Randomized trial shows 43% reduction in cardiovascular events among dialysis patients — Evidence Review
Published in The New England Journal of Medicine, by researchers from Monash Health, School of Clinical Sciences at Monash University, University Health Network, University of Calgary
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Table of Contents
A large randomized trial has found that daily fish oil supplementation reduces the risk of major cardiovascular events in dialysis patients, supporting its use in this high-risk group. Most previous research aligns with these findings, suggesting cardiovascular benefits of fish oil, especially among patients with kidney disease, as detailed by Monash University.
- Earlier meta-analyses and randomized controlled trials have consistently shown that fish oil supplementation lowers cardiovascular events, improves blood lipid profiles, and may decrease inflammation in hemodialysis patients, supporting the new study's results 4 5 13.
- While the overall cardiovascular benefit in the general population is more modest, evidence is stronger in secondary prevention and high-risk groups such as those with chronic kidney disease or on dialysis 6 9.
- Previous studies have also confirmed the safety of fish oil supplementation in dialysis patients, with minimal adverse effects and no clinically significant increase in bleeding risk 3 12.
Study Overview and Key Findings
Cardiovascular disease is the leading cause of death among patients undergoing dialysis for kidney failure, and few interventions have demonstrated substantial risk reduction in this population. The PISCES trial addresses this critical gap by evaluating whether high-dose fish oil supplementation can lower the incidence of major heart-related complications in dialysis patients—a group with typically low levels of protective omega-3 fatty acids. The trial's robust design, large sample size, and focus on clinically meaningful endpoints make its findings particularly relevant for nephrology practice.
| Property | Value |
|---|---|
| Study Year | 2025 |
| Organization | Monash Health, School of Clinical Sciences at Monash University, University Health Network, University of Calgary |
| Journal Name | The New England Journal of Medicine |
| Authors | Kevan Polkinghorne, Charmaine Lok |
| Population | Patients undergoing dialysis for kidney failure |
| Sample Size | 1,228 participants |
| Methods | Randomized Controlled Trial (RCT) |
| Outcome | Cardiovascular events including heart attacks and strokes |
| Results | 43% reduction in serious cardiovascular events observed |
Literature Review: Related Studies
To contextualize the new findings, we searched the Consensus database (over 200 million research papers) using key search queries designed to identify the most relevant related studies. The following queries were used:
- fish oil dialysis cardiovascular events
- heart risk reduction fish oil supplementation
- dialysis patients fish oil heart health
The related studies address several key themes:
| Topic | Key Findings |
|---|---|
| Does fish oil supplementation reduce cardiovascular events in dialysis patients? | - Multiple meta-analyses and RCTs find significant reductions in cardiovascular events among maintenance hemodialysis patients taking fish oil 4 5. - Some studies report improved vascular access patency and reduced thrombosis, though effects on overall cardiovascular mortality vary 1 5. |
| What are the effects of fish oil on lipid profiles, inflammation, and risk biomarkers? | - Fish oil supplementation reliably lowers triglyceride levels, increases HDL cholesterol, and may reduce C-reactive protein in dialysis patients 2 11 13. - Improvements in cardioprotective biomarkers have been observed in both short- and long-term studies 2 13. |
| Is fish oil supplementation safe for dialysis patients? | - Studies indicate no significant increase in bleeding risk or severe adverse effects with n-3 fatty acid supplementation in chronic dialysis patients 3 12. - Most adverse effects are minor, predominantly gastrointestinal, and generally well-tolerated 12. |
| Are cardiovascular benefits of fish oil specific to high-risk groups or generalizable? | - Evidence for cardiovascular event reduction is stronger in secondary prevention (high-risk or disease populations) than in the general population 6 7 9. - Observational studies suggest modest benefit in the general population, but large RCTs show greater effect in patients with existing disease 6 10. |
Does fish oil supplementation reduce cardiovascular events in dialysis patients?
The new study's finding of a 43% reduction in serious cardiovascular events among dialysis patients receiving fish oil is consistent with previous meta-analyses and RCTs, which have reported significant reductions in cardiovascular morbidity in this population. While some earlier trials focused on vascular access outcomes, the cumulative evidence supports a broader cardiovascular benefit from fish oil in maintenance hemodialysis patients.
- Meta-analyses demonstrate significant reductions in cardiovascular events with fish oil supplementation in dialysis patients 4 5.
- Some RCTs found improved vascular access patency and fewer graft-related events, which may contribute indirectly to reduced cardiovascular risk 1 5.
- The magnitude of cardiovascular event reduction in the new study aligns with pooled results from earlier trials 5.
- Effects on overall mortality remain less certain, but cardiovascular event reductions are consistent across most high-risk groups 4 5.
What are the effects of fish oil on lipid profiles, inflammation, and risk biomarkers?
Fish oil supplementation has been repeatedly shown to improve lipid profiles and decrease inflammation markers in dialysis patients, both of which are important for cardiovascular risk reduction. The new trial's cardiovascular outcome findings are supported by these established changes in risk biomarkers.
- Studies consistently show reduced triglyceride and total cholesterol levels, and increased HDL cholesterol in dialysis patients taking fish oil 11 13.
- Reductions in C-reactive protein and trends toward lower triglycerides have been observed in short-term randomized trials 2.
- Improved omega-3 index and favorable lipid changes suggest a mechanism for reduced cardiovascular events 2 13.
- These biomarker improvements are most pronounced in populations with low baseline omega-3 levels, such as dialysis patients 2.
Is fish oil supplementation safe for dialysis patients?
The safety of fish oil supplementation is well established in the dialysis population. The new study, like most previous research, reports no significant increase in bleeding risk or severe adverse events.
- Controlled trials show no clinically important increase in bleeding times or adverse hematologic effects from n-3 fatty acids in dialysis patients 3.
- Adverse effects are primarily mild gastrointestinal symptoms, with high tolerability reported in most studies 12.
- Safety data support the feasibility of long-term supplementation in this group 3 12.
- The risk-benefit profile is especially favorable given the high baseline cardiovascular risk in dialysis patients 12.
Are cardiovascular benefits of fish oil specific to high-risk groups or generalizable?
Existing research indicates that the cardiovascular benefits of fish oil supplementation are more pronounced in high-risk populations—such as those with chronic kidney disease or prior cardiovascular events—than in the general public.
- Systematic reviews and observational studies show stronger effects in secondary prevention or high-risk groups compared to the general population 6 7 9.
- In the general population, fish oil use is associated with lower all-cause and cardiovascular mortality, but absolute risk reduction is smaller 6 10.
- Major guidelines highlight secondary prevention as the main context where fish oil supplementation is likely to have the greatest benefit 7 9.
- The new trial's restriction to dialysis patients, a prototypical high-risk group, is consistent with where the strongest benefit is expected 6 9.
Future Research Questions
While the new study adds important evidence supporting fish oil supplementation for cardiovascular risk reduction in dialysis patients, several research questions remain. Further studies are needed to clarify long-term outcomes, optimal dosing, applicability to other patient populations, and mechanisms of benefit.
| Research Question | Relevance |
|---|---|
| What are the long-term effects of fish oil supplementation in dialysis patients? | Most trials, including the new study, have follow-up periods of 1-2 years or less; assessing long-term safety and sustained efficacy is essential for clinical recommendations 4 12. |
| Does fish oil reduce overall mortality in dialysis patients? | While reductions in cardiovascular events are observed, effects on all-cause mortality remain uncertain and require larger or longer-term studies 4 5. |
| What is the optimal dose and formulation of fish oil for cardiovascular protection in dialysis? | Dose-response relationships and differences among various fish oil formulations have not been fully explored in this population 13. |
| Are the cardiovascular benefits of fish oil supplementation seen in other chronic kidney disease populations? | The new trial focuses on dialysis patients; whether similar benefits occur in earlier stages of kidney disease is unclear 4. |
| What are the mechanisms underlying fish oil's cardioprotective effects in dialysis patients? | Understanding molecular and physiological pathways may inform targeted therapies and improve risk stratification 2 11. |