Clinical application of low erythrocyte sedimentation rate/high C‐reactive protein to antineutrophil cytoplasmic antibody‐associated vasculitis

BACKGROUND: This study investigated whether the discordance between erythrocyte sedimentation rate (ESR) and C‐reactive protein at diagnosis could estimate the simultaneous clinical and laboratory variables and predict the poor outcomes during follow‐up in patients with antineutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV). METHODS: The medical records of 254 AAV patients were reviewed. Clinical and laboratory and AAV‐specific indices at diagnosis and all‐cause mortality, relapse and end‐stage renal disease during follow‐up were obtained. ESR and CRP levels were categorised as high and low based on the median values. Accordingly, the patients were divided into the following four groups: high ESR/low CRP; low ESR/high CRP; low ESR/low CRP; and high ESR/high CRP. RESULTS: Of the 254 AAV patients, 51 patients exhibited discordance between ESR and CRP. Among the 51 AAV patients, the median age was 59.0 years, and 20 patients were men (29 MPA, 13 GPA and 9 EGPA). Cardiovascular and nervous systemic manifestations were observed more frequently in AAV patients with low ESR/high CRP than in those with high ESR/low CRP. Six patients from the low ESR/high CRP group died. AAV patients with low ESR/high CRP exhibited significantly lower cumulative patients' survival rates than both those with high ESR/low CRP and those with low ESR/low CRP. Also, AAV patients with low ESR/high CRP exhibited significantly higher simultaneous BVAS than those with low ESR/low CRP. CONCLUSIONS: Low ESR/high CRP at diagnosis could not only estimate the simultaneous high BVAS but also predict all‐cause mortality during follow‐up in AAV patients.