Renal recovery after severe acute kidney injury in critically ill myeloma patients: a retrospective study

BACKGROUND: Despite substantial improvements in the management of multiple myeloma, renal failure remains an important burden that tremendously impairs prognosis. The purpose of this study was to describe the characteristics and to establish prognostic factors of renal recovery in myeloma patients admitted to the intensive care unit (ICU) for acute kidney injury (AKI) Stage 3 treated with renal replacement therapy (RRT). METHODS: A retrospective single-centre cohort study was performed, including consecutive myeloma patients admitted to one medical ICU between 1 January 2007 and 1 September 2015 and treated with RRT. Patients were evaluated 60 days after initiation of RRT and divided into three groups: alive without dialysis, alive and dialysis-dependent or deceased. A univariate analysis was performed to identify factors associated with renal recovery (alive without dialysis 60 days after initiation of RRT). RESULTS: Fifty patients were included in the study. Mean age was 63 (interquartile range: 58–70) years and 32 (64%) were male. Patients were admitted to the ICU 4 (1–7) years after the diagnosis of myeloma. Twenty-one (42%) had already been treated with high-dose therapy combined with autologous stem cell transplantation. Baseline renal function evaluated by estimated glomerular filtration rate (GFR) before ICU admission was 63 (44–90) mL/min/1.73 m(2). The mean SOFA score at Day 1 was 7 (4–8). The three main reasons for ICU admission were AKI (n = 31, 62%), acute pulmonary oedema (n = 17, 32%) and sepsis (n = 10, 20%). During ICU stay, RRT was implemented in all patients, 16 (32%) patients required invasive mechanical ventilation and 12 (24%) received vasopressors. The mean ICU and hospital length of stay were 6 (1–7) and 28 (13–34) days, respectively. At Day 60, 23 (46%) patients were alive without dialysis, 17 (32%) had died and 10 (20%) were still undergoing dialysis. Among the 23 patients who recovered, the mean duration of dialysis was 6 (2–18) days and renal function was not significantly different from baseline [estimated GFR at baseline = 65 (25–74) mL/min/1.73 m(2) versus 63 (56–70) mL/min/1.73 m(2) at Day 60, P = 0.70]. By univariate analysis, two factors were associated with nonrecovery of renal function at Day 60: a history of high-dose therapy combined with autologous stem cell transplantation [odds ratio (OR) = 6.1, 95% confidence interval (CI) 1.7–21.6; P = 0.008] and a proteinuria at ICU admission >370 mg/mmol creatinine (OR = 4.2, 95% CI 1.1–17; P = 0.02). None of the other variables related to the haematological malignancy or to the ICU stay was associated with renal recovery at Day 60. CONCLUSIONS: AKI Stage 3 in critically ill myeloma patients was associated with a lower than expected hospital mortality. Patients with a high level of proteinuria and a history of high-dose therapy combined with autologous stem cell transplantation were less likely to recover their renal function at Day 60. KEY WORDS: dialysis, intensive care, multiple myeloma, prognosis, proteinuria