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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
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
A randomized trial of midazolam versus placebo on cognitive recovery in adult patients following elective outpatient colonoscopy using postoperative quality of recovery scale.
Scientific title
A randomised trial of midazolam versus placebo on the quality of recovery after colonoscopy (MIMiCRY)
Secondary ID [1] 286479 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cognitive recovery following anaesthesia 294667 0
Condition category
Condition code
Anaesthesiology 294969 294969 0 0
Mental Health 294970 294970 0 0
Studies of normal psychology, cognitive function and behaviour
Oral and Gastrointestinal 295549 295549 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Study type
Description of intervention(s) / exposure
Eligible and consented patients will be randomly allocated to receive an intravenous injection of 0.04 mg/kg (total body weight) upto a maximum of 5 mg midazolam immediately prior to the sedation with intravenous propofol.The dose of propofol will be titrated by the administering anaesthetist to a sedation level suitable to perform the procedure.
Intervention code [1] 291565 0
Treatment: Drugs
Comparator / control treatment
The control group will receive same volume of 0.9% saline as the volume of midazolam calculated according to the patient's body weight.
Control group

Primary outcome [1] 294724 0
Incidence of cognitive recovery as measured by Postoperative quality of recovery ( Postop QRS) questionnaire. The definition of recovery is a return to baseline values or better in all of the recovery domains, with adjustment for performance variability in the cognitive domain
The Postoperative Quality of Recovery Scale (PostopQRS) is a brief tool that has been widely used in many studies to assess quality of recovery in multiple domains at various time points. The final version of PostopQRS consists of six domains (physiologic, nociceptive, emotive, activities of daily living, cognitive and ‘overall patient perspective’).
Timepoint [1] 294724 0
Day 3 following procedure
Secondary outcome [1] 313932 0
Recovery for all domains (physiological, nociceptive, emotive activities of daily living, cognitive) and within domains over time and overall patient perspective as measured by PostopQRS questionnaire
Timepoint [1] 313932 0
15 minutes and 40 minutes, day 1, day 3, day 7 and 3 months following colonoscopy

Key inclusion criteria
Adult patients undergoing elective outpatient colonoscopy
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. History of psychiatric illness, neurological disease, visual or auditory disturbances
2. History of drug/alcohol abuse
3. History of preexisting memory or cognitive disturbance
4. Not fluent in English, sufficient to complete the PostopQRS survey.
5. Patient refusals or non-compliance
6. Clinically significant renal or hepatic dysfunction.
7. Significant cardiorespiratory instability

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Adult patients undergoing colonoscopy at the Prince Charles Hospital will be recruited for this study prior to but on the day of the procedure. Letters to the patient informing about the study will be posted to the patient a few days before the surgery. These patients will be contacted either at the colon consent clinic or on the day of the procedure to sign the consent for the study. This is a parallel randomized trial with allocation ratio 1:1
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomization table will be produced using a computer generated randomization sequence. Concealment will be by placing the card containing the allocation information in double opaque sealed envelopes. A non-participant in any process of the study will perform preparation of the envelopes. Concealment will be maintained until after recruitment and patient is admitted for the procedure. A non-investigator medical or nursing staff/research coordinator will then open the envelopes to reveal the allocation. The trial preparation will be drawn in a syringe by a non-investigator anaesthetist or nurse, labeled as “trial drug” and documented as “trial drug” in the chart.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Phase 4
Type of endpoint(s)
Statistical methods / analysis
Analysis of the primary endpoint will be performed using the chi-squared analysis for difference in the incidence of recovery in the cognitive domain at day 3. For recovery across all time points for each domain, the Cochran Mantel Haenszel test will be used to examine the difference in the proportions of recovery between the groups with continuity correction over the different time periods. Continuous data will be analysed using independent samples t test, or repeated measures ANOVA for repeated measurements. The level of significance will be defined as p<0.05. Based on the previous studies, the cognitive recovery on day 3 is around 70% in elderly patients. Considering that an absolute difference of 15% would constitute significant difference between groups and using a two-tailed design, a sample size of n= 174 per group will provide a power of 80% with an alpha value of 0.05. 400 patients will be recruited to compensate for the dropouts and loss to follow up.

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] 3658 0
The Prince Charles Hospital - Chermside
Recruitment hospital [2] 8178 0
Royal Melbourne Hospital - City campus - Parkville
Recruitment postcode(s) [1] 9490 0
4032 - Chermside
Recruitment postcode(s) [2] 16240 0
3050 - Parkville

Funding & Sponsors
Funding source category [1] 291043 0
Name [1] 291043 0
The Prince Charles Hospital
Address [1] 291043 0
Department of Anaesthesia, The Prince Charles Hospital, Rode Road, Chermside, QLD 4032
Country [1] 291043 0
Primary sponsor type
Usha Gurunathan
Department of Anaesthesia, The Prince Charles Hospital, Rode Road, Chermside, QLD 4032
Secondary sponsor category [1] 289726 0
Name [1] 289726 0
Address [1] 289726 0
Country [1] 289726 0

Ethics approval
Ethics application status
Ethics committee name [1] 292627 0
The Prince Charles Hospital Human Research and Ethics committee
Ethics committee address [1] 292627 0
Rode Road, Chermside, QLD 4032
Ethics committee country [1] 292627 0
Date submitted for ethics approval [1] 292627 0
Approval date [1] 292627 0
Ethics approval number [1] 292627 0

Brief summary
Patients undergoing day surgery procedures are usually discharged the same day. They are not assessed further unless they come back for follow up or they have some medical or surgical complications. The recovery from general anaesthesia can vary considerably between individuals. Due to paucity of randomized trials, it is unclear if the brief anaesthesia the patients receive for their surgery, can affect longer-term recovery (especially cognitive recovery). Midazolam, a short-acting benzodiazepine, enhances the action of gamma aminobutyric acid (GABA), thereby acting as a neural inhibitor. It increases binding of GABA to GABA-a receptors that are highly concentrated in hippocampus. It is widely used as anxiety relieving, sedative and as a premedicant. There are concerns about the residual effect of midazolam on the cognitive status of patients following its administration as a part of anaesthetic induction.
In day surgery procedures, quality of recovery has profound implications for the individual patient and for the community, in terms of return to work and safe driving. An ideal anaesthetic for day surgery procedures should not affect the mental capabilities for a long period of time.
Our objective is to identify if administering midazolam in addition to propofol affects the recovery of cognitive function in patients undergoing elective colonoscopy.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 56310 0
Dr Usha Gurunathan
Address 56310 0
Department of Anaesthesia, The Prince Charles Hospital, Rode Road, Chermside, QLD 4032
Country 56310 0
Phone 56310 0
+61 7 3139 4000
Fax 56310 0
Email 56310 0
Contact person for public queries
Name 56311 0
Dr Usha Gurunathan
Address 56311 0
Department of Anaesthesia, The Prince Charles Hospital, Rode Road, Chermside, QLD 4032
Country 56311 0
Phone 56311 0
+61 7 3139 4000
Fax 56311 0
Email 56311 0
Contact person for scientific queries
Name 56312 0
Dr Usha Gurunathan
Address 56312 0
Department of Anaesthesia, The Prince Charles Hospital, Rode Road, Chermside, QLD 4032
Country 56312 0
Phone 56312 0
+61 7 3139 4000
Fax 56312 0
Email 56312 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Individual participant data is not of much clinical utility with this trial.
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary