The risk of mortality and morbidity could be accurately estimated using perioperative risk score systems

doi:10.21203/rs.3.rs-3459309/v1

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The risk of mortality and morbidity could be accurately estimated using perioperative risk score systems

https://doi.org/10.21203/rs.3.rs-3459309/v1

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Context
According to national guidelines, a mortality risk assessment should be performed on all patients undergoing emergency surgery at the time of admission. This will allow the hospital to assign the "high-risk" patient the proper seniority and level of care. Our goal was to determine whether perioperative risk scoring systems could reliably estimate the risk of death and morbidity.
Methods
86 consecutive emergency laparotomies had their mortality risk scores determined using pre-operative risk calculation techniques (ASA, Lee index) and post-operative risk calculation tools (POSSUM, P-POSSUM, and CR-POSSUM). Using the Clavien-Dindo classification, morbidity risk scores were computed using the POSSUM projected morbidity and compared to actual morbidity.
Results
In reality, the death rate was 10.5%. All laparotomies had average predicted risk scores of 26.5% for ASA, 2.5% for Lee Index, 29.5% for POSSUM, 18.5% for P-POSSUM, and 10.5% for CR-POSSUM.
Seventy-eight percent of the 67 laparotomies had complications. Most (51%) of the problems were categorized as non-life-threatening in Clavien-Dindo grades 2–3.
Compared to patients who projected a morbidity risk of less than or equal to 50%, patients with a POSSUM morbidity risk of greater than 50% suffered significantly more life-threatening complications (CD 4-5) (P = 0.01).
Summary
Because the ASA overpredicts mortality risk and the Lee Index underpredicts it, pre-operative risk categorization is still difficult. We propose that patients who need intensive care after surgery can be identified with greater accuracy by utilizing the CR-POSSUM for post-operative risk grading.
In conclusion
It is impossible to audit the fulfillment of national standards of care for the "high-risk" patient in a reliable manner in the absence of reliable risk scoring instruments that can be utilized at the time of hospital admission.

mortality risk prediction for emergency laparotomy

With mortality rates as high as 25%, the Royal College of Surgeons of England has determined that emergency surgical care delivery in England and Wales is currently subpar [1–2]. As a result, the college has provided guidelines that highlight the significance of early patient identification for those who are at high risk of dying. A consultant should be present during surgery for patients whose mortality is expected to be more than 5%. A consultant should examine patients with a mortality prediction of more than 10% within 4 hours of arrival, and Level 3 care should be provided after surgery [1], [3].

The 2011 study "Knowing the Risk" by the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) acknowledges the existence of multiple risk scoring tests (Table 1) [4], many of which are imprecise. Furthermore, a lot of these systems need data that isn't available at the moment the patient is admitted to the hospital, which is when the Royal College advises a risk assessment to be done. In spite of this, a lot of surgical departments use these kinds of risk-soring instruments prior to surgery, depending on anticipated results. It is far from ideal to score patients using instruments not intended for pre-operative usage, as in the case of this "best guess" method [5]. Therefore, if the criteria of the Royal College are to be followed, it is crucial to develop practical and precise methods for identifying the high-risk patient at the time of admission.

Table 1

Surgical risk scores categorized according to the necessity for intraoperative information and outcome measures .
Empty Cell	Scores predicting mortality	Scores predicting morbidity
Scores not requiring operative information	ASA1	ASA
	APACHE-II	APACHE-II
	Donati score	Goldman cardiac risk index
	Hardman index	Veltkamp score
	Glasgow aneurysm score	VA respiratory failure score
	Sickness assessment	VA pneumonia prediction index
	Boey score
	Hacetteppe score
	Physiological POSSUM
Scores requiring operative information	Mannheim peritonitis index	POSSUM
	Reiss index	P-POSSUM
	Fitness score
	POSSUM
	P-POSSUM
	Cleveland colorectal model
	Surgical risk scale

Techniques for risk scoring are examined in this series.

Our goal was to determine which risk rating techniques may best predict the observed morbidity and death of patients receiving emergency laparotomies at our facility between January and July of 2012. For use and comparison, we used two pre-operative risk ratings (ASA and Lee Index) and three post-operative risk scores (POSSUM, P-POSSUM, and CR-POSSUM). These haven't been contrasted in a group of emergency patients before. The Royal College of Surgeons report [1] and the NCEPOD report [4] both recommend the use of the ASA and Lee index as pre-operative instruments for risk assessment, and they are both readily calculable at the time of admission. For these reasons, they were selected. For the purpose of evaluating technologies that need more operational data, the POSSUM scores were used (Table 4, Table 5).

Table 2

Predicted mortality risk following major surgery treated as an emergency or urgent procedure

(adapted from Donati et al. [7]])
ASA class	Age < 50	Age 50–69	Age ≥ 70
I	1.6%	2%	0%
II	4.5%	8.2%	12.9%
III	12.4%	21%	30.6%
IV	29.6%	44.3%	56.8%

Index Lee

For the purpose of classifying the risk of significant cardiac problems after non-cardiac surgery, the Lee Index has been validated [8]. The scoring system outlined in Table 3 is used to calculate the score, which is composed of six independent points: insulin therapy for diabetes mellitus; high-risk surgery, defined as intraperitoneal, intrathoracic, or suprainguinal vascular procedures; ischemic heart disease, congestive heart failure, and cerebrovascular disease; and a pre-operative creatinine level greater than 176 µmol/l.

Table 3

Major cardiac problems and Lee class risk
Points	Class	Risk
0	I	0.4%
1	II	0.9%
2	III	6.6%
3 or more	IV	11%

Table 4

lists the physiological and operational factors that go into determining POSSUM and P-POSSUM scores.
Physiological	Operative
Age	Operation type (minor – complex major)
Cardiac comorbidity	Number of procedures
Respiratory comorbidity	Operative blood loss
ECG changes	Peritoneal contamination
Systolic BP	Malignancy status
Pulse rate	CEPOD
Haemoglobin
WBC
Urea
Sodium
Potassium
GCS

Table 5

lists the physiological and operational factors that go into CR-POSSUM scores.
Physiological	Operative
Age	Operation type (minor – complex major)
Cardiac failure	Peritoneal contamination
Systolic BP	Malignancy status
Pulse rate	CEPOD
Haemoglobin
Urea

ASO

Despite not being initially defined as a risk prediction score, the ASA (American Society of Anesthesiologists) categorization of fitness for surgery [6] has a quantitative correlation with the anticipated percentage post-operative mortality (Table 2) [7].

Possum and its alterations

It has previously been established that the POSSUM [9] (Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity) is a reliable indicator of post-operative complications [10]. To evaluate the risk of morbidity and death, it takes into account 12 physiological and 6 operative variables (Table 4).

Studies demonstrating that POSSUM over-predicted death led to the development of the Portsmouth POSSUM (P-POSSUM) [11] With a modified regression equation, it makes use of the same physiological and operational variables as POSSUM. A specific risk-adjustment scoring approach for mortality in colorectal surgery is called the Colorectal POSSUM (CR-POSSUM) [12] (Table 5). In order to investigate the possibility of a correlation between the CR-POSSUM scoring system and real post-operative mortality risk, even in patients without colorectal diseases, we chose to compute the score for all patients, including non-colorectal cases.

TECHNICS

Individuals with pain

A retrospective examination of 108 consecutive emergency laparotomies performed between January and July of 2012 was conducted. Laparotomies were carried out at the University Hospital Birmingham, a tertiary referral facility that also offers acute general surgery to the Birmingham community. Figure 1 lists the inclusion and exclusion criteria, which are derived from the National Emergency Laparotomy Audit (NELA). Up until the point of release or death, post-operative morbidity was documented. Incomplete data led to the exclusion of 22 instances, leaving 86 laparotomy cases in the research group.

.Information extraction

Medical records were used to get or figure out the following information: patient demographics; co-existing morbidity; ASA grade; Lee index classification; POSSUM, P-POSSUM, and CR-POSSUM grade; surgery indication and type; post-operative re-intervention; ITU admission; length of stay; postoperative morbidity (as defined by the Clavien-Dindo classification [13]); and 30-day mortality. The medical casenotes also revealed the amount of training that anesthetists and surgeons received in the operating room, the number of hours between surgical admission and documented consultant review, and the quality of post-operative care delivered. Our facility provided only level 1 care, which was ward-based care, or level 3 care, which was a location for critical or intense care. Level 2 care, or a high dependency unit, was not available.

Analyzing risks

Data from the admissions were used to calculate the ASA and Lee index. Based on the Donati et al. conversion table to % that only includes ASA grades 1–4 (Table 2), we employed the mortality risk prediction for ASA grade 4 in cases where patients had six laparotomies and an ASA score of 5. With the aid of the internet calculator http://www.riskprediction.org.uk/, post-operative POSSUM morbidity and mortality risk scores were determined.

Analysis using statistics

By using predetermined cut-off points of the POSSUM morbidity prediction percentage, the number of cases in low- and high-risk groups was compared using Fisher's exact test.

2.5 The seniority of care audit

The Royal College's standard, which states that patients with a mortality risk score of more than 10% at admission should get a consultation with a consultant surgeon within four hours of admission, was used for this part of the study. When it came to 49 new admissions, we audited this quality of care for patients whose ASA and Lee Index suggested a mortality risk of more than 10%. An audit of the royal college criteria was deemed inappropriate in the remaining 37 patients, 23 of whom had emergency laparotomies after elective surgery, 8 of whom had been initially hospitalized under a different specialty, and 6 of whom had re-laparotomies after emergency laparotomies. The rationale behind this is that before their decline or transfer from another specialty to the surgical department, these 37 patients were previously admitted and had undergone a consultation.

OCTAVIA

Based on the predetermined criteria for exclusion, 43 women and 43 men underwent 86 emergency laparotomies. A range of 19 to 86 years old made up the median age.

Gastrointestinal perforation (number 21), non-malignant intestinal obstruction (number 16), anastomotic leak/iatrogenic (number 13), malignancy (number 8), hemorrhage (number 6), bowel ischaemia (number 5), and other reasons (17) were present at the time of surgery.

Estimates of results

The five approaches' predictions of risk varied greatly from one another (Fig. 2). All patients had the following average anticipated mortality percentage risks and Lee Index of life-threatening morbidity risk: ASA: 26.5% (average ASA grade of 3), Lee Index: 2.5% (average Lee Index Class of 2.3), POSSUM: 29.5%, P-POSSUM: 18.5%, and CR-POSSUM: 10.5%.

For all patients included, the average estimated POSSUM morbidity risk score was 69.4%.

Observed results

Nine deaths (10.5%) occurred within 30 days following laparotomy. The range of days between the operation and death was 1–29, with 18 being the median. Seven more hospital fatalities occurred, with a median of 56 days (range 39–124) passing between the procedure and the death.

Complications followed 67 laparotomies. Clavien-Dindo grade 2 or 3 was assigned to most problems (51%; Table 6). Intra-abdominal collections (13.9%), chest infections (12.8%), and wound infections (8.1%) were the three most common complications after laparotomy (Fig. 3).

Table 6

Clavien-Dindo classification-based frequency of complications
Clavien–Dindo morbidity classification	Frequency of complications (number of laparotomies)
0	19
1	1
2	28
3a	8
3b	15
4a	4
4b	2
5 (Death)	9

A comparison between expected and actual results

The death rate

The CR-POSSUM, which was 10.5% equal to the actual mortality, was the mortality prediction score that best matched the observed 30-day mortality. POSSUM, P-POSSUM, ASA, and Lee-Index overestimated danger, while Lee-Index underestimated it. Symptomatology

A positive association was seen between the real CD morbidity and the POSSUM morbidity score, as illustrated in Fig. 4. Comparing patients with a predicted POSSUM morbidity risk of greater than 50% versus those predicted to have a risk of less than or equal to 50%, a significant increase in life-threatening complications (CD 4–5) was seen (P = 0.01). When a higher cutoff score was selected, like 85% (P = 0.0001) (Fig. 5), this disparity significantly increased.

Duration of the visit

Predicted POSSUM morbidity ratings and postoperative duration of stay were associated. In this investigation, the median was 23 days. The length of stay (11 days) was substantially shorter for patients with a forecasted morbidity score of ≤ 50% than for those with a predicted morbidity risk of > 50% (26 days) (P = < 0.05). An examination of the Royal College's policies

After an acute hospitalization, 49 laparotomies were performed. Between being admitted to the acute surgical unit and having a consultant surgeon review, the time delay was, on average, 15 hours (range: 1–88 hours). Based on the ASA and Lee Index, respectively, 30 and 2 of these acute cases were anticipated to be high-risk (above 10%). Six of these cases (20%) resulted in a consultant evaluation within 4 hours (Table 7).

Table 7

4-hour review of the patient by a consultant
Empty Cell	> 10% Mortality (ASA)	> 10% risk (Lee Index)
Number of patients	30	2
Number seen within 4 Hours	6	0
Percentage	20%	0%

Approximately 80% of the 79 and 18 patients, respectively, who were categorized as having a risk level above 5% based on the ASA and Lee Index, underwent surgery in a theater with the presence of a consultant surgeon. Of these instances, 43 (or 50%) had consultant anesthetists present in the operating room (Table 8).

Table 8

Surgeon consultant and anesthetist in the operating room
Empty Cell	Total	> 5% ASA	> 5% Lee Index
Number of laparotomies	86	79	18
Number with consultant surgeons	71 (83%)	65 (82%)	15 (83%)
Number with consultants anaesthetists	43 (50%)	38 (48%)	12 (67%)

Thirty-three patients received Level 3 (intensive care), and thirty-one patients received Level 1 (non-intensive care) treatment right after surgery. Patients receiving Level 3 care had an average estimated risk that was at least double that of patients receiving ward management, according to all prediction techniques (Fig. 6).

According to the guidelines, an acute surgical unit admission should include a risk assessment of the emergency surgical patient. Risk scoring tools can help the clerking doctor identify patients who need urgent review by the consultant (less than four hours), consultant supervision in the operating room, and level 2 or 3 post-operative care, as per the guidelines. This is due to the fact that at this time, a surgical team member who is relatively inexperienced frequently reviews the patient. On the other hand, the Royal College hasn't made it apparent which risk assessment instrument should be utilized. It has been proposed that the ASA and Lee Index are helpful pre-operative instruments. However, we discovered that the risk predictions made by these two tools were erroneous. Most of the time, the ASA grade was found to be 3 or 4, which indicates an overprediction of risk. The majority of emergency surgery cases have been reported to have ASA grades of 1 or 2, according to other, bigger research [14]. This discrepancy may arise from the exclusion of lower-risk emergency cases from our study cohort, including appendices. When documenting ASA, we also noticed differences in the anesthetist's judgments. Researchers have shown that the ASA grading method's use of the word "systemic disease" adds a level of subjectivity because some anesthetists might call an urgent surgical condition requiring an emergency laparotomy a "systemic disease" even though the patient already has another medical systemic disease [15]. This might have happened in our study since higher-risk conditions were typically the reason for laparotomies. We view the ASA as a rough metric overall, and attempts to convert the ASA grade into % risk have proven to be intrinsically inconsistent. For instance, Donati et al. found that in patients with ASA grade 1, the percentage of risks decreased with age (Table 2). The low correlation between the ASA and real risk is confirmed by our research.

Although the Lee index is less subjective than ASA grading, it underpredicted risk in our group. Additionally, it was not created with the intention of accurately predicting mortality risk. Instead, its original purpose was to forecast the likelihood of serious cardiac problems, such as cardiac arrest. Based on these statistics, the Lee Index undervalues the true rates of death and morbidity after laparotomy, making it an ineffective risk prediction tool in real-world scenarios. Therefore, applying these recommended risk prediction techniques will not allow for the pre-operative identification of the high-risk patient. It is therefore impossible to fairly audit national standards for the "high-risk patient," given the stark disparities in the number of patients classified as high-risk by the ASA and Lee Index.

The P-POSSUM score at admission was used by the Mersey General Surgery group to predict post-operative risk in 494 surgeries (including appendectomy and hernia repairs) across 8 acute trusts. Three national guidelines were audited: level 2–3 treatment for high-risk patients and supervision by consultant surgeons and anesthetists. Of the 65 "high-risk" instances, only 46 percent satisfied all three of these requirements [16]. There are two issues with using P-POSSUM to identify high-risk patients, though. First of all, operational findings must be estimated when utilizing P-POSSUM scores at the time of admission. Second, we have shown that P-POSSUM ratings overestimate risk in our population.

The fact that a doctor assessed a minority (20%) of "high-risk" patients within four hours after admission raised concerns. However, these data have limits because they are based on documentation evidence, and it's likely that patients were reviewed by consultants or at least discussed with them without any documentation of that. For this reason, it is essential that all conversations with senior clinicians are documented in the patient's case records. Conversely, the presence of consultant surgeons in the operating room throughout the procedure was more positive than the presence of consultant anesthetists, who were present in only 50% of cases. According to the P-POSSUM score, high-risk patients had a lower percentage of consultant anesthetists present (66%), compared to consultant surgical presence (71%). This information was also discovered in the Mersey Surgical Group study described earlier. It could be argued that these figures ought to be the opposite. Considering that the patient's physiology plays a major role in determining their risk score and the necessity of critical care during surgery, having a consultant anesthetist present may be just as necessary or even more crucial.

The post-operative risk scores examined in this study, as opposed to pre-operative risk scoring techniques, might play a part in determining the proper degree of care for emergency surgical patients. The Royal College and NCEPOD have prepared a set of recommendations regarding the importance of raising the standard of post-operative care for high-risk patients. We found the CR-POSSUM to be the most accurate modified POSSUM score. Table 5 revealed that the CR-POSSUM was the most straightforward to compute and accurately represented actual risk, even in cases that were not colonic.

Less than one-third of emergency surgery patients in the UK are admitted to the intensive care unit (ITU) [17]. Furthermore, a higher risk of post-surgical death has been linked to delayed ICU admission [18]. In our patient series, a greater percentage (62%) of level 3 care was observed post-operatively, which could account for the reduced mortality rate in our cohort when compared to national statistics. The data suggests that patients were receiving Level 3 treatment adequately when comparing the patients who were admitted to the intensive care unit (ICU) with their retrospective risk score estimations (Fig. 6). When the CR-POSSUM was utilized as a risk predictor, there was an especially suitable association, with patients handled on the ward having a risk of less than 10%, which is the suggested threshold for ITU admission. Since admittance to the intensive care unit (ICU) following surgery depends on numerous factors, including patient bed prioritization and the opinion of the intensivist or anesthesiologist, we propose that an accurate and objective method of determining the necessity for ITU could be found in a widely-used scoring system like the CR-POSSUM.

Despite the comparatively low observed death rate in this series, there was 67% of any morbidity, as opposed to the 50% morbidity rate reported in the "high-risk surgical patient report 2011". A positive correlation was found between the actual morbidity and the single POSSUM score system (http://www.riskprediction.org.uk/) for predicting morbidity. The link between predicted and actual morbidity is more significant (P < 0.0001) when the threshold POSSUM score for predicting "life-threatening" morbidity, as indicated by a Clavian-Dindo rating of 4–5, is greater. As a result, the POSSUM morbidity score can accurately identify patients who may experience consequences that are either non-threatening or potentially fatal.

It has already been shown that P-POSSUM scoring is more accurate than POSSUM scoring [19]. According to earlier research, which focused mostly on elective colorectal surgeries [20], the CR-POSSUM rating method is the most accurate and easiest to use when compared to other POSSUM scores. However, the CR-POSSUM has not been demonstrated to be a more accurate risk predictor in a patient population that is exclusively emergency-related prior to this investigation.

The risk scores assigned to each patient were determined retroactively, allowing for the availability of operative information in every case, which is a significant drawback of this study. As previously said, if post-operative modified POSSUM scoring is to be used as a risk prediction tool at admission, then a "best guess" strategy must be employed in practice. A further constraint is the low volume of cases involving emergencies. The National Emergency Laparotomy Audit's (NELA) guidelines, which exclude laparotomy for cholecystitis and appendicitis, are a major contributing factor in this. We acknowledge another limitation: although the Royal College's guidelines mandate "on-admission" pre-operative risk grading, the most reliable risk prediction tools we found need operational data to be calculated. The lack of recommendations on the risk prediction tool to use, given that the majority of validated scoring systems require data unavailable at the time of admission, may be a point of criticism for the national guidelines. Additionally, one of the recommended instruments is the Lee Index, which predicts major cardiovascular mortality as opposed to all-cause mortality, even though it does not require operational data to be calculated. It's possible that surgical departments' low-risk rating compliance stems from these rules' ambiguity. Indeed, our organization does not currently have a standardized risk scoring approach. We believe that a large number of emergency surgical units in the UK are now unable to come to a consensus on a model to determine the mortality risk at the time of admission in order to direct care.

Pre-operative risk scoring techniques are inconsistent, imprecise, and hence untrustworthy when it comes to choosing the emergency surgery patient's post-operative care level and seniority of treatment. The Royal College does not provide guidelines regarding the best appropriate risk assessment methodology, but it does highly encourage risk assessment for all emergency surgery patients upon admission to the hospital. In this series, post-operative risk scoring techniques were more accurate; CR-POSSUM predicted the death rate that was closest to reality. Therefore, we propose that the CR-POSSUM may serve as a valuable tool to direct the post-operative level of care for patients having an emergency laparotomy. If matching the seniority and level of care for the high-risk emergency surgery patient is to be considered at the time of admission, we suggest evaluating additional risk prediction methods.

Acknowledgment is not applicable

Zagagic University's Academic and Ethical Committee gave this research their seal of approval in terms of ethics. All participants or their guardians provided their written, informed consent. According to the World Medical Association's ethical standard for testing on humans, the Helsinki Declaration, the research protocol complied.

Consent for publication is not applicable

Availability of data and materials: a database is available to the corresponding author. The database is available upon review and request. All authors have shared the database.

Competing interests

The authors declare they have no competing interests or financial disclosures.

Funding

No specific funds were received for this study

Authors Affilatiion

Hassan A. Saad¹,

Azza Baz²,

Mohamed Riad¹,

Mohamed E Eraky¹,

Ahmed K El-Taher¹,

Mohamed I Farid¹,

Khaled Sharaf¹

¹Surgical Department, Faculty of Medicine, Zagazig University, Zagazig City, Egypt.

²Surgical Department, Alahrar Teaching Hospital, Zagazig University, Zagazig City, Egypt.

Corresponding author: Hassan A. Saad, Telephone: (+20) 01221025689, ORCID:0000-0002-6242-7823. E-mail: [email protected]

Author contributions

HAS, ME: contributed to the conception and design of

MR. AKE organised the database and

performed the statistical analysis.

HAS,KS: wrote sections of the manuscript

and prepared tables.

MIF, AB: contributed to the manuscript.

revision and investigation.

All authors read, approved, and equally shared the submitted version

Authors information

Authors' email and billing addresses

Hassan A. Saad: -1

[email protected]

Zagagic City, Sharquia

12 Saad Zagloul, St. Egypt

Corresponding author

Postcode (PC): 44661

01221025689

Azza Baz-2

[email protected]

Zagagic City, Sharquia, Egypt,

13 Kawmia St.

Post code 55971

01226534689

Mohamed Riad-3

[email protected]

Zagagagic City, Sharquia, Egypt

,13 orbi st

Post code 55971

01277438642

Mohamed E Eraky-4

[email protected]

52 reiad St.

Post code 55971

01019598000

Ahmed k El-Taher-5

[email protected]

Zagagic City, Sharquia, Egypt,

13 Kawmia St.

Post code 55971

01226534689

Mohamed I Farid-6

[email protected]

Zagagic City, Sharquia, Egypt,

13 Kawmia St.

Post code 55971

01226534689

Khaled Sharaf-6

[email protected]

Zagagic City, Sharquia, Egypt,

25 Kawmia St.

Post code 55971

01019754434

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The risk of mortality and morbidity could be accurately estimated using perioperative risk score systems

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Abstract

Figures

BACKGROUND

Index Lee

ASO

Possum and its alterations

TECHNICS

Individuals with pain

.Information extraction

Analyzing risks

Analysis using statistics

OCTAVIA

Estimates of results

Observed results

The death rate

Duration of the visit

DISCUSSION

CONCLUSION

Declarations

References

Additional Declarations

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