Good clinical practiceGood clinical practice

Evidence-based medicine Biological knowledge of health and disease

(Rational of clinical judgment). Awareness of social and cultural values.

Clinical ReasoningClinical Reasoning

EvidenceDoctorPatient

Clinical reasoning: Clinical reasoning: different scenariosdifferent scenarios

Evidence Physician

Patient

1 Cancer treatment

Evidence

Physician

Patient

2 Infertility treatment

Problems With Evidence-Based Problems With Evidence-Based Medicine in Infertility Medicine in Infertility

• Insufficient evidence to supportInsufficient evidence to support

some diagnostic tests.some diagnostic tests.

• Many treatment modalities. Many treatment modalities.

Problems with Evidence Based Problems with Evidence Based Infertility TreatmentInfertility Treatment

Problems of Diagnosis (Example)Problems of Diagnosis (Example)

Semen analysis:Semen analysis:

Count : 80,60,40,20, lessCount : 80,60,40,20, lessMotilityMotilityAbnormal formsAbnormal forms

Problems with evaluating evidence Problems with evaluating evidence ErrorsErrors

Type I error:– P<0.05: we accept this chance of error (5%).

The error could be inflated by a subgroup analysis.

Type II error: (more common)– Investigators did not detect a difference when a

difference actualy exists.– We accept 20% error = power of the study is

80%.

Problems with evaluating evidenceProblems with evaluating evidence

Confounding factor:

Factor associated with both treatment (as risk factor) and the outcome under study.

e.g.: low dose contraceptive pills.

Problems with evaluating evidenceProblems with evaluating evidence

Bias: is systematic error in collection or interpretation of study information.– Selection bias:

Dissimilar selection criteria.

– Information bias: IUI*PID

Problems with evaluating evidenceProblems with evaluating evidence Number needed to treatNumber needed to treat

Until recently, it was acceptable to look for (P values) in the results and the difference is considered significant if P <0.05.

The magnitude of the effect of the intervention is of utmost clinical importance to evaluate the implications of this significance.

we should remember that what is we should remember that what is statistically significant might not statistically significant might not

always be clinically relevantalways be clinically relevant