Background: Primary Systemic Amyloidosis (AL) is a fatal disorder characterized by uncontrolled deposition of light chain derived amyloid with variable survival dependent on extent of organ involvement and degree of individual organ dysfunction. We previously demonstrated that troponin T (cTnT) and N-terminal fragment of brain natriuretic peptide (NT-ProBNP) together can allow prognostic stratification in AL. Uric acid (UA) is a marker of increased mortality in congestive heart failure and we examined its prognostic value in AL.
Methods: A cohort 1977 patients with AL seen at our institution and 293 patients with AL undergoing stem cell transplant (PBSCT) were studied retrospectively to examine the value of serum UA.
Results: The median OS for those with UA>8mg/dL was 9 months from diagnosis (95% CI; 7.4, 10.6) compared to 20.3 months for those with UA<=8mg/dL (95% CI; 17.8, 22.7), P<0.001 (Figure 1). As previously demonstrated both cTnT≥0.035μg/L and NT-ProBNP≥332ng/L were prognostic for OS. The median OS for patients (n=617) with a cTnT>0.035g/L was 6.7 months (95% CI; 5.0, 8.4) compared to 35.2months (95% CI; 29.4, 41.0) for those with cTnT<=0.035μg/L, P<0.0001. Similarly, the median OS for patients with NT-ProBNP > 332ng/L was 11.8 months (95% CI; 9.4, 14.2) compared to 36.2 months (95% CI; 26.7, 45.8) for those with NT-ProBNP <=332ng/L; P<0.0001. The prognostic value of UA was independent of cTnT and NT-ProBNP and together with these allowed a novel prognostic classification. Patients with none (Stage-I), 1 (Stage-II), 2 (Stage-III) or 3 (Stage-IV) of these risk factors (UA>8mg/dl, cTnT>0.035μg/L and NT-ProBNP>332ng/L) had a median OS of 36.6, 29.2, 11.1, and 3.6 months respectively (P<0.0001) (Figure 2). We also explored various predictors of OS in this large cohort of patients. The parameters that were significant for a shorter median OS included septal thickness>15mm, ejection fraction<50%, alkaline phosphatase>upper limit of normal, serum creatinine>2.0mg/dL, serum albumin<3.0gm/dl, 24-hour urine albumin>5gm, UA>8 mg/dL, cTnT>0.035μg/L and NT-ProBNP>332ng/L. We then performed a multivariate analysis with all these variables and those predicting for shorter OS were cTnT>0.035μg/L, serum uric acid>8mg/dL, and ejection fraction<50%. The stage determined at the time of PBSCT also predicted outcome with a median OS from PBSCT not reached in stages 1 and 2, 55 months for stage 3 and 16 months for stage 4 patients.
Interpretation: The data confirms the prognostic value of serum UA in AL and allows development of a novel and simple but powerful, reproducible staging system with applicability at all stages of AL.
Disclosure: No relevant conflicts of interest to declare.
This feature is available to Subscribers Only
Sign In or Create an Account Close Modal