SM LDLT RISK ASSESSOR: EXPLAINABILITY

 SM LDLT RISK ASSESSOR:

Evidence Base & Scoring Rationale

Volumetric & Steatosis Index (VSI)

Graft-to-Recipient Weight Ratio (GRWR)

The GRWR is a critical determinant of post-transplant outcomes, preventing both small-for-size and large-for-size syndrome.

·         Pass (≥0.8%): Generally considered safe, associated with low rates of small-for-size syndrome.

·         Marginal (0.6-0.8%): Increased risk, requires careful consideration and potential use of portal flow modulation.

·         Fail (<0.6%): High risk of graft dysfunction. Considered a relative contraindication (Hard Stop).

Functional Liver Remnant (FLR%)

Ensuring an adequate future liver remnant for the donor is paramount for their safety.

·         Pass (≥35%): Standard safe remnant volume.

·         Marginal (30-35%): Acceptable, but warrants caution, especially with other risk factors.

·         Fail (<30%): High risk of post-hepatectomy liver failure in the donor. Relative contraindication (Hard Stop).

Hepatic Steatosis

Macrovesicular steatosis is associated with increased risk of primary non-function and poorer graft regeneration.

·         Pass (<10%): Minimal risk.

·         Marginal (10-20%): Acceptable, but may impair graft function, especially with other insults.

·         Fail (>20%): High risk of poor graft function. Relative contraindication (Hard Stop).

Recipient Risk Index (RRI)

MELD-Na Score

While a predictor of waitlist mortality, very high MELD scores in LDLT correlate with higher post-operative morbidity.

·         Pass (<20): Standard risk.

·         Marginal (20-25): Increased risk of early allograft dysfunction and infectious complications.

·         Fail (>25): High risk profile, often considered for deceased donor listing first.

Liver Frailty Index (LFI)

LFI is an objective measure of functional status, strongly predicting post-transplant outcomes independent of MELD.

·         Pass (<4.0): Good functional status.

·         Marginal (4.0-4.5): Moderate frailty, associated with longer hospital stays.

·         Fail (>4.5): Severe frailty, high risk for post-op complications and mortality. Pre-habilitation recommended.

Recipient Psychosocial Support

Strong social support is crucial for medication adherence, follow-up, and managing post-transplant challenges.

·         Strong: Low risk.

·         Limited/None: Higher risk for non-adherence and complications.

Donor Technical Complexity Index (DTC)

Portal Vein Complexity Index (PVCI)

Anatomical variations of the portal vein can significantly increase the complexity and risk of the donor hepatectomy.

·         Pass (Nakamura A): Standard bifurcation, straightforward procedure.

·         Marginal (B, C): Trifurcation or early branching requires more complex dissection.

·         Fail (D, Rare): Complex venous drainage patterns pose significant risk to the remnant graft and donor safety.

Arterial Complexity Index (ACI)

Hepatic artery variants (Michels classification) can complicate reconstruction and increase risk of thrombosis.

·         Pass (I, II, III, V, VI): Generally require single, straightforward anastomosis.

·         Marginal (IV, VII): May require multiple or more complex reconstructions.

·         Fail (VIII, IX, X): High risk of arterial complications.

Venous Complexity Index (VCI)

Hepatic venous outflow is critical. Variants can lead to congestion in both the graft and the donor remnant.

·         Pass (Standard): Single RHV, common MHV/LHV trunk.

·         Marginal (Accessory IRHV): Requires reconstruction or venoplasty, adding complexity.

·         Fail (Complex variants): High risk to donor safety (e.g., S4 drainage to MHV) or recipient outcome (MHV dominant graft). Often a hard stop.

Biliary Complexity Index (BCI)

Biliary anatomy (Huang classification) is a major predictor of post-transplant biliary complications.

·         Pass (A1): Single duct, low risk.

·         Marginal (A2): Trifurcation, requires precise anastomosis.

·         Fail (A3, A4, A5): Anomalous drainage patterns significantly increase risk of leaks and strictures.

Sociodemographic Risk Score (SRS)

Insurance Status

Lack of insurance can create barriers to essential post-donation follow-up and care for unexpected complications.

Education Level

Education level can be a proxy for health literacy, impacting a donor's ability to navigate the complex medical system and adhere to post-operative instructions.

Caregiver Support

A dedicated caregiver is critical during the immediate post-operative recovery period for practical and emotional support.

Residence Stability

Unstable housing can pose a significant challenge to recovery and attending follow-up appointments.