Polyneuropathy in Kidney Transplant Recipients: Accuracy of a New Clinical Diagnostic Scoring System.

Background And Aims: Polyneuropathy is highly prevalent among kidney transplant recipients (KTR), underscoring the need for an accurate yet easy-to-perform diagnostic method to improve understanding and enable early identification of treatable cases.

Methods: This study included KTR at least 12 months post-transplant at the University Medical Centre Groningen, the Netherlands. An expert panel assessed polyneuropathy through a structured neurological examination, quantitative sensory testing, and nerve conduction studies. The modified Toronto Clinical Neuropathy Score (mTCNS) was obtained from all participants. Logistic regression analyses with Firth penalization validated the mTCNS components. A new model, the Kidney Transplant Neuropathy Score (KTNS), was developed through stepwise elimination. Diagnostic performance was evaluated with bootstrapped metrics and ROC curve analyses.

Results: Among 160 KTR, 91 (57%) were diagnosed with polyneuropathy. All 10 mTCNS components were univariably associated with polyneuropathy; numbness (OR = 4.9 [1.8-18.0]), tingling (OR = 2.5 [1.2-5.9]), impaired nociception (OR = 1.5 [1.1-2.2]), and reduced vibration perception (OR = 1.5 [1.0-2.4]) remained independently associated in multivariable analysis. The mTCNS achieved an area under the curve (AUC) in ROC analysis of 0.83 [0.76-0.89]. Two KTNS were derived: the KTNS, including history of numbness, tingling in the feet, and pinprick and vibration perception testing (AUC-ROC: 0.85 [0.79-0.90]); and the KTNS, replacing vibration perception with Achilles and patellar deep tendon reflex testing (AUC-ROC: 0.90 [0.85-0.94]).

Interpretation: The mTCNS is a valid diagnostic tool for polyneuropathy in KTR. The KTNS offers a simplified alternative based on key symptoms and sensory tests, with reflex testing included in the KTNS for settings with neurological expertise.

Trial Registration: ClinicalTrials.gov identifier: NCT04664426.