title: Cigarette smoking and progression of IgA nephropathy.
abstract: BACKGROUND
  Multiple community-based cohort studies of mainly middle-aged and elderly populations have shown that cigarette smoking is a risk factor for chronic kidney disease. However, little information is available about an effect of cigarette smoking on progression of primary kidney diseases, including immunoglobulin A (IgA) nephropathy.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  971 of 1,001 patients with a diagnosis of IgA nephropathy in 3 major nephrology centers in Osaka, Japan, between 1992 and 2005 who enrolled in the Study of Outcome and Practice Pattern of IgA Nephropathy (STOP-IgAN).
  
  
  METHODS
  Smoking status and number of cigarettes smoked at the time of diagnosis using kidney biopsy. Dose-dependent associations between cigarette smoking and outcomes were assessed in multivariate Cox proportional hazards models. Significantly different clinical characteristics between non-/past and current smokers were controlled for using propensity score-based adjustment, stratification, and matching.
  
  
  RESULTS
  50% increase in serum creatinine level as primary outcome. A composite outcome of a 100% increase in serum creatinine level or end-stage renal disease (ESRD) and ESRD alone as secondary outcomes.
  
  
  RESULTS
  During the median 5.8 years (interquartile range, 2.6-10.2) of the observational period, 117 participants progressed to a 50% increase in serum creatinine level and 47 advanced to ESRD. Multivariate Cox proportional hazards models identified current smokers (HR, 2.03 [95% CI, 1.33-3.10] for primary outcome) and number of cigarettes at kidney biopsy (HR, 1.21 [95% CI, 1.06-1.39] per 10 cigarettes per day) as significant predictors of outcomes. Propensity score-based models confirmed these results. Tests for interaction showed that the association of current smoking with adverse outcomes was stronger in those with lower compared with higher estimated glomerular filtration rates.
  
  
  CONCLUSIONS
  Baseline smoking status was not verified using biochemical tests. Smoking status during the observational period was unavailable.
  
  
  CONCLUSIONS
  Cigarette smoking, in a dose-dependent manner, was identified as a key prognostic factor in IgA nephropathy. Smoking cessation should be encouraged as part of the treatment for IgA nephropathy.
authors.affiliation: Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yamamoto
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nagasawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shoji
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Iwatani
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hamano
authors.forename: Noritaka
authors.initials: N
authors.lastname: Kawada
authors.forename: Kazunori
authors.initials: K
authors.lastname: Inoue
authors.forename: Takuya
authors.initials: T
authors.lastname: Uehata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kaneko
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Okada
authors.forename: Toshiki
authors.initials: T
authors.lastname: Moriyama
authors.forename: Masaru
authors.initials: M
authors.lastname: Horio
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamauchi
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Tsubakihara
authors.forename: Enyu
authors.initials: E
authors.lastname: Imai
authors.forename: Hiromi
authors.initials: H
authors.lastname: Rakugi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Isaka
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood; D018450:Disease Progression; D015987:Effect Modifier, Epidemiologic; D005260:Female; D005922:Glomerulonephritis, IGA / Q000097:blood / Q000453:epidemiology* / Q000473:pathology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood; D016015:Logistic Models; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D003404:Creatinine