The Lancet November 26, 2005

Effects of long-term fenofibrate therapy on cardiovascular events in 9795 people with type 2 diabetes mellitus (the FIELD study)

Anthony Keech et al. (FIELD study investigators)

Bottom Line

In patients with type 2 diabetes, long-term fenofibrate therapy did not significantly reduce the primary composite outcome of coronary events, but it did significantly reduce total cardiovascular events, non-fatal myocardial infarctions, and microvascular complications such as retinopathy requiring laser treatment.

Key Findings

1. The primary outcome of coronary events (coronary heart disease death or non-fatal myocardial infarction) occurred in 5.2% of the fenofibrate group and 5.9% of the placebo group, showing an 11% relative risk reduction that was not statistically significant (HR 0.89, 95% CI 0.75-1.05; p=0.16) [1.2.7].

2. Fenofibrate significantly reduced the risk of non-fatal myocardial infarction by 24% (HR 0.76, 95% CI 0.62-0.94; p=0.010).

3. There was a non-significant increase in coronary heart disease mortality in the fenofibrate group compared to placebo (HR 1.19, 95% CI 0.90-1.57; p=0.22), primarily driven by an excess in sudden cardiac death.

4. Total cardiovascular disease events were significantly reduced from 13.9% in the placebo group to 12.5% in the fenofibrate group (HR 0.89, 95% CI 0.80-0.99; p=0.035), largely driven by fewer non-fatal MIs and a 21% reduction in coronary revascularisation (p=0.003).

5. Fenofibrate therapy was associated with significant microvascular benefits, including less progression to albuminuria (p=0.002) and a 30% reduction in the need for laser treatment for diabetic retinopathy (3.6% vs 5.2%, p=0.0003).

6. Adverse events included a slight but significant increase in pancreatitis (0.8% vs 0.5%, p=0.031) and pulmonary embolism (1.1% vs 0.7%, p=0.022) in the fenofibrate arm.

Study Design

Design

Randomized Controlled Trial

Double-Blind

Sample

9,795

Patients

Duration

5 years (median)

Median

Setting

Multinational, 3 countries

Population Patients aged 50-75 years with type 2 diabetes mellitus, not taking statin therapy at baseline, with total cholesterol 3.0-6.5 mmol/L and either a total cholesterol/HDL ratio ≥4.0 or triglycerides 1.0-5.0 mmol/L.

Intervention Micronised fenofibrate 200 mg daily

Comparator Matching placebo

Outcome Coronary events (composite of coronary heart disease death or non-fatal myocardial infarction)

Study Limitations

• A higher-than-expected rate of drop-in statin therapy in the placebo arm (17% vs. 8% in the fenofibrate arm) likely attenuated the observed treatment effect and reduced the statistical power for the primary endpoint.

• The primary event rate was lower than initially projected (approximately 1% per annum), reducing the study's overall statistical power to detect a significant difference.

• The non-significant increase in coronary heart disease mortality, primarily due to sudden cardiac death, was a concerning signal that was not fully mechanistically explained.

• The trial population was predominantly of European ancestry, which may limit the generalizability of the findings to other populations with differing baseline cardiovascular or metabolic risks.

Clinical Significance

The FIELD study demonstrated that while fenofibrate does not significantly reduce the risk of primary coronary events in type 2 diabetes—especially when its effect is diluted by contemporary statin use—it confers benefit in reducing total cardiovascular events, non-fatal MIs, and revascularizations. More importantly, FIELD unveiled profound, unexpected microvascular benefits, significantly reducing the progression of albuminuria and the need for retinal laser therapy. This shifted the clinical paradigm, establishing fenofibrate less as a primary macrovascular protectant and more as a valuable adjunctive therapy for mitigating diabetic eye and kidney complications, paving the way for trials like ACCORD-Eye.

Historical Context

Before FIELD, cardiovascular disease was firmly established as the leading cause of morbidity and mortality in type 2 diabetes. Dyslipidemia in diabetes is typically characterized by high triglycerides and low HDL cholesterol, abnormalities theoretically responsive to fibrates (PPAR-alpha agonists). Earlier trials like the Helsinki Heart Study and VA-HIT suggested fibrate benefits, but robust data specifically dedicated to type 2 diabetes were lacking. FIELD was the largest trial of its time evaluating fibrate therapy in diabetes. Although its primary macrovascular results in 2005 were considered somewhat disappointing—largely confounded by the rapid ascendance of concurrent statin therapy—the landmark microvascular findings spurred immense interest and redefined guidelines regarding fibrate use for diabetic retinopathy.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

What is the mechanism of action of fenofibrate, and what specific lipid profile abnormalities typical of type 2 diabetes mellitus does it target?

Key Response

This question tests foundational pharmacology and pathophysiology. Fenofibrate is a PPAR-alpha agonist that increases lipolysis and elimination of triglyceride-rich particles from plasma by activating lipoprotein lipase and reducing production of apolipoprotein C-III. It specifically targets 'diabetic dyslipidemia,' which is classically characterized by high triglycerides, low HDL cholesterol, and a shift toward small, dense LDL particles.

Resident

Given the findings of the FIELD study, in which patients with type 2 diabetes would you consider adding fenofibrate to statin therapy, and what adverse effects must be actively monitored?

Key Response

This focuses on clinical application. Since FIELD (and later ACCORD) did not show a primary cardiovascular benefit for routine use, fenofibrate is generally reserved for patients with severe hypertriglyceridemia (typically >500 mg/dL) to prevent acute pancreatitis. When combining with a statin, residents must monitor for an increased risk of myopathy, rhabdomyolysis, and mild to moderate reversible increases in serum creatinine and liver transaminases.

Fellow

The FIELD study demonstrated a highly significant, unexpected reduction in the need for retinal laser treatment. How does this microvascular benefit alter our understanding of PPAR-alpha activation in diabetic retinopathy compared to its systemic macrovascular effects?

Key Response

This explores nuanced subspecialty concepts. The reduction in retinopathy (later corroborated by the ACCORD-Eye study) occurred largely independent of the lipid-lowering effects, suggesting that PPAR-alpha activation has direct anti-inflammatory, anti-angiogenic, and endothelial-protective mechanisms in the retinal microvasculature, contrasting with its minimal impact on large-vessel atherosclerosis when statins are used.

Attending

A major challenge in interpreting the FIELD study was the unequal 'drop-in' statin therapy between the placebo and fenofibrate groups. How do you teach learners to interpret pragmatic trials where evolving standards of care confound the primary macrovascular outcome?

Key Response

This addresses teaching points and real-world evidence appraisal. During the long-term FIELD study, evidence for statins in diabetes solidified, leading to disproportionate statin initiation in the placebo group (17%) compared to the fenofibrate group (8%). Attendings must teach how this 'drop-in' attenuates the statistical power to detect a difference in the primary intention-to-treat analysis, highlighting the tension between ethical patient care and clean trial data.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

How does the high rate of off-protocol statin crossover in the placebo group of the FIELD study compromise the statistical power of the intention-to-treat (ITT) analysis, and what advanced causal inference methods could be employed to adjust for this time-varying confounding?

Key Response

This targets expert-level methodology. Relying solely on ITT when extensive differential crossover occurs heavily biases results toward the null. PhDs should discuss alternative approaches, such as per-protocol analysis, inverse probability of censoring weighting (IPCW), or marginal structural models, which can estimate the true treatment effect of fenofibrate had the confounding drop-in therapy not occurred.

Journal Editor

The FIELD study reported a non-significant primary composite outcome but emphasized significant secondary outcomes like total cardiovascular events and non-fatal MI. As an editor, how do you evaluate the risk of 'spin' and alpha-error inflation in this manuscript?

Key Response

This requires critical appraisal and editorial rigor. Emphasizing secondary endpoints when the primary endpoint fails is a classic example of potential 'spin.' Editors must assess whether the authors pre-specified these secondary outcomes, whether statistical adjustments for multiple comparisons (like Bonferroni) were applied, and whether the abstract accurately reflects the primary failure before allowing claims of drug efficacy.

Guideline Committee

Current AHA/ACC and ADA guidelines explicitly recommend against the routine addition of fenofibrate to statin therapy for macrovascular risk reduction based on FIELD and ACCORD-Lipid. Should guidelines be updated to incorporate fenofibrate specifically for the prevention of diabetic retinopathy progression, and what level of evidence supports this?

Key Response

This evaluates how evidence informs guidelines. While macrovascular guidelines (AHA/ACC) dismiss fibrates, ophthalmology and comprehensive diabetes guidelines (like those in Australia) have integrated fenofibrate for diabetic retinopathy based on the robust microvascular data from FIELD and ACCORD-Eye. Committees must weigh whether an off-label indication (Level of Evidence A for retinopathy) warrants a standalone guideline recommendation despite the lack of overall mortality benefit.

Clinical Landscape

Noteworthy Related Trials

2004

CARDS Trial

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Population

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Comparator

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Endpoint

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Key result: Atorvastatin safely and significantly reduced the risk of first cardiovascular disease events by 37%.

2010

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Key result: Adding fenofibrate to statin therapy did not significantly reduce the rate of fatal cardiovascular events, nonfatal MI, or nonfatal stroke compared with simvastatin alone.

2022

PROMINENT Trial

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Pemafibrate 0.2 mg twice daily

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Comparator

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Endpoint

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Key result: Pemafibrate lowered triglycerides but did not reduce the risk of cardiovascular events compared to placebo.

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