Effects of Platelet-Rich Fibrin on Postoperative Outcomes Following Nasosinusal Surgery

## Methodology

This study was designed as a prospective, controlled, double-blind trial. Data were collected using a standardized clinical questionnaire completed by the attending physicians of patients undergoing sinonasal surgery at the Centro de Otorrinolaringologia e Fonoaudiologia de São Paulo (COF), São Paulo, Brazil. A specific data collection form was used to record postoperative clinical findings.

• Study Procedures

  1. The study population consisted of patients undergoing sinonasal surgery at COF, who were evaluated at 1 week and 1 month postoperatively.
  2. Platelet-rich fibrin (PRF) was prepared intraoperatively through autologous blood collection followed by centrifugation in the operating room, requiring approximately 20 minutes.
  3. PRF membrane was randomly applied topically to one nasal cavity, while the contralateral cavity served as the control.
  4. At the end of the procedure, while the patient remained under general anesthesia, the PRF membrane was placed by the assisting surgeon without the presence of the attending surgeon in the operating room.
  5. Neither the attending surgeon responsible for postoperative evaluations nor the patient was aware of which nasal cavity had received PRF treatment.
  6. The questionnaire (Figure 1) was completed during routine postoperative visits at 1 week and 1 month following surgery, after otorhinolaryngological examination performed by the attending surgeon.
  7. The physician completed a separate evaluation form for each nasal cavity, allowing intra-patient comparison between treated and untreated sides.
  8. Confidentiality of patient records and questionnaire data was ensured through the signing of confidentiality and informed consent agreements by all participants.
  9. Collected data were organized in standardized databases. The study was conducted in accordance with the principles of the Declaration of Helsinki and Resolution No. 466/2012 of the Brazilian National Health Council regarding research involving human subjects.
  10. A database was created for each participant, including the following variables: descriptive nasal bleeding scale, descriptive crust formation scale, sex, age, and type of surgical procedure performed.
• Inclusion Criteria

Patients undergoing sinonasal surgery at the Centro de Otorrinolaringologia e Fonoaudiologia de São Paulo (COF), São Paulo, Brazil, were eligible for inclusion.

Confidentiality of medical records and questionnaire data was ensured through the execution of confidentiality agreements between study participants and the institution.

### Exclusion Criteria

Patients who declined participation or failed to sign the informed consent form were excluded.

Patients who did not attend either the 1-week or 1-month postoperative follow-up visits were also excluded.

## Statistical Methodology

### Sample Characteristics

The initial sample consisted of 18 patients, including 8 women and 10 men, aged between 25 and 43 years.

During the study period, 4 patients were excluded because they failed to attend the scheduled postoperative visits at either 1 week or 1 month. Consequently, the final sample comprised 14 patients, including 7 women and 7 men.

All surgical procedures included partial inferior turbinectomy (100%).

### Statistical Analysis

Exploratory data analysis included calculation of means, medians, standard deviations, and ranges for continuous variables, as well as frequencies and proportions for categorical variables.

The distribution of numerical variables was assessed using descriptive statistics, histograms, boxplots, and the Shapiro-Wilk test for normality.

Comparative analyses of outcomes between postoperative time points (1 week and 1 month) and treatment groups (PRF-treated versus control side) were performed using Rank-Based Analysis of Variance (Rank ANOVA) as described by Wobbrock et al. (2011).

Partial eta squared (η²ₚ) was calculated as a measure of effect size for the overall ANOVA model and interpreted according to conventional thresholds:

• η²ₚ = 0.01: small effect
• η²ₚ = 0.06: medium effect
• η²ₚ = 0.14: large effect