Study design and patients
We performed a single-blinded randomized controlled trial (NCT04042948) in the Department of Orthopaedics in our hospital from July 2019 to January 2020. Approvals were attained from the Ethics Committee of our hospital.
Samples were collected from patients who underwent lumbar operations in our hospital. We calculated the sample size with a 5% significance level and 80% power, and 78 patients per group were necessary. We finally decided to recruit 95 patients in each group to allow for dropouts. The patients were randomly divided into 2 groups using a computer-generated random number list: the study group and the control group. The patients in the study group received an acetaminophen pill (Tylenol, 650 mg) before the removal of the lumbar drainage tube, and another pill was administered at 8 p.m., while the patients in the control group did not receive acetaminophen. In this study, we controlled the time of drainage tube removal to be from 8 a.m. to 10 a.m. in the morning to ensure that the first pill of acetaminophen was taken in the morning.
The inclusion criteria were as follows: 1. adult patients conscious enough to provide informed consent; 2. clear diagnosis of degenerative lumbar spinal disease; 3. 1-2 surgical segments; 4. indwelling drainage tube after the operation; and 5. normal hepatic function. The exclusion criteria were as follows: 1. age < 18 years; 2. refusal to participate; 3. no indwelling drainage tube; 4. more than 2 surgical segments; and 5. abnormal hepatic function.
Protocol
Our team was divided into four groups. The first group’s responsibility was to screen and divide the patients into 2 groups, explain all the details to the patients and have them sign the conformed consent form if they agreed to participate. The second group comprised the attending physicians treating the patients. The third group collected clinical data, and the fourth group performed statistical analysis and wrote the manuscript.
All the included patients signed the conformed consent form on the day before the surgery, and the first group checked the computer-generated random number list, divided the patients into their corresponding groups and informed the second and third groups. The second and third groups were blinded to the patients’ allocation before receiving information from the first group. The first group was blinded to all the clinical messages from the patients postoperatively.
All operations were performed by skilled surgeons under general anesthesia and fluoroscopy control on a radiolucent operation table. The extent of the surgery depended on the severity of the disease, and all the patients had a closed wound drain placed below the deep fascia over the exposed dura before wound closure. No complications were discovered during the operations.
All patients received traditional treatment and care before the drainage tubes were removed. Our nurses recorded the patient’s daily temperature four times a day and the volume of the drainage collections once a day. All the data were uploaded to the medical system. When the recorded drainage volume of the in the last 24 h was below 50 ml [18], the attending physician decided to remove the drainage tube. All patients underwent laboratory tests for the concentrations of white blood cells (WBCs) and C-reactive protein (CRP) the day after drainage tube removal. For the study group, the extra intervention was a pill of acetaminophen before the removal of the drainage tube and another pill taken orally at 8 p.m. Our nurse team kept recording the patients’ temperatures four times a day and uploading the data to the medical system. The upper limit of a normal temperature was 37.7°C [11], so a temperature >37.8°C at any time within the first 24 h after the removal of the drainage tube indicated that a fever developed.
Data and observation
All the patients’ basic clinical information was collected, including age, sex, height, weight, body mass index (BMI), surgical segments, surgical time, blood loss, blood transfusion, American Society of Anesthesiologists (ASA) score, duration of drainage tube use, and total drainage volume.
The main observation index was temperature within the first 24 h after the drainage tube was removed. Once a fever developed, the data collection of that patient ended. The attending physician would start the diagnostic workups depending on the medical history and physical examination to identify the etiology of fever. The possible workups included chest X-ray, urinalysis, urine culture, and blood culture. The other observation indexes were the variations in WBC and CRP levels, the length of hospital stay from the removal of the drainage tube to discharge and the whole hospital stay.
Statistical analysis
A descriptive analysis was performed of the main study variables. All continuous data were tested for normality with the Shapiro-Wilk test. If the data were normally distributed, Student’s t test was used for analysis. The Mann-Whitney U test was performed for non-normally distributed data. For ranked data, the chi-square test was used for analysis. P < 0.05 was considered statistically significant. All analyses were performed with SPSS Statistics (version 24.0; IBM Corp., Armonk, NY, USA).