OPTIMAL Selection for and Timing to Start Renal Replacement in Critically Ill Older Patients with Acute Kidney Injury (OPTIMAL-AKI)

This study sought to address the severe lack of information on the optimal circumstances for starting dialysis in older patients with acute kidney injury (AKI) and older critically ill Canadians.

About the Project

Severe AKI has a high risk of death and permanent loss of kidney function and usually occurs in an intensive care setting. Dialysis is commonly prescribed and there is substantial debate about when to start, particularly in the elderly who make up half of all patients receiving this treatment.

The results will ensure these decisions are consistently guided by high-quality evidence across Canada. The study also addressed the large variations in practice between providers, hospitals and across jurisdictions that undermines the optimal selection and delivery of high-quality care to older critically ill patients with AKI. Practice will be improved and tools will be developed to select older patients who are most likely to benefit from acute dialysis in the setting of critical illness.

Project Team

Principal Investigators:

Sean Bagshaw, MD, MSc, FRCPC — University of Alberta

Ron Wald, MDCM, MPH, FRCPC — St. Michael’s Hospital/University of Toronto


Neill Adhikari, MDCM, MSc, FRCPC — Sunnybrook Health Sciences Centre/University of Toronto

Karen Burns, MD, MSc, FRCPC — St. Michael’s Hospital/University of Toronto

Jan Friedrich, MD, MSc, DPhil, FRCPC — St. Michael’s Hospital/University of Toronto

Project Contact: Dr. Sean Bagshaw — bagshaw@ualberta.ca

Key words: frail elderly; renal replacement therapy; acute kidney injury; critical illness

Rationale & Research Plan

Rationale: We know that older frail critically ill patients represent approximately half of all patients who receive life support with acute dialysis therapy while in intensive care. However, we currently have very limited information on the optimal circumstances for starting dialysis in these older patients with AKI. Indeed, we are not only uncertain about who to start on acute dialysis, but also about when to ideally start it. In addition, we are uncertain about the associated clinical outcomes for these older frail patients, in terms of balance between potential life sustaining benefits versus the risk of adverse complications.

Research Plan: We are currently engaged in a large inter-disciplinary program of research focused on the optimal timing for starting acute dialysis in critically ill patients (STandard versus Accelerated initiation of Renal Replacement Therapy in Acute Kidney Injury [STARRT-AKI] study – ClinicalTrials.gov Identifier: NCT01557361). As a part of this ongoing program, we believe we are in a unique position to ideally investigate decision making around acute dialysis in older critically ill frail patients. Accordingly, we will leverage our current infrastructure to perform a prospective observational cohort study concurrent with the STARRT-AKI study, to evaluate whether in older critically ill frail patients with AKI, there are clinically important differences in survival, receipt of life-sustaining therapies, commitments to ongoing support, and changes in goals of care amongst those who do receive or those do not receive acute dialysis while in intensive care.

Communication to Researchers

Lay Title: Selection and Receipt of Renal Replacement Therapy in Critically Ill Older Patients with Acute Kidney Injury

Key Findings:

  • The majority of older critically ill patients with severe acute kidney injury admitted to ICU were perceived as candidates for renal replacement therapy.
  • Approximately half of older critically ill patients with severe acute kidney injury received renal replacement therapy while in ICU.
  • Both clinician willingness to offer renal replacement therapy and reasons for not starting renal replacement therapy showed marked heterogeneity. This was related to a range of patient-specific factors and clinician perceptions of the benefits of renal replacement therapy.

Why was this study needed?

There is limited information on factors that trigger initiation of renal replacement therapy in older ICU patients with acute kidney injury. The factors that influence clinician decision-making on willingness to offer renal replacement therapy are also unknown. We aimed to describe factors, care processes, and outcomes associated with a willingness to initiate kidney replacement therapy and the actual receipt of such therapy in older ICU patients.

Brief overview of the methodology:

  • The OPTIMAL-AKI (OPTIMAL Selection for and Timing to Start Renal Replacement in Critically Ill Older Patients with Acute Kidney Injury) study was a multi-center prospective observational cohort study conducted in ICUs at 16 academic/tertiary hospitals across Canada.
  • OPTIMAL-AKI recruited older ICU patients with severe AKI and a high likelihood of receiving renal replacement therapy. Specific inclusion criteria were age ≥65 years and severe AKI.
  • Primary exposure was receipt of renal replacement therapy and secondary exposure was the reported willingness by the attending physician to offer renal replacement therapy.
  • The primary study outcome was 90-day all-cause mortality. Secondary outcomes were: mortality in-hospital and at 12-months; renal replacement therapy dependence at hospital discharge and at 12-months; health-related quality-of-life at 6-months and 12-months; and re-hospitalization through 12-months.

Potential impact of findings on clinical practice/patient care and how this impact might be measured:

  • The OPTIMAL-AKI study highlights the challenges and nuances around decision-making for renal replacement therapy initiation in older ICU patients.
  • While select older patients may derive clinical benefit from starting renal replacement therapy, such decisions should ideally be juxtaposed with the potential intermediate and long-term implications.
  • Important patient-centered considerations of renal replacement therapy treatment in the ICU include failure to recover kidney function and development of new or worsened chronic kidney disease or end-stage kidney disease with chronic dialysis dependence, which is also associated with greater impairment in quality-of-life.

Remaining knowledge/research gaps:

  • Frailty was more prevalent among older patients in whom clinicians were less willing to offer renal replacement therapy and among those who did not receive therapy; however, frailty was not associated with 90-day mortality or dialysis dependence.
  • Future work should aim to describe how frailty may modify clinicians’ approach to advanced organ support, such as renal replacement therapy, among older patients admitted to ICU.