Bias in Before-After Studies: Narrative Overview for Anesthesiologists

Area of Science:

• Medical research methodology
• Anesthesiology practice

Background:

• Before-after study designs are valuable research tools with the potential to influence clinical practice.
• However, these designs are susceptible to various forms of bias that can compromise study validity.

Purpose of the Study:

• To illustrate potential sources of bias in before-after studies relevant to anesthesiologists.
• To provide strategies for mitigating bias and improving the transparency and interpretation of these studies.

Main Methods:

• Overview of common biases in before-after studies.
• Discussion of strategies to enhance study design and reporting.

Main Results:

• Identified biases include selection, history, regression to the mean, observer bias, and reporting bias.
• Mitigation strategies involve control groups, blinding, matching cohorts, prospective data collection, and using Enhancing Quality and Transparency of Health Research (EQUATOR) checklists.

Conclusions:

• Anesthesiologists can improve the design and appraisal of before-after studies by understanding potential biases.
• Implementing bias mitigation strategies and adhering to reporting guidelines enhances study transparency and reliability.