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ASPIRE CLASS 6: Interpreting Scientific Data Sarah J. Billups, PharmD, BCPS, Clinical Pharmacy Specialist
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RR: Relative Risk Used in prospective studies Tells you the comparative risk in each group over a given period of time
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RR: Relative Risk Example Question: – Does ingesting dark chocolate reduce the risk of stroke? Fabricated data based on a real retrospective study by Buijsse: European Heart Journal (2010) 31, 1616–1623
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RR: Relative Risk Study: Randomize 9,000 people over age 50 with no known heart disease to: intervention: dark chocolate (7 g daily) control: white “chocolate” Follow x 8 years
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RR: Relative Risk
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Calculate RR & RRR and interpret Calculate ARD & NNT and interpret StrokeNo Stroke Dark Chocolate404,4604,500 Control704,4304,500
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RR: Relative Risk Stroke risk: chocolate group= 50/4500 = 1.1% control group= 70/4500 = 1.6% 1.1% RR = 1.6% = 0.7
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RR: Relative Risk RRR= 1 - 0.7 = 0.3 Given an individual consumes daily dark chocolate, he has a 30% lower risk of having a stroke over the next 8 yrs
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ARD: Absolute Risk Difference Stroke risk: chocolate group= 50/4500 = 1.1% control group= 70/4500 = 1.6% ARD = 0.016 – 0.011 = 0.005 NNT = 1/0.005 = 200
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OR: Odds Ratio UUsed in retrospective studies EExample Question: Is colchicine associated with an increased incidence of Very Bad Outcomes, specifically blood dyscrasias or rhabdomyolysis ?
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Study: 1. Identify all patients with VBO (CASES) 2. Identify a comparable CONTROL group 3. Match cases to controls on key characteristics 4. Look back in time for exposure of interest
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OR: Odds Ratio Very Bad Outcome No Very Bad Outcome Colchicine exposure613 No exposure8948,987
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OR: Odds Ratio Odds of drug exposure in cases: 6 / 13 = 46.2% controls: 894 / 8,987 = 9.9% 46.2% OR = 9.9% = 4.7
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OR: Odds Ratio Desired Question: Given colchicine risk of VBO? Actual odds ratio answer: Given that a patient had a VBO, his odds of being exposed to colchicine are 4.7 times that of someone without a VBO.
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HR: Hazard Ratio Used in prospective studies with time-to-event or survival analysis Incorporates TIME
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HR: Hazard Ratio Hazard h(t) = event rate for an individual who has already survived to time t Calculation: # of patients dying over a given time interval # still alive at the start of that interval For example…
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HR: Hazard Ratio Example Background: A bunch of moms want to find a way to get their teenagers to stop playing video games and come eat lunch. Calling their names gets a response of “as soon as I finish this level.” They decide to appeal to the teen’s sense of smell and design a study to test the effects of 2 different fragrances.
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HR Example, continued Study design: They randomize teens to have one of two different smells pumped into their gaming area: lavender, or pizza, and measure how much time it takes each teen to “finish this level” and come eat lunch.
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HR: Hazard Ratio: Study in head & neck cancer
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HR: Hazard Ratio hazard rate in treatment group HR= hazard rate in control group What’s true if HR = 1 ? 2 ? 0.5 ?
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HR: Hazard Ratio: Study in head & neck cancer HR = 3.0 (CI 1.9 – 5.2) Interpretation: At any given time, about 3 times as many teens smelling pizza manage to tear themselves from their video game to eat lunch compared to the control group.
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ASPIRE CLASS 5: Preparing Abstracts for conference Submission Sarah J. Billups, PharmD, BCPS, Clinical Pharmacy Specialist
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WSC Specifics Read the submission guidelines carefully http://www.westernstates-rx.org/index.php/abstracts/seven-steps-to-success http://www.westernstates-rx.org/index.php/abstracts/seven-steps-to-success Deadline: Feb 21, 2014 300 words recommended (max 500 words) 5-7 Key Words required 2 Presentation Objectives required Platform Presentation Category
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