An observational study in Hysterectomy, Chronic Pain and Central Sensitisation, sponsored by KK Women's and Children's Hospital. Recruiting at 1 site in Singapore. Open to female participants aged 21 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-14.
Sponsored by KK Women's and Children's Hospital · Observational
Phase 1 (started in July 2019):
Central Sensitization Inventory (CSI), Fear-Avoidance Components Scale (FACS), pain-pressure threshold are factors associated with chronic post-hysterectomy pain (CPHP), but a complete understanding on the development of CPHP is lacking. The study aims to identify clinically-relevant factors for CPHP that can be reliably assessed preoperatively.
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Phase 2 (anticipated start May 2022):
In addition to above factors, the association between heart rate variability (HRV) parameters, anxiety level, anticipated pain, and anticipated analgesia requirement with significant postoperative pain and CPHP will be investigated.
Phase 1 (started in July 2019):
Chronic post-surgical pain is persistent pain after a surgical procedure that lasts for at least 3 months with other causes of pain excluded. It is a major socioeconomic and healthcare burden, and has impact on quality of life, physical function, emotional wellbeing and healthcare costs. In Singapore, hysterectomy for benign indications incurs 32% risk of developing chronic post-hysterectomy pain (CPHP). CPHP can occur around the surgical site, lower abdominal or pelvic region. Based on the pathophysiology underlying chronic pain, the investigators hypothesize that central sensitization, pain fear-avoidance and low pain-pressure threshold are plausible risk factors for CPHP. However, none of these three risk categories has been evaluated in patients with CPHP.
The investigators hypothesize that preoperatively abnormal central sensitization, pain fear-avoidance and decreased pain-pressure threshold are associated with increased risk of developing CPHP. The investigators will evaluate these risk factors preoperatively, and follow-up study participants at 4- and 6-months after hysterectomy, to assess the associations between these risk factors and CPHP.
The investigators will perform a prospective study of 236 patients undergoing abdominal/laparoscopic hysterectomy for benign indications, recruited at KK Hospital, Singapore. Central Sensitization Inventory (CSI), Fear-Avoidance Components Scale (FACS), pain-pressure threshold and other known factors associated with CPHP will be assessed and recorded. Participants will be followed up at 4- and 6-months postoperatively to assess CPHP. Logistical regression analysis will be used to evaluate the associations between these factors and CPHP.
Knowledge of risk factors for CPHP will guide future studies to identify high-risk patients for implementation of individualized targeted therapies to optimize surgical outcomes of this patient group, and to confirm the hypothetical pathophysiological processes of chronic post-surgical pain similarly applicable to CPHP.
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Phase 2 (anticipated start May 2022):
Recent evidence suggests that changes in heart rate variability (HRV) parameters, anxiety level, anticipated pain, and anticipated analgesia requirement may be associated with significant postoperative pain (numerical pain score >3 out of 10). The associations between HRV, anxiety level, anticipated pain, and anticipated analgesia requirement with significant pain or CPHP after hysterectomy have yet been investigated.
The investigators hypothesize that preoperative changes in HRV parameters, increased anxiety level, higher anticipated pain, and higher anticipated analgesia requirement are associated with increased risk of developing significant postoperative pain or CPHP. HRV, anxiety level, anticipated pain, and anticipated analgesia requirement will be assessed preoperatively, and follow-up study participants at 24 hours, 48 hours, 4- and 6-months after hysterectomy to assess their associations with significant postoperative pain and CPHP.
The investigators will perform a prospective study of 200 patients undergoing abdominal/laparoscopic hysterectomy for benign indications, recruited at KK Hospital, Singapore. HRV, anxiety level, anticipated pain, and anticipated analgesia requirement will be assessed and recorded. Participants will be followed up at 24 hours, 48 hours, 4- and 6-months postoperatively to assess significant pain and CPHP. Logistical regression analysis will be used to evaluate the associations between these factors and significant pain or CPHP.
Knowledge of risk factors for significant pain and CPHP will guide future studies to identify high-risk patients for implementation of individualized targeted therapies to optimize surgical outcomes of this patient group.
3,227 studies on the registry are indexed under Chronic Pain; 729 are open to participants now.
This study's planned enrollment of 436 is above the median of 120 across 753 observational studies indexed under Chronic Pain.
Browse Chronic Pain studies →KK Women's and Children's Hospital is the lead sponsor of 137 studies on the registry; 33 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Women scheduled for elective abdominal or laparoscopic hysterectomy at KK Women's and Children's Hospital, Singapore.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Preoperative assessment with questionnaires, Mechanical Temporal Summation, Pain-Pressure Threshold, and heart rate variability. All patients will undergo elective abdominal or laparoscopic hysterectomy. Patients will be assigned to this group if no significant pain is noted during the follow up evaluations at 4 and 6 months.
Diagnostic Test: Pain-Pressure Threshold · Diagnostic Test: Mechanical Temporal Summation · Diagnostic Test: Hospital Anxiety and Depression Scale · Diagnostic Test: Pain Catastrophizing Scale · Diagnostic Test: Central Sensitization Inventory · Diagnostic Test: Fear-Avoidance Component Score · Diagnostic Test: EQ-5D · Diagnostic Test: heart rate variability · Diagnostic Test: Anxiety, anticipated pain, anticipated analgesia · Diagnostic Test: State-trait anxiety inventory · Diagnostic Test: Beck's Depression Inventory
Preoperative assessment with questionnaires, Mechanical Temporal Summation, Pain-Pressure Threshold, and heart rate variability. All patients will undergo elective abdominal or laparoscopic hysterectomy. Patients will be assigned to this group if significant pain is noted during the follow up evaluations at 4 and 6 months.
Diagnostic Test: Pain-Pressure Threshold · Diagnostic Test: Mechanical Temporal Summation · Diagnostic Test: Hospital Anxiety and Depression Scale · Diagnostic Test: Pain Catastrophizing Scale · Diagnostic Test: Central Sensitization Inventory · Diagnostic Test: Fear-Avoidance Component Score · Diagnostic Test: EQ-5D · Diagnostic Test: heart rate variability · Diagnostic Test: Anxiety, anticipated pain, anticipated analgesia · Diagnostic Test: State-trait anxiety inventory · Diagnostic Test: Beck's Depression Inventory
Preoperative assessment with questionnaires, Mechanical Temporal Summation, Pain-Pressure Threshold, and heart rate variability. All patients will undergo elective abdominal or laparoscopic hysterectomy. Patients will be assigned to this group if no significant pain is noted during the follow up evaluations at 24 and 48 hours.
Diagnostic Test: Pain-Pressure Threshold · Diagnostic Test: Mechanical Temporal Summation · Diagnostic Test: Hospital Anxiety and Depression Scale · Diagnostic Test: Pain Catastrophizing Scale · Diagnostic Test: Central Sensitization Inventory · Diagnostic Test: Fear-Avoidance Component Score · Diagnostic Test: EQ-5D · Diagnostic Test: heart rate variability · Diagnostic Test: Anxiety, anticipated pain, anticipated analgesia · Diagnostic Test: State-trait anxiety inventory · Diagnostic Test: Beck's Depression Inventory
Preoperative assessment with questionnaires, Mechanical Temporal Summation, Pain-Pressure Threshold, and heart rate variability. All patients will undergo elective abdominal or laparoscopic hysterectomy. Patients will be assigned to this group if significant pain is noted during the follow up evaluations at 24 and 48 hours.
Diagnostic Test: Pain-Pressure Threshold · Diagnostic Test: Mechanical Temporal Summation · Diagnostic Test: Hospital Anxiety and Depression Scale · Diagnostic Test: Pain Catastrophizing Scale · Diagnostic Test: Central Sensitization Inventory · Diagnostic Test: Fear-Avoidance Component Score · Diagnostic Test: EQ-5D · Diagnostic Test: heart rate variability · Diagnostic Test: Anxiety, anticipated pain, anticipated analgesia · Diagnostic Test: State-trait anxiety inventory · Diagnostic Test: Beck's Depression Inventory
Performed on bilateral trapezius muscles. Pressure will be applied at 90 degrees downward with an algometer, with the speed of pressure increase approximately 1kgf/s. Upon the sensation of pain, the patient will vocalize or raise her hand to terminate the test, and the highest reading will be recorded (up to maximum 6kgf). If two values are recorded within 0.2kgf of each other, the mean value will be recorded. If two values are greater than 0.2kgf of each other, a third test will be performed and the mean obtained.
Also known as: PPT
Pinprick hyperalgesia will be evoked using a Von Frey filament, applied to the volar aspect of the dominant forearm. Participants will report using the numerical rating scale the intensity of pain from the first stimulus. Subsequently, ten repetitive stimuli one second apart will be applied with the same filament within an area of 1cm diameter of the same forearm. Subjects will report the rate the pain intensity of the tenth stimulus. The magnitude of MTS is calculated as the difference between the last to the first pain scores. The investigators will classify the participants according to "evoked MTS" if the last stimulus is rated higher than the first, or "no MTS" if the last stimulus is rated equal or lower than the first. The research team administering the test will follow a set script.
Also known as: MTS
Standardized questionnaire to determine the level of anxiety and depression.
Also known as: HADS
Standardized questionnaire to determine the level of pain catastrophizing.
Also known as: PCS
Standardized questionnaire to determine the level of central sensitization.
Also known as: CSI
Standardized questionnaire to determine the level of fear and avoidance.
Also known as: FACS
Standardized questionnaire to assess generic health-related quality of life.
Heart rate variability will be determined from the R-to-R intervals obtained from a 5-minute ECG recording.
Also known as: HRV
Preoperative anxiety (0 to 100), anticipated pain (0 to 100), and anticipated analgesia requirement (0 to 5).
Standardized questionnaire to assess anxiety.
Also known as: STAI
Standardized questionnaire to assess depressive symptoms.
Also known as: BDI
Chronic Post-Hysterectomy Pain at 4 months
The primary outcome measure is the development of chronic post-hysterectomy pain, which is defined as pain that lasts for at least 3 months around the surgical site, lower abdominal, or pelvic region. This will be determined by phone or online assessment at 4 months after surgery, based on the protocol used by Brandsborg et al and the investigators' previous study.
Time frame: 4 months after hysterectomy
Significant postoperative pain at 24 hours
Numerical pain score (0: no pain; 100: worst pain imaginable) will be assessed at 24 hours after hysterectomy with patient moving from supine to sitting position.
Time frame: 24 hours after hysterectomy
Central Sensitization Inventory (CSI)
Assessment via the validated Central Sensitization Inventory (CSI) questionnaire prior to hysterectomy. Central sensitization is defined as an increased responsiveness of nociceptive neurons in the central nervous system to normal or sub-threshold afferent stimuli. The CSI a 25-item questionnaire, with each item rated 0 to 4. A higher value indicates greater central sensitization, and a threshold score of 40 was shown to be associated with increased risk of chronic pain.
Time frame: 2 months (upon recruitment until before surgery)
Fear Avoidance Components Scale (FACS)
Assessment via the validated Fear Avoidance Components Scale (FACS) questionnaire prior to hysterectomy. Fear-avoidance is defined as the negative emotional perception of pain as terrorizing, which can generate catastrophic thoughts and vigilance. Pain fear-avoidance behavior can be assessed with the FACS, a 20-item questionnaire, with each item rated 0 to 5.
Time frame: 2 months (upon recruitment until before surgery)
Hospital Anxiety and Depression Scale (HADS)
Assessment via the validated Hospital Anxiety and Depression Scale (HADS) questionnaire prior to hysterectomy. Anxiety and depression are known risk factors associated with CPHP. HADS is a combination test for both anxiety and depression, is a 14-item questionnaire, with each item rated 0 to 3. HADS \> 8 has been associated specifically with increased CPHP.
Time frame: 2 months (upon recruitment until before surgery)
Pain Catastrophizing Scale (PCS)
Assessment via the validated Pain Catastrophizing Scale (PCS) questionnaire prior to hysterectomy. Pain catastrophizing refers to the negative thought processes patients have when they are exposed to pain or painful experiences. The PCS is a 13-item scale, with each item rated on a 5-point scale: 0 (Not at all) to 4 (all the time). It is broken into three subscales being magnification (0-12), rumination (0-16), and helplessness (0-24). A higher value in each subscale indicates a higher tendency to that subscale (worse outcome).
Time frame: 2 months (upon recruitment until before surgery)
Quality of life via EQ-5D
Assessment via the validated EQ-5D questionnaire prior to hysterectomy. Lower preoperative quality of life has been associated with CPHP. EQ-5D is a validated questionnaire to assess generic health-related quality of life, consisting of two components: health state description and evaluation. The description component measures health status via five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, with each dimension rated according to severity using a three-level scale. The evaluation component assesses overall health status using the visual analogue scale (EQ-VAS).
Time frame: 2 months (upon recruitment until before surgery)
Mechanical Temporal Summation (MTS)
Assessment via Mechanical Temporal Summation before hysterectomy. A 180 gram von Frey filament is applied on the subject's forearm. Patient will then be asked to rate the pinprick pain score on a verbal rating scale, 0-100. Following this, 10 consecutive touches at random locations are applied with a 1 second interstimulus interval and within a 1 cm diameter circle. The patient will then be asked to rate the 10th pain score (0-100). The Mechanical Temporal Summation Score is obtained by the difference between the 11th pain score and the 1st pain score. If the score is greater than zero, the patient is implied to have presence of Mechanical Temporal Summation.
Time frame: 2 months (upon recruitment until before surgery)
Pain-Pressure Threshold (PPT)
Assessment of Pain-pressure threshold (PPT) prior to hysterectomy. PPT is measured via an algometer in both groups. Pressure is applied 90 degree straight down force on the subject's right/left centre of the trapezius muscle using an algometer, with a speed of pressure \~ 1kgf/s. The above procedure is then repeated 3 times at each site (left/right) which is indicated on the pressure mark with each time having the reading recorded. When patient shows no response ≥ 6kgf, the threshold is recorded as 6kgf. The patient upon feeling pain will say stop or raise the hand to terminate the test. The mean value is obtained by averaging the readings and will then be recorded as the threshold estimate.
Time frame: 2 months (upon recruitment until before surgery)
Chronic Post-Hysterectomy Pain at 6 months
The primary outcome measure is the development of chronic post-hysterectomy pain, which is defined as pain that lasts for at least 3 months around the surgical site, lower abdominal, or pelvic region. This will be determined by phone or online assessment at 6 months after surgery, based on the protocol used by Brandsborg et al and the investigators' previous study.
Time frame: 6 months after hysterectomy
heart rate variability
Heart rate variability will be determined from the R-to-R intervals obtained from a 5 minute ECG recording with the patient supine.
Time frame: Preoperative and 24 hours after hysterectomy
Preoperative anxiety
Patients will be asked to rate, using a 0-100 mm visual analog scale (VAS), their surgical anxiety level ("On a scale of 0-100, with 0 being not anxious at all through 100 being extremely anxious, how anxious are you about your upcoming surgery?")
Time frame: Preoperative
State-Trait Anxiety Inventory
Assessment via State-Trait Anxiety Inventory questionnaire prior to hysterectomy, a standardized assessment of anxiety. This is a validated 40-item questionnaire, each item scored using a categorical scale from 1-4, with total score from 40 to 160.
Time frame: 2 months (upon recruitment until before surgery)
Beck's Depression Inventory
Assessment via Beck's Depression Inventory questionnaire prior to hysterectomy, a standardized assessment of depressive symptoms.This is a validated 21-item questionnaire, each item scored using a categorical scale from 0-3, with total score from 0 to 63.
Time frame: 2 months (upon recruitment until before surgery)
Anticipated pain
Patients will be asked to rate, using a 0-100 mm visual analog scale (VAS), their anticipated pain ("On a scale of 0-100, with 0 being no pain at all and 100 being pain as bad as you can imagine, how much pain do you anticipate experiencing after your upcoming surgery?")
Time frame: Preoperative
Anticipated analgesia requirement
Patients will be asked to rate, using a categorical scale, their anticipated pain medication need ("On a scale of 0-5, with 0 being none at all, 1 being much less than average, 2 being less than average, 3 being average, 4 being more than average, and 5 being much more than average, how much pain medication do you anticipate needing after your upcoming surgery?")
Time frame: Preoperative
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Started Jul 2019 (actual). Primary completion is estimated for Dec 2027, 101 months after the start.
Of 336 non-industry observational studies under Chronic Pain, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 56. This study's planned 101 months is above that.
Counting every sponsor, half of 362 studies reached it within 24 months; a quarter within 12 and three quarters within 56.
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