[xhedley]

The 17M is the data set from detailed primary care records linked to 5,683 of the deaths recorded in English hospitals in the time period. The data could be improved by linking to more primary care records - but the population of England is 56 million so they already captured almost a third.

Sadly there will be more data as there are more deaths, and this team will be able to pull more analytics out. However 5,683 is a big enough sample size to find some interesting information on hazard rates.

For the team doing the analysis, plugging data analytics into 17 million primary care records is definitely a significant achievement. Medical records are intended for use by doctors and letting researchers into them has confidentiality issues. The process they followed was covered in the paper and seemed thorough.