# Preoperative Risk Assessment and Optimization

## Introduction

Preoperative risk assessment is a fundamental competency for the general surgeon. The goals are to identify patient-specific risk factors, estimate the likelihood of perioperative complications, guide shared decision-making, and implement strategies to optimize modifiable risk before surgery. A systematic approach to risk assessment reduces complications, shortens hospital stays, and improves patient satisfaction. This lecture covers validated risk assessment tools, organ-system-specific evaluation, and evidence-based optimization strategies.

## General Risk Assessment Tools

### ASA Physical Status Classification

| ASA Class | Description | Examples |
|-----------|-------------|---------|
| I | Normal healthy patient | No comorbidities |
| II | Mild systemic disease | Well-controlled HTN, BMI 30–40, current smoker |
| III | Severe systemic disease | Poorly controlled DM, COPD, BMI >40, ESRD on dialysis |
| IV | Severe disease, constant threat to life | Recent MI/stroke (<3 mo), ongoing ischemia, severe valvular disease, sepsis |
| V | Moribund, not expected to survive without surgery | Ruptured AAA, massive trauma, intracranial hemorrhage |

The ASA classification assigns patients to one of five categories. ASA I denotes a normal healthy patient. ASA II indicates mild systemic disease such as well-controlled hypertension or BMI of 30 to 40. ASA III indicates severe systemic disease, including poorly controlled diabetes mellitus, COPD, BMI above 40, active hepatitis, alcohol dependence, pacemaker, or end-stage renal disease on dialysis. ASA IV indicates severe systemic disease that is a constant threat to life, such as recent MI or stroke within 3 months, ongoing cardiac ischemia, severe valve dysfunction, sepsis, or disseminated intravascular coagulation. ASA V describes a moribund patient not expected to survive without surgery. The ASA classification is limited by its subjectivity, poor inter-rater reliability, and failure to account for surgical complexity.

### ACS-NSQIP Surgical Risk Calculator

The ACS-NSQIP Surgical Risk Calculator is the most comprehensive validated tool for preoperative risk estimation. It uses 21 patient-specific variables including age, BMI, ASA class, functional status, comorbidities, and procedure-specific CPT code to predict 30-day outcomes: mortality, overall morbidity, and specific complications including surgical site infection, pneumonia, cardiac events, renal failure, VTE, UTI, readmission, reoperation, and discharge destination. It facilitates informed consent, guides optimization efforts, and benchmarks institutional quality, and is available at riskcalculator.facs.org.

### Frailty Assessment

Frailty is a state of decreased physiologic reserve and increased vulnerability to stressors that independently predicts postoperative complications, length of stay, discharge to facility, and mortality. The Modified Frailty Index (mFI) is an 11-item index derived from NSQIP variables, with a score of 0.27 or greater associated with significantly increased complications. Clinical indicators of frailty include unintentional weight loss exceeding 10 pounds in the past year, self-reported exhaustion, low grip strength, slow walking speed, and low physical activity. Importantly, frailty is potentially modifiable through prehabilitation programs targeting exercise, nutrition, and psychosocial support.

<image>Infographic showing the major preoperative risk assessment tools arranged as a clinical decision framework: ASA classification for global risk, ACS-NSQIP calculator for procedure-specific risk prediction, frailty index for physiologic reserve, and organ-specific assessments (cardiac, pulmonary, hepatic, nutritional) with their respective validated scoring systems and cutoff values</image>

## Cardiac Risk Assessment

### Revised Cardiac Risk Index (RCRI/Lee Index)

The RCRI identifies six independent predictors of major adverse cardiac events (MACE): high-risk surgery (intraperitoneal, intrathoracic, or suprainguinal vascular), history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, diabetes requiring insulin, and preoperative creatinine above 2.0 mg/dL. The MACE risk stratifies accordingly: 0 factors carries a 0.4% risk, 1 factor 0.9%, 2 factors 6.6%, and 3 or more factors 11%.

### ACC/AHA Algorithm for Noncardiac Surgery

The ACC/AHA stepwise algorithm guides cardiac evaluation. The first step asks whether the surgery is an emergency; if so, proceed with perioperative risk reduction. The second step evaluates for active cardiac conditions including unstable coronary syndromes, decompensated heart failure, significant arrhythmias, and severe valvular disease, delaying surgery if present. The third step considers whether the surgery is low-risk, such as superficial, endoscopic, or cataract procedures, in which case one may proceed. The fourth step assesses functional capacity: if the patient can achieve 4 or more METs without symptoms, such as climbing a flight of stairs, walking up a hill, or doing heavy housework, one may proceed. The fifth step applies when functional capacity is poor or unknown: calculate the RCRI, and if 3 or more risk factors are present, consider pharmacologic stress testing and proceed if negative.

### Preoperative Cardiac Testing

A resting ECG is reasonable for patients with known cardiovascular disease, arrhythmias, or risk factors undergoing intermediate-to-high-risk surgery. Echocardiography is not routinely indicated but should be obtained for unexplained dyspnea, new murmur, suspected severe valvular disease, or heart failure assessment. Stress testing should only be pursued if results will change management; routine stress testing is discouraged. Nuclear or dobutamine stress echocardiography is used for patients unable to exercise. Preoperative coronary revascularization does not reduce perioperative cardiac events in stable coronary artery disease, as demonstrated by the CARP trial; it is indicated only for acute coronary syndrome or left main disease.

### Beta-Blocker Management

Beta-blockers should be continued in patients already taking them, as abrupt withdrawal increases cardiac events. New beta-blockers should not be initiated at high doses on the day of surgery, as the POISE trial demonstrated that while this approach reduced MI, it increased stroke and mortality. If beta-blockers are to be initiated, they should be started at least 1 week before surgery and titrated to a heart rate of 60 to 80.

## Pulmonary Risk Assessment

Risk factors for postoperative pulmonary complications include age above 60, COPD, current smoking, ASA class III or higher, functional dependence, congestive heart failure, obstructive sleep apnea, upper abdominal or thoracic surgery, prolonged surgery exceeding 3 hours, and general anesthesia. The ARISCAT score is a validated tool for predicting postoperative pulmonary complications. Preoperative pulmonary function tests are not routinely indicated for non-thoracic surgery but may be obtained for unexplained dyspnea or to guide operative planning in lung resection.

Optimization strategies include smoking cessation a minimum of 4 weeks and ideally 8 weeks preoperatively, incentive spirometry education beginning preoperatively with a target of 10 breaths every hour while awake, ensuring COPD and asthma are well controlled with bronchodilator optimization, and screening for obstructive sleep apnea using the STOP-BANG questionnaire with consideration of preoperative sleep study and CPAP for high-risk patients.

## Hepatic Risk Assessment

| CTP Class | Score | Perioperative Mortality | Elective Surgery |
|-----------|-------|------------------------|-----------------|
| A | 5–6 | ~10% | Acceptable risk |
| B | 7–9 | ~30% | High risk, optimize first |
| C | 10–15 | ~80% | Prohibitive for elective surgery |

The Child-Turcotte-Pugh (CTP) score uses albumin, bilirubin, INR, ascites, and encephalopathy to stratify risk. CTP-A carries approximately 10% perioperative mortality, CTP-B approximately 30%, and CTP-C approximately 80%, making it prohibitive for elective surgery. The MELD score uses bilirubin, creatinine, and INR, with a MELD above 15 associated with significantly increased mortality and a MELD above 20 generally prohibitive for elective surgery. Optimization includes correcting coagulopathy, optimizing nutrition, controlling ascites, treating encephalopathy, avoiding hepatotoxic medications, and considering TIPS for refractory ascites before surgery.

## Nutritional Assessment

Malnutrition is present in 30 to 50% of surgical patients and independently predicts complications, particularly surgical site infection and anastomotic leak. Screening tools include the Malnutrition Universal Screening Tool (MUST) and Nutritional Risk Screening (NRS-2002). Key indicators include albumin below 3.0 g/dL, prealbumin below 15 mg/dL, BMI below 18.5, and unintentional weight loss exceeding 10% in 6 months. Optimization involves 7 to 14 days of preoperative nutrition support with oral supplementation preferred, and consideration of enteral or parenteral nutrition if caloric goals cannot be met orally. Immunonutrition is considered for major GI cancer surgery.

<image>Flowchart of the ACC/AHA stepwise approach to preoperative cardiac evaluation for noncardiac surgery, showing decision nodes for emergency surgery, active cardiac conditions, surgical risk level, functional capacity assessment in METs, and clinical risk factor count with final recommendations for proceeding to surgery versus further cardiac testing</image>

## Medication Management

Anticoagulant management requires holding warfarin 5 days preoperatively targeting an INR below 1.5, and DOACs are held 2 to 3 days depending on the agent and renal function. Bridging with LMWH is considered for high-risk mechanical valves and recent VTE. For antiplatelet agents, aspirin is generally continued for most non-neuraxial procedures, while P2Y12 inhibitors such as clopidogrel are held 5 to 7 days. Patients on dual antiplatelet therapy after coronary stenting require cardiology consultation for timing.

Diabetes medications require specific adjustments: metformin is held on the day of surgery, SGLT2 inhibitors are held 3 to 4 days preoperatively due to risk of euglycemic DKA, and insulin dosing is adjusted with basal insulin reduced to 50 to 80% of the usual dose. Patients on chronic corticosteroids require stress-dose steroids with hydrocortisone 100 mg IV followed by 50 mg every 8 hours for major surgery. Herbal supplements including garlic, ginkgo, ginseng, St. John's wort, and ephedra should be discontinued 1 to 2 weeks preoperatively because they affect bleeding and drug metabolism.

## Glycemic Optimization

Hemoglobin A1c above 8% is associated with increased surgical site infection, readmission, and mortality. The target is to optimize A1c below 8% and ideally below 7% before elective surgery when time permits. The perioperative glucose target is 140 to 180 mg/dL, avoiding both hyperglycemia above 200 and hypoglycemia below 70.

## Clinical Pearls

The ACS-NSQIP risk calculator is the best validated tool for procedure-specific risk prediction and should be used to guide informed consent discussions. Frailty is a stronger predictor of surgical outcomes than chronologic age and is potentially modifiable through prehabilitation. Routine preoperative cardiac stress testing is rarely indicated and should only be pursued if results will change management. Home beta-blockers should be continued perioperatively, but high-dose beta-blockers should not be initiated immediately before surgery. Preoperative nutritional optimization for 7 to 14 days in malnourished patients reduces complications even if it delays surgery.

## References

1. Fleisher LA, Fleischmann KE, Auerbach AD, et al. 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery. *J Am Coll Cardiol*. 2014;64(22):e77-e137.
2. Bilimoria KY, Liu Y, Paruch JL, et al. Development and evaluation of the universal ACS NSQIP surgical risk calculator: a decision aid and informed consent tool for patients and surgeons. *J Am Coll Surg*. 2013;217(5):833-842.
3. McIsaac DI, Bryson GL, van Walraven C. Association of frailty and 1-year postoperative mortality following major elective noncardiac surgery. *JAMA Surg*. 2016;151(6):538-545.
4. Devereaux PJ, Yang H, Yusuf S, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial). *Lancet*. 2008;371(9627):1839-1847.