Limited Invasive Protocol: Optimizing Diagnostic Modalities in Corticotropin Mediated Cushing Syndrome

Area of Science:

• Endocrinology
• Diagnostic Imaging
• Minimally Invasive Procedures

Background:

• Distinguishing Cushing disease (CD) from ectopic Cushing syndrome (ECS) often relies on bilateral inferior petrosal sinus sampling (BIPSS).
• A noninvasive approach combining biochemical testing and radiological imaging has been proposed as an alternative to conventional invasive strategies (CIS).
• Further validation is needed for noninvasive strategies to limit the role of BIPSS.

Purpose of the Study:

• To evaluate two limited invasive protocols (LIP-1 and LIP-2) as alternatives to CIS.
• To assess the ability of LIPs to reduce the need for BIPSS while maintaining diagnostic accuracy.
• To compare the cost-effectiveness of LIPs versus CIS.

Main Methods:

• A single-center study involving patients with corticotropin-dependent Cushing syndrome.
• LIPs involved high-dose dexamethasone suppression tests (cutoff >50% for LIP-1, >80% for LIP-2) and sella MRI.
• Selective computed tomography of the chest and abdomen was used before BIPSS in the LIPs.

Main Results:

• BIPSS could have been avoided in 62.3% (LIP-1) and 35.9% (LIP-2) of eligible patients, compared to 25.4% with CIS.
• Positive predictive values for CD were high: 98.9% for LIP-1 and 100% for LIP-2.
• Cost per patient was lower for LIP-1 ($602.21) and LIP-2 ($966.81) compared to CIS ($1107.78).

Conclusions:

• Limited invasive protocols (LIPs) are equally accurate alternatives to CIS for differentiating CD and ECS.
• LIPs offer a less invasive approach, reducing the reliance on BIPSS.
• The evaluated LIPs are more cost-effective than the conventional invasive strategy.