Finding, Evaluating, and Presenting Evidence

Sharon E. Lock, PhD, ARNP

NUR 603

Spring, 2001

Sources of Knowledge

Intuition Trial and error Tradition Authority Experience Scientific

Stevens & Ledbetter, 2000, p. 91

Sources of knowledge

“…not all sources of knowledge are highly reliable, nor when applied do they consistently produce desired outcomes.”

“Experience, although a good teacher, results in conclusions about care that contain bias”

Stevens & Ledbetter, 1999, p. 92

Scientific Approach

Research evidence provides a scientific basis for nursing practice.

A scientific approach to clinical decision-making results in a “practice with known cause and effect and predictable outcomes.

Types of Research Studies

Single research studies• Randomized Controlled Trials (RCT’s)• Descriptive studies

Evidence summaries• Systematic reviews• Meta-analysis• Integrative reviews

Finding Evidence

What counts as evidence?• RCT’s• Systematic reviews• Meta-analysis• Quasi-experimental• Prospective cohort studies• Case-control studies• Cross-sectional surveys• Correlational studies• Qualitative studies

Retrospective vs. Prospective

Verschuere, 1999

Formulate question to guide search

Break question down into searchable components

PICO formula• Patient population/problem• Intervention or exposure• Comparison• Outcome

Retrieve relevant evidence effectively

Textbook Journal Bibliographic database (MEDLIBE, CINAHL) Evidence-based journal series Systematic reviews (Cochrane Library, STTI Online Journal) Evidence-based clinical practice guidelines

• AHRQ• National Guideline Clearinghouse• U. S. Preventive Services task Force

Internet

Harris, 2000

Designs that produce the best evidence

Treatment (interventions)– RCT’s– Systematic reviews– Meta-analyses

Diagnosis (screening & assessment)– Positive & negative ratios of diagnostic tests

Prognosis (nature of the disease)– Prospective cohort studies

Causation (risk or harm)– Cohort studies– Case-control studies

Nicoll & Beyea, 2000

Evaluating info on the internet

Are you PLEASED with the site?• Purpose• Links• Editorial• Author• Site• Ethical• Dates

Evaluating evidence

Who is qualified to judge?• Clinical experts• Methodology experts• Other stakeholders

Lohr & Carey, 1999

Variables thought to affect quality of evidence

Sample selection Randomization Blinding Sample size Description of

intervention

Outcomes Length of follow-up Attrition Confounding variables Statistical analysis

Strength of evidence:Bradford-Hill Criteria for Causation

Temporality Strength Dose-response Reversibility Consistency Biologic plausibility Specificity Analogy

Presenting Evidence to the Patient

The patient has a choice

Gray, 1997

ProviderProvider PatienPatientt

The last patientThe last patient

ExperienceExperience

LitigationLitigation

EducationEducation

ResourcesResources

AuditAudit EvidenceEvidence

Other professionalsOther professionals

The mediaThe media

ResourcesResources

Friends & relativesFriends & relatives

EvidenceEvidence

Gray, 1997

Elements of face-to-face decision-making

Information given by nurse Interpretation by patient Discussion between nurse and patient

Gray, 1997

Providing information

Finding research evidence Systematic appraisal

• Probability that pt will benefit• magnitude of benefit• probability that pt will have adverse effects of

intervention• magnitude of adverse effects

Gray, 1997

Patient Interpretation

Pt may need time to think Educational pamphlets Pt will interpret in two ways

• How evidence appears to him/her• How outcome of intervention correlates with his/her

values

Gray, 1997

Discussion between patient & nurse

Nurse/patient relationship How evidence is presented Confidence demonstrated by nurse Time