Background
Patients receiving renal replacement therapy (RRT) for acute kidney injury (AKI) are at high risk of mortality and morbidity in-hospital and post-discharge. However, these outcomes appear largely driven by age and pre-morbid conditions. Hence, we sought to compare long-term outcomes of young (<55 yo) and older (≥55yo) patients who require RRT for AKI.
Methods
We conducted a monocentric observational study including all consecutive patients admitted to our institution’s ICU between January 2015 and April 2018 and required RRT for AKI. We collected their characteristics on ICU admission as well as RRT initiation. We cross-referenced this dataset with the Swiss National Death Registry to assess 90-day mortality and identify current survivors. We contacted those survivors over the phone, asked about their dialytic status and assessed their Quality of Life (QoL) through an EQ-5D-3L survey with the visual analogue scale (VAS). We assessed determinants of 90-day mortality and compared QoL data obtained in patients <55 yo (young group) survivors to those ≥55yo (older group). Finally, we used logistic regression models to account for the influence of comorbidities and illness severity on those associations.
Results
453 patients were included in our study (101 (22.3%) <55 yo and 352 (77.7 %) ≥55 yo. 90-day mortality was significantly lower in < 55 yo (34.7%) as compared with ≥ 55yo (53.7%), p=0.001. However, after correction for illness severity and comorbidities, age was not found to be associated with 90-day mortality.
At the time of the survey, 170 patients were still alive and 118 (69.4%) agreed to participate in the study (35 <55 yo and 83 ≥55yo). Median follow-up time was 3.19 years post admission. Among survey responders, 6.8% were dependent on chronic RRT (2 (5.7%) < 55 yo, 6 (7.2%) ≥55 yo, p value >0.999). Median health utility score was 0.664 (0.344) in the <55 yo versus 0.779 (0.313) in the ≥55 yo (p value 0.006). Similarly, median VAS was 50 (IQR 35) in <55 yo versus 75 (IQR 30), in ≥55 yo (p value 0.008). No limitation in QoL were reported in 7 (20%) patients <55 yo and 33 (39.8%) patients ≥55 yo (p value 0.005). However, after correction for illness severity, comorbidities and follow-up duration, no association was found between age and QoL indices.
Conclusions:
Irrespective of age, in-hospital and post-discharge mortality was very high among patients who received RRT while dialysis dependence among survivors was low. Young (<55 yo) patients had a higher survival but a lower QoL compared to older (≥55yo) survivors. However, these differences appeared to be mainly related to illness severity and comorbidities.