mid-quintile (e.g. 40–60%), or those outside the high-risk group (0–90%). Comparing the upper and lower tails maximises the odds ratio for impact but raises concerns about the arbitrariness of the quantile used.B: Individual level In a clinical setting, the focus is on a single person: what information does their PRS give about their risk of disease? Possible outcome measures that are relevant at an individual level include: (a) At what percentile in the distribution of PRS does this individual lie? This is between 0 and 100%, with scores having a normal distribution. (b) What is this person’s relative risk of disease compared to the average risk in the population? (c) What is this person’s absolute risk of disease, and by what age [17]?
