Validation of the Boston University staging system in AL amyloidosis

Objectives: We aimed to externally validate Lilleness' et al. Boston University (BU) prognostic score that replaced NT-proBNP with brain natriuretic peptide (BNP), which will allow centres without access to NT-proBNP to accurately stage and prognosticate AL amyloidosis. Patients/methods: Forty-four were identified that had BNP, NTpro-BNP and TnI taken simultaneously, with a mean follow up of 7.3 years. Median age of the 44 patients was 67 years and 27% were female, with 61% having cardiac involvement, and 61% having renal involvement. Results: Using the BU BNP-based staging system, we identified 12/44 (27%) of patients as stage I, 18/44 (41%) of patients as stage II and 14/44 (31%) of patients as stage III. This correlated closely with stratification via the Mayo score, with only one patient miscategorised (97.7% agreement, k = 0.98). Median overall survival for our BU stage I was not reached, stage II was 40 months and stage III was 5 months (long rank p = .0012). Mayo 2004 median overall survival was identical for stages I, II and III. Conclusion: We have provided external validation of the BU staging system, a novel prognostic scoring system incorporating BNP, instead of NT-proBNP, for AL amyloidosis.