title: Prolonged Duration of Renal Recovery Following ANCA-Associated Glomerulonephritis.
abstract: BACKGROUND
  As renal biopsies are not routinely repeated to monitor treatment response in anti-neutrophil cytoplasm antibody (ANCA)-associated glomerulonephritis, serum creatinine (SC) and proteinuria assessed by urine protein:creatinine ratio (UPCR) measurements are relied upon to provide a non-invasive estimate of disease activity within the kidney. However, sparse information exists about the time to achieve maximal improvement in these parameters, which has important implications for treatment decisions and disease-scoring systems.
  
  
  METHODS
  We analysed patients with ANCA-associated glomerulonephritis and renal impairment from cohorts in the United Kingdom and Ireland, with the primary objective of determining actuarial time to nadir SC and UPCR. Time to disappearance of haematuria was analysed as a secondary objective.
  
  
  RESULTS
  Ninety-four patients fulfilled our selection criteria, with 94 (100%) and 66 (70%) having reached their nadir SC and UPCR respectively during the follow-up period. Nadir SC was achieved after a median of 88 days (95% CI 74-102), UPCR at 346 days (95% CI 205-487). Those of Indo-Asian ethnic origin reached their nadir SC faster (34 days) than other ethnicities (p < 0.01). There were no significant differences in time to nadir SC or UPCR on the basis of gender, clinical diagnosis, ANCA positivity or renal biopsy findings.
  
  
  CONCLUSIONS
  In this retrospective study, nadir creatinine and proteinuria occur later than other signs of clinical remission, suggesting that ongoing renal recovery continues for a significant time after diagnosis. It may benefit disease-scoring systems to take into account SC levels beyond the initial assessment.
authors.affiliation: UCL Centre for Nephrology, Royal Free, London, UK.
authors.forename: Amin
authors.initials: A
authors.lastname: Oomatia
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Moran
authors.forename: Claire
authors.initials: C
authors.lastname: Kennedy
authors.forename: Rachel
authors.initials: R
authors.lastname: Sequeira
authors.forename: Sally
authors.initials: S
authors.lastname: Hamour
authors.forename: Aine
authors.initials: A
authors.lastname: Burns
authors.forename: Mark A
authors.initials: MA
authors.lastname: Little
authors.forename: Alan D
authors.initials: AD
authors.lastname: Salama
mesh_terms: D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000150:complications / Q000628:therapy*; D044466:Asian People / Q000706:statistics & numerical data*; D003404:Creatinine / Q000097:blood / Q000652:urine; D005260:Female; D005921:Glomerulonephritis / Q000208:ethnology / Q000209:etiology / Q000503:physiopathology*; D006417:Hematuria / Q000652:urine; D006801:Humans; D008297:Male; D011507:Proteinuria / Q000652:urine; D020127:Recovery of Function; D012189:Retrospective Studies; D013997:Time Factors; D044465:White People / Q000706:statistics & numerical data*
chemical_list: D003404:Creatinine