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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Can the use of a non-invasive monitor (QNox) predict stronger pain after an operation?
Scientific title
The accuracy of the EEG-based qNox monitor to predict moderate-severe acute postoperative pain in peri-operative patients
Secondary ID [1] 296088 0
nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
moderate-severe pain after surgery 309664 0
Condition category
Condition code
Anaesthesiology 308465 308465 0 0
Pain management

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
Monitoring of the electroencephalogram-based QNox score during anaesthesia and recording 4 pain scores (5 minutely for first 15 min) after admission of a patient to the recovery room after surgery, as well as the total consumption of opioid-analgesics during the entire stay of a patient in the recovery room. This involves placement of a sticky sensor (single use QNox sensor) on the patient's forehead, as well as the patients to rate their pain (0-10) three times on a numeric rating scale for 15 min after recovery room admision.
Intervention code [1] 312427 0
Not applicable
Comparator / control treatment
no control group
Control group

Primary outcome [1] 307448 0
Predictive value of the QNox score for the prediction of moderate-severe postoperative pain.
Assessed by the placement of a sensor electrode on the paricipants forehead during surgery and recording of the QNox score at the end of the procedure. Participants then rate their pain (0-10) on a verbal rating scale four times for 15 min after recovery room admission.
Timepoint [1] 307448 0
Qnox monitored at the end of surgery, prior to patient arousal. Primary endpoint is the prefictive value of the QNox score for the highest Of four Pain scores measured four
times (T0, T5, T10, T15) for 15 minutes after admission of the patient to the recovery room (once able to communicate their pain effectively).
Secondary outcome [1] 366470 0
Timepoint [1] 366470 0

Key inclusion criteria
Patients at/over 18 years of age scheduled for non-emergency surgery and anaesthesia with sevoflurane/opioid
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Patients will be excluded from further analysis if they lack sufficient English language skills to communicate pain on a self-rated pain scale, have a condition or medication known or suspected of interacting with the acquisition of the eeg data (i.e. know epilepsy, known severe mental disorder), chronic pain (with opioid medication at home), use of ketamine at home or perioperatively within 30 min prior to the commencement of QNOX measurements, abuse of amphetamines or opioids, allergy to sticky tape.

Study design
Natural history
Convenience sample
Statistical methods / analysis
Statistical analysis:

Data exploration for normal distribution: K-S Test; investigation of the predictive value of the score: receiver-operating curves for qNox and exploration of the "best-fit" cut-off point with the combined highest sensitivity and specificity (Youden's Index); comparison between pain groups: students T-test, ANOVA or appropriate non-parametric alternatives (if tested non normally distributed).
Sample size estimate: In order to detect any significant predictive value of qNox for postoperative pain prediction (as defined as an area under the receiver-operating curve of at least 0.7) 50 subjects in each pain category (no-mild vs. moderate-severe) are required. As, in our experience, the ratio between these pain groups may be as low as 1:2, we estimate that 150 subjects are required to prevent loss of statistical power.

The level of significance to be used is P = 0.05
In addition to the above described methods data of 100 patients will be used to calculate the qnox with the highest combined sensitivity/specificity to distinguish between no-mild vs moderate-severe pain in the recovery room. The calculated cut-off value will the be tested prospectively in the next 50 patients for the purpose of validation. This analysis will only take place at the end of the full data collection (n=150) and will not exclude analysis/calculation of a "best-fit" qnox cut-off value for the entire data set.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 11911 0
Royal Perth Hospital - Perth
Recruitment postcode(s) [1] 24047 0
6000 - Perth

Funding & Sponsors
Funding source category [1] 300677 0
Name [1] 300677 0
Royal Perth Hospital
Address [1] 300677 0
197 Wellington St, Perth WA 6000
Country [1] 300677 0
Primary sponsor type
Prof THomas Ledowski
Royal Perth Hospital
Dept. of Anaesthesia
197 Wellington St, Perth WA 6000
Secondary sponsor category [1] 300205 0
Name [1] 300205 0
Address [1] 300205 0
Country [1] 300205 0

Ethics approval
Ethics application status
Ethics committee name [1] 301459 0
South Metropolitan Health Service Human Research Ethics Committee (EC00265)
Ethics committee address [1] 301459 0
Level 2, Education Building, Fiona Stanley Hospital

14 Barry Marshall Parade, MURDOCH WA 6150

Postal address: Locked Bag 100, PALMYRA DC WA 6961

Ethics committee country [1] 301459 0
Date submitted for ethics approval [1] 301459 0
Approval date [1] 301459 0
Ethics approval number [1] 301459 0

Brief summary
The qNox monitoring System (Conox Monitor; Fresenius Kabi) is an electroencephalogram-based (sticky electrode on forehead) dimensionless score (0-100) which claims to reflect levels of analgesia in anaesthetized patients. Higher levels of the score may reflect higher levels of noxious stimulation, or a higher likelihood of a patient to respond to noxious stimuli. Aim of the current study is to investigate whether a higher qNox score during, and at the end of surgery may be associated with a higher likelihood of significant postoperative pain.
150 patients scheduled for non-emergency surgery under sevoflurane/opioid anaesthesia and state entropy depth of anaesthesia monitoring will be included. In addition to standard monitoring, a row of sticky electrodes (similar to the ones used for monitoring the long-established state entropy monitor) will be placed on the patients’ forehead. No other intervention is done for the trial. QNox will be monitored specifically at the end of surgery before patient arousal. Once awake in recovery, patients’ pain will be rated on a numeric rating scale (0-10) every 5 minutes (as per recovery room routine). The first 4 pain ratings will be used to analyse any relationship between qNox and postoperative pain. No other study-related intervention will take place. Participating patients will neither be inconvenienced nor harmed in any way by inclusion in this trial.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 87078 0
Prof Thomas Ledowski
Address 87078 0
Royal Perth Hospital
Dept. of Anaesthesia
197 Wellington St, Perth WA 6000
Country 87078 0
Phone 87078 0
+61 (08) 92241036
Fax 87078 0
Email 87078 0
Contact person for public queries
Name 87079 0
Prof Thomas Ledowski
Address 87079 0
Royal Perth Hospital
Dept. of Anaesthesia
197 Wellington St, Perth WA 6000
Country 87079 0
Phone 87079 0
+61 (08) 92241036
Fax 87079 0
Email 87079 0
Contact person for scientific queries
Name 87080 0
Prof Thomas Ledowski
Address 87080 0
Royal Perth Hospital
Dept. of Anaesthesia
197 Wellington St, Perth WA 6000
Country 87080 0
Phone 87080 0
+61 (08) 92241036
Fax 87080 0
Email 87080 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
The investigators reserve the right to withhold the data set from certain requesting parties in case the request is not related to the intend to verify our data analysis (i.e. by a related ethics committee or research governance institution) but likely to be used for commercial interest or in any way that is not endorsed by the investigators.
What supporting documents are/will be available?
Study protocol
Informed consent form
Ethical approval
Summary results
No Results