What does an epidemiologist actually do?

When people hear the word “epidemiologist”, most automatically think “epidemic”, and think of researchers tracking the progress of infectious diseases such as Influenza and Ebola. However, there is also another sub-set of epidemiologists like me that study chronic non-communicable diseases, like rheumatoid arthritis, Parkinson’s disease, and heart disease.

In many ways, these diseases are much easier to study. There is no person-to-person transmission, and once a person is diagnosed with the disease they are generally considered to have it for life.

When studying the epidemiology of non-communicable diseases, common questions include:

• How many people have the disease today?
• How many people are likely to have the disease in 20 years?
• What types of people have the disease?
• How many people are going to die from the disease?
• How much does the disease decrease quality of life?
• What are the current interventions used to treat the disease?
• Can we use a computer model to estimate the percentage of people in Africa who have the disease?
• Are we on track to meet the WHO’s target of a 25% reduction in premature mortality from noncommunicable diseases by 2025?

We also often work in collaboration with health economists to answer questions such as:

• How much does it cost to treat a person with this disease today?
• How much will it cost to treat all people with this disease in 20 years?
• How cost-effective are the various interventions used to treat the disease?

Since epidemiological studies are by observational, not randomised, we need to be very careful not to assume causality. For example, often in real-world observations, we see that patients treated with old cheaper generic drugs have better outcomes that patients treated with new expensive branded drugs. However, in the real-world, patients are not randomly assigned drugs. Their doctor chooses the best drug for them. Usually, the doctor prescribes old cheaper generic drugs for patients with mild disease severity, and reserves new expensive branded drugs for patients with a very severe form of the disease. Thus, while at first glance it can appear that the drugs are causing the difference in outcomes, it is actually a difference between the two populations. This is why independent head-to-head randomised trials are vital for determining which drug is truly superior.

It is an occupation that I find satisfying and fascinating. I can still be a scientist and conduct studies and write papers, yet without working at the bench in “wet” research. Though I do miss my lab coat sometimes.