A New Formula Consisting of the Initial Independent Predictors of All-Cause Mortality Derived from a Single-Centre Cohort of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Objective: In this study, we develop a new formula for predicting all-cause mortality in an ethnicity/region-specific cohort of antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Methods: We included 290 Korean patients with AAV in this study and retrospectively reviewed their medical records regarding clinical data at diagnosis and during follow-up. We introduce a new index, called the NFPM value after the initials of New Formula for Predicting Mortality, which we derived using the independent predictors of all-cause mortality obtained in the multivariable Cox proportional hazard analysis. The cut-offs of the parameters for mortality were determined using the highest or lowest tertile of each parameter according to its positive or negative association with all-cause mortality, respectively. Results: The median age was 60.0 years and 35.9% were male patients. Of the 290 patients, 39 died during follow-up (13.4%). In the multivariable Cox analysis, male sex, the five-factor score (FFS), and serum albumin were independent predictors of all-cause mortality. A new formula was developed as follows: NFPM = male sex (yes = 1 or no = 0) + FFS ≥ 2.0 (yes = 1 or no = 0) + serum albumin ≤ 3.2 mg/dL (yes = 1 or no = 0). We demonstrated that patients with a NFPM value ≥ 2 seemed to have an increased risk for all-cause mortality compared to those with a NFPM value < 2. Conclusions: This study demonstrated that it could be clinically useful and significant to develop a new formula to predict all-cause mortality using independent predictors in each different ethnicity/region-specific cohort of AAV.