This is complete rubbish.
For starters, the average age of prisoners is around 24-28, straight away you can see the problem of comparing this with the average population between 15 and 64.
Next is that the average prison terms renders it extremely unlikey that the prisoner will die, despite what you may think, the average time served in prison is less than 5 years.
In the UK, and average citizen is classed in medical terms as being elderly at around 60, and for prisoners this figure is 47, but there is debate as to wether this should be reduced to 45.
The reason that this is significant is that patient on a GPs roll are funded on certain criteria, so that greater allowance is made to fund a GP who has a disproportionate number of elderly folk on their roll, other criteria that are considered when funding patients in our Health system include diabetes, socio economic levels in the area.
One significant trigger point for increased funding is age, and its recognised that older prisoners will be more ill more often and require more intervention, and will die earlier than the general population.
The figures I have seen suggests a death rate that is at least twice the rate for prisoners as against the general population aged between 15-44 years, and to my mind this is rather optimistic, given that the median age range for prisoners is around 25.
Even the normalised figures suggest the rate for ex-offenders is around three times as high as the control, and for those doing non-prison community, the rate is even higher.
None of these should come as a surprise, as known suicide risk factors include mental illness, drug use, unemployment, and that’s without the known risk taking behaviour of the individuals concerned, and the poor health that goes along with abuse and sefl neglect.
This report relates mainly to suicide,
http://www.homeoffice.gov.uk/rds/pdfs/hors231.pdf