. The primary outcome measure was improvement in functional status following FESS, assessed through changes in SNOT-22 scores from baseline to 12 months. Secondary outcomes included: • Improvement in nasal obstruction • Improvement in facial pressure and discharge • Recovery of olfactory function • Endoscopic healing status • Disease recurrence • Requirement for revision surgery Successful surgical outcome was defined as significant symptomatic improvement with reduction in SNOT-22 score and absence of disease recurrence requiring additional surgical intervention. Assessment of Predictive Factors Potential predictors influencing postoperative outcomes were analyzed, including: Patient-related factors: • Age • Sex • Smoking status • Allergy history • Asthma • Duration of disease Disease-related factors: • Presence of nasal polyps • CRS phenotype • Baseline SNOT-22 score • Lund–Kennedy endoscopic score • Lund–Mackay CT score • Olfactory dysfunction Surgical factors: • Extent of FESS • Intraoperative findings • Surgical duration • Postoperative adherence These variables were evaluated to identify independent predictors associated with successful or unfavorable outcomes after FESS. Statistical Analysis Data analysis was performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation (SD) or median with interquartile range depending on data distribution. Categorical variables were presented as frequencies and percentages. Normality of continuous variables was assessed using the Shapiro–Wilk test. For comparison of preoperative and postoperative outcomes, paired t-test or Wilcoxon signed-rank test was applied as appropriate. Associations between categorical variables and surgical outcomes were assessed using the Chi-square test or Fisher’s exact test. Correlation between clinical, endoscopic, radiological parameters, and postoperative improvement was evaluated using Pearson or Spearman correlation analysis. Multivariate logistic regression analysis was performed to identify independent predictors of successful postoperative outcomes. Variables with a p-value <0.10 in univariate analysis were entered into the multivariate model. A p-value <0.05 was considered statistically significant.

A total of 90 patients with chronic rhinosinusitis undergoing Functional Endoscopic Sinus Surgery (FESS) were included and followed prospectively for 12 months. The mean age of the study population was 41.8 ± 12.6 years, with the majority of patients belonging to the 31–50 years age group (46.7%). Male patients predominated, accounting for 56.7% (n=51) of the study cohort. The mean duration of symptoms before surgery was 4.2 ± 2.1 years.

Among disease phenotypes, chronic rhinosinusitis with nasal polyps (CRSwNP) was observed in 55.6% of patients, whereas 44.4% had chronic rhinosinusitis without nasal polyps (CRSsNP). A history of allergic rhinitis was present in 42.2% of patients, while asthma was reported in 18.9%. Olfactory dysfunction was observed in 38.9% of participants.

Table 1. Demographic and baseline clinical characteristics of study participants (n=90)

Baseline evaluation showed significant sinonasal disease burden among study participants. The mean preoperative SNOT-22 score was 47.6 ± 14.2, indicating considerable impairment in disease-specific quality of life.

The mean Lund–Kennedy endoscopic score was 6.8 ± 2.7, whereas the mean Lund–Mackay CT score was 13.4 ± 5.1. Patients with CRSwNP demonstrated significantly higher endoscopic and radiological disease severity compared with CRSsNP patients.

Table 2. Preoperative clinical, endoscopic, and radiological assessment

All patients underwent FESS according to individualized disease involvement. Bilateral endoscopic sinus surgery was performed in 72.2% (n=65) patients, whereas unilateral surgery was performed in 27.8% (n=25).

The most frequently performed surgical procedures were middle meatalantrostomy (91.1%), anterior ethmoidectomy (86.7%), and posterior ethmoidectomy (61.1%). Frontal sinusotomy was required in 34.4% of patients.

The mean operative duration was 82.5 ± 24.6 minutes. No major intraoperative complications were recorded.

Table 3. Surgical procedures and intraoperative characteristics

A significant improvement in patient-reported outcomes was observed after FESS during follow-up. The mean SNOT-22 score decreased progressively from 47.6 ± 14.2 preoperatively to 21.8 ± 11.4 at 12 months (p<0.001).

Maximum improvement was observed between baseline and 6 months, with sustained benefit at 12 months. Endoscopic healing scores also improved significantly during follow-up.

Table 4. Changes in SNOT-22 scores after FESS during follow-up

At 12 months follow-up, 74 patients (82.2%) achieved successful functional outcomes, whereas 16 patients (17.8%) had persistent symptoms or recurrent disease.

Univariate analysis demonstrated that nasal polyposis, asthma, higher baseline Lund–Mackay score, and higher Lund–Kennedy score were associated with poorer outcomes.

Multivariate logistic regression identified presence of nasal polyps (OR 3.42, p=0.012), asthma (OR 2.86, p=0.031), and higher CT severity score (OR 1.18 per unit increase, p=0.018) as independent predictors of unfavorable postoperative outcomes.

Table 5. Factors associated with successful postoperative outcome after FESS

A significant negative correlation was observed between baseline disease severity scores and postoperative improvement. Higher preoperative Lund–Kennedy and Lund–Mackay scores were associated with reduced improvement in SNOT-22 scores at 12 months.

The strongest association was observed between CT severity and functional outcome (r = -0.42, p<0.001).

Table 6. Correlation of predictive factors with postoperative SNOT-22 improvement

Figure 1. Distribution of chronic rhinosinusitis phenotypes among patients undergoing Functional Endoscopic Sinus Surgery

Figure 1 Among the 90 study participants, chronic rhinosinusitis with nasal polyps (CRSwNP) represented the predominant phenotype (55.6%), whereas chronic rhinosinusitis without nasal polyps (CRSsNP) accounted for 44.4% of cases.

Figure 2. Trend of mean SNOT-22 scores before and after Functional Endoscopic Sinus Surgery during 12 months follow-up

Figure 2 Mean SNOT-22 scores demonstrated progressive improvement after surgery, decreasing from 47.6 ± 14.2 at baseline to 21.8 ± 11.4 at 12 months (p<0.001), indicating significant improvement in disease-specific quality of life.

Functional Endoscopic Sinus Surgery (FESS) has become the cornerstone surgical intervention for patients with chronic rhinosinusitis (CRS) who fail to achieve adequate symptom control with optimized medical therapy. However, despite improvements in surgical techniques and postoperative management, outcomes following FESS remain variable due to the complex interaction between anatomical obstruction, inflammatory disease mechanisms, comorbidities, and patient-specific factors. The present prospective longitudinal study evaluated predictive factors influencing functional outcomes after FESS among 90 patients with chronic rhinosinusitis and demonstrated significant improvement in disease-specific quality of life, with 82.2% of patients achieving successful functional outcomes at 12 months. The findings further identified nasal polyposis, asthma, and increased radiological disease severity as significant predictors associated with unfavorable postoperative outcomes. In the present study, the mean age of participants was 41.8 ± 12.6 years, with a male predominance (56.7%). Similar demographic patterns have been reported in previous studies evaluating CRS surgical outcomes, where CRS commonly affects adults in the third to fifth decades of life with slightly higher prevalence among males. However, demographic variables such as age and sex have generally demonstrated inconsistent associations with postoperative outcomes. Smith et al. reported that although demographic characteristics contribute to baseline symptom burden, they have limited independent predictive value for surgical success when compared with disease-specific factors and inflammatory phenotype [10]. The present study demonstrated that CRSwNP was the predominant disease phenotype, accounting for 55.6% of cases. Patients with CRSwNP showed significantly poorer postoperative outcomes compared with those with CRSsNP, with successful outcomes achieved in 74.0% versus 90.0%, respectively. This finding supports previous evidence suggesting that nasal polyposis represents a more challenging CRS phenotype due to persistent type 2 inflammatory mechanisms, eosinophilic infiltration, and increased tendency for recurrence. Stevens et al. highlighted that CRSwNP is associated with elevated inflammatory cytokines, impaired epithelial barrier function, and increased disease recurrence following surgical intervention, explaining the reduced long-term success observed in these patients [11]. Quality-of-life improvement following FESS remains one of the most important measures of surgical effectiveness. In this study, the mean SNOT-22 score significantly decreased from 47.6 ± 14.2 preoperatively to 21.8 ± 11.4 at 12 months (p<0.001), demonstrating substantial improvement in sinonasal symptoms and functional well-being. These findings are consistent with large prospective studies showing significant and sustained improvements in patient-reported outcomes after FESS. Rudmik and Smith reported that endoscopic sinus surgery provides clinically meaningful improvement in health-related quality of life, particularly among patients with medically refractory CRS, although the degree of improvement varies depending on baseline disease characteristics [12]. The magnitude of improvement observed in the present study was comparable with findings from the national comparative audit conducted by Hopkins et al., which demonstrated significant postoperative improvement in symptoms and quality of life after sinus surgery. However, the authors also emphasized that a proportion of patients continue to experience persistent symptoms, highlighting the importance of identifying preoperative predictors of treatment response [13]. Radiological severity assessed by the Lund–Mackay scoring system was found to significantly influence postoperative outcomes in the current study. Patients with higher CT severity scores showed reduced improvement in SNOT-22 scores, with multivariate analysis identifying increased Lund–Mackay score as an independent predictor of unfavorable outcome (OR 1.18 per unit increase, p=0.018). Previous studies have reported variable associations between CT severity and surgical outcomes. Lund et al. initially proposed the Lund–Mackay scoring system as a standardized method for evaluating sinus disease extent; however, later studies demonstrated that radiological severity alone does not always correlate with symptom severity because CRS represents both inflammatory and structural disease processes [14]. Nevertheless, extensive radiological involvement may indicate greater inflammatory burden and more widespread mucosal disease, which can negatively affect postoperative recovery. Endoscopic disease severity also demonstrated significant association with outcomes in this study. Higher Lund–Kennedy scores were correlated with reduced postoperative improvement (r=-0.38, p<0.001). This finding supports previous observations that persistent mucosal edema, polyposis, and inflammatory changes observed during endoscopy may reflect active disease processes that continue despite surgical correction. In a prospective evaluation of postoperative CRS patients, DeConde et al. demonstrated that higher baseline endoscopic disease burden was associated with reduced improvement following FESS, suggesting that endoscopic assessment provides valuable prognostic information [15]. Asthma was another important predictor of unfavorable outcome in the present study. Patients with asthma demonstrated lower surgical success rates compared with those without asthma (64.7% vs 86.3%, p=0.028), and multivariate analysis confirmed asthma as an independent negative predictor. The association between asthma and poor CRS outcomes has been extensively documented, particularly among patients with CRSwNP. Bachert et al. described CRS as a systemic inflammatory disorder in which lower airway disease and sinonasal inflammation share common immunological pathways, particularly type 2 inflammation involving eosinophils and interleukin-mediated responses [16]. Persistent airway inflammation may therefore contribute to incomplete symptom resolution after sinus surgery. Smoking history was observed in 23.3% of patients in the current study; however, it was not an independent predictor of unsuccessful outcome. Previous evidence regarding smoking and FESS outcomes remains controversial. Some studies suggest that smoking impairs mucociliary clearance and promotes chronic mucosal inflammation, whereas others report that smokers may still achieve meaningful improvement following surgery when appropriately selected. A systematic review by Kim et al. concluded that smoking may negatively influence certain postoperative parameters but should not be considered an absolute contraindication for FESS [17]. The current study also demonstrated that disease duration showed a modest negative correlation with postoperative improvement. Longer disease duration may represent prolonged inflammatory stimulation, irreversible mucosal changes, and delayed intervention. Although CRS is traditionally considered reversible after restoration of sinus ventilation, chronic inflammatory remodeling may limit postoperative recovery in patients with longstanding disease. Similar observations were reported by Soler et al., who found that baseline symptom severity and duration of disease influenced patient-reported outcomes following endoscopic sinus surgery [18]. The overall surgical success rate of 82.2% observed in the present study supports the effectiveness of FESS as a functional procedure for medically refractory CRS. However, the findings emphasize that surgical success is influenced by multiple interacting variables rather than surgical technique alone. A personalized approach incorporating disease phenotype, comorbid inflammatory conditions, endoscopic findings, CT severity, and patient expectations may improve treatment planning and postoperative counselling. The present study has several strengths, including prospective longitudinal follow-up, standardized assessment using validated outcome measures, and evaluation of multiple potential predictive variables. However, certain limitations should be acknowledged. The study was conducted at a single centre with a relatively moderate sample size, which may limit generalizability. Inflammatory biomarkers such as eosinophil count, tissue cytokine profiles, and molecular endotyping were not evaluated. Longer follow-up may also be required to assess late recurrence and revision surgery rates. Overall, the findings demonstrate that FESS provides significant functional improvement for patients with chronic rhinosinusitis; however, outcomes are strongly influenced by underlying disease phenotype and inflammatory severity. Nasal polyposis, asthma, and extensive radiological disease should be considered important predictors during preoperative assessment to optimize patient selection, counselling, and postoperative management strategies.

Functional Endoscopic Sinus Surgery provides significant and sustained improvement in symptom burden and disease-specific quality of life among patients with chronic rhinosinusitis refractory to medical therapy. In the present prospective longitudinal study, the majority of patients (82.2%) achieved successful functional outcomes at 12 months, demonstrated by a significant reduction in SNOT-22 scores and improvement in postoperative sinonasal function.