New opiate and crack-cocaine users: characteristics and trends 26 
 
Figure 9: Estimated incidence trend, 2005–2013. 
 
Before discussing the trend implied by this chart, it is important first to sense-check the general 
level of new users implied. Analysis from the previous section suggested that the number of 
new OCUs for 2013 was unlikely to be much higher than 10,000 with only a proportion of those 
involved with crime. The 2013 estimate implied by Model 1 is 8,290 and for Model 2 it is 5,092, 
so both are in line with the earlier analysis. The NDTMS data only covers England, not England 
and Wales, and our estimates will of course miss any OCUs who never come to treatment. 
Hence the estimates for both models may be slightly conservative in that sense. But putting all 
the partial evidence together, it can be said with a degree of certainty that the total number of 
individuals who begin using opiates or crack-cocaine each year is probably not markedly higher 
than 10,000, and that fewer than half of these are likely to be involved in significant amounts of 
acquisitive crime. 
To put this into historical context, an incidence rate of 10,000 works out at a rate of 0.18 
individuals per 1,000 population. Published estimates of incidence in Manchester during the 
epidemic period of the late 1980s and early 1990s included rates above two per 1,000 
population, i.e. more than 11 times higher (Millar et al., 2001).  
Turning to the trend implied by Figure 9: both models imply that numbers of new OCUs in 2013 
are lower than in 2005. Model 1 implies that they have fallen by around a fifth during that period 
and Model 2 suggests a fall of around 45%. But secondly, the way the methodology works 
means that the most recent years are the least reliable because they use the least amount of 
data. This is why the distance between the estimates from the two models widens for the more 
recent years. It means that it is difficult to say for certain whether the period of flattening from 
2011 onwards, which occurs in both estimated trends but is more obvious in Model 1, is a blip in 
an otherwise downward trend or the start of a turning point. Either way, a flattening of the trend