Risk in Health

Kashika M. Sahay MPH, PhD (c)Date: February 3, 2015Module SummaryThis module is going to introduce you to some key statistical terms and concepts that are going to be helpful in discussing different examples of health risk. 1TodayGo over infographics and discuss the process/challenges of creating the graphic (get into your groups and finish up graphic right away)HousekeepingReminder Office hours today from 2-3:30 Genomic Sciences Building 1334; Tomorrow from 11:30-1Summary of this module: How do we calculate risk from a health perspective? Evaluations of moduleGenre analysis and overview of the final projectThursday: Guest lecturer Jennifer Hill Due on Thursday: 3 potential topics and a paragraph for each topic

Presenting infographicsEmail graphic to kmsahay@live.unc.edu if electronic, provide drawing if hand-drawnIn 1-2 minutes:What strategies did you use to decide which health statistics you chose? Which statistics did you end up usingChallenges in presenting the information in the infographic? What was the story you wanted What principles of design did you use/reject in designing your infographic?Summary of this moduleLearning objectives (from the syllabus) By the end of this course, you should be able to:Exhibit numerical literacy, specifically in modes and methods of calculating risk.Critically evaluate and interpret presentations of risk in the popular media.Write clearly and concisely in a variety of disciplines and for multiple audiences (e.g. academic, professional, lay)

How did we do this in this module?Personal assessment of riskScientific assessment of (health) riskReconciling personal Personal Assessment of Risk Personal Assessment of RiskA Risk is A DECISION you MAKE that has different OUTCOMES A Level at which you MAKE a DECISION about an OUTCOMEHow we EVALUATE your own PERCEPTIONS about a BEHAVIOR or OUTCOMEWhat is Risk Perception?Ones estimate of the likelihood that something bad/undesirable will happen in a given time frame

Ones feeling or opinion of the existence or size of a risk

What is an Acceptable Risk?The degree to which someone or some society is able to tolerate the existence of something that poses a danger

How do we decide which risks are acceptable? ConsiderationRationaleExample Is the risk assumed voluntarily? Less acceptable if involuntarySecondhand smoke v. smokingIs it natural or man-made? Less acceptable if manmade Chemical spill v. tsunamiLikely to be used as intended? Less likely if likely to be misusedEx. Guns v. microwavesAre alternatives available?Less acceptable Unsafe toy v. driving through trafficCatastrophic or common?Less acceptable if potential for catastropheAirplane crash v. automobile crashFair or unfair? Less acceptable if risk is borne by a single group People living near chemical plant v. those living awayIs evidence in the scientific community unanimous?Less acceptable if contradictory information from responsible sourcesHealth risks of smoking v. vaccines and autism For more, please read the supplementary material on Acceptable Risk published by the 9The Socioecological model

Our assessment of risk depends on:Our knowledge about the risks of a behaviorOur affective responseAnxiety about a behaviorSatisfaction with the outcomeCertainty of our conclusionsAssessment of the information provided Decision making processCompliance with recommendationsLazarus and Folkmans stress and coping theory from our uncertainty reading posits that we deal with unknowns in 2 ways: 1) interprets the meaning of a stressor and its relationship to his or her experiences and values. 2) person assesses his or her resources and capacity for coping with a given stressor.10Scientific Assessment of Health Risk Epidemiology

What is the distribution of disease in a population?What is the distribution of exposure in a population?Over what time frame?Are the results from your study generalizable to the overall population of interest? How certain are you of your estimates?When thinking about if acne medication reduces acne in a population of teenagers, you need to think about how those who have acne may be different from those who do no have acne. You should also note that those who use the prescription medication may be different from those who do not take the prescription medication. How would you feel about the validity of an acne study that followed people for 2 weeks? 2 months? 2 years? Finally, you should consider the age, sex, race and other factors of the people who are in the study. Are these people generalizable to the overall population? 12Some study designsE=exposureDZ=disease Note that the timing of data collection, timing of exposure, and timing of disease are factors that differ across study design

The type of study design can tell you a lot about the scientific questions of interest. See the readings about proportions, odds and risk for more details on calculations and study differences. 13How do you decide which study design is best?

Which study design is best? It really depends as each study design has its own strengths and weaknesses. Some of the factors that come into playRegulations, time urgency, how much is known about the association, money, beneficial nature of the exposure; 14Risk as a mathematical quantityThe probability that a health event will occur (usually comparing probabilities in two groups)

See other lecture notes for more definitions and calculations. 15

OddsImportant point: Whats the difference between a proportion and an odd?

Proportions involve comparing parts to a whole and can only be between 0 to 1. Proportion: Orange squares/all squares= 3/5=0.6

Odds can range from positive infinity to negative infinity. Odds: orange squares/brown squares= 3/2 or 1.5/1 ; The odds of picking an orange square is 1.5 times the odds of picking a brown squareReconciling personal experiences with scientific dataSome mistakes to avoid and tips to keep in mind; An example of oddsOne year Odds: Numerator= # of people in America who were alive

Denominator= # people who died from that disease

Ex. Drowning : 275306000 people alive /3248 died of drowning

79,065 people alive/1 died of drowningOdds of dying of drowning 1 to 79065 in the year 2000 in the US population overall Correlation does not equal causationDoes ice cream cause murder?Based on this graph, the number of murders increases with the # of ice creams sold. Does that mean that ice creams cause murder?

No. Always remember, correlation (sometimes called association) DOES NOT EQUAL Causation.

How did we determine that concussions lead to brain injury?

Q: How do you establish causation?A: Bradford Hill Criteria

Temporality: Exposure comes before the disease. Plausibility: biological pathway from exposure to disease is establishedConsistency: results are reproducible in scientific studyDose-response relationship: if you increase exposure incrementally, disease also increasesSpecificity: single cause leads directly to an effectReversibility: in the absence of exposure, disease does not occurCoherance: compatible with existing knowledge You hear that microwave use is associated with brain cancer. If you want to see if microwave use causes brain cancer (there is no scientific evidence of this), then you would want to see if there is a study that tries to address all or as many as possible the Bradford Hill criteria for causation. 21What can we do to better process information about risk?How do science and perception come together?Great, you did this valid studyHow sure are you that you found the right answer?

We are really uncomfortable with uncertainty. However, its important to recognize that uncertainty is a part of life. Also, when we are drawing samples from a general population we need to be careful about assuming that the sample is the same as the general population. Thats why we generate confidence intervals to see how much variation we have in the sample. Note that the true population value however, is ALWAYS UNKNOWN. We can never know how close we are to a true population value, only how much spread we have in the data that we sampled. For more about the 23BiasBias in scientific study Bias in our perception

All of us show bias when it comes to what information we take in. We typically focus on anything that agrees with the outcome we want.Noreena Hertz, professor of Decision SciencesAsk yourself: Are the study participants generalizable to the overall population?Remember, we rarely know the true population value we are trying to estimate. Numbers and Information can be presented in misleading waysEven though we are skeptical, we should always critically evaluate information

Journalists, scientists, others, may not be intentionally misleading us, they all have their own reasons for presenting information

What can we do to better process information about risk?Evaluate: Emotion: Is this statement trying to elicit an emotional response from me? Is the framing of the statement in terms of gain or loss?Numeracy: Are numbers presented as proportions, rates, or odds? Source: What is the source of this information? Is it credible?Absolute v. Relative Risk: If totals are presented, are they related to any other quantity?

Guidelines for Evaluating Risk Context MattersEx. If you want to tell me how many chickens were killed because they were suspected of avian flu, tell me what proportion of chickens in all of England were killedPractice good number hygiene Consider your audiences numeracy and computational skillsMake big numbers and small numbers relatableAvoid nonsensical comparisonsBe wary of surveys and who collects dataEx. A survey on Taylor Swifts fan page may not be nationally representativeConsider conflicts of interestA skin care company may have a vested interest in showing you it reduces acne

Guidelines for Reporting NumbersMean or Median which to reportMean- when you believe your data is normally distributed (evenly spaced throughout the population but centered around an average value, ex. Men in the United States have an average height of 6 feet)Median-when your data may be skewed to have values at extreme ends of the spectrum (ex. Income, most of us are not billionaires, but Uncertainty: Confidence intervals should be renamed uncertainty intervalsNote that we never know the true population value; We are trying to approximate it P-valuesdebates with the values, statistical significance Statistical significance does not mean actual significance. (Just because there are statistical difference between groups, does not mean that that statistical difference has any practical value. TrendsBe wary of trends; Remember that you can always cherry pick information over the last 5, 10, 15, 100 years to prove a point. Please refer to the video at scijourno.com for a more in-depth discussion of each of these topics28Guidelines for Risk PerceptionRandom v. likely events (winning the lottery v. freeze warning)Realize that we tend to think of common events as less risky (see section on risk acceptance)Relative Risk v. Absolute Risk Be wary of people telling you that a drug reduces your chances of death by x% (a relative risk); Always ask what your absolute risk of death isEx) Remember the class example where the risk of death from Miracle drug is reduced by 20%. However Another example of this: Your risk of blood clots when using birth control (the pill) is doubled. However your absolute risk of blood clots goes from 2 in 10,000 to 4 in 10,000.

I hope this module inspires more questions than answers!Some questions to think about.. How do we store numerical information in our minds?How do we quantify and avoid bias in our perception and in scientific study?How can you design a study to be generalizable to an entire population?Why are some studies believed more readily than others?

Thank YOU!! Questions/commentsPlease complete evaluations!

GENRE ANALYSISRubric for Analysis Identify the communication purpose(s)Identify the audiences (internal, external, peers, up or down the hierarchy.)Identify the organizational patternWhat opening information is there headers, titles, communication chains, dates, etc.Organization What purpose do the sections of the document serve for the audience?What is the purpose of the conclusion (to summarize, provide information, provide highlights, to give contact information)?

Rubric for Analysis ContinuedFinal questionsWhat are the style expectations (formal, consultative, informal)?What is the medium for delivery?Where does there seem to be flexibility in the genre expectations? Your assignment for ThursdayIn order to begin thinking about directions for your introduction, theses, and arguments you might use, you will generate a list of at least three possible topics for your project. Each topic should be accompanied by a paragraph that explains your interest in the possible topic, suggests the places in science, politics, and culture you might look to for source material, and point to possible arguments you might find useful in the larger project. Journal Prompt #4 Considering that analyzing numbers and statistics is a complicated process, think about how you would design a study to learn more about [a disease of your choice]. What kind of study design would you use? Who would be in your population? How would you collect information and evaluate risk of the disease? What biases might your study still have? How would you present your study findings to general audiences in a cohesive way?36