21 Hierarchy of research evidence

The hierarchy of research evidence is a framework used to categorise different types of research studies based on their methodological rigor, validity, and potential for bias. It helps researchers and healthcare professionals determine the strength of evidence when making clinical decisions or recommendations. The hierarchy generally progresses from lower levels of evidence (less rigorous) to higher levels (more rigorous). Keep in mind that this hierarchy may slightly vary depending on the field or context, but the following outline provides a common framework (lower levels to higher levels):

1. Expert opinion, editorials, and anecdotal evidence

• At the lowest level of the hierarchy.
• Includes opinions, editorials, and anecdotal reports without systematic research methods.
• Provides minimal or no scientific rigor and often lacks peer review.

2. Case reports and case series

• Descriptive accounts of individual cases or a series of cases.
• Limited in terms of generalisability and potential for bias.
• Often used to generate hypotheses for further research.

3. Cross-sectional studies (descriptive studies)

• Examines relationships among variables at a single point in time.
• Observational and descriptive in nature, often based on surveys.
• Limited in establishing cause-and-effect relationships due to lack of temporal sequence.

4. Case-control studies (analytical observational studies)

• Compares individuals with a specific outcome (cases) to individuals without that outcome (controls).
• Retrospective design, examines associations, but causation is difficult to establish.

5. Cohort studies (prospective and retrospective)

• Follows a group of individuals (cohort) over time to assess the development of outcomes.
• Can be prospective (forward in time) or retrospective (backward in time).
• Provides stronger evidence for causality compared to case-control studies.

6. Randomised controlled trials (RCTs)

• Experimental studies with random assignment of participants to different interventions.
• Gold standard for establishing cause-and-effect relationships.
• Involves manipulation of variables to determine the effect of interventions.

7. Systematic reviews and meta-analyses

• Synthesise and analyse the results of multiple studies on a specific research question.
• Provide a comprehensive overview of the available evidence.
• Meta-analyses statistically combine results from different studies to increase statistical power.

8. Clinical practice guidelines

• Summarise evidence-based recommendations for clinical practice.
• Developed by expert panels based on systematic reviews and research evidence.
• Serve as a resource for healthcare professionals to make informed decisions.

It’s important to note that the hierarchy is not strictly linear; different study designs serve different purposes and can provide valuable insights. Researchers and healthcare professionals need to consider the specific research question, study design, potential biases, and the applicability of findings to the patient population in question. While higher levels of evidence are generally considered more reliable, the entire hierarchy contributes to the body of knowledge and informs evidence-based decision-making.

Evidence based practice, clinician supported and patient focused – the triad

The evidence-based triad in nursing and midwifery healthcare refers to the integration of three key elements: clinical expertise, patient values and preferences, and the best available external evidence. This approach emphasises the importance of combining these three components to guide clinical decision-making and improve patient outcomes.

1. Clinical expertise

Clinical expertise refers to the knowledge and skills that healthcare professionals, including nurses and midwives, develop through education, training, and experience. This expertise allows them to make informed judgments about patient care. Research emphasises that clinical expertise should not be undermined in the pursuit of evidence-based practice. Instead, it should complement the other components of the triad. Experienced clinicians can bring a deep understanding of the unique needs of individual patients, recognising subtleties and nuances that may not be captured by research evidence alone.

2. Patient values and preferences

Patient-cantered care has become a cornerstone of modern healthcare. Recognising and respecting patients’ values, preferences, and individual circumstances is essential for providing effective care. The evidence-based triad encourages healthcare professionals to engage patients in shared decision-making, where the patient’s perspective is considered alongside clinical expertise and research evidence. Studies emphasise that involving patients in the decision-making process can lead to greater adherence to treatment plans, increased patient satisfaction, and improved health outcomes.

3. Best available external evidence

The third component of the evidence-based triad involves integrating the best available research evidence into clinical decision-making. This evidence is typically derived from well-designed research studies, systematic reviews, and clinical guidelines. Evidence-based practice encourages healthcare professionals to critically appraise and apply research findings to their patient care decisions. The emphasis on external evidence aims to ensure that clinical decisions are based on scientifically sound and validated information.

Synthesis and application

The synthesis of these three components—clinical expertise, patient values, and best available evidence—forms the foundation of evidence-based practice in nursing and midwifery. This approach seeks to strike a balance between scientific rigor and individualised patient care. Literature indicates that successful implementation of the evidence-based triad requires ongoing professional development, interdisciplinary collaboration, and a commitment to lifelong learning. This approach acknowledges that evidence-based practice is not a rigid formula but a dynamic process. It requires healthcare professionals to continually update their knowledge and skills, adapt guidelines to individual patient contexts, and remain open to evolving research and patient preferences. Successful implementation of the evidence-based triad can lead to improved patient outcomes, increased patient satisfaction, and enhanced healthcare quality. The evidence-based triad in nursing and midwifery healthcare recognises the importance of combining clinical expertise, patient values and preferences, and the best available external evidence to guide clinical decision-making. This approach acknowledges the complexities of healthcare and emphasises the need for a patient-centred and holistic approach to providing high-quality care.

References

Shearer, M. (1989). Maternity patient movements in the United States 1820-1985. In I. Chalmers, M. Enkin,  M. Keirse (Eds.), Effective care in pregnancy and childbirth (pp. 110-130). Oxford University Press.

van Wagner, V. (2017). Midwives using research: Evidence-based practice and evidence-informed midwifery. Open Library. Creative Commons Attribution-NonCommercial 4.0 International License

van Wagner, V. (2013). Reconsidering evidence: Evidence-based practice and maternity care in Canada. [Doctoral dissertation, York University]. YorkSpace. http://yorkspace.library.yorku.ca/xmlui/handle/10315/31318