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EVIDENCE BASED PRACTICE-PROGNOSTICS. FAJAR AWALIA YULIANTO. reference. Does every patients with ACD become heart failure grade 4? Does every patients with ARF become RHD? Will the patients of leukemia survive for 3 months? Will the patients die or stay healthy for a few years?.
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EVIDENCE BASED PRACTICE-PROGNOSTICS FAJAR AWALIA YULIANTO
Does every patients with ACD become heart failure grade 4? • Does every patients with ARF become RHD? • Will the patients of leukemia survive for 3 months? • Will the patients die or stay healthy for a few years?
Cohort studies: best design for answering prognosis questions • Randomized trial: particularly since they usually include detailed documentation of baseline data • Case control studies: particularly useful when the outcome is rare or the required follow up is long • Systematic review: combines all prognosis studies • Inception cohort: the similarity of other prognostic factors at the beginning of the study PROGNOSTIC STUDIES
Was a defined, representative sample of patients assembled at a common point in the course of their disease? • Was follow-up of study patients sufficiently long and complete? • Were objective outcome criteria applied in a “blind” fashion? • If sub-groups with different prognosis are identified: • Was there adjustment for important prognostic factor? • Was there validation in an independent group of ‘test-set” patients? VALID COMPONENTS
How likely are the outcomes over time? • How precise are the prognostic estimates IMPORTANT COMPONENTS
The study started with collected samples according to standardized criteria • The target disorder is defined and how the samples FIRSTLY assembled is described • Ideally, the best of its kind is participants are all at a similar stage in the course of the same disease • Inception cohort SAMPLE ASSEMBLED AT A COMMON POINT
Ideally, every patient in the cohort would be followed until fully recover or develop one of the disease outcomes • Too short=too few patients develop the outcome of interest • Too little=the less accurate the estimate of the risk of the outcome will be • “5 and 20” rule= fewer than 5% loss leads to little bias, greater than 20% loss threatens validity FOLLOW UP SUFFICIENTLY LONG AND COMPLETE
The investigators use the established specific criteria to define each important outcome and then used them throughout the patient follow up • Death is objective, but judging underlying cause is very prone to error • Determining the underlying cause of death (or clinical outcomes), the investigator must not knowing prior clinical characteristic and prognostic factors-> blinding BLINDED OBJECTIVE OUTCOME CRITERIA
Adjustment of (other) prognostic factors similar to adjustment of confounding factors • Prognostic factor are associated to the outcome of interest • If the study reports that one group of patients had a different prognosis than another, first we need to see if there was any adjustment for known prognostic factors ADJUSTMENT OF PROGNOSTIC FACTORS IN DIFFERENT PROGNOSIS SUB-GROUPS
Typical results of prognosis study: • As a percentage of survival at particular point in time (such as 1-year or 5-year survival rate) • As a median survival (the length of follow up by which 50% of study patients have died) • As a survival curves that depict the proportion of the original study sample who have not yet had a specified outcome (Kaplan-Meier curves) LIKELIHOOD OF THE OUTCOMES OVER TIME
A: Good prognosis (or too short study!). B: Poor prognosis early, then slower increase in mortality, with median survival of three months. C: Good prognosis early, then worsening, with median survival of 9 months. D: Steady prognosis. KAPLAN-MEIER CURVES
A good prognostic study include the confidence intervals for its estimates of prognosis PRECISION OF PROGNOSIS ESTIMATION
