By scouring large numbers of patient records and tracking patients over time, RWE makes it practical to identify subsets of patients who can most benefit from a particular medicine due to their genetics, the particulars of their illness, environmental and other factors. Potential side-effects and contraindications can also be identified much more quickly.
This helps pharma companies and healthcare providers decide which members of a given population to target with a particular medicine, and makes it easier for insurers and other payers to justify the cost.