What is the Apfel score and how is it used to assess the risk of postoperative nausea and vomiting (PONV)?

Apfel Score for Postoperative Nausea and Vomiting Risk Assessment

What is the Apfel Score

The Apfel score is a simplified 4-factor risk assessment tool that predicts postoperative nausea and vomiting (PONV) by assigning one point each for: female gender, non-smoking status, history of PONV or motion sickness, and postoperative opioid use. 1

The score ranges from 0-4 points, with each additional risk factor increasing PONV probability by approximately 20% 2:

• 0 risk factors: 10% PONV incidence 2
• 1 risk factor: 21% PONV incidence 2
• 2 risk factors: 39% PONV incidence 2
• 3 risk factors: 61% PONV incidence 2
• 4 risk factors: 79% PONV incidence 2

Clinical Validation and Performance

The Apfel score demonstrates moderate but acceptable discriminating power with area under the ROC curve values of 0.70-0.73 across multiple validation studies 3, 4. The score has been validated across different surgical centers and maintains predictive accuracy regardless of local surgical or anesthesiological circumstances 2. Research confirms that patients with Apfel score III experienced 59.7% PONV incidence and score IV patients experienced 91.3% incidence, closely matching predicted values 5.

How to Use the Score Clinically

Risk Stratification Algorithm

For patients with Apfel score ≥2 (two or more risk factors), prophylactic antiemetic therapy is strongly recommended 1, 2:

• Score 0-1 (low risk): Consider single antiemetic or no prophylaxis 1
• Score 2 (moderate risk): Administer combination of two antiemetics from different drug classes 1
• Score 3-4 (high risk): Administer 2-3 antiemetics from different drug classes 1

First-Line Antiemetic Classes

The ERAS Society guidelines recommend selecting from these six drug classes 1:

1. 5-HT3 receptor antagonists (ondansetron, tropisetron) 1
2. Corticosteroids (dexamethasone 4-8 mg at induction) 1
3. Dopamine (D2) antagonists (droperidol, metoclopramide) 1
4. Neurokinin-1 receptor antagonists (aprepitant for highest risk) 1
5. Antihistamines (promethazine) 1
6. Anticholinergics (scopolamine) 1

Each individual antiemetic provides approximately 25% relative risk reduction when used alone 1. Multimodal administration reduces PONV even further 1.

Additional Risk Reduction Strategies

Beyond pharmacologic prophylaxis, the following interventions reduce PONV risk 1:

• Use total intravenous anesthesia (TIVA) with propofol instead of volatile anesthetic gases 1
• Avoid nitrous oxide 1
• Implement opioid-sparing multimodal analgesia (epidural, regional blocks, non-opioid analgesics) 1
• Ensure adequate hydration with mildly positive fluid balance 1
• Consider carbohydrate loading preoperatively 1

Critical Clinical Pitfalls

If rescue antiemetic treatment is required for breakthrough PONV, you must administer a different drug class than what was used for prophylaxis 1. Using the same class for both prophylaxis and rescue therapy significantly reduces effectiveness 6.

The Apfel score predicts early PONV (0-24 hours) more accurately than late PONV (24-72 hours) 7. Patients with scores of 3-4 show significantly higher emetic symptoms in the first 24 hours despite prophylaxis, but late symptoms (24-72 hours) are low and unrelated to the initial Apfel score 7.

Why This Score Over Others

The Apfel score is recommended over more complex scoring systems (like Koivuranta or Palazzo scores) because simpler scores provide better discrimination and are more practical for clinical implementation 1. While the Koivuranta score showed marginally better predictive accuracy in one study (AUC 0.71 vs 0.70), the Apfel score's simplicity makes it superior for routine clinical practice 4. The score has been proven to reduce PONV significantly in randomized controlled trials when combined with specific therapeutic interventions 1.