Trial Design
This trial is a prospective, randomized, controlled clinical trial comparing the safety and efficacy of oxycodone and sufentanil for postoperative patient-controlled analgesia in patients undergoing hip surgery, and it will be executed in general hospitals in China and Singapore. It has been registered on http://www.clinicaltrials.gov, with the registration number: NCT 03685188 on September 13th, 2018. It will be conducted according to rules of the Declaration of Helsinki. A brief flow diagram of the trial under the guidance of Consolidated Standards of Reporting Trials (CONSORT) statement (http://www.consort-statement.org/)is summarized in Figure 1, and a checklist of Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) is provided in Figure 2.
This trial is supported by grant from the West China Hospital scientific research project (HX-H1810182) supported by Chinese Research Hospital Association, the Key research and development (R&D) Program of Science & Technology Department of Sichuan Province (2019YFS0224), and the National Natural Science Foundation of China (81502722). There is no conflict of interests. The study team, including anesthesiologists, orthopedic surgeons, clinical research coordinators, research nurses, and ward nurses will be trained with a training manual before starting the trial.
Fig. 1 Flowchart for participant eligibility, interventions, assessments and follow-up
Fig. 2 Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) figure (numbers beside t represent days)
Sample size calculation
The primary hypothesis of this trial is that the analgesic effect of oxycodone PCA is not inferior to the equipotency dose of sufentanil PCA, and the incidence of PONV is lower in oxycodone PCA than in sufentnail PCA during postoperative period. Therefore, the effect of postoperative analgesia is considered as one primary outcome and compared between groups with non-inferiority design, and the incidence of PONV is another primary outcome and compared with superiority design. According to preliminary observation, for the primary outcome of postoperative analgesia, the mean numerical rating scales (NRS) pain score of patients receiving sufentanil PCA and oxycodone PCA at 30 minutes after operation were 3.5 and 3 respectively, with a common standard deviation of 0.866. So we conservatively assumed that the difference in NRS between the two groups is 0 and the common standard deviation is 0.866. We chose the non-inferior margin as 1/10 of the mean value 0.3, assuming the difference between two groups at a 2.5% significance level and a power of 0.80, 132 subjects are required in each group. Considering an estimated 20% dropout rate, 165 subjects in each group, and a total of 330 subjects are required. For the primary outcome of incidence of PONV, it is reported to be 38.8% in sufentanil and 25.3% in oxycodone [9]. Assuming the difference between two groups at a 2.5% significance level and a power of 0.80, 223 subjects are required in each group. Considering an estimated 20% dropout rate, 279 subjects in each group, and a total of 558 subjects are required. We plan to enroll 570 subjects in this study.
Randomization and blinding
A Central Randomization System (CRS) will be applied to randomize the subjects. According to the sequence of time that the subjects are enrolled, after entering the subject’s information, the randomized number and allocated group could be retrieved on the website of the CRS.
The trial is designed as prospective randomized clinical trial. After obtaining the random number of the patients in the central randomized system (http://www.medresman.org/login.aspx), the researchers or the clinical research coordinators will inform the research nurses to formulate the study drugs into 100ml patient-controlled analgesic pumps according to the study group. The pump will be given to the clinical investigators before the operation. In China, both sufenanil and oxycodone are controlled drugs, and patient who receive treatment of these drugs must be registered with real name, and these drugs must be marked and labelled on the patient-controlled analgesic pumps. So the researchers, the patients, and the clinical staffs know the group allocation, but the follow-up personnel, and the statisticians are blinded to the group allocation.
Study organization and quality control
The implement of the study, the data completeness and accuracy will be supervised by Department of Anesthesiology of West China Hospital and the Office of Scientific Research at West China Hospital. Dr. Ren Liao will be the alert personnel of serious complications. Data collection and follow-up will be performed by clinical research coordinators. The data safety and monitoring board, including a statistician, an ethicist, an orthopedic surgeon, an anesthesiologist, and an internal physician who are not unrelated to this trial, will be involved for the entire duration of the trial to review all investigational data for accuracy and completeness periodically to ensure protocol compliance. There are no stop rules in this study, and no preliminary analysis will be performed before the completion of the study.
Interventions
After admission, preoperative examinations will be arranged according to the routine arrangements of participating hospitals. Vital signs including electrocardiogram, blood pressure, and pulse oximetry will be monitored during operation. General anesthesia, epidural, spinal, or combined epidural-spinal anesthesia, or nerve block could be applied for the surgery, but indwelling catheter for postoperative analgesia should be avoid if epidural or nerve block anesthesia has been chosen. Antiemetic drugs (such as granisetron, ondansetron, tropisetron, etc.) should be given 30 minutes before the end of the operation, and local anesthetics or cocktails for incision infiltration can be applied according to the routine of participating centers.
According to the analgesic formula of postoperative patient-controlled analgesia, the subjects are randomly divided into Oxycodone group and Sufentanil group.
Oxycodone group: PCA is formulated at 0.4 mg/ml of oxycodone.
Sufentanil group: PCA is formulated at 2 μg/ml of sufentanil.
No background dose will be applied for PCA in both groups. When the subject feels the pain, he could activate the analgesic pump to infuse 2 ml of analgesic drugs. The lock-out time is 12 minutes and the maximum times the pump could be activated are 5 times per hour.
Recruitment
A total of 570 patients undergoing hip surgery will be enrolled at West China Hospital of Sichuan University.
Enrollment criteria
Inclusion criteria
· Patients undergoing unilateral hip surgery, with both genders;
· Age above 18 years;
· Informed consent signed.
Exclusion criteria
· Pregnancy or lactating;
· History of drug abuse, including but not limited to opioids, amphetamines, ketamine, etc.;
· History or family history of malignant hyperthermia;
· Known allergy to opioids or any other anesthetic agent;
· History of nervous system diseases such as peripheral neuropathy, or psychiatric mental illness, or postoperative delirium;
· Other conditions that the investigators consider unsuitable for participation in the study, such as Parkinson's disease, unable to communicate, or impairment of cognitive function;
· Participation in another trial in the past three months.
Exit criteria
Subjects enrolled in this study have the right to decline further participation at any time of the study without giving any reason, and the participation will be terminated immediately once the subject raises the request. On the other hand, the investigators can terminate the study for the participant at any time during the study. If a subject develops any kind of condition that meets the exclusion criteria during the study, or if the patient’s safety is compromised, the study must be terminated immediately.
Preoperative visit and evaluation, informed consent form
All patients scheduled for hip surgery will be screened on the day of hospitalization. We will take the general information about the patient, current and past medical history. We will also assess the patient’ eligibility based on the pre-determined inclusion criteria, and exclusion criteria. For the eligible patient, the clinical research coordinator will present the “informed consent form” to explain our study in details, and inform the subject that he is free to withdraw his consent from this trial at any time. Written informed consent form shall be obtained from each subject.
Outcome measures
Primary outcome
i. The resting numerical rating scales (NRS) pain scores at 30 min, 2 h, 6 h, 24 h, 48 h, and 72h after surgery.
ii. The incidence of PONV.
Secondary outcomes
- Postoperative NRS pain score on movement during 3 days after operation.
- Time from the end of operation to the first onset of PONV (hours).
- The severity of first PONV and the most severe PONV, which is scored from 0 to 10, and 0 represents no PONV at all, and 10 represents very severe PONV.
- In-hospital complications, which are divided into five grades:
- GradeⅠ:Recovery after temporary treatment, e.g., postoperative anxiety, insomnia.
- Grade Ⅱ:Prolonged hospitalization, e.g., pulmonary infection requiring antibiotics or other treatment, surgical wound infection requiring wound debridement.
- Grade Ⅲ:Life threatening complications requiring intense treatment during hospitalization, and resulting in good functional recovery e.g., dialysis therapy for acute renal insufficiency, mechanical ventilatory support for respiratory failure, or postoperative bleeding requiring re-operation.
- Grade Ⅳ:Life threatening complications resulting in significantly decreased quality of life, e.g., myocardial infarction, stroke that left with paralytic limbs.
- Grade Ⅴ:All-cause mortality by 30 days after operation, which is defined as a secondary outcome.
- Range of motion of hip joints during 3 days after operation.
- Straight leg raising time, defined as the time from the end of operation to the time that patient can raise his affected lower limb by himself (Unit: hour).
- Groundexercise time, defined as the time from the end of operation to the time that patient can do the ground exercise by himself (Unit: hour).
- Mobilization time, which is defined as the time frame from the end of operation to able to walk without external assistance (Walking aids such as crutches can be used, unit: hour).
- Residual amount of drug in the analgesic pump.
- Postoperative analgesics requirement during 3 days after operation.
- Total in-hospital cost.
- Length of stay (LOS) in hospital, which is defined as time frame from the day of hospital admission to discharge from the hospital (Unit: day).
- Postoperative hospital stay, which is defined as time frame from the day of operation to discharge from the hospital (Unit: day).
- Readmission rate by 30 days after discharge from the hospital.
Statistical analysis
All outcomes will be analyzed by using SPSS18.0 software (Statistic Package for Social Science, SPSS, Inc., Chicago, IL, USA) with intent-to-treat analysis. The repeated measurement variance analysis will be used to compare the resting NRS pain scores at 30 min, 2 h, 6 h, 24 h, 48 h, and 72 h after the surgery, as well as NRS pain scores on movement from day 1 to day 3 after operation. The quantitative data will be tested for normal distribution, for example, the total hospitalization days, days of postoperative hospital stay, total hospitalization expenses, etc. The data in accordance with the normal distribution is presented as mean ± standard deviation, the analysis is performed by using the Student-t test. The data of the non-normal distribution is presented as the median (minimum, maximal), and the comparison between groups are performed by Kruskal-Wallis tests. The Z test will be used to compare the incidence of PONV, postoperative adverse reactions, and the incidence of re-admission within 30 days after surgery. The T test will be used to compare the dosage of postoperative analgesics which been used by the patients. P < 0.05 indicates a statistical difference.
For the primary outcome, we will perform subgroup analysis based on group differences. Subgroups are defined by age (<65, ≥65), gender (Male, Female), acute trauma (from injury time to surgery time <14 days) or chronic joint disease (disease course >1 year), and whether regional or local anesthesia (including epidural, spinal anesthesia, nerve block, and local infiltration) applied. Analyses will be performed for each subgroup in a similar way to the primary analysis. Forest plots will be draw based on the odds ratios and corresponding 95% confidence intervals.