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EBM Asking questions. Background and foreground question. Background question (novice) Basic knowledge of disease or condition eg. “What is diabetes?” “Why did this patient present with polyuria?” “How might we manage the problem?” Foreground question (expert)
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Background and foreground question • Background question (novice) • Basic knowledge of disease or condition eg. • “What is diabetes?” • “Why did this patient present with polyuria?” • “How might we manage the problem?” • Foreground question (expert) • Interest in individual patient with specific situation and condition eg. • “Using of cardiac resynchronization therapy in heart failure, is it reduce mortality?
Novice Expert
Where to find answers? • Background question • Standard textbook • Review or monograph of related subjects • Foreground question • Using of EBM to • asking the question • search the evidence • appraise the evidence • Synthesise and apply to patient
Types of clinical question • Diagnostic test • Treatment effect • Prognosis of disease • Risk factors and exposures of disease
Structures of clinical question • Patient • Intervention • Comparison intervention • Outcome • P • I • C • O
Example • An anxious laboratory technician phoned about a potassium of 7.3 mmol/l (Ref Range 3.5-5.0) found on a routine blood test of a 50 year old woman. • I arranged an urgent repeat of the electrolytes (to rule out a spurious elevation) and an ECG. • The latter was reassuringly normal, but left me asking: Does a normal ECG rule out a serious elevation of potassium?
Population/patient – hyperkalemia • Indicator – EKG • Comparator – • Outcome – sensitivity and specificity of EKG to confirm hyperkalemic status
Example 2 • A 60-year-old man presented to the emergency department due to left side weakness. His past medical history was significant for hypertension. He had been treated with enalapril 5 mg per day. • He had a CT brain done on his visit and was shown to have an ischemic stroke. He was observed for 4 days in the stroke unit and was ready to go home. • You planned to prescribe low dose aspirin for recurrent stroke prevention but the chief resident recalled a recent data showing that a combination of aspirin and dipyridamole may be better in terms of prevention of recurrent stroke. You wondered whether that claimed was correct.
Population/patient – patient with MI + DU • Indicator – PPI + ASA • Comparator – clopidogrel • Outcome – reduce recurrent ulcer bleeding