To the best of our knowledge, there are few studies to explore outcomes of elective lung surgery patients and start time while many studies have explored the relationship between other organ surgery and outcomes. In this retrospective, a high surgery-volume center study of impact of start time and surgery outcomes, we found there was no difference in early start group and late start group concerning short outcomes and total hospital cost. Besides, we also revealed that late start also was not risk factor for longer postoperative duration, higher total hospital cost and longer operation time. This result was according with our primary hypothesis completely. By the way, complication incidence of lung surgery patients was decreased to an extremely low level in high surgery-volume center by all kinds of perioperative elaborate management and there were only 25 patients suffered postoperative complications in this study. Hence, we omitted to conduct multivariable analysis for postoperative complication owing to the extreme low sample. As for the cut-off time, we selected 4pm as some previous study,7, 10, 14 another reason for selection of this time was that related labour law defines routine work duration of 8 hours and surgeons begin work 8am in our hospital.
As for the most common question of patients before surgery “May I be the first one to receive surgery in surgery order of tomorrow?” And now we could definitely answer “it is not necessary” loudly from results of this study. All the outcomes and total hospital cost were comparable between two groups, there are several possible reasons including surgeons could work continually with strong will, have a rest between surgery interval and all the surgery team could keep concentrating on patient status insuring surgery safely. Among baseline characteristics comparison between two groups, all the variables were comparable that procedure of conduction of propensity-scored match was omitted. Among the outcomes, no significant differences were found in all the variables. Besides, it is interesting that total hospital cost in the early start group was prone to be higher than late start group while it was no statistical significance. This result further proved late start for elective lung surgery did not have any negative impact even towards to cost less than start early which strongly testified our primary hypothesis. Similarly, surgery start time did not impact cost, postoperative hospital duration and operation time in multivariable analysis, though start late was associated with high cost and prone to result in longer postoperative hospital duration in single variable analysis. In summary, no association was found between elective lung surgery stat time and any outcome.
In elective thoracic surgery, Bao and his colleagues also find a later start time has no impact on both short- and long-term outcomes for patients undergoing minimally invasive McKeown esophagectomy via a propensity-scored match study11. Besides, studies concerning elective cardiac surgery also find no association between start time and perioperative outcomes, operative mortality, length of stay and total hospital cost.10, 12, 13, 15 Studies above all agree same conclusion with this study, possible reasons including reasonable shift of assisted staff, sufficient supply of surgery related materials and surgeons’ strong will and concentration. However, some different voices do exist. A study enrolled 208 patients find lobectomy conducted in late in the week will significantly increase length of hospital stay than in early in the week.9 Yount et. al also find late start cardiac surgery will increase absolute and risk-adjusted mortality.5 Another study enrolled more than 100000 patients demonstrates that incidence of anesthetic adverse events are more higher in late start group (P༜0.0001) though bias exist in the study.7 Similar to these studies, a study from New England Journal of Medicine finds patients with serious diseases have higher mortality when they are admitted on a weekend day than weekday. 16 Besides, medical education studies of fatigue and sleep deprivation have also found surgical skills of residents could be affected by these unfavorable situations.4, 17 These studies believe these unfavorable outcomes resulted from all aspects including fatigue of both surgeons, anaesthetists and nurses and lack of sources. However, in large medical center like our center, sources of materials supply will always be sufficient, nurses and anaesthetists also have proper shift at fixed time, so outcomes in different level of hospitals could also be different.
There were several limitations existing in this study. First of all, as a retrospective study, inherent shortcomings could decrease the reliability degree of evidence. Second, a sample of about 400 patients was relatively small and more multi-center, large sample and prospective studies could be beneficial in future. Third, incidence of postoperative complication was too low to do further analysis for the relationship with start time of lung surgery. Forth, patients enrolled in this study contained different histology and different surgery approach which could result in bias, but the variables were comparable in different groups which made the results still reliable. Finally, this study only enrolled elective lung surgery, association start time and urgent or emergent lung surgery is needed further investigated in future.