Postoperative Pain, Central Sensitization, and Sleep Quality in Breast Cancer Surgery Patients

Investigation of the Relationship Between Postoperative Pain and Both Central Sensitization Severity and Sleep Quality in Patients Undergoing Breast Cancer Surgery

This prospective observational study aims to investigate whether preoperative central sensitization and sleep quality are associated with acute postoperative pain levels in patients undergoing breast cancer surgery.

The study includes 41 female patients scheduled for unilateral breast cancer surgery. Before surgery, participants are evaluated using two self-report questionnaires: the Central Sensitization Inventory (CSI) and the Pittsburgh Sleep Quality Index (PSQI). Based on their scores, participants are categorized into groups according to central sensitization level and sleep quality.

After surgery, all participants receive a standardized multimodal analgesia protocol. Pain severity is measured using the Numeric Rating Scale (NRS) at five time points within the first 24 hours: 30 minutes, 2, 6, 12, and 24 hours postoperatively. Additional assessments include sedation level (Ramsay Sedation Scale), nausea and vomiting (Verbal Descriptive Scale), and presence of delirium (Nursing Delirium Screening Scale - NuDESC).

The primary question this study seeks to answer is whether higher levels of central sensitization and/or poor sleep quality prior to surgery are predictive of greater acute postoperative pain.

Study Overview

• Status: Completed
• Conditions: Postoperative Pain; Central Sensitization; Breast Cancer Surgery; Sleep Quality

Detailed Description

This prospective observational cohort study is designed to evaluate the association between preoperative central sensitization levels, sleep quality, and acute postoperative pain intensity in female patients undergoing breast cancer surgery. The study is being conducted at Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty, Department of Anesthesiology and Reanimation, in collaboration with the Department of General Surgery, from March 2025 to June 2025, following ethics committee approval and prospective registration.

A total of 41 female patients, aged between 18 and 80 years, undergoing unilateral breast surgery with sentinel lymph node biopsy (SLNB)-including simple mastectomy, breast-conserving surgery, or mastectomy with immediate reconstruction-are included. All participants provide written informed consent before enrollment.

Preoperative assessments are performed one day prior to surgery. Central sensitization is measured using the Central Sensitization Inventory (CSI), a 25-item self-report questionnaire assessing symptoms commonly associated with central sensitization. A CSI-A score ≥40 is considered indicative of high central sensitization. Sleep quality is evaluated with the Pittsburgh Sleep Quality Index (PSQI), a validated instrument assessing sleep characteristics over the past month; PSQI scores ≥5 are accepted as reflecting poor sleep quality.

All patients receive standardized general anesthesia and multimodal analgesia including:

Induction: Fentanyl 2 mcg/kg (lean body weight), propofol 2 mg/kg (lean body weight), rocuronium 0.6 mg/kg (actual body weight).

Maintenance: Sevoflurane and additional opioid supplementation as needed. Intraoperative analgesia: Morphine 0.05 mg/kg (lean body weight). Postoperative analgesia: Scheduled paracetamol and NSAIDs; opioids as rescue medication if required.

Pain severity is measured using the Numeric Rating Scale (NRS) at five postoperative time points: 30 minutes, 2, 6, 12, and 24 hours. Additional assessments include:

Sedation level: Ramsay Sedation Scale (RSS) Nausea and vomiting: Verbal Descriptive Scale (VDS) Delirium screening: Nursing Delirium Screening Scale (NuDESC) Participants are categorized into groups according to their CSI and PSQI scores. Postoperative pain scores and secondary outcomes are compared across these groups using non-parametric statistical methods (e.g., Mann-Whitney U test for independent samples). Correlation analyses (Spearman's rank) are performed to assess relationships between CSI, PSQI, and postoperative pain scores.

The primary objective is to determine whether high central sensitization and/or poor sleep quality are predictive of increased acute postoperative pain. Secondary objectives include evaluating the relationship between preoperative risk factors and sedation, nausea/vomiting, and delirium outcomes.

A power analysis was conducted based on expected effect sizes from previous literature, targeting a minimum of 31 participants for 80% statistical power with an alpha of 0.05. A 20% dropout margin was included, resulting in a final sample size of 41 participants.

All data are collected using standardized case report forms. Data entry is conducted by trained personnel and monitored for consistency and completeness. Ethical approval was obtained from the institutional review board prior to participant recruitment. The study does not receive external funding.

• Study Type: Observational
• Enrollment (Actual): 41

Contacts and Locations

Study Locations

• Turkey
  • Istanbul, Turkey, 34147
    • İstanbul Üniversitesi-Cerrahpaşa Cerrahpaşa Tıp Fakültesi

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of female patients aged 18 to 80 years who were admitted for elective breast cancer surgery at the Department of Anesthesiology and Reanimation, Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty Hospital. Participants were selected consecutively among those scheduled for unilateral simple mastectomy, breast-conserving surgery, or mastectomy combined with immediate breast reconstruction. All surgeries were performed under general anesthesia. Preoperative evaluations and postoperative follow-up (within 24 hours) were conducted in a tertiary-care academic hospital setting. Patients were evaluated using standardized self-report questionnaires.

Description

InclusionCriteria:

• Female patients aged between 18 and 80 years
• Scheduled to undergo one of the following unilateral breast cancer surgeries with sentinel lymph node biopsy (SLNB):
• Simple mastectomy
• Breast-conserving surgery (BCS)
• Simple mastectomy with immediate breast reconstruction
• ASA Physical Status Classification I-III
• Able to understand the study procedure and provide informed consent
• Fluent in Turkish and capable of completing self-report questionnaires
• Preoperative completion of the following assessments:
• Central Sensitization Inventory (CSI)
• Pittsburgh Sleep Quality Index (PSQI)

ExclusionCriteria:

• Pregnant or lactating women
• Allergy or contraindication to any component of the analgesic regimen (e.g., paracetamol, dexketoprofen, tramadol, fentanyl, or morphine)
• Planned or performed intraoperative regional nerve block (e.g., paravertebral or PECS block)
• Use of sedative-hypnotic drugs, opioids, or gabapentinoids within the last 7 days
• History of prior breast or axillary surgery
• Conversion to emergency surgery or development of major intraoperative complications
• Admission to the intensive care unit (ICU) postoperatively
• Patient refusal to participate in postoperative assessments
• Evidence of metastatic disease

Study Plan

How is the study designed?

Number of groups / cohorts

4

Cohorts and Interventions

Group / Cohort
Good Sleep Quality Group; Participants with Pittsburgh Sleep Quality Index (PSQI) score less than 5, indicating good sleep quality. No intervention is applied to alter sleep patterns; this is a stratification based on preoperative sleep assessment.
Poor Sleep Quality Group; Participants with PSQI score of 5 or greater, indicating poor sleep quality. This group is used to assess the relationship between preoperative sleep disturbance and postoperative pain outcomes. No intervention is applied.
Low Central Sensitization Severity Group; Participants with Central Sensitization Inventory (CSI) score below 40, indicating low central sensitization severity. Used for comparative analysis of postoperative pain scores. No therapeutic intervention applied.
High Central Sensitization Severity Group; Participants with CSI score of 40 or greater, indicating high central sensitization severity This grouping aims to evaluate the effect of central sensitization on postoperative pain perception and analgesic needs. No intervention administered.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Acute Pain Intensity Measured by the Numeric Rating Scale (NRS)	Postoperative acute pain intensity will be assessed using the Numeric Rating Scale (NRS; range 0-10, where 0 = no pain and 10 = worst imaginable pain) at rest and during movement. Measurements will be taken at 30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours after surgery.	Day 0 (30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours post-surgery)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sedation Level Assessed by Ramsay Sedation Scale (RSS)	Sedation level will be assessed using the Ramsay Sedation Scale (RSS; range 1-6, where higher scores indicate deeper levels of sedation). Assessments will be conducted at 30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours after surgery.	Day 0 (30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours post-surgery
Postoperative Nausea and Vomiting Severity Scored on a 4-Point Scale (0-3)	Postoperative nausea and vomiting (PONV) will be assessed using a 4-point verbal rating scale. Patients will be asked to rate their overall PONV severity as follows: 0 = No nausea or vomiting; = Mild nausea only, no vomiting; = Moderate nausea and/or one episode of vomiting; = Severe nausea and/or two or more episodes of vomiting Higher scores indicate more severe PONV. Evaluations will be performed at 30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours after surgery.	Day 0 (30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours post-surgery)
Delirium Assessment Using the Nursing Delirium Screening Scale (NuDESC)	Delirium will be assessed using the Nursing Delirium Screening Scale (NuDESC), a validated 5-item observational tool. Each item is scored from 0 to 2, yielding a total score range of 0-10. A total score ≥2 is considered indicative of delirium. Assessments will be conducted at 30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours after surgery.	Day 0 (30 minutes, 2 hours, 6 hours, 12 hours, and 24 hours post-surgery)

Collaborators and Investigators

• Sponsor: Istanbul University - Cerrahpasa

Study record dates

Study Major Dates

• Study Start (Actual): March 13, 2025
• Primary Completion (Actual): June 30, 2025
• Study Completion (Actual): June 30, 2025

Study Registration Dates

• First Submitted: June 28, 2025
• First Submitted That Met QC Criteria: July 11, 2025
• First Posted (Actual): July 22, 2025

Study Record Updates

• Last Update Posted (Actual): July 22, 2025
• Last Update Submitted That Met QC Criteria: July 11, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Pain, Postoperative; Breast Neoplasms
• Other Study ID Numbers: 2025/81

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No