The central hypothesis for surgical queue generation is the imbalance between demand and capacity. Nevertheless, observation of the behavior of queues raises other hypotheses. If the demand were continuously greater than the capacity, the queues would grow exponentially, but one observes stability when a certain number of patients is reached in most queues11. So, other hypotheses were proposed, such as the "Backlog" Theory, a period in which there was a marked imbalance between demand and capacity above expectation. This theory would support the proposal of corrective measures to adjust the waiting time in queues with a transient increase in capacity11. In the present work, we observed the behavior of the backlog as described and the importance of interventions to limit its growth and adjust the waiting time in the queue.
Loss of surgical schedules due to patient non-attendance, lack of clinical conditions for surgery, or lack of ICU or ward beds for postoperative care could also be confounders12. The factors arising from the patients were around 3 to 7% in the present study, consistent with what was observed by Hovlid et al.13. We reduced the impact of the lack of intensive care and ward beds through the intervention of the institution's Internal Regulation Nucleus (IRN)14.
The co-management of the queue with the elaborated criteria allowed the gradual reduction of the refractoriness of surgical specialties to list centralization and queue management. Teams can use long queues as an argument to get more appointments for their specialty2. Procedures considered less challenging or less "urgent" are postponed by list managers1. This phenomenon became known as "the inverse burden law of specialists"11. We minimized these factors helping to obtain the resources for the procedures for those requests in the centralized list, and the specialties began to appreciate the proactive management mechanisms implemented by the Administration.
Although surgical queues have a negative connotation, they ensure transparency of the system's liability to solve and enable planning interventions. Although the disproportion between production capacity and demand recognition is very variable between healthcare systems and regions of the same system, as is the case of the UHS, all are susceptible to rationing periods. We demonstrated how effective prioritization helped manage priorities during the COVID-19 Pandemic. Another advantage of surgical queues is scheduling according to the availability of resources, reducing the loss of surgical schedules due to lack of material, and better scheduling to ensure teaching. The opposition to these arguments is that a long surgical queue could cause harm to patients, in addition to anxiety and uncertainty about when the scheduling of the procedure.
The centralized queue management observed in this study showed an objective reduction in waiting time. Although the waiting time may be adequate for a given situation, the perception of time and acceptance of the waiting condition can generate dissatisfaction on the part of patients, leading to the search for internal or external administrative interventions or the search for the media. With the advent of information technology and social networks, some institutions seek to make the waiting process transparent by making the lists available on their websites. However, there is evidence that comparing queues made available by the institutions is difficult to interpret, as the management is peculiar to each institution15. Although data transparency is desirable, this process must consider Brazil's recently enforced General Data Protection Law.
Queue management must ensure the removal from the list of already operated patients or who no longer have an indication16. The internal audit has a proactive role, such as confirming the attendance of patients on the day of surgery, assessing whether the surgeries performed involved removing the patient from the queue, and relocating the surgical grid to avoid loss of schedules in case of unexpected cancellations.
In addition to these already implemented activities, there are other possibilities, such as establishing a pattern of acceptable queuing for each specialty and using artificial intelligence to identify predictors of this condition, allowing preventive action. Levy et al. point out the need to modify the paradigm of a list for managing waiting time to a tool that accompanies the preparation of patients for the surgical procedure17. It is noteworthy that the existence of a centralized queue management mechanism must have execution tools represented by the IRN or by case managers in order to guarantee the interventions.
The definition of an adequate waiting time for each type of surgery is still being determined. In the original conceptions of the British NHS, up to one year was accepted2. Currently, the waiting time between the referral of the patient and the beginning of his treatment for elective circumstances is 18 months. For Canada, there is a recommendation of 4 to 17 weeks4. The waiting time in the queue can and should be variable for each condition. With the development of waiting lists, several specialties, and their societies recommend the average waiting time considered acceptable18,19. Ballini et al. performed a systematic review to evaluate different strategies to reduce the waiting time for surgical procedures. The high heterogeneity of the collected data prevented the performance of a meta-analysis. However, the conclusions presented may help compare the individual conditions of each situation, even though they do not allow generalization20. However, there are no data for all types of surgery, and no established standard for the Brazilian reality.
The COVID-19 Pandemic had overwhelming implications for the world and Brazil, with a significant increase in directly related mortality21. In addition, the redirection of the hospitals' capacity to face the enormous challenge had the reduction of the installed surgical capacity. Undoubtedly, the need of health professionals to compose additional intensive care teams was the main reason, but there was also fear of patients undergoing elective procedures, amplified by the association of COVID-19 with higher perioperative mortality22.
Regardless of the most significant factor, the reduction in surgical capacity increased the backlog of surgeries23. Several institutions have described the most significant impact on surgeries whose delay implied less risk of life or loss of function24–26. Among these initiatives, the implementation of surgical lists or priority changes are cited as strategies27–29. We confirmed the prioritization of oncological surgeries as an efficient strategy when the institution faced a decrease in its general surgical capacity to cover all the Pandemic's demands.
This work is limited because external referral urgent surgeries were managed in another hospital, which does not occur in other services30. However, during the Pandemic, several elective surgeries on hold became emergencies, and there was a need to balance the demand daily. This could have mimicked in a fashion the competition between the programmed and the urgent in walk-in institutions.
The unified management of the surgical queue at a tertiary public hospital proved feasible and required the development of co-management principles. These principles allowed for reducing the median waiting time in the queue and prioritizing patients during the COVID-19 Pandemic to achieve institutional goals.
This is the first study of a centralized list and management of the surgical waiting queue in Brazil. The guidelines developed open the possibility of replication for other services and may contribute to national centralization, as observed in other countries.
Although the results are specific to the institution, they certify that the centralization of the list and queue management are essential strategies for managing surgical teams, internal auditing, and improving the performance of hospital institutions. Efforts to implement the list and the queue simultaneously affected the organization of resources and the provision and programming of services to the UHS manager, improving institutional results and, consequently, the region. In this sense, its constancy and improvement actively contribute to ensuring equity in the SUS.