TOPIC 1.2, RISK

SPECIFICATIONS: RISK 1.18 Analyse and interpret quantitative data on illness and mortality rates to determine health risks (including distinguishing between correlation and causation and recognising conflicting evidence) Evaluate design of studies used to determine health risk factors (including sample selection and sample size used to collect data that is both valid and reliable) Explain why people’s perceptions of risks are often different from the actual risks (including underestimating and overestimating the risks due to diet and other lifestyle factors in the development of heart disease).

INTRODUCTION What does risk mean? The probability of an unwanted event or outcome (accident/injury/disease) happening in a given time. Examples: Lung cancer, Car crash How do we work out probability? We look at how often it happens. Flip a coin, what is the probability? 1 in 2, decimally 0.5, or 50% Every time you flip the coin you have a 50% chance of heads. Example: In a class of 30 students, 10 caught head lice in 1 year. What was the probability of a student catching head lice last year? 3 ways to calculate the answer: 1 in _______, decimally or as a percentage 1 in 30/10 = 1 in 3 risk 1/3 = x 100 = 33%

EXAMPLE CALCULATIONS & ACTIVITY In a year 5 class of 30 pupils, 6 children caught head lice in 1 year. What was the risk of catching head lice in this class? Give your answer in a 1in ______ form and as a percentage. 1 in 30/6 = 1 in 5 chance or a 1/5 = (0.2 x 100) = 20% risk 2. In 2005, people in the UK died due to injuries or poisoning. The total UK population at the time was What is the risk in a year of someone in the UK dying from injuries or poisoning? 1 in / = 1 in 3099 or a 1/3099=( x 100) = 0.032% Complete Q1 on activity 1.9 ONLY

RISK – PERCEPTION What makes us underestimate? the risk is undertaken voluntarily the risk is natural the risk is familiar the risk is not feared (the activity is looked forward to) the risk is fair the risk is common the consequences are in the long term. What makes us overestimate? Involuntary Not natural Unfamiliar Dreaded Unfair Rare Consequences are sudden

PERCEPTION & CALCULATION OF RISK Complete the remaining questions Q5-Q6. Add data to the table in your booklet- Table 4 Read page 19 in the book Complete Q1.8 and Q1.9.

IS RISK THE SAME FOR EVERYONE? We calculate risk for the population but it is different for individuals. What might affect your chances of getting cardiovascular disease? Heredity Physical environment Social environment Lifestyle choices

CORRELATION To determine what the risk factors are for a particular disease, scientists look for correlations between potential risk factors and occurance of the disease. Positive correlation: when X increases, Y increases too. Example: Age and risk of death Negative correlation; when X increases, Y decreases Example: Age and heart rate Causation: when one factor has a direct effect on another. The faster one runs, the faster his/her heart rate is. Do you see a correlation below? Causation? Shark attacks and ice-cream sales Children’s foot sizes and spelling abilities Lung cancer and smoking Graph on life expectancy and tv in your handout. Correlation does not mean causal relationship

Complete Activity 1.9 Q7 & 8. (Note: with Q7, the data in Table 3 has already been put into a graph format for you in your handout.) Controlling variables, having control groups and setting up a null hypothesis & statistics helps to show causal relationships.

IDENTIFYING RISK FACTORS Define: Epidemiologist: one who looks for correlations (and possible causal relationships) between risk factors & disease Risk factor: is something which is likely to increase the chances that a particular event will occur. Epidemiologists study statistics to try to identify risk factors for a specific disease.

TWO MAIN TYPES OF STUDY  Cohort studies  group of people followed forward over time to see who develops the disease  one population followed forward over time- risk factors are compared between the group who get the disease and the group who do no.  two populations followed forward over time one group is exposed to risk factor and the other not, and compare outcomes and draw conclusions  Case-control studies  Two populations of people who have the disease are compared with a group who does not - look back at their histories

ARE THESE GOOD STUDIES? CASE OR COHORT? « All four of my grandparents smoked but none of them died from lung cancer.» A research group surveyed 6000 people about their drinking habits and their medical history. It was decided that the most efficient way to contact people was by ringing them up at home during the day. The government decided that it would carry out a large scale survey on the dietary intake of the population and heart disease. It gave 10,000 people a food diary to keep over a week and analysed their medical records. This would then be repeated for the next five years.

FEATURES OF A GOOD STUDY Aim: Hypothesis: Representative sample: Valid results: Reliable results: Sample size: Control group (matched to sample): What you are trying to investigate. It should be clear and the design should match it. An explanation for a set of observations. This also should be clear and the design should match it. a) Important to select appropriate numbers from each age, soical, racial, health and lifestyle and all other groupings. b) Selected from the wider population avoiding selection bias. c) Be aware that non participants may differ in important aspects from the participants. Results should be collected with equipment and methods which give accurate results, results close to the true value. The method produces similar results when the experiment is repeated. Variables which could affect the result have been controlled or taken into account or else these variables could affect the results rather than the variable being investigated. A large number of people being studied/tested. This ensures that the results are less likely to have occured by chance. Both groups are matched on variables which might cause CVD (for example). Only one variable should differ. This means that we know that only this one variable is influencing our results.

FEATURES OF A GOOD STUDY Activity 1.10 Identifying health risks Read about the Wakefield study (1st three paragraphs) What is the MMR vaccination? What type of study was the Wakefield study? What is meant by an unconntrolled case study? What evidence was there that the MMR vaccination caused autism? What are the weaknesses of this study Answer question 1. Were the studies well designed? Were the data reliable and accurate? What type of case studies were they?