Introduction
More than 330 million surgical procedures are performed worldwide every year. There are significant differences in the assessment of postoperative complications and mortality due to the heterogeneity of the design of postoperative outcome reports [1, 2, 3]. For example, about five million surgical procedures are performed annually in the UK and about 1 % of patients die within the first 30 postoperative days [4, 5]. Most perioperative studies use the 30-day mortality as a marker of adverse outcomes associated with surgical intervention [6].
Modern approaches to determining perioperative risk tend to focus on isolated determination of either the risk of death or the risk of specific complications, less often critical events. Postoperative adverse outcomes, such as infections, cardiovascular diseases, pulmonary complications, acute renal injury, etc., occur after every fifth surgical intervention [7]. The results of a large multicenter cohort study in the USA revealed a strong association between postoperative complications and decreased survival [8]. Studies show that 7–15 % of patients who underwent extensive surgery developed postoperative complications [9, 10]. In addition, the overall level of postoperative mortality varies from 0.79 to 5.7 % [11]. The presence of postoperative complications also affects the long-term outcome. The two-year mortality rate was almost 3 times higher in patients with a complicated postoperative period [12].
According to the Clavien Dindo Scale of Surgical Complications, postoperative complications are defined as any deviation from the normal course of the postoperative period, which means that the severity varies from non-life-threatening complications without long-term disability to fatal outcomes [13, 14]. Postoperative complications can have a serious impact on a particular patient, potentially leading to a decrease in both the quality of life and the functional capabilities of the body [9]. And from the point of view of society, these are additional costs for healthcare, treatment in the intensive care unit (ICU), repeated surgery or re–hospitalization [15].
According to the National Confidential Enquiry into Perioperative Deaths (NCEPOD) report [16] “Knowledge of Risk”, the risk of death after surgery compared with the absence of disease was about two times higher in patients with respiratory diseases, coronary heart disease, type 2 diabetes mellitus and oncological diseases. It was three times higher in patients with cerebrovascular diseases, type 1 diabetes mellitus and arrhythmias and five times higher in the presence of congestive heart failure and confirmed cirrhosis of the liver. Regarding the postoperative treatment of patients who have undergone surgery, it is necessary to know which patients most often develop complications or death, and which factors contribute the most to this. To this end, in 2019, at the initiative of the Federation of Anesthesiologists and Resuscitators of Russia (FAR), in cooperation with the Federal State Budgetary Educational Institution of Higher Medical Education of Kuban State Medical University of the Ministry of Health of the Russian Federation, the national observational multicenter FAR study "The Role of concomitant diseases in the risk stratification of postoperative complications in abdominal surgery - STOPRISK" was initiated.
Objective
The purpose is to determine the frequency, structure, severity and timing of postoperative complications in patients after elective abdominal surgery based on the analysis of the STOPRISK database.
Material and methods
Twelve thousand patients from 38 centers representing 8 federal districts operated on abdominal and pelvic organs from July 1, 2019 to April 30, 2024 were included into the study. All centers were approved by local ethics committees prior to the start of the study. The patients signed a voluntary informed consent to participate in the study.
The study protocol [17] assumed the collection of information about all patients who met the inclusion criteria for the selected day.
Gender and age characteristics, comorbidity, methods of anesthesia and surgical intervention were recorded in all patients who met the inclusion criteria, In the postoperative period, 30-day complications and death were recorded according to the classification of the European Society of Anaesthesiology (ESA) and the European Society of Intensive Care Medicine (ESICM).
After excluding 522 (4.4 %) individuals due to missing or incomplete data, 11,478 operated patients were included in the subsequent analysis. Depending on the degree of operational risk, they were divided into low risk — 3630 patients (31.6 %), medium risk — 6481 patients (56.5 %), high risk — 1367 patients (11.9 %). Depending on the physical condition (ASA), they were divided into class 1 — 1664 (14.5 %), class 2 — 6000 (52.3 %), class 3 — 3814 (33.2 %). Of these, there were 7164 (62.4 %) women and 4314 (37.6 %) men.
The frequency and structure of complications were determined at the first stage of the study. At the second stage, the severity of complications was analyzed according to the Clavien-Dindo scale of surgical complications. At the third stage, the timing of complications was analyzed for 1–3, 4–5, 6–8, 9–15, 16–30 days, and after 30 days [18].
The Clavien Dindo scale of surgical complications divides postoperative complications from grades I to V, depending on the need for treatment. Grade I complications include deviations from the normal course of the postoperative period that do not require surgical, endoscopic, radiological, or pharmacological treatment, but may include the use of antiemetics, antipyretics, analgesics, diuretics, electrolyte solutions, physiotherapy, and wound bedside treatment. Grade II complications require pharmacological treatment beyond the permitted treatment for grade I, and also include blood transfusion or complete parenteral nutrition. Grade III complications require surgical, endoscopic, or radiological intervention, meanwhile, grade IIIa interventions are performed under local anesthesia and grade IIIb interventions are performed under general anesthesia. Grade IV complications are life-threatening, including complications from the central nervous system that require ICU treatment. Grade IVa complications indicate single organ failure (including dialysis), and grade IVb complications indicate multiple organ failure. Grade V complications death of the patient [19].
Research registration
The study is registered in an international database https://clinicaltrials.gov under the auspices of the All—Russian public organization "Federation of Anesthesiologists and Resuscitators" (chief researcher — I.B. Zabolotskikh), study number NCT03945968.
Statistical analysis
Statistical analysis was performed using the Excel application: selecting a pivot table in a layout, analyzing data in several tables in a pivot table report in Excel, and creating relationships between them in a Power Pivot table.
Results
Of the 11,478 patients, 521 (4.5 %) developed complications in the postoperative period. There were 71 (0.62 %) lethal outcomes. Isolated complications (1 complication) prevailed. They were noted in 332 patients (63.7 %). Combined complications (2 or more complications) were observed in 189 patients (36.3 % of patients). The most common complications in the overall population are intestinal paresis (1.4 %), wound infection, postoperative bleeding, pneumonia — 0.79–0.83 %; anastomotic leakage — 0.58 %; acute kidney injury, acute respiratory failure (ARF) and arrhythmia — 0.46–0.55 each %; cardiac arrest with fatal outcome and postoperative delirium — 0.41 %, sepsis — 0.35 %, other complications were observed with a frequency of 0.3 % and lower. Thus, surgical, infectious, and respiratory complications were most common in patients in the overall population (table 1).
| Adverse outcomes | Total number | Рercentage of total complications |
|---|---|---|
| Cardiac: | ||
| Arrhythmias | 53 | 0.46 |
| Non-fatal cardiac arrest | 5 | 0.04 |
| Cardiac arrest followed by death | 47 | 0.41 |
| Cardiogenic pulmonary edema | 8 | 0.07 |
| Acute myocardial infarction | 13 | 0.11 |
| Pulmonary embolism | 11 | 0.10 |
| Acute cerebrovascular accident | 4 | 0.03 |
| Respiratory: | ||
| Acute respiratory distress syndrome | 33 | 0.29 |
| Pneumonia | 91 | 0.79 |
| Acute respiratory failure | 63 | 0.55 |
| Reintubation due to acute respiratory failure | 35 | 0.30 |
| Infectious: | ||
| Wound infection | 95 | 0.83 |
| Sepsis | 40 | 0.35 |
| Cerebral: | ||
| Postoperative delirium | 47 | 0.41 |
| Renal: | ||
| Acute kidney injury | 60 | 0.52 |
| Surgical: | ||
| Anastomotic leakage | 66 | 0.58 |
| Intestinal paresis | 161 | 1.4 |
| Postoperative bleeding | 92 | 0.8 |
| Wound dehiscence | 15 | 0.13 |
Figure 1 shows the structure of complications. A total of 939 complications were reported. The most common complications were: intestinal paresis — 161 (17.1 %), wound infection — 95 (10.1 %), postoperative bleeding — 92 (9.8 %), pneumonia — 91 (9.7 %), anastomotic leakage — 66 (7.0 %), acute kidney injury — 60 (6.4 %), ARF — 63 (6.7 %), less frequent arrhythmias — 5.6 %, cardiac arrest with fatal outcome — 5.0 %, postoperative delirium — 5.0 %, sepsis — 4.3 %, ARDS — 3.5 %, reintubation due to acute respiratory failure — 3.7 %, divergence of wound edges — 1.6 %, AMI — 1.4 %, pulmonary embolism (PE) — 1.2 %. Cardiogenic pulmonary edema, nonfatal cardiac arrest, and acute cerebrovascular accident (CVA) were rarely observed in 0.8 %, 0.5 %, and 0.4 %, respectively.
Fig. 1. The structure of complications (n = 939)
Figure 2 shows the severity of the complications. Grade 1 complications were observed in 27 cases (2.9 %), grade 2 in 330 cases (35.1 %), grade IIIa in 159 cases (16.9 %), grade IIIb in 80 cases (8.5 %), grade IVa in 188 cases (20.0 %), grade IVb in 108 cases (11.5 %), grade V in 47 cases (5.0 %). The severity of complications was mainly represented by: grade II for intestinal paresis, grade II and III for wound infection, wound dehiscence and arrhythmias, grade IV — delirium, sepsis, tracheal reintubation due to acute respiratory failure; grade I and IV — acute kidney injury and acute respiratory failure colspan="3". Thus, 92.1 % of complications were severe (grade II and higher), which, as a rule, required treatment of these patients in the intensive care unit.
Fig. 2. Severity of complications according to the Clavien-Dindo scale
The majority of complications (as shown in figure 3) developed on days 1–3 (344 complications — 36.6 %) and days 4–5 (286 complications — 30.5 %). One hundred thirty-four complications (14.3 %) were detected on days 4–8, 110 complications (11.7 %) on days 9–15, 50 complications (5.3 %) on days 16–30, and 15 complications (1.6 %) on days over 30.
As can be seen from Table 2, there is some heterogeneity in the timing of the development of various complications. Thus, among cardiac complications, arrhythmias were observed mainly on days 1–3, 4–5, and 6–8; nonfatal and fatal cardiac arrest, AMI, and PE in almost every time interval. The overwhelming number of cases of cardiogenic pulmonary edema and CVA were observed on the 1st–3rd day of the postoperative period. Among respiratory complications (ARDS, pneumonia, ARD), the largest number of complications were observed up to 8 days. Infectious complications (wound infection, sepsis) developed significantly on days 1–3 and 4–5, 9–15. Cerebral complications (delirium) and renal complications (acute renal injury) occur mainly on 1–3 days. Surgical complications (anastomotic leakage, postoperative bleeding, and wound dehiscence) were reported at all stages of follow–up, but mainly on days 1–3 and 4–5, and in 20 % of cases, wound dehiscence was also reported on days 9–15.
Fig. 3. Periods of complications
| Adverse outcomes | Number of complications | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1–3 days | 4–5 days | 6–8 days | 9–15 days | 16–30 days | Over 30 days | |||||||
| Аbs. | % | Аbs. | % | Аbs. | % | Аbs. | % | Аbs. | % | Аbs. | % | |
| Cardiac | ||||||||||||
| Arrhythmias | 35.0 | 66.0 | 10.0 | 18.9 | 6.0 | 11.3 | 2.0 | 3.8 | 0.0 | 0.0 | 0.0 | 0.0 |
| Nonfatal cardiac arrest | 1.0 | 20.0 | 2.0 | 40.0 | 0.0 | 0.0 | 1.0 | 20.0 | 1.0 | 25.0 | 0.0 | 0.0 |
| Fatal cardiac arrest | 11.0 | 23.4 | 6.0 | 12.8 | 6.0 | 12.8 | 10.0 | 21.3 | 8.0 | 16.7 | 6.0 | 14.6 |
| Cardiogenic pulmonary edema | 4.0 | 50.0 | 2.0 | 25.0 | 0.0 | 0.0 | 2.0 | 25.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Acute myocardial infarction | 4.0 | 30.8 | 2.0 | 15.4 | 2.0 | 15.4 | 3.0 | 23.1 | 2.0 | 15.4 | 0.0 | 0.0 |
| Pulmonary embolism | 6.0 | 54.5 | 1.0 | 9.1 | 2.0 | 18.2 | 1.0 | 9.1 | 1.0 | 9.1 | 0.0 | 0.0 |
| Acute cerebrovascular accident | 3.0 | 75.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 1.0 | 25.0 | 0.0 | 0.0 |
| Respiratory | ||||||||||||
| Acute respiratory distress syndrome | 13.0 | 39.4 | 6.0 | 18.2 | 7.0 | 21.2 | 5,0 | 15.2 | 1.0 | 3.0 | 1.0 | 3.0 |
| Pneumonia | 31.0 | 34.1 | 24.0 | 26.4 | 18.0 | 19.8 | 11.0 | 12.1 | 6.0 | 6.6 | 1.0 | 1.1 |
| Acute respiratory failure | 33.0 | 52.4 | 12.0 | 19.0 | 6.0 | 9.5 | 6.0 | 9.5 | 5.0 | 3.5 | 1.0 | 1.8 |
| Reintubation due to acute respiratory failure | 10.0 | 28.6 | 2.0 | 5.7 | 10.0 | 28.6 | 8.0 | 22.9 | 4.0 | 9.7 | 1.0 | 3.2 |
| Infectious | ||||||||||||
| Wound infection | 26.0 | 27.4 | 25.0 | 26.3 | 15.0 | 15.8 | 19.0 | 20.0 | 9.0 | 9.5 | 1.0 | 1.1 |
| Sepsis | 11.0 | 27.5 | 7.0 | 17.5 | 10.0 | 25.0 | 8.0 | 20.0 | 3.0 | 2.7 | 1.0 | 2.7 |
| Cerebral | ||||||||||||
| Postoperative delirium | 38.0 | 80.9 | 3.0 | 6.4 | 5.0 | 10.6 | 1.0 | 2.1 | 0.0 | 0.0 | 0.0 | 0.0 |
| Renal | ||||||||||||
| Acute kidney injury | 41.0 | 68.3 | 9.0 | 15.0 | 5.0 | 8.3 | 3.0 | 5.0 | 1.0 | 1.7 | 1.0 | 1.7 |
| Surgical | ||||||||||||
| Anastomotic leakage | 24.0 | 36.4 | 19.0 | 28.8 | 11.0 | 16.7 | 9.0 | 13.6 | 2.0 | 3.0 | 1.0 | 1.5 |
| Intestinal paresis | 0.0 | 0.0 | 136.0 | 84.5 | 17.0 | 10.6 | 7.0 | 4.3 | 1.0 | 0.6 | 0.0 | 0.0 |
| Postoperative bleeding | 50.0 | 54.3 | 15.0 | 16.3 | 11.0 | 12.0 | 11.0 | 12.0 | 4.0 | 2.2 | 1.0 | 1.1 |
| Wound dehiscence | 3.0 | 20.0 | 5.0 | 33.3 | 3.0 | 20.0 | 3.0 | 20.0 | 1.0 | 6.7 | 0.0 | 0.0 |
Discussion
The analysis of unfavorable outcomes of elective abdominal surgical interventions showed some differences from previously published results [20]. Among such severe complications as acute respiratory distress syndrome and pulmonary embolism, acute myocardial infarction with the development of cardiogenic pulmonary edema, acute cerebrovascular accident, with an increase in the analyzed sample of patients, a decrease in the frequency of occurrence was noted — 1.2 % (2-4 %), 2,3 % (2.6 %), 0.4 % (1 %), respectively. At the same time, 1 complication was noted in 63.7 % of patients, versus 74 %, 2 or more complications occurred in 36.3 % of patients, versus 26 %. Postoperative intestinal paresis accounted for 17.1 % of complications, as opposed to a quarter (25.57 %) according to the results of the preliminary assessment. The distribution of percentages of other complications did not differ significantly and ranged from 7 to 10 %.
In terms of the number of complications and mortality, the STOPRISK study demonstrated results comparable to those of a large-scale study by Mullen M.G. (2017), which included an analysis of 173.643 surgical procedures. During elective operations, complications were noted in 6.7 % of patients, and mortality was 0.4 % [21]. In the STOPRISK study, complications were reported in 4.5 % of patients with a mortality rate of 0.62 %.
A recent study compared the National Surgical Quality Improvement Program (NSQIP) with the study of surgical outcomes in Latin America (LASOS) and Africa (ASOS). Mortality from various causes in three studies did not exceed 2 %, while postoperative complications were almost 1.5–2 times higher in LASOS and ASOS (16–18 %) compared with NSQIP (10 %), and mortality was 2 times higher in LASOS compared with NSQIP, which allowed the authors to conclude that it is necessary to improve the standards of postoperative management of patients [22].
According to the Clavien–Dindo Scale of Surgical Complications, the majority (35.1 %) of complications identified in the STOPRISK study were classified as grade II, i.e. they can be treated with pharmacological agents. Complications requiring surgical correction under local anesthesia (grade III) were detected in 16.9 % of patients, and organ failure (grade IV) in 20 %, which is generally consistent with the data of the world literature [19]. There are indications that the number of complications and their severity are not significantly related to the type of surgical intervention [23].
In a large multicenter study carried out by Downey C.L. in 2023, the following complications according to the Clavien Dindo Scale of Surgical Complications were revealed in 19685 patients who underwent elective abdominal surgery: 54.5 % of patients had no complications at all (Grade 0), 16.0 % of patients had grade I complications, 18.5 % had grade II complications, 7.0 % had grade III, 2.7 % had grade IV, and 0.8 % were fatal (grade V). At the same time, relatively mild and moderate forms (I–II) were most common, while severe complications (III–IV) and deaths were less common [24]. Compared with the STOPRISK study, where the incidence of postoperative complications in 11,478 patients was 4.5 % (with a mortality rate of 0.62 %), there was a lower overall percentage of undesirable outcomes and a lower proportion of severe complications (grade III–IV) compared with the data of the British authors. The authors also studied how the severity of complications affected the quality of life within 12 months after surgery (according to the EQ 5D questionnaire). The results showed that an increase in severity on the Clavien Dindo scale of surgical complications correlated with a pronounced and persistent decrease in quality of life. The total loss of QALY per year for patients with grade I complications was approximately 0.012, for II — 0.026, for III — 0.033, and for IV reached 0.086 relative to those who did not have complications, which indicates the importance of complications and their role in the long term period. To what extent this relationship is expressed in the national cohort, we will probably learn from the results of another multicenter all-Russian study RuSOS [25] which design fully corresponds to the modern concept of perioperative risk [26].
Duraes L.C. et al. (2018) analyzed data from 2266 patients who underwent elective resections for stage I–III colorectal cancer. The study showed that 669 patients (30 %) had complications (at least one), and the remaining 1597 had no complications [27]. The authors classified patients with any undesirable phenomena according to the most severe degree of Clavien-Dindo recorded in them. As a result, 211 people had grade I complications, 176 had grade II complications, 198 had grade III complications, and 84 had grade IV complications. Thus, almost a third of the patients suffered postoperative complications of varying severity.
It should be noted that in the study of Duraes L.C. et al. (2018) more than 70 % of patients with complications belonged to ASA physical status III–IV, whereas only 33 % of patients with ASA III status were included in STOPRISK. Differences in the initial status of the analyzed patients, apparently, explain the revealed discrepancy in the results.
Limitations
The analysis revealed an uneven distribution of the severity of surgical interventions with a bias towards low-traumatic operations, which affects the frequency of analyzed outcomes and can lead to a distorted understanding of the patterns present in the population.
Not all possible outcomes were included in the protocol, which probably requires its correction and retrospective recovery of some of the data.
Conclusions
Isolated (1 complication) complications prevailed in the structure of complications (63.7 % of patients with complications), while combined complications (2 or more) were observed in 36.3 % of patients with complications. The most common complications in the overall population were intestinal paresis, followed by wound infection, postoperative bleeding, and pneumonia, while cancer and nonfatal cardiac arrest were the least common complications. Sixty-two point one per cent of complications were severe (grade III and higher), which usually required treatment of these patients in the intensive care unit. At the same time, two thirds of complications were recorded in the first five days of the postoperative period.
Disclosure. K.M. Lebedinskii — the President of the all-Russian public organization “Federation of anesthesiologists and reanimatologists”, I.B. Zabolotskikh — First Vice-President of the all-Russian public organization “Federation of anesthesiologists and reanimatologists”, A.I. Gritsan — Vice President of the all-Russian public organization “Federation of anesthesiologists and reanimatologists”. Other authors declare no competing interests.
Author contribution. All authors according to the ICMJE criteria participated in the development of the concept of the article, obtaining and analyzing factual data, writing and editing the text of the article, checking and approving the text of the article.
Ethics approval. The study was approved by the Independent ethical committees of the participating centers.
Registration of the study. The study was registered in the international database https://clinicaltrials.gov under the auspices of the All-Russian Public Organization ”Federation of Anesthesiologists and Reanimatologists” (principal investigator I.B. Zabolotskikh), study number NCT03945968.
