What is the preferred measure to evaluate the efficacy of a new treatment, Absolute Risk Reduction (ARR) or Relative Risk Reduction (RRR), in determining the usefulness of a drug?

From the Guidelines

Absolute Risk Reduction (ARR) is the preferred measure to evaluate the efficacy of a new treatment, as it provides a more realistic picture of a treatment's actual benefit by showing the actual percentage point difference in outcomes between treated and untreated groups. When considering the usefulness of a drug, it is essential to prioritize measures that accurately reflect real-world benefits. ARR offers a more nuanced understanding of treatment effects, unlike Relative Risk Reduction (RRR), which can be misleading due to its dependence on baseline risk 1.

Key Considerations

• ARR accounts for the baseline risk, providing a clearer picture of the treatment's benefit in absolute terms.
• RRR, while sometimes presenting more impressive numbers, does not account for baseline risk and can thus be misleading.
• The example from the studies, such as the 4S-DM trial, shows an ARR of 42.5% versus an RRR of 50%, highlighting how ARR gives a more realistic view of the treatment's efficacy 1.

Clinical Implications

• In clinical practice, understanding the ARR is crucial for making informed decisions about treatment options.
• It helps in assessing the actual benefit a patient can expect from a particular treatment, making it a more patient-centered approach.
• The studies referenced, including the HPS-DM and CARE-DM trials, demonstrate the importance of considering ARR in evaluating treatment efficacy for conditions like diabetes 1.

Evidence-Based Decision Making

• For evidence-based medical decision-making, especially in the context of USMLE Step 3, recognizing the value of ARR over RRR is vital.
• It ensures that healthcare providers can critically evaluate the efficacy of new treatments and make decisions that maximize patient benefits while minimizing risks.
• The correlation between the 10-year CVD risk of the control group and the ARR with statin therapy, as noted in the studies, further emphasizes the significance of ARR in clinical decision-making 1.

From the Research

Evaluating Treatment Efficacy

The preferred measure to evaluate the efficacy of a new treatment is a topic of discussion among researchers. When comparing Absolute Risk Reduction (ARR) and Relative Risk Reduction (RRR), studies suggest that:

• RRR is often preferred for presenting treatment benefits, as it is easily interpreted by patients 2
• ARR is also easily interpreted, but may not be as effective as RRR in presenting treatment benefits 2
• NNT (Number Needed to Treat) is often misinterpreted by patients and should not be used alone to communicate risk 2

Understanding Risk Reduction

Research highlights the importance of understanding risk reduction when evaluating treatment efficacy. Key points include:

• Relative risk reduction (RRR) can lead to false expectations among clinicians and patients regarding the potential impact of treatment 3
• Absolute risk reduction (ARR) and NNT are absolute measures that take baseline risk and clinical benefit into account, making them more meaningful for rational decision-making 4
• RRR, ARR, and NNT are all useful measures of association, but should be presented in a simple and clear manner to facilitate understanding 5

Presenting Statistical Information

The presentation of statistical information can impact understanding, perception, and decision-making. Studies have found that:

• Natural frequencies are better understood than probabilities 6
• RRR is perceived to be larger and more persuasive than ARR and NNT, but may lead to misinterpretation 6
• ARR is better understood and perceived to be larger than NNT, but there is little difference in persuasiveness 6
• The quality of evidence for these comparisons is moderate, and more research is needed to explore the impact of presenting RRR, ARR, and NNT on decision-making 6