AKI in the hospital: What does this mean for my long term kidney health?

As renal fellows, we are always involved in the most severe cases of hospital acquired AKI that require dialysis. Previously on RFN, we examined the impact that these cases have on the long term risk of ESRD. What we often don't see are the less severe cases of hospital acquired AKI that non-nephrologists feel comfortable managing on their own. There is now a growing body of evidence that these cases have long term implications for kidney function.

A nice example of this literature was published this past month in CJASN by a group from Cincinnati examining 3679 diabetic veterans over an average followup of about 5 years looking at how hospital acquired AKI, defined using AKIN criteria, influenced the development of stage IV CKD and mortality. Individuals with less than 3 outpatient serum creatinine measurements or eGFRs of less that 30 ml/min/1.73m2 where excluded from the study.

Hospital acquired AKI occurred in 29% of the cohort and in the vast majority of cases, 88%, was of mild severity (AKIN stage I) with only 12% of cases in AKIN stages 2 and 3. The group was unfortunately unable to capture data on the need for inpatient dialysis. Of those who developed hospital acquired AKI, 23.4% went on to develop stage IV CKD as compared with 10.4% of hospitalized patients who avoided AKI. Hospital acquired AKI was a significant risk factor for the development of stage IV CKD with HR of 3.56.

As with severe dialysis requiring AKI, these less severe cases of AKI were also significantly associated with mortality with 38% of the patients who developed hospital acquired AKI dying by the end of the study period as compared with 24% of the hospitalized patients who did not develop AKI.

Interestingly the group looked at individuals who developed multiple episodes of AKI and with each episode up to 3 there was an approximate doubling of the risk for developing stage IV CKD. It was additionally notable that the hazard ratio for AKI was similar to that of proteinuria, a well known risk factors for CKD progression.

So how should the post hospital followup of these less severe cases of AKI be handled? Some have asked whether these patients should be seen by nephrologists, however given the already strained capacity of many renal clinics this would seem difficult to achieve. More practically, educating housestaff and primary care physicians on the importance of AKI as a risk factor for CKD and encouraging them to refer when CKD becomes present seems more achievable. In addition, in integrated systems such as the VA these patients could be followed remotely and brought into nephrologic care when our services are of value to the patient.