Are more older than younger women dying from drugs?

Readers of the Telegraph this morning might have spotted a surprising claim:

The Telegraph, 30 August 2012

Unlike most of the articles Full Fact looks into, the Telegraph piece provided a link to the source of its claim, for which it deserves credit straight away. The stats come from the Office for National Statistics (ONS) yesterday in their bulletin 'Deaths related to drug poisoning in England and Wales, 2011.' 

The first thing to note is that the ONS records both the number of deaths from drug poisoning (which involves both legal and illegal drugs) and deaths involving drug misuse (illegal drugs only), but only the latter are broken down by both age and gender. So the Telegraph's claim is referring exclusively to deaths from illicit drugs.

A quick flick through the document reveals the data on 'age specific mortality rates for deaths related to drug misuse' for females between 2007 and 2011. The mortality rate is measured by deaths per million of the population.

The graph below presents data for the past five years:

According to the report:

"[t]he female mortality rate for 50-69-year-olds has increased steadily over the last couple of years and is now 14.4 deaths per million population — its highest level since records began in 1993. Moreover, in 2011, for the first time the female mortality rate in this age group was higher than the rate for 20 to 29-year olds (13.3 deaths per million population)."

This would appear to be where the Telegraph's claim is coming from, assuming that women should be classified as 'older' when over the age of 50.

Why has this pattern emerged?

Not content with the figures alone, Full Fact contacted the National Treatment Agency for Substance Misuse (NTA) to see if they knew why the mortality rate of 'older' women had increased in such a way. 

We were informed that much of the pattern can be explained by an aging drug dependent population in England and Wales.

Although the NTA could not give us comprehensive statistics on the scope of drug use in England and Wales, they pointed us to the most recent statistics from the National Drug Treatment and Monitoring System.

The table below presents data from the report on the number of 'new presentations to treatment' by year and age group. It is worth noting that this data refers to both men and women:

Using this data, we can calculate the number of new presentations for each age group as a proportion of all new presentations for that year: for example, in 2005/6 22 per cent of the 82,395 new presentations were aged 18-24 years old.

We can also express the data graphically to show the trend over time:

Examining the graph, we notice a convergence in the relative treatment use of each age group as a proportion of all new presentations in a given year.

More interestingly we can see that, in 2005/6, the oldest age group made up the smallest proportion of new presentations yet by 2010/11 it accounted for the largest share, thereby suggesting a possible increase in the number of 'older' people involved in illicit drugs.  

Clearly this analysis is far from perfect. It would be useful, for example, to know if there were significant changes in drug consumption (as opposed to treatment) across age groups within this time period. Likewise, some might argue that five years is insufficient time to observe a radical change in the demographic of England and Wales's drug dependant population.

However, the evidence presented in the latter part of this article may well go some way to explaining why we can observe an increase in the mortality rate of 'older' women related to drug misuse.