Effectiveness of imaging studies in acute appendicitis: a simplified decision model

Area of Science:

• Medical Imaging
• Diagnostic Decision Making
• Health Economics

Background:

• Acute appendicitis diagnosis relies on clinical assessment, but imaging aids are increasingly used.
• Clear guidelines for employing computed tomography (CT) and ultrasonography (US) in suspected appendicitis are currently lacking.
• Non-invasive imaging modalities like CT and US offer potential benefits for diagnosing acute appendicitis.

Purpose of the Study:

• To develop a decision-analytic model for evaluating the effectiveness of US and CT in patients with suspected acute appendicitis.
• To establish critical threshold probabilities (ctp) for the selective use of US and CT based on clinical suspicion.
• To provide a framework for optimizing the use of imaging in acute appendicitis diagnosis.

Main Methods:

• A decision analysis model was constructed using published data.
• The model calculates critical threshold probabilities (ctp) for US and CT.
• Individual diagnostic decisions are guided by comparing ctp with the pre-test clinical probability of appendicitis.

Main Results:

• The calculated critical threshold probability for ultrasonography (US) was 0.58 (58%).
• The calculated critical threshold probability for computed tomography (CT) was 0.74 (74%).
• These values indicate that US is indicated when clinical probability is <58% and CT when clinical probability is <74%.

Conclusions:

• Selective, rather than routine, use of imaging studies (US and CT) is recommended for suspected acute appendicitis.
• The optimal decision threshold for employing imaging should be adapted to local clinical settings and resources.
• This model supports evidence-based, patient-specific decisions regarding imaging in appendicitis diagnosis.