Blood tests helped predict who would live longer - study

Researchers at Duke Health, along with colleagues at the University of Minnesota, have reported that a routine blood test in the future may help understand how high the risk of dying in the next two years is in older people. They found molecules that are particularly good at "signalling" this risk are small fragments of RNA called piRNA.

The researchers studied blood samples from people 71 and older and compared the rates to those of participants who had lived at least two years after donating blood. It turned out that lower levels of some piRNAs were associated with longer survival.

Next, the team used machine learning techniques: they "fed" the model 187 clinical factors (e.g., habits, health) and 828 different small RNAs from more than 1,200 blood samples. They found that six piRNAs by themselves were able to predict two-year survival rates with 86 per cent accuracy, and tested the result on a second independent group of elderly people.

The authors note that piRNAs were stronger than age, cholesterol, physical activity and a host of other familiar indicators in short-term prediction (for the next two years). Lifestyle factors become more important for the longer term, but piRNAs still provide useful information about what's going on in the body.

It's not yet a ready-made "immortality test": the study is about risk prediction and linkage, not about being able to accurately "assign longevity". The next step is to understand whether the levels of these molecules can be influenced by treatment or lifestyle changes, and what exactly they reflect about the biology of ageing.