Serum uric acid: Novel prognostic factor in primary systemic amyloidosis

OBJECTIVE: To determine the prognostic value of serum uric acid (UA) in patients with primary systemic (light chain) amyloidosis (AL). PATIENTS AND METHODS: A cohort of 1977 patients with newly diagnosed AL seen at our institution between April 1, 1960, and August 1, 2006, and 293 patients with AL who underwent peripheral blood stem cell transplant between March 1, 1996, and October 1, 2006, were studied retrospectively to examine the value of serum UA. The prognostic value of several variables was examined using Cox proportional hazards models, and the survival time was estimated using Kaplan-Meier analysis; curves were compared using the log-rank test. RESULTS: Patients with UA levels greater than 8 mg/dL had a median overall survival of 9 months from diagnosis compared with 20.3 months for the remaining patients (P<.001). The prognostic value of UA was independent of the known cardiac prognostic markers cardiac troponin T (cTnT) and N-terminal propeptide of brain-type natriuretic peptide (NTProBNP). Addition of UA to these factors allows us to classify patients into 4 groups with significantly different outcomes. Patients with none, 1, 2, or 3 of these risk factors (UA, >8 mg/dL; cTnT, >0.035 ng/mL; and NTProBNP, >332 pg/mL) had a median overall survival of 36.6, 29.2, 11.1, and 3.6 months, respectively ( P<.001). Similarly, UA levels helped predict overall survival in patients undergoing peripheral blood stem cell transplant for AL and added to the value of cTnT and NTProBNP. CONCLUSION: The data confirm the prognostic utility of cTnT and NTProBNP in a large group of patients and highlight the value of serum UA in allowing better forecasting of probable outcomes for patients with AL.