FAbry STabilization indEX (FASTEX): an innovative tool for the assessment of clinical stabilization in Fabry disease

Clinical Kidney Journal, 2016, vol. 9, no. 5, 739–747

Authors: Renzo Mignani, Federico Pieruzzi, Francesco Berri, Alessandro Burlina, Benito Chinea,Maurizio Gallieni,Maurizio Pieroni, Alessandro Salviati and Marco Spada

Two disease severity scoring systems, the Mainz Severity Score Index (MSSI) and Fabry Disease Severity Scoring System (DS3), have been validated for quantifying the disease burden of Fabry disease. We aimed to develope dynamic mathematical model [theFASTEX(FAbrySTabilizationindEX)] toassess the clinical stability. A multidisciplinary panel of experts in Fabry disease first defined a novel score of severity [raw score (RS)] based on three domains with a small number items in each domain (nervous system domain: pain, cerebrovascular events; renal domain: proteinuria, glomerular filtration rate; cardiac domain: echocardiography parameters,electrocardiographparameters and New York Heart Association class) and evaluated the clinical stability over time. The RS waste sted in 28 patients (15 males,13 females) with the classic form of Fabry disease. There was good statistical correlation between the newly established RS and a weighted score (WS), with DS3 and MSSI (R2=0.914, 0.949, 0.910 and 0.938, respectively). In order to refine the RS further, a WS, which was expressed as a percentage value, was calculated. This was based on the relative clinical significance of each item within the domain with the panel agreeing on the attribution of a different weight of clinical damage to a specific organ system. To test the variation of the clinical burden over time, the RS was repeated after 1 year. The panelagreed on acut-off of a 20% change from baseline asthe clinical WS to define clinical stability. The FASTEX model showed good correlation with the clinical assessment and with clinical variation over time in all patients.