Permanence, cost and mortality related to surgical admissions by the Unified Health System

Objective to analyze the time trend of surgical admissions by the Unified Health System according to hospital stay, costs and mortality by subgroups of surgical procedures in Brazil. Method ecological study of time series. The variables surgical hospitalization, permanence, cost and mortality were obtained from the Department of Informatics of the Unified Health System. The trend analysis used the polynomial regression model. Results in nine years, 37,565,785 surgical admissions were recorded. The mean duration of surgical admissions was constant (p = 0.449); the mean stay (3.8 days) was decreasing and significant (p <0.01); the mean cost (389.16 dollars) and mortality (1.63%) were increasing and significant (p <0.01). In subgroups of eye, thoracic, oncological and other surgeries, the temporal evolution of surgeries was increasing and significant (p <0.05). In contrast, endocrine glands, digestive tract, genitourinary, breast, reconstruction and buco-maxillofacial surgeries showed a significant trend of decline (p <0.05). In the other subgroups, the trend was constant. Conclusion evidence shows the trend of surgical admissions in the last decade in the country and provide subsidies for the efficient elaboration of public policies, planning and management towards universal coverage in surgical care.


Introduction
Over the next 20 years, as a result of the epidemiological transition in many low-and middleincome countries, the need for surgery will increase continuously and substantially (1) . Estimated data on global surgical volume showed that 312.9 million surgical procedures occurred in 2012. Comparing this period with data from 2004, in eight years, there was a 38% increase in surgical volume, being more significant in countries with very low and low per capita expenditure in health, i.e., those who have invested $ 400 or less, per capita, in health care (2) .
Globally, in the last decade, investments in health systems have increased. Despite this, the effect of this investment on the volume of surgeries is little known (3) . In that direction, in 2013, a group of surgeons approached the editors of Lancet magazine to discuss surgery in the context of global public health, believing that the importance and role of surgeries in the health context were being neglected when compared to the other levels of health care (4) .
In response to this initiative, that magazine to meet the global demand for surgery. In order to achieve this goal, at the global level, the Commission has set as a goal to be met by countries to perform 5,000 annual surgical procedures per 100,000 people by 2030 (4) .
In Brazil, there is a shortage of available scientific evidence that discusses epidemiological data regarding surgeries that contemplate the different surgical specialties and their trend over the years (5) . In addition, scholars mention the scarcity of information on surgical volume in countries that can direct public policies to improve access to surgical care (1) .
In this sense, the present study was conducted to answer the following research question: In Brazil

Method
This is an ecological study of time series (6)  Brazil is a country of continental dimensions, composed of five regions, which are subdivided into 26 states and one Federal District. It is the fifth most populous country in the world and the fifth in regional and social inequalities (8)(9) . In relation to health, with the advent of SUS, the country became the largest in the world to have a public health system based on the principle of universality, equity and comprehensiveness (10) . It is estimated that the majority of the Brazilian population, approximately 80%, are SUS-dependent for actions related to health care (11) .
To obtain the data, access to DATASUS occurred  The time trend analysis was performed using polynomial regression models, considering that it has high statistical power and also because it is easier to formulate and interpret (12) . The polynomial model aims to find the curve that best fits the data, so as to describe the relationship between the dependent variable Y (surgical admission, length of stay, costs and surgical mortality), and the independent variable X (year of study). To deviate from the serial correlation between the terms of the regression equation, the variable year was centered in X-2012, since 2012 was the midpoint of the historical series.
As a measure of the accuracy of the model, the coefficient of determination was used (the closer R 2 is to 1, the more adjusted the model is). Initially, the simple linear regression model (Y = β0 + β 1X) was tested and, then, those with higher orders, with second (Y = β0 + β1X + β2X2) or third degree (Y = β0 + β1X + β2X2 + β3X3). The best model was considered the one that presented the highest statistical significance Because it is a study using data obtained from secondary sources, without identification of research subjects and whose access is in the public domain, there was no need of appreciation by the Ethics Committee for Research with Human Beings. Regarding the subgroups, eye, thoracic, oncologic surgery and other surgeries showed a significant upward trend (p <0.05). In contrast, surgeries of endocrine glands, digestive tract, genitourinary, breast, reconstruction and buco-maxillofacial tissues showed a significant trend of decline (p <0.05).

In
The others presented a constant trend, according to Table 1.
Overall, the mean hospital stay was 3.8 days. The highest mean length of stay (9.5 days) was in thoracic surgery. In contrast, eye surgeries had the shortest length of stay (0.6 days). In the trend analysis, the mean permanence was decreasing and significant (p <0.01). When analyzed by subgroups, the trend was increasing and significant (p <0.05) in head and neck surgeries, musculoskeletal and obstetric surgeries.
With the exception of reconstructive and breast surgery that showed a constant trend, the other subgroups showed a significant decreasing tendency (p <0.05), as shown in Table 2.      inhabitants/year (8) . This surgical volume was lower than the goal of 5,000 procedures/100,000 inhabitants/year established by the Commission to guarantee access to essential surgical and anesthetic care when necessary by the population (4) . Additionally, the average length of stay was 3.6 days and the mortality rate was 1.71% (8) .
Despite estimates of significant growth in demand for surgery (1) , this study showed that the temporal trend constant, falls short of the international guidelines that recommend the definition of strategies to increase the access and coverage of the surgical procedures considered essential (2,4) .
In addition, universal access and coverage to health are not satisfactorily guaranteed. Often, when demand is greater than the capacity of the public system, there is inadequacy of public financing for health. This situation constitutes one of the main problems of public health systems, being a permanent source of political and social discontent (13) .
Despite the progress made by the SUS in improving access to health care for a significant portion of the Brazilian population, it is still a developing health system that continues to strive to ensure universal and equitable coverage (14) .
A systematic review conducted in 2017 to analyze the effect of economic decline in the countries on surgical volume found that there was a reduction in surgical volume when economic indicators decreased, both in elective and non-elective surgeries (15) .
In the Brazilian context, despite the approximate four-fold increase in federal funding, since the beginning of the last decade, the federal budget for the health sector has not grown, which has culminated in financing, infrastructure and human resources constraints. In addition, other challenges arise due to changes in the demographic and epidemiological characteristics of the Brazilian population. In order to overcome the challenges faced by the Brazilian health system, a new financial structure and a revision of public-private relations are crucial. Therefore, one of the major challenges faced by SUS is of political order (14) .
Financing, public-private articulation and persistent inequalities cannot be solved solely in the technical sphere. The legal, normative and operational bases have been established. From now on, it is necessary to guarantee to the SUS its political, economic, scientific and technological sustainability (14) .
Regarding the subgroups of procedures in the different specialties, it was evidenced that in the thoracic surgery, the variables hospital stay and mortality rate presented the highest figures. A study carried out to evaluate the surgical mortality rate in the thoracic surgery department in a hospital in Porto Alegre found that thoracic surgery had a mortality rate that was considerably higher than the total surgical mortality.
In 2013, the overall surgical mortality rate was 2.62%, while in the thoracic surgery it was 9.22%. The authors suggested that most surgeries in this specialty is performed in patients with a wide variety of severe conditions, with high risk and emergency ratings that increase surgical morbidity and mortality (16) .
The subgroup of circulatory surgeries had the highest average cost of hospitalization (US$ 1,506.26).
Importantly, the aggravation of many cardiovascular diseases that will require surgical treatment could have been avoided with investment at the primary level (17) .  (19) .
In an attempt to improve access to cataract its continuity was discouraged (19) .
Regarding oncological surgeries, of the 15.2 million new cases of cancer in 2015, more than 80% needed surgery. In the world, by 2030, it is estimated that, annually, there will be a need of 45 million surgical procedures (20) .
Despite advances in the field of radiotherapy and chemotherapy, surgery is important in the prevention, diagnosis, curative treatment, treatment support measures, palliative treatment and reconstruction. In this sense, surgery is considered vital for the reduction of premature mortality due to cancer (21) . However, globally, less than 25% of cancer patients receive safe, accessible or timely surgery (20) . In this sense, in Brazil, only 9% of the total resources allocated to oncology are assigned to cancer surgery (22) .
In conducting this study, some limitations should be considered. In the system, the secondary data obtained may be underreported and contribute to information However, we believe that this study is a precursor in the production of knowledge about surgical admissions by SUS in the last decade with national coverage and that the generated evidence can contribute to filling the knowledge gap and scientific advance in this area.
Regarding the implications for the area of health and nursing, the scarcity of available evidence on the epidemiological aspects and trends of surgical admissions and surgeries by specialties in the national context (5,8) entails a vast field for the development of future research, since knowledge of these trends can be useful for the management, planning and distribution of resources for the health area (15) .
It is believed that the knowledge produced on the epidemiological data of surgeries performed in each country and its progression over the years is essential for defining strategies and priorities in public health policies (5) . In the field of nursing, the nurse