Incidence and outcomes of acute kidney injury in a referred chronic kidney disease cohort.

BACKGROUND

Whilst chronic kidney disease (CKD) has been identified as a risk factor for the development of acute kidney injury (AKI), little has been published about the incidence and outcomes of those acute injuries on chronic stable kidney disease and even less in a referred cohort of CKD patients followed up by nephrologists.

METHODS

We followed up 6862 patients registered as CKD in British Columbia, Canada for a median time of 19.4 months after they achieved an estimated glomerular filtration rate (eGFR) value < or =30 mL/min/1.73 m(2). AKI was defined as a decrease in eGFR of > or =25% compared to a moving baseline eGFR within 25 days.

RESULTS

Of the CKD patients, 44.9% had at least one AKI episode. Crude incidence rate for a first AKI event was 34.8 per 100 person-years. Older age [adjusted relative risks (RR) = 0.93 by 10 years, 95% confidence intervals (CI) = 0.90, 0.95] was associated with a lower risk of AKI. Of the patients, 15.3% died before dialysis and 18.1% initiated dialysis. AKI was associated with both a higher risk of death (adjusted RR = 2.32, 95% CI = 2.04, 2.64) and an increased risk of dialysis (adjusted RR = 2.33, 95% CI = 2.07, 2.61).

CONCLUSIONS

In a referred CKD population, AKI was a frequent event and associated with higher risks of dialysis and mortality. The incidence of AKI appears to be less with older age in this population. Quantification of AKI incidence and its risk factors in different populations is important for clinicians and planners, so that appropriate identification, prevention and treatment strategies can be tested.