Objectives: To investigate the detection rate of double positivity for antineutrophil cytoplasmic antibody (ANCA) and anti-glomerular basement membrane (GBM) antibody at diagnosis and its clinical implication during follow-up in Korean patients with ANCA-associated vasculitis (AAV). Methods: We retrospectively reviewed the medical records of 96 Korean AAV patients. We obtained data at diagnosis and assessed the poor outcomes of AAV such as all-cause mortality, relapse and end-stage renal disease (ESRD). Comparison of cumulative survivals were analysed by the Kaplan-Meier survival analysis, and hazard ratios (HRs) were obtained by the multivariable Cox hazard model. Results: Seven of 96 AAV patients (7.3%) had double positivity for ANCA and anti-GBM. Among variables at diagnosis, there were no significant differences between patients with double positivity for ANCA and anti-GBM and those without. In the cumulative survival analysis, AAV patient with double positivity for ANCA and anti-GBM at diagnosis exhibited the lower cumulative ESRD-free survival rate than those without (P = 0.044) and furthermore, than those with positive for only ANCA and those with double negativity (P = 0.022). Myeloperoxidase (MPO)-ANCA, renal manifestation and five-factor score at diagnosis were also associated with ESRD occurrence in AAV patients. In the multivariable Cox hazards model using these 4 variables, only double positivity for ANCA and anti-GBM exhibited the significant association with ESRD occurrence during follow-up (HR 3.831). Conclusions: Double positivity for ANCA and anti-GBM at diagnosis were observed in 7.3% of AAV patients, and it could predict ESRD occurrence during follow-up in Korean patients with AAV.Key Points• 7.3% of AAV patients had double positivity for ANCA and anti-GBM at diagnosis (total n = 96)• Double positivity for ANCA and anti-GBM could predict ESRD occurrence during follow-up (HR 9.021, P = 0.004)• AAV patients with double positivity for ANCA and anti-GBM exhibited the lower cumulative ESRD-free survival rate compared with those without (P = 0.044).
Bibliographical noteFunding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A1B03029050) and a grant from the Korea Health Technology R and D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (HI14C1324).
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