بسم الله الرحمن الرحیم

Types of Questions

Types of Study

? Types of Research The Level of Evidence Depends on the Question Type Treatment Prognosis Diagnosis Etiology ? Types of Clinical Questions II III III IV IV III II III III II IV III II The Level of Evidence Depends on the Question Type RCT Cohort Case- control Case Series Cross sectional I I I I Types of Research Systematic Reviews Meta-analyses

Appraise Are the results of the study valid? What are the results? Will the results help in caring for my patient?

Step 1: Are the results Valid? Did intervention and control groups start with the same prognosis? 1. Were patients randomized? 2. Was group allocation concealed? 3. Were patients in the study groups similar with respect to known prognostic variables?

Were patients randomized?

Was group allocation concealed?

Were patients in the study groups similar with respect to known prognostic variables? : Table 1: The study groups did not differ significantly in baseline characteristics.

Was prognostic balance maintained as the study progressed? 4.To what extent was the study blinded?

Were the groups prognostically balanced at the study's completion? 5. Was follow-up complete? 6. Were patients analyzed in the groups to which they were first allocated? 7. Was the trial stopped early?

Are the results of this study valid? Key validity issues for studies of Therapy: randomization concealed allocation baseline similarities blinding follow-up complete intention-to-treat

Step 2: What are the results? How precise was the estimate of the treatment effect? What were the confidence intervals? P value How large was the treatment effect? What was the relative risk reduction? What was the absolute risk reduction?

Statistical Precision P-value: hypothesis, chance, type one error CI: point-estimation, width CI of treatment effects

Measurment of Treatment Effects for Outcomes

Measurment of Treatment Effects

Not Clinically important Not Statistically significant Distinction between statistical significance and clinical importance (Berry 1986) Not Clinically important Clinically important True Negative Clinically important Null Hypothesis Statistically significant Not Statistically significant

Size of Effectcs Clinical important effects The distance of point estimate from null hypothesis Statistical and clinical differences

How can I apply the results to patient care? Were the study patients similar to my population of interest? Does your population match the study inclusion criteria? If not, are there compelling reasons why the results should not apply to your population? Were all clinically important outcomes considered? What were the primary and secondary endpoints studied? Were surrogate endpoints used? Are the likely treatment benefits worth the potential harm and costs?

Thank You !