We performed a retrospective observational study examining long-term outcomes of patients, aged > 55, admitted to the ICU and who required RRT for AKI. We studied 352 patients over a median duration of 33 months. We found that, compared to younger patients, those older than 75 yo had a similar (very high) in-hospital and post discharge mortality rate. However, we found that they had a higher rate of long-term dialysis dependence rate and a lower quality of life as assessed by EQ-5D and VAS scale. More importantly, we found that their quality of life was significantly lower than an age/sex matched reference population. A higher proportion of them experienced pain, mobility limitation, depression and or required help for their daily activities.
Long term follow-up studies of patients undergoing RRT have reported similar mortality rates to our series (51.9%) ranging between 35% and 71% [5–9, 11, 18, 19] The even higher mortality of > 75 yo patients (73.5%) was also observed in other works: it was 61.7% in a Korean series (562 patients) and 71% in a Croatian series (178 patients) [8, 9]. This rate is actually not that different to the mortality observed in a group of old (75–84 yo) ICU patients who did not receive RRT (63%)[20].
Similarly, the low rate of dialysis dependence among ICU survivors is consistent with previous findings with reported rates of 5.4% (Gallagher) and 5% (Schiffl) [5, 6]. A higher (23%) rate was reported by Prskalo et al, however the follow-up in this study was only four weeks.
Our finding that ICU survivors < 75 had a similar QOL than the reference population [15] is consistent with data from Finland, where ICU survivors were found to have similar QOL compared to their baseline (pre-ICU) value, 6 months after discharge from ICU. This finding was observed in both AKI and non-AKI patients [19] as well as RRT and non-RRT patients [7]. In these two studies median age was respectively 62 and 65.
However, we observed a lower than predicted QOL in patients > 75 yo which has not been described yet. Most studies reporting QOL in > 80 yo ICU survivors have suggested a similar to pre-admission QOL [2]. However, among those studies very few patients had received RRT and the majority of those who did ended up dying.
This study has several strengths. We studied all consecutive patients who received RRT for AKI in our ICU during a 2.7 years period. Long term mortality data were obtained from national statistics bureau. Hence, we are able to report reliable long term outcomes in all patients. We managed to approach and administer the survey to a large proportion of the survivors (85%).
However, our study also has some limitations worth discussing. First, due to our retrospective design, we were not able to record pre-admission QOL. This limitation was, in part, overcome by the ability to compare QOL with predicted values based on local reference population data. Second, indications for RRT were not standardized and might not be consistent throughout the study period and different to other centers. However, mortality rate and renal recovery rates in our study were similar to those observed in other studies suggesting some form of external validity. Third, the administration of the survey over the phone in geriatric patients could be seen as problematic. However, the EQ-5d has been validated for telephone administration and only one patient needed to be excluded because the survey could not be administered on the phone (deafness). Fourth, the number of patients in the > 75 yo group was small (15 patients) reflecting the very high mortality in this group. Our results should be confirmed by other studies. Fifth, the lower than predicted QOL in patients > 75yo could have been confounded by our long term follow-up (> 3 years in more than 60% of patients in this group). Indeed, a faster deterioration has been observed in ICU survivors compared the general population [21]. Finally, our study might have been underpowered to demonstrate significant difference in terms of mortality or dialysis dependence between our patients' groups. Indeed, a trend for higher mortality and dialysis dependence was observed.
Altogether, our study confirms that, the need for RRT identifies a population at very high risk of in-hospital and post-discharge death. It suggests that unlike their younger counterparts, patients > 75 yo who survive to ICU discharge have a lower QOL compared to age-matched population. It therefore questions the relevance of RRT initiation in such a population.
Obviously, age alone cannot justify such limitations of medical therapy. Factors such as frailty [22] and low pre-admission VAS score [20] should be considered before age when discussing such limitations. Age should rather correspond to a modulating factor in these decisions. Our data however supports the view that such limitations should be discussed with those patients or their relative either at the time of ICU admission or on RRT initiation.