Prevalence and mortality rate of abdominal surgical emergencies in Sub-Saharan Africa: a systematic review and meta-analysis

Introduction Abdominal surgical emergencies remain prevalent in various healthcare settings, particularly in regions with limited access to basic surgical care, such as Africa. The aim of this literature review is to systematically assess publications on abdominal surgical emergencies in adults in sub-Saharan Africa to estimate their prevalence and mortality rate. Methodology A systematic review was conducted. The latest search was performed on October 31, 2022. We estimated the pooled prevalence with a 95% confidence interval (CI) for each abdominal surgical emergency, as well as overall postoperative mortality and morbidity rates. Results A total of 78 studies were included, and 55.1% were single-center retrospective and monocentric studies. The mean age of the patients was 32.5 years, with a sex ratio of 1.94. The prevalence of each abdominal surgical emergency among all of them was as follows: appendicitis: 30.0% (95% CI: 26.1–33.9); bowel obstruction: 28.6% (95% CI: 25.3–31.8); peritonitis: 26.6% (95% CI: 22.2–30.9); strangulated hernias: 13,4% (95% CI: 10,3–16,5) and abdominal trauma: 9.4% (95% CI: 7.5–11.3). The prevalence of complications was as follows: mortality rate: 7.4% (95% CI: 6.0-8.8); overall postoperative morbidity: 24.2% (95% CI: 19.4–29.0); and surgical site infection 14.4% (95% CI: 10.86–18.06). Conclusion Our study revealed a high prevalence of postoperative complications associated with abdominal surgical emergencies in sub-Saharan Africa. More research and efforts should be made to improve access and quality of patient care.


Introduction
Emergency surgery refers to surgical procedures that cannot be safely postponed without adversely affecting the patient's clinical condition.It is typically conducted urgently, often within a brief period after the patient's admission to the hospital, usually within hours.This situation presents a distinctive context compared to elective surgery, as patients undergoing emergency procedures require special monitoring due to their lack of preparation and the physiological disorders that can further compromise them in addition to the surgical stress [1].
Abdominal surgical emergencies remain frequent in practice regardless of the context.Africa represents one of the regions most affected by the lack of access to basic surgical care, particularly in emergency settings.In fact, it is estimated that 93% of its population does not have access to emergency surgery when they need it [1].
This represents a significant burden in addition to other public health emergencies, such as HIV, tuberculosis, and malaria.Abdominal surgical emergencies accounted for a large proportion of surgeries performed in African hospitals, with a frequency varying between 20 and 22.7% [2,3].
Patients with abdominal surgical emergencies, when compared to those operated on in a scheduled setting, have their risk of death multiplied up to five times [4].The factors that can explain this higher rate of complications in emergency surgery are: the lack of patient preparation in the context of urgency, acute physiological disorders caused by urgent pathologies such as sepsis, hypovolemia, and hydro-electrolytic disorders.Additionally, comorbid conditions that may be present in emergency patients are often not optimized, increasing the anesthetic risk of postoperative complications [4].
Furthermore, there is a significant lack of data in Sub-Saharan Africa.Indeed, the majority of these countries do not have national registries or audit systems to monitor surgical care and associated complications [6].
To improve the quality of care for patients and tailor risk assessment for our specific context, there is an urgent need for quality data on this topic [7].This will address the limited understanding of the burden of abdominal surgical emergencies and help identify areas for improvement .
To better understand this topic, we performed a systematic review to assess publications on abdominal surgical emergencies in adults in sub-Saharan Africa to estimate their prevalence and mortality rate.

Methodology
We conducted a systematic review to study abdominal surgical emergencies in adults in Sub-Saharan Africa.
The main objectives were to: • Determine the prevalence of each abdominal surgical emergency (appendicitis, bowel obstruction, peritonitis, strangulated hernias and abdominal traumas) in Sub-Saharan Africa; • Determine the pooled prevalence of postoperative mortality and overall morbidity associated with abdominal surgical emergencies in Sub-Saharan Africa.

Research strategy
The protocol of this systematic review was registered at https://www.researchregistry.com/(reviewregistry1771). Two individuals, AN and LT, jointly conducted the study search, inclusion, and data extraction.This review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [27].An extensive search was performed on the following online databases: • Pub Med/Medline and; • African Journal Online.
The keywords used in the search process included the following: • "emergency general surgery OR emergency laparotomy" OR "emergency laparotomy OR emergency general surgery, " • "Abdomen, Acute/surgery"[MeSH] and; • "Africa South of the Sahara" [MeSH].
The search was carried out using various combinations of these terms.Additionally, a supplementary manual search was conducted on the following search engines: ResearchGate and Google Scholar.Furthermore, we checked the references of all included articles to find relevant publications.The latest search was conducted on October 31, 2022.
The retrieved references were managed using Rayyan software [28].Zotero software was used to download the references, remove duplicates, and perform primary and secondary selection analyses.

Inclusion criteria
Using the PICOS framework (Patient, Intervention, Comparison, Results, Study type), the inclusion criteria were as follows:

Exclusion criteria
We excluded studies that described the following: where data on abdominal emergencies could not be extracted.
Letters to editors, literature reviews, and duplicated studies were also excluded.

Data extraction
The extracted data included study type, year of publication, country, total number of patients, age, sex, number of each surgical emergency, surgical site infection and mortality and overall morbidity rates.For data extraction of postoperative outcomes, we considered the following: • Surgical site infection: infection at the abdominal wound during the postoperative period, whether superficial or deep; • Overall morbidity: the total number of complications (of any type) among the total number of patients; • Mortality: the number of reported deaths among the total number of patients in the study, regardless of the evaluation period (at 30 days, 90 days, during hospitalization, or unspecified).

Quality assessment
The Newcastle-Ottawa Scale (NOS) (selection criteria and outcome criteria) was used to assess the quality of the included studies [8][9][10][11].
• A score of 6 was considered good quality.
• A score of 4 or 5 as moderate quality; and.
• A score of 3 or less was considered poor quality.

Risk of bias assessment
A funnel plot was used to depict publication bias using Jamovi software Version 2.4.1.0.A rank correlation test with Kendall's tau statistic was employed to detect asymmetry when p ≤ 0.05, indicating a publication bias.

Data analysis and statistical methods
Statistical analysis was performed using R Studio software Version 1.2.5042.Graphs and maps were created using Microsoft Excel.For qualitative variables, the number with their proportions were described.For quantitative variables, the mean and standard deviation were used.
A meta-analysis was conducted to estimate the combined prevalence with a 95% confidence interval (CI) for each abdominal surgical emergency and the overall mortality and morbidity rates in Sub-Saharan Africa.
Heterogeneity among the studies was tested using the I 2 test.A random-effects model was used when I 2 > 50%, and a fixed-effects model was used when I 2 ≤ 50%.

Results
We found 112 articles in the databases and 224 through manual internet searches.After removing duplicates, 198 articles were evaluated.We identified 79 studies on abdominal surgical emergencies over the explored period of 32 years (1981-2022).After excluding articles that did not meet the inclusion criteria, we had 78 articles for the qualitative synthesis, of which 75 were included in the quantitative synthesis.The PRISMA flow chart is illustrated in Fig. 1.

Study characteristics
In total, there were 38,187 patients with a range of 48 to 3,717 patients per study.The mean age of the patients was 32.5 years, with a range of 22.9 to 47 years.The sex ratio was 1.94, with 65.9% male (n = 17,656) and 34.1% female (n = 9,097).Most studies were retrospective (55.1%, n = 43).The quality of the studies was judged as good in 12.8% (n = 10), moderate in 50% (n = 39), and low in 37.2% (n = 29).
Table 1 and Table 2 summarize the characteristics of the different studies used for the literature review.
There was a progressive increase in the number of studies published over the years, with 55 studies (70.5%) published after 2015.
Figure 3 represents the trend in the number of publications on abdominal surgical emergencies in Sub-Saharan Africa over the last 32 years.

Meta-analysis
The heterogeneity was high accross all studies, and a random effect model was used for the meta-analysis.There was a high publication bias for the meta-analysis of outcomes, as represented in the funnel plot at Fig. 4. The results of the meta-analysis estimating the pooled prevalence of each abdominal surgical emergency and the postoperative complications are detailed in Table 3.

Discussion
Several research studies on abdominal surgical emergencies in Africa have been conducted; however, the data have often been reported in specific settings.The aim of this review was to assess the prevalence of each surgical emergency among all causes of abdominal surgical emergencies and to determine the prevalence of postoperative complications in Sub-Saharan Africa.This review included 78 research studies published over a 32-year period involving 38,187 patients.
In our literature review, acute appendicitis was the leading cause of abdominal surgical emergencies in Sub-Saharan Africa, with a combined prevalence of 30.0%(95% CI: 26.1-33.9).Our review encompasses 112 articles from 20 countries in sub-Saharan Africa.The majority of studies on this topic were conducted within a single country or institution.This shows how our pooled data appears to be representative, providing insight into the prevalence of appendicitis in sub-saharan Africa.Globally, it is the most frequent cause of digestive surgical emergencies.Its prevalence ranges from approximately 44.2% and 62.8% depending on countries [87,88].For a condition with well-codified treatment and not requiring a significant amount of resources, the associated mortality remains high.It was estimated in 2019 that out of 17.7 million cases worldwide, there were 33,400 deaths Table 2 Characteristics of studies included in the systematic review (n = 78) (B) [89].In addition, existing data suggest a mortality rate of 54 per 1000 appendectomies in Sub-Saharan Africa, compared to 3.03 per 1000 appendectomies in developed countries [90].This significant difference is mainly attributed to difficulties in accessing surgical care and diagnostic delays.
Our review revealed that acute intestinal obstruction had a prevalence of 28.6% (95% CI: 25.3-31.8)among abdominal surgical emergencies in Sub-Saharan Africa.It constitutes the leading cause of surgical emergencies in different studies, accounting for 43.2% in some studies [79].
The causes of intestinal obstructions differ in frequency depending on the geographical area.In developed countries, obstruction due to adhesions and tumors are predominant, while colonic volvulus is more prevalent in Sub-Saharan Africa [2,91,92].Associated mortality reached 9.2% in certain series in Africa, mainly due to long delays in seeking medical care and the occurrence of bowel necrosis [91].
Strangulated hernias had a pooled prevalence of 13,4% (95% CI : 10,3-16,5).With this important rate of emergency surgery for hernia, efforts should be made to improve the availability and accessibility of surgery for the entire population [93].This will help to prevent the occurrence of strangulation and reduce the risk of postoperative complications.A recent literature review on inguinal hernias in Sub-Saharan Africa showed that patients operated on in emergencies had a significantly higher risk of death than those operated on electively (OR = 47) [94].
Peritonitis was ranked third, with a prevalence of 26.5% (95% CI: 22.2-30.9).The etiologies are diverse and are particularly dominated by complicated appendicitis, ranging from 35.7 to 25.5% [95,96].With the improvement in medical treatment, including antibiotics and proton pump inhibitors, perforations due to gastroduodenal ulcers and typhoid fever remain less frequent as causes of peritonitis [97,98].The occurrence of complications mainly depends on the promptness of initiating treatment [97].
Traumas have a significant impact in terms of frequency on healthcare systems.In our review, abdominal traumas (penetrating and blunt) had a combined prevalence of 9.4% (95% CI: 7.5-11.3).The relatively lower prevalence of abdominal trauma among abdominal emergency surgeries, ranking 6th, may be attributed to advancements in nonoperative management.This leads to fewer surgical interventions due to trauma in abdominal surgical emergency cohorts.However, it is crucial to identify the factors influencing the outcomes of  abdominal trauma in Africa to enhance patient care and minimize morbidity and mortality rates [99,100].The combined overall mortality was 7.4% (95% CI: 6.0-8.8) in our literature review.Patients undergoing abdominal emergency surgery, when compared to other patients receiving elective surgery, have a higher risk of death (up to 5 times) [4].In addition, mortality related to surgical emergencies remains consistently high in the world's poorest countries, where it is estimated to be between 4.9% and 13.2% [4,5,9].To improve both the availability and quality of treatments, it is essential to have a detailed understanding of the treatments and associated outcomes for patients, particularly operative mortality.The Lancet Commission on Global Surgery recommends the compulsory assessment of postoperative mortality in all healthcare facilities by 2030 as one of the six measures to evaluate the safety of a country's surgical system [1,101].Analyzing factors related to early postoperative death would enable preventive measures to better plan treatment and postoperative outcomes.
The overall morbidity was 24.2% (95% CI: 19.4-19.0) in abdominal surgical emergencies in Sub-Saharan Africa.This high rate is particularly associated with the occurrence of postoperative infections, which are the main    complication with an estimated frequency of 14.4% (95% CI: 10.86-18.06).The high rate of complications could be mainly related to a lack of access to surgical care when needed.In fact, financial and geographic components have previously been identified as barriers in Sub-Saharan Africa [10,102].

Limitations and perspectives
This review primarily focused on published data collected from databases and excluded unpublished studies such as dissertations or reports, as well as certain data from nonindexed databases or paper-based journals.This exclusion may result in publication bias, as shown by funnel plots with statistically significant Kendall tau tests.
There is also a need for improvement and standardization in future studies to elevate the overall level of evidence and effectively guide health system policies.Furthermore, the review did not investigate additional important topics, such as the cost of surgical procedures and patient satisfaction.The I 2 test revealed significant heterogeneity, indicating that the included studies may not be comparable when considering design, sample size, patient characteristics, and follow-up.More than half of the included studies were retrospective, single-center studies.Also, due to the non-indexed nature of most articles, it is possible that some published articles were not identified in our search.
As a perspective, given that our review revealed a non-negligible prevalence of death and complications in abdominal surgical emergencies, future studies should be conducted with a more specific focus on exploring the factors associated with mortality and complications in abdominal surgical emergencies.This emphasis on understanding these factors can contribute to the development of preventive measures in health systems and patient management, aiming to effectively reduce the overall rate of deaths in such cases.
Despite these limitations, our review provides significant insights and an overall perspective on the state of research and practice in abdominal emergency surgery in Sub-Saharan Africa.This knowledge can be used to direct future research efforts and to improve the quality of care and identify areas for further improvement.

Conclusion
Our study suggested a high prevalence of complications, such as deaths and infections.Appendicitis is the main cause of these surgical emergencies.Therefore, it is essential to make efforts to improve access to and quality of patient care.With the relatively low quality of data and heterogeneity of studies, more research is needed to fully understand the quality of care and outcomes for patients undergoing these procedures.

Fig. 2
Fig. 2 Map of Sub-Saharan Africa showing the number of studies on abdominal surgical emergencies per country (n = 78)

Fig. 3 Fig. 5
Fig. 3 Trend in the number of publications on abdominal surgical emergencies in Sub-Saharan Africa (n = 78)

Fig. 6
Fig. 6 Forest plot estimating the pooled prevalence of overall morbidity

Table 1
Characteristics of studies included in the systematic review (n = 78) (A)

Table 3
Meta-analysis estimating the pooled prevalence of each abdominal surgical emergency and postoperative complications