title: Serum Anion Gap Predicts All-Cause Mortality in Patients with Advanced Chronic Kidney Disease: A Retrospective Analysis of a Randomized Controlled Study.
abstract: OBJECTIVE
  Cardiovascular outcomes and mortality rates are poor in advanced chronic kidney disease (CKD) patients. Novel risk factors related to clinical outcomes should be identified.
  
  
  METHODS
  A retrospective analysis of data from a randomized controlled study was performed in 440 CKD patients aged > 18 years, with estimated glomerular filtration rate 15-60 mL/min/1.73m2. Clinical data were available, and the albumin-adjusted serum anion gap (A-SAG) could be calculated. The outcome analyzed was all-cause mortality.
  
  
  RESULTS
  Of 440 participants, the median (interquartile range, IQR) follow-up duration was 5.1 (3.0-5.5) years. During the follow-up duration, 29 participants died (all-cause mortality 6.6%). The area under the receiver operating characteristic curve of A-SAG for all-cause mortality was 0.616 (95% CI 0.520-0.712, P = 0.037). The best threshold of A-SAG for all-cause mortality was 9.48 mmol/L, with sensitivity 0.793 and specificity 0.431. After adjusting for confounders, A-SAG above 9.48 mmol/L was independently associated with increased risk of all-cause mortality, with hazard ratio 2.968 (95% CI 1.143-7.708, P = 0.025). In our study, serum levels of beta-2 microglobulin and blood urea nitrogen (BUN) were positively associated with A-SAG.
  
  
  CONCLUSIONS
  A-SAG is an independent risk factor for all-cause mortality in advanced CKD patients. The positive correlation between A-SAG and serum beta-2 microglobulin or BUN might be a potential reason. Future study is needed.
  
  
  BACKGROUND
  Clinicaltrials.gov NCT 00860431.
authors.affiliation: Department of Internal Medicine, Eulji General Hospital, Seoul, 01830, Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, 13620, Korea.
authors.forename: Sejoong
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, 13620, Korea.|Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 03080, Korea.
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Na
authors.affiliation: Department of Internal Medicine, National Medical Center, Seoul, 04564, Korea.
authors.forename: Ran-Hui
authors.initials: RH
authors.lastname: Cha
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine 03722, Seoul, Korea.
authors.forename: Shin Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, 06591, Korea.
authors.forename: Cheol Whee
authors.initials: CW
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Korea University Ansan-Hospital, Korea University, Ansan, Gyeonggi-do, 15355, Korea.
authors.forename: Dae Ryong
authors.initials: DR
authors.lastname: Cha
authors.affiliation: Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi-do, 14068, Korea.
authors.forename: Sung Gyun
authors.initials: SG
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Uijeongbu, Gyeonggi-do, 11765, Korea.
authors.forename: Sun Ae
authors.initials: SA
authors.lastname: Yoon
authors.affiliation: Department of Internal Medicine, Inje University Ilsan-Paik Hospital, Goyang, Gyeonggi-do, 10380, Korea.
authors.forename: Sang Youb
authors.initials: SY
authors.lastname: Han
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, 05030, Korea.
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Gachon University Gil Medical Center, Gachon University of Medicine and Science, Incheon, 21565, Korea.
authors.forename: Jae Hyun
authors.initials: JH
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 03080, Korea.|Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, 08708, Korea.
authors.forename: Chun Soo
authors.initials: CS
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 03080, Korea.|Kidney Research Institute, Seoul National University, Seoul, 03080, Korea.
authors.forename: Yon Su
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000838:Anions; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies
chemical_list: D000838:Anions