We found a significant reduction in AKI with Nephrology On-Site and a baseline AKI incidence with Nephrology On-Demand of 31.9%, similar to previous studies [3
]. As expected, a higher positive impact was achieved in patients with intermediate risk. Of note, the cutoff points for Thakar scores [13
] were adapted to our population, RST in 1.54% corresponding to scores 0-2, in 3.52% to scores 3-4 and in 18.56% to scores ≥5.
With Nephrology On-Site, there was a trend towards a higher proportion of patients receiving RST, together with some parameters of earlier dialysis, even though the proportion of severe AKI was lower than previously reported [4
]. Although no specific criterion was used to determine when RST should be started, in our center patients with RIFLE-I/AKIN-2 plus an unfavorable state (mechanical ventilation, hemodynamic instability, inputs higher than urine output or sepsis) are usually considered for RST, and with Nephrology On-Site this recognition process might be accelerated. While patients requiring RST usually are at higher risk, as an early intervention it could contribute to better outcomes [14
]. Nevertheless, in our study, lower values of SCr and urea nitrogen at the start of RST were not associated with renal recovery or survival. It is clear that supporting patients with less severe AKI and those who are maybe less critically ill would produce a bias towards survival benefit; however, our outcomes among patients with severe AKI were better with Nephrology On-Site with or without RST (fig. ). Without RST, 45.4% of patients either died or did not recover renal function with Nephrology On-Demand versus 0.0% with Nephrology On-Site (fig. ). In this sense, daily evaluation not only consists of starting RST early, but also of preventing and choosing the right patient for RST.
Nephrology On-Site resulted in an increased renal recovery rate in patients with severe AKI or RST. In a study by Hobson et al. [15
], 45% of patients undergoing cardiothoracic surgery were dialysis dependent at hospital discharge and 21% had complete recovery, while in our study 15.4% of patients were dialysis dependent in both periods; further, we found a nonsignificant increase in the complete recovery rate from 42.9 to 63.2%. It is remarkable that, even though in both study periods patients who required RST were treated by nephrologists, the collaborative work might have contributed to adjust the therapeutic strategies more efficiently for multiorgan benefits.
There was a reduction in mortality among patients with severe AKI from 55.9 to 34.1%, and among patients with RST from 69.6 to 42.4%, which is similar to results reported in the literature [3
]. Of course, it is to be expected that high-quality centers with baseline mortality rates lower than ours might obtain a lower proportional benefit with the same approach.
Equivalent approaches in the literature have shown similar survival benefits. Higher adherence to evidence-based practice and lower rates of complications have been reported when intensivists are present in the ICU 24 h a day versus only on demand [17
]. In systematic reviews, the constant presence of intensivists or obligatory consultation in the ICU has shown relative reduction rates for mortality of around 13.8-60% [18
], while in our center this relative reduction was between 36.3 and 39.0% among the different AKI stages. This survival benefit seems plausible as it is associated with both a lower incidence of AKI and a higher renal recovery rate.
In our study, some variables associated with worse outcomes had an unbalanced distribution. Lower body weight, severe infections such as pneumonia as well as mechanical ventilation were more prevalent in patients with Nephrology On-Site, which could have played a major role reducing benefits in the length of stay at the ICU. Specifically, surgical techniques might explain the increase in mechanical ventilation.
The limitations of our study include that missing information on urine output and fluid balance could have influenced AKI diagnosis; however, as preventing and treating fluid overload were part of the tasks, we hypothesize that with Nephrology On-Demand the percentage of fluid overload could have been higher, and therefore also the real incidence of AKI. In this sense, 29.6% of patients with Nephrology On-Demand had a reduction in their SCr levels from baseline to day 1 versus 21.9% with Nephrology On-Site (p = 0.004), which could indicate a positive fluid balance. Other missing information such as medications including diuretics and severity scores would have allowed us to assess factors potentially associated with our results. As this was a retrospective/observational study, we could not control or assess the specific interventions with Nephrology On-Site; we recognize that these positive results could have been achieved by the original ICU team, simply by the effect of being observed and becoming sensitive towards renal care, but in our perspective this is still a positive achievement. Although not originally planned, we could have influenced the anesthesiology team towards avoiding the intraoperative use of NSAIDs and diuretics, which could explain the change in the early onset of AKI.
In the 90's, Ronco and Bellomo [20
] emphasized that the complexity of AKI in ICUs demands nephrologists and intensivists to join forces in a new academic structure called Critical Care Nephrology, and an example of this new structure is the ‘Vicenza Model’ [21
]. This multidisciplinary multitarget model with low costs by only optimizing human resources can have benefits beyond clinical outcomes through promoting cordial relationships among specialists, improving academic programs for fellows and potentiating research work.