Multicentre versus single centre approach to rare diseases: The model of systemic light chain amyloidosis

Background. Early diagnosis and supportive therapy are important in primary systemic amyloidosis (AL). In 1986, a national network was started in Italy to increase the awareness of medical professionals, achieve early diagnoses, and provide locally qualified care. We compared the AL patient population observed at a referral center, Mayo Clinic, with that recruited through the Italian network. Methods. All the patients diagnosed with AL between 1988 and 1998 at Mayo Clinic or in any of the centers of the Italian Amyloidosis Study Group were included. Findings. The median survival of Italian patients was 30 months versus 12 months in the Mayo cohort (P < 0.001). Mayo Clinic patients were older (66.4 vs. 60.1 y, P < 0.001). In the Italian cohort, dominant kidney involvement was more frequent (49.3% vs. 27.8%, P < 0.001), while in the Mayo group more patients had dominant cardiac amyloidosis (37.4% vs. 27.8%, P = 0.03). Italian patients were more likely to have kidney involvement without heart involvement (43.7% vs. 19.6%, P < 0.001). Among Italian patients, 78.9% received alkylating agents versus 60.9% in the Mayo cohort (P < 0.001). The multivariate analysis showed that age, performance status, dominant heart involvement, ≥ 2 organs involved, and treatment with alkylating agents independently predicted survival. This study shows that AL patient populations may differ significantly between centers according to their accrual systems, with possible impact on treatment trials.