title: Acute kidney injury increases the risk of end-stage renal disease after cardiac surgery in an Asian population: a prospective cohort study.
abstract: BACKGROUND
  Acute kidney injury (AKI) after cardiac surgery is associated with increased morbidity and mortality. The long-term association between AKI and end-stage renal disease (ESRD) in an Asian population is unknown. Given the high prevalence of diabetes and a younger age of presentation for cardiac surgery, it is important to track this progression of kidney disease. Therefore, we studied the long-term risk of ESRD and mortality in our Asian patients who developed AKI after cardiac surgery.
  
  
  METHODS
  With ethics approval, we prospectively recruited 3008 patients who underwent cardiac surgery in Singapore between 2008 and 2012, and followed them up till 2014. ESRD and mortality information were obtained from the Singapore Renal Registry and Singapore Registry of Births and Deaths respectively. AKI was defined using the Acute Kidney Injury Network (AKIN) criteria, and ESRD was defined as stage 5 chronic kidney disease requiring renal replacement therapy. The Cox proportional hazards regression model was used to analyze associations between AKI and the primary outcome of ESRD and the secondary outcome of death.
  
  
  RESULTS
  The AKI incidence was 29.1%. During a mean follow-up of 4.4 ± 2.8 years, 0.9% developed ESRD. The hazard ratio (HR) for developing ESRD was 4.7 (95% C.I. = 1.736-12.603, p = 0.002) for AKIN stage 1 patients, and 5.8 (95% C.I. = 1.769-18.732, p = 0.004) for AKIN stage 2 and 3 patients; while the HR for mortality was 1.7 (95% C.I. = 1.165-2.571, p = 0.007) for AKIN stage 1 patients, and 2.5 (95% C.I. = 1.438-4.229, p < 0.001) for AKIN stage 2 and 3 patients.
  
  
  CONCLUSIONS
  AKI is associated with ESRD and mortality after cardiac surgery in our Asian population. The trajectory from AKI to ESRD is rapid within 5 years of cardiac surgery. A concerted periodic follow-up assessment is advocated for AKI patients post-cardiac surgery.
authors.affiliation: Department of Anaesthesiology, Singapore General Hospital, 20 College Road, Academia, Level 5, Singapore, 169856, Singapore. rnsctlk@gmail.com.|Department of Cardiovascular and Metabolic Disorders, Duke-National University of Singapore Graduate Medical School, 8 College Road, Singapore, 169857, Singapore. rnsctlk@gmail.com.|Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore, 119228, Singapore. rnsctlk@gmail.com.
authors.forename: Sophia Tsong Huey
authors.initials: ST
authors.lastname: Chew
authors.affiliation: Department of Anaesthesiology, Singapore General Hospital, 20 College Road, Academia, Level 5, Singapore, 169856, Singapore.
authors.forename: Roderica Rui Ge
authors.initials: RR
authors.lastname: Ng
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore, 119228, Singapore.
authors.forename: Weiling
authors.initials: W
authors.lastname: Liu
authors.affiliation: Health Promotion Board/NRDO, 3 Hospital Avenue, Singapore, 168937, Singapore.
authors.forename: Khuan Yew
authors.initials: KY
authors.lastname: Chow
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore, 119228, Singapore.|Department of Anaesthesia, National University Health System, 5 Lower Kent Ridge Road, Singapore, 119074, Singapore.
authors.forename: Lian Kah
authors.initials: LK
authors.lastname: Ti
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000401:mortality*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000401:mortality* / Q000706:statistics & numerical data; D059347:Cardio-Renal Syndrome / Q000401:mortality*; D015984:Causality; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality*; D011446:Prospective Studies; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D015996:Survival Rate
keywords: Acute kidney injury; Cardiac surgical procedures; Chronic; Kidney failure; Perioperative care