title: The effects of acute kidney injury on long-term renal function and proteinuria in a general hospitalised population.
abstract: BACKGROUND
  Acute kidney injury (AKI) is common in hospitalised patients and is associated with adverse long-term consequences. There is an urgent need to understand these sequelae in general hospitalised patients utilising a prospective cohort-based approach. We aimed to test the feasibility of study methodology prior to commencing a large-scale study and investigate the effects of AKI on chronic kidney disease (CKD) progression and proteinuria.
  
  
  METHODS
  Pilot study testing novel methodology for remote patient recruitment within a prospective case-control design. 300 cases (hospitalised patients with AKI) and controls (hospitalised patients without AKI) were matched 1:1 for age and baseline estimated glomerular filtration rate (eGFR). 70% of cases had AKI stage 1, 16% AKI stage 2 and 14% AKI stage 3. Renal function and proteinuria were measured 3 and 12 months after hospital admission.
  
  
  RESULTS
  The study met pre-defined recruitment, withdrawal and matching criteria. Renal function was worse in the AKI group at 3 (eGFR 61 ± 20 vs. 74 ± 23 ml/min/1.73 m(2), p < 0.001) and 12 months (eGFR 64 ± 23 vs. 75 ± 25 ml/min/1.73 m(2), p < 0.001). More cases than controls had CKD progression at 3 months (14 vs. 0.7%, p < 0.001). This difference persisted to 12 months, but there was no significant change between 3 and 12 months. Proteinuria and albuminuria were more prevalent in the AKI group and associated with CKD progression.
  
  
  CONCLUSIONS
  We describe a method of remote patient recruitment which could be employed more widely for prospective observational studies. Even mild AKI is associated with long-term renal dysfunction. Further investigation using this methodology is now underway.
authors.affiliation: Department of Renal Medicine, Royal Derby Hospital Derby, Derby, UK.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Horne
authors.forename: Rebecca
authors.initials: R
authors.lastname: Packington
authors.forename: John
authors.initials: J
authors.lastname: Monaghan
authors.forename: Timothy
authors.initials: T
authors.lastname: Reilly
authors.forename: Christopher W
authors.initials: CW
authors.lastname: McIntyre
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Selby
mesh_terms: D058186:Acute Kidney Injury / Q000150:complications* / Q000503:physiopathology*; D000368:Aged; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D006760:Hospitalization; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D011507:Proteinuria / Q000209:etiology*; D051436:Renal Insufficiency, Chronic / Q000209:etiology*; D013997:Time Factors