ASPIRE CLASS 6: Interpreting Scientific DataSarah J. Billups, PharmD, BCPS, Clinical Pharmacy Specialist

RR: Relative Risk

Used in prospective studies

Tells you the comparative risk in each group over a given period of time

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

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

RR: Relative Risk

RR: Relative Risk

Calculate RR & RRR and interpret Calculate ARD & NNT and interpret

Stroke No Stroke

Dark Chocolate 40 4,460 4,500

Control 70 4,430 4,500

RR: Relative Risk

Stroke risk: chocolate group= 50/4500 = 1.1%

control group= 70/4500 = 1.6%

1.1%

RR = 1.6% = 0.7

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

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

OR: Odds Ratio

Used in retrospective studies

Example Question: Is colchicine associated with an increased incidence of Very Bad Outcomes, specifically blood dyscrasias or rhabdomyolysis?

OR: Odds Ratio

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

OR: Odds Ratio

Very Bad Outcome

No Very Bad Outcome

Colchicine exposure 6 13

No exposure 894 8,987

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

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.

HR: Hazard Ratio

Used in prospective studies with time-to-event or survival analysis

Incorporates TIME

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…

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.

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.

HR: Hazard Ratio: Study in head & neck cancer

0

10

20

30

40

50

60

70

80

90

100

0 15 30 45 60 75 90 105 120 135

% s

top

pin

g v

ideo

gam

e

minutes

Pizza fragrance

Lavender fragrance

HR: Hazard Ratio

hazard rate in treatment group

HR= hazard rate in control group

What’s true if HR = 1 ?

2 ?

0.5 ?

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.

ASPIRE CLASS 5: Preparing Abstracts for conference SubmissionSarah J. Billups, PharmD, BCPS, Clinical Pharmacy Specialist

WSC Specifics

• Read the submission guidelines carefully 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