Gastric cancer (GC) is a kind of gastrointestinal malignancy with high morbidity and mortality. A total of 18.1 million new cases and 9.6 million cancer deaths occurred worldwide during 2018. The number of new cases of GC in 2019 is estimated to be about 1.03 million and holds sixth place in the number of new cancer cases. More than half of all the new cases and deaths will occur in Asia.[1,2]
In China, many GC patients present at the clinic at an advanced stage or with metastasis. The technical and physical requirements of surgeons are high. However, Chinese surgeons usually need to complete more than 2 operations a day and the total operative time is long. Thus, this tests the physical strength of the surgeons and the surgeon's workload can be considerable.
The biggest factor in human error has recently been attributed to doctors’ fatigue, which led to the enactment of work-hours limitations. The work-hours limitations were brought into force in July 2003. The Accreditation Council for Graduate Medical Education recommended that work time should be limited to no more than 80 hours per week. Nevertheless, relevant research found that more than half of the medical workers work more than 80 hours a week.
Long working hours can lead to lack of sleep and fatigue in surgeons. Fatigue may result in loss of attention and affect surgical outcomes. Some studies suggest that technical skills may change at different time of the day. Therefore, fatigue and changes in the circadian rhythm of a doctor may decrease technical ability at different time. In recent research, the time-of-day is linked to prognosis after elective surgery,[5,6] especially in general surgery, vascular surgery, and cardiac surgery.[5,7–9] However, other studies have reported different results.[10,11]
At present, there is a lack of research on the correlation between the start time and the outcome of radical gastrectomy for GC. We hypothesized that the outcome of radical gastrectomy would vary with different surgical start time. The present study aimed to compare the operative and survival outcomes of patients who underwent radical gastrectomy at different start time.
2.1 Case selection and data acquisition
A retrospective cohort study of 117 patients who underwent radical gastrectomy in the First Affiliated Hospital of Soochow University from 2008 to 2012 was investigated (Fig. 1). All the information was collected from the Haitai electronic medical record database and the electronic anesthesia records. The definition of the start of surgery was the commencement of the operation (knife to skin) and the end of the operation was closing the incision. We categorized the start time according to the median time (before or after 11:23, the median start time) or 13:00 (operating room schedule 09:00–17:00). All cases were performed from Monday through Friday. Patients who received chemotherapy or radiotherapy, were emergency cases, were cachexic, or were multiple-organ resection cases were excluded. The Ethics Committee of The First Affiliated Hospital of Soochow University approved this study. Because the data were collected from the electronic medical records and had no personally identifiable information, the requirement to obtain informed consent was waived.
2.2 Peri-operative contrast indicators
To clarify the difference between the morning group and the afternoon group, perioperative indicators were compared. These included intraoperative complications (intraoperative organ injury rate), postoperative complications (abdominal abscess, anastomotic fistula, anastomotic stenosis, intestinal obstruction, gastroparesis, dumping syndrome, and postoperative gastric bleeding), postoperative hospitalization time, operation duration, estimated blood loss, preoperative and postoperative white blood cell count, and albumin count. The compared indices also included the patients’ gender, age, American Society of Anesthesiologists (ASA) score, tumor location, tumor size, and tumor node metastasis (TNM) stage. The TNM stage for GC was analyzed according to the 8th Edition of The American Joint Committee on Cancer Staging Manual. These covariables can help remove confounding bias at a later stage.
2.3 Statistical Analyses
The numerical data between the 2 groups were analyzed via Student t-tests. The classified data were calculated by the chi-squared test. The data were represented as the mean plus or minus the standard deviation for numerical variables and the percentage of nominal variables. P-values < .05 indicated significant difference. SPSS 22.0 was used for the statistical analyses.
3.1 Baseline and pathological characteristics
We conducted correlation analysis to investigate whether the baseline and pathological characteristics of the patients affected the surgeons’ scheduled operation start time. The results are summarized in Tables 1 and 2. There was no significant difference between the morning and afternoon group for gender, age, previous abdominal surgery, hypertension, albumin, tumor size, tumor invasion, lymph node metastasis, pathological TNM, nerve invasion, or vascular invasion (P > .05).
3.2 Intraoperative outcomes
As the results in Table 3 show, the surgical start time exerted a significant impact on the duration of surgery and the operative time in the morning group was generally longer than that in the afternoon group, regardless of start time before or after 13:00 (P = .008), or median start time (P = .016). In addition, during the radical gastrectomies, patients in the afternoon group lost significantly more blood than those in the morning group (P < .001). No statistical difference was found in the ASA score and type of resection between the morning group and afternoon groups (P > .05).
To further analyze the relationship between the start time of surgery, the estimated intraoperative blood loss, and the duration of surgery, we calculated the variation in trends in the amount of blood loss and the duration of surgery in different operation start times. The analysis revealed that later operation start time was associated with more blood loss and the operative time tended to decrease gradually with later start time (Fig. 2A and B).
3.3 Postoperative outcomes
Table 4 lists the results of the correlation analysis of the postoperative characteristics and the operation start times. Interestingly, we observed that patients whose surgery started after 13:00 resumed oral intake later than patients with earlier surgical time (P = .042). However, this did not significantly affect postoperative complications. The length of stay in the hospital after surgery was similar in the morning and the afternoon groups and in the before and after median time groups.
3.4 Survival outcomes
In the prognosis analysis, we found that the overall survival (OS) between the morning and afternoon groups or between the before and after median time groups were not significantly different (Fig. 3A and B). Subgroup survival analysis was also performed according to the type of resection and the total patients were divided into 3 subgroups. Contrary to our expectations, the afternoon distal gastrectomy group had a poorer prognosis than the morning group (P = .030) and the other subgroups did not differ from each other (Fig. 4A-F).
To further explore the reason behind the poorer prognosis in the afternoon distal gastrectomy group, we performed subgroup analysis. The entire cohort was subgrouped to reassess the risk and survival rates. The results indicated that OS was increased only in the distal gastrectomy morning surgery group and no other subgroups (Fig. 5).
GC is associated with high morbidity and mortality worldwide. In addition to early GC and metastatic GC (TNM IV period), the most effective treatment for GC is still surgery.[12–14] Many patients with GC are diagnosed at an advanced stage, which enhances the complexity of surgery to some degree. Workload and surgical complexity have been shown to contribute to surgeon fatigue. Because surgeon fatigue may affect surgical outcomes, this study aimed to analyze whether the outcomes of radical gastrectomy were related to surgical start time.
To explore whether start time was related to surgical outcomes, we analyzed the correlation between the surgical start time and intraoperative conditions, postoperative complications, and prognosis. The results revealed no statistical difference between the general condition and pathological features of the different time-of-day surgeries.
Similar to the results of previous studies, the start time of surgery had a significant impact on the duration of surgery and the operative time in the morning group was usually longer than in the afternoon group.[3,5,7,9] This may suggest that there is usually only 1 major operation scheduled in the morning. Surgeons may also feel more energetic and pace their procedure to use the available time (ie, more time available in the morning due to fewer procedures than in the afternoon). In addition, the estimated blood loss was generally higher in the afternoon group and patients who received surgery in the afternoon generally needed longer time to resume oral intake.
In our hospital, the operating room nurses take over for the daily workgroup at 17:00. In principle, the operating room schedule should not affect the surgeons, however, the surgeons might be affected by the psychological hint—“to rush to finish the operation” to some degree by the shift in nurses. In addition, no noon break might be an important reason for the perioperative differences related to fatigue of the surgeons in the afternoon. Lack of sleep and fatigue affect hand-eye coordination.[15–17] Sleep deprivation and fatigue can be caused by extended working hours and circadian rhythm disorders.[18–20] It has been reported that in general surgery, neurosurgery, cardiac surgery, orthopedics and gynecology, the surgical start time and operative time had significant impacts on the surgical results, which was largely attributed to the fatigue of the surgeons and changes in human circadian rhythm.[21,22]
However, the duration of postoperative hospitalization was similar between the morning and afternoon groups. And in the prognosis analysis, no difference in OS was found between the 2 groups. However, in subgroup survival analysis performed according to the type of resection, the OS of distal gastrectomy patients in the afternoon group was poorer and there was no difference between the other groups. Previous studies have suggested that differences in operation start time and the duration of surgery did not affect patient prognosis.[10,11,23] However, the results of the subgroup analysis in this study suggested that the start time of surgery may play an important role in prognosis. However, there were some limitations to this study. First, the outcome may also be related to the small sample size of the study. We avoided surgical techniques and treatment bias by including patients in the fixed treatment teams, but this led to insufficient sample size. Second, the number of operations a surgeon performed in 1 weekday was not listed as a parameter in this study and the performance of other team members, like fellows and nurses, was too difficult to include in the analyses. These limited the accuracy and significance of the subgroup analysis.
In summary, our results suggested that operation start time may influence surgical outcomes. Compared to patients who underwent radical gastrectomies in the morning, patients operated in the afternoon had more intraoperative blood loss, shorter operative time and longer recovery time of gastrointestinal function. There was also a significant difference in OS in the subgroup comparison of distal gastrectomy patients.
Conceptualization: Xinguo Zhu.
Formal analysis: Linhua Jiang.
Investigation: Bin Wang, Yizhou Yao, Xuchao Wang, Hao Li, Huan Qian, Xinguo Zhu.
Methodology: Xinguo Zhu.
Writing – original draft: Bin Wang, Yizhou Yao, Xuchao Wang, Linhua Jiang, Xinguo Zhu.
Writing – review and editing: Bin Wang, Xinguo Zhu.
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