Pre-Surgical Risk Stratification Pathway

Perioperative Risk, Domain by Domain

1. ACC/AHA Stepwise Algorithm (Cardiology)

Five questions in order. The first affirmative answer ends the algorithm.

2. The 4-MET Question (Physician's Bedside Tool)

1 MET = 3.5 mL O2/kg/min. Surgery imposes 4-6 METs of stress on a patient who has no way of declining it, so a patient who cannot reach 4 METs in ordinary life has no reserve left for the theatre. That is why this one bedside question predicts better than most laboratory tests.

• Ask: "Can you climb one flight of stairs without stopping?" or "Can you walk 500 metres on flat ground without breathlessness?" If yes, functional capacity is likely ≥4 METs.
• 2024 refinement. Subjective clinician estimation of METs performs poorly. Where the answer is borderline or unclear, the 2024 ACC/AHA guideline prefers a structured questionnaire: a Duke Activity Status Index (DASI) score above 34 identifies patients at low risk.
• Self-reported inability to climb two flights of stairs is independently associated with postoperative complications.

3. RCRI (Lee Index, 1999), with the 2017 MACE Re-estimates

The critical threshold is 2: RCRI ≥2 with poor functional capacity triggers the decision for non-invasive stress testing. Two sets of percentages exist for the same score, and the tool prints the newer one.

The four percentages this tool prints are the re-estimates published by Duceppe and colleagues in the Canadian Cardiovascular Society guideline of 2017, reference 18 below.

Indian Context: South Asian patients may carry higher baseline cardiovascular risk due to the "thin-fat" Indian phenotype (visceral adiposity with normal BMI), higher insulin resistance, and earlier-onset CAD. A lower threshold for cardiac evaluation in Indian patients with metabolic syndrome, even where the RCRI reads reassuringly, is the practice this page follows. It was attributed here to Yaddanapudi et al.; that citation could not be traced on 28 August 2026 (see reference 17), so the recommendation is offered as practice rather than as a sourced statement until it is.

4. STOP-BANG and Non-Obese OSA

• Bands: 0-2 = Low; 3-4 = Intermediate; 5-8 = High risk for OSA. Score ≥3 mandates postoperative continuous pulse oximetry and caution with opioid analgesia.
• Non-obese patients. STOP-BANG was validated in predominantly obese Western populations. In non-obese or underweight elderly patients, common in India, a score of 3-4 driven solely by age + gender + hypertension has lower specificity for obstructive sleep apnoea. Consider central sleep apnoea or upper-airway anatomical factors rather than classic obesity-driven OSA. Clinical correlation is essential.

5. Caprini VTE and Indian Context

Surgery activates all three arms of Virchow's triad: endothelial injury, stasis, and hypercoagulability. VTE is the most preventable cause of in-hospital death.

• Which Caprini. This tool uses the 2005 model as adopted by the ACCP (Gould et al., Chest 2012): malignancy scores 2 points, and the highest-potency events (stroke, elective arthroplasty, hip or leg fracture, multiple trauma, spinal cord injury, each within 1 month for the acute events) score 5 points each. A patient listed for elective hip or knee replacement therefore starts at 5 points and is high risk before any other factor is counted.
• Indian data. The ASI guidelines recommend pharmacological thromboprophylaxis for Caprini ≥3. Venous thromboembolism was long held to be less common in Indians. That belief rests largely on unscreened series, and under-prophylaxis remains a real problem on Indian surgical wards. The comparable-incidence claim was attributed here to Agarwala et al.; that citation could not be traced on 28 August 2026 (see reference 18), so it is stated as the direction the evidence points rather than as a sourced figure until it is.

6. ARISCAT: Postoperative Pulmonary Risk

Postoperative pulmonary complications are as frequent as cardiac ones and carry comparable mortality, yet most preoperative pathways score only the heart. ARISCAT (Canet et al., Anesthesiology 2010) predicts the composite of respiratory failure, infection, effusion, atelectasis, pneumothorax and bronchospasm from seven routine items, every one of them already on the chart.

• Bands: <26 low risk (1.6% complications), 26-44 intermediate (13.3%), ≥45 high (42.1%).
• Intermediate and high scores justify preoperative chest physiotherapy training, incentive spirometry, smoking cessation, treating any active infection, lung-protective intraoperative ventilation, and a lower threshold for postoperative monitored care.

7. Frailty and Postoperative Delirium (Age 65+)

Frailty, not age, is the risk factor. The 2024 ACC/AHA guideline recommends preoperative frailty screening in adults of 65 and older; a validated instrument such as the Clinical Frailty Scale (Rockwood) takes under a minute.

• CFS 5 or more predicts mortality, complications, delirium, institutional discharge and prolonged stay better than chronological age does. It should prompt Comprehensive Geriatric Assessment, prehabilitation, and an explicit goals-of-care conversation before major elective surgery.
• Delirium prevention is mostly non-pharmacological: correct hearing and vision (bring the spectacles and hearing aid to the ward), reorientation cues, early mobilisation, night-time sleep protection, adequate analgesia while avoiding benzodiazepines, anticholinergics and pethidine, and daily screening with a brief instrument such as the 4AT.
• Frail patients also warrant scrutiny of every anticholinergic and sedative on the drug chart.

8. Medication Reconciliation (2024 Guidance)

• PCI to surgery timing (2024 ACC/AHA): balloon angioplasty, delay elective surgery ≥14 days. BMS, ≥30 days. DES, ≥6 months for elective surgery (12 months after ACS or complex PCI); time-sensitive surgery may proceed from 3 months after discussion with interventional cardiology.
• Interrupting a P2Y12 inhibitor before surgery: clopidogrel 5 days, ticagrelor 3 days, prasugrel 7 days, continuing aspirin. Premature DAPT discontinuation causes stent thrombosis with >30% mortality.

Neuraxial anaesthesia and anticoagulation. The risk is epidural haematoma, and the DOACs and the P2Y12 inhibitors need longer holds before a neuraxial block than before surgery itself.

9. Prehabilitation Checklist

10. What This Tool Does Not Print

• A preoperative biomarker result. BNP or NT-proBNP has a defined role in the 2024 guideline. In an elevated-risk patient with poor or unknown functional capacity, a BNP < 92 ng/L or NT-proBNP < 300 ng/L supports proceeding without further cardiac testing. An elevated value should prompt a team discussion and consideration of postoperative troponin surveillance. The tool does not score it.
• Postoperative troponin surveillance for myocardial injury after noncardiac surgery (MINS), which may be considered in elevated-risk patients even without symptoms.
• A sourced Indian figure for either the metabolic syndrome threshold or the venous thromboembolism incidence claim. Both citations were untraceable on 28 August 2026 and both statements are offered as practice rather than as sourced figures.
• A revascularisation recommendation. The CARP principle at the head of this page governs: test only where the result would change perioperative management.