Assumptions used in estimating a population benchmark
The assumptions used in estimating the number of needles and syringes required for a benchmark of over 100% coverage (that is, each individual having more than one sterile needle and syringe available for every injection) are based on the following sources of information:
- epidemiological data on the prevalence of injecting drug use
- expert opinion of the topic-specific advisory group, based on practice and literature review.
For the purpose of this commissioning guide the adult population has been defined as people aged between 15 and 64 years. This is because of the availability of prevalence data on injecting drug use. Approximately 66% of the population in England is aged between 15 and 64 years. The recommendations in NICE public health guidance PH18 on needle and syringe programmes relate to people aged 18 years and older.
The true extent of injecting drug use is difficult to determine. Latest data suggest the number of injecting drug users aged 15-64 years in England is between 115,000 and 122,000, although it could be over 200,000. Prevalence varies across regions, ranging from around 3 per 1000 in London, the East and the South East to 6 per 1000 in Yorkshire and the Humber. These estimates relate to people injecting heroin, other opiate drugs or crack cocaine, and do not include people injecting performance and image-enhancing drugs (PIEDs) such as anabolic steroids.
The proportion of people who frequently access a needle and syringe programme (NSP) is not known. The 2007 Unlinked Anonymous Prevalence Monitoring Programme's survey found that, in England, around 90% (2757 of 3025) of people who inject drugs (or have previously injected drugs) reported that they had accessed a NSP. In the UK, 86% (415 of 480) of recent initiates (people who reported first injecting during the previous 3 years) had contact with NSPs. However, both these figures are likely to include people who may have accessed an NSP infrequently in a year.
According to the National Treatment Agency for Substance Misuse report Findings of a survey of needle exchanges in England there is large variability between services in the number of contacts (visits) per client and the total number of syringes given out in a drugs (and alcohol) action team area, as well as wide differences in the numbers of syringes given to clients per contact per year.
The number of needles and syringes and other equipment needed in a locality to achieve individual coverage of over 100% depends on many factors. These include the prevalence of injecting drug use, the proportion of people who inject drugs who are receiving opioid substitution therapy (OST) and the proportion of people who inject drugs who access other treatment services.
PH18 Needle and syringe programmes: economic modelling - revised full report (2008) used data collected from Bristol and Teesside that suggests the proportion of people who inject drugs and receive OST is 50-75%. This estimate is likely to vary around the country.
The National Treatment Agency for Substance Misuse and the Department of Health provide an online coverage calculator as part of their harm reduction works campaign. The coverage calculator allows the modelling of key factors that impact on the adequacy of local provision of needles and syringes. It does not provide definitive estimates of need because of uncertainty in the accuracy of estimates at a local level, but when taken together with relevant local knowledge, it can enhance commissioner discussions of the suitability of their needle and syringe programme provision.
The tool requires the average number of injections per day per person out of treatment and the average number of injections per day per person in treatment.
The default settings for these are:
- three needles and syringes are needed each day for each person injecting drugs not in treatment
- one needle and syringe is needed approximately every 3 days for people receiving OST.
The proportion of injecting drug users who are receiving OST is likely to vary across the country and commissioners will need to take this into account when assessing service need. The consensus opinion of the topic-specific advisory group is that 75% is the optimal proportion of people who inject drugs who could also be receiving OST, and this proportion is therefore considered appropriate to use in the benchmark.
The 2008 British crime survey reports that 0.1% of people aged 16-59 have injected PIEDs. Commissioners will need to consider the needs of people who inject PIEDs when planning services, since recent anecdotal reports from across the country suggest that the use of anabolic steroids is on the increase, particularly among young men, and that this group is increasingly accessing NSPs for their own use and for secondary distribution.
The number of needles and syringes provided to people who inject PIEDs and other drugs such as stimulants is not included in the coverage provided by the coverage calculator or the commissioning and benchmarking tool; therefore commissioners will need to include these numbers when considering the overall requirements and cost of an NSP.
Based on the epidemiological data and other information outlined above, it is concluded that to achieve individual coverage of over 100% for a population of 100,000, the number of needles and syringes required would be at least 85,000 per year. This is based on the following assumptions:
- 66% of the base population are aged 15-64 years (the same age profile as the English population in 2007)
- the prevalence of injecting drug use is 0.35% of the population aged 15-64 years (the national mean prevalence of injecting drug use)
- 100% of people who inject drugs access NSPs (suggested by the topic-specific advisory group)
- 75% of people who inject drugs receive OST (based on information presented in the economic modelling above)
- one needle and syringe is needed approximately every 3 days for people receiving OST
- three needles and syringes are needed each day for each person injecting drugs and not receiving OST.
Commissioners and providers will need to use local data to determine the number of needles and syringes currently supplied and may wish to use the coverage calculator to determine current coverage and the number of needles and syringes needed to reach the benchmark rate of over 100% individual coverage.
Commissioners can use the NSPs commissioning and benchmarking tool to determine the level of service that might be needed locally and to calculate the cost of commissioning the service using the indicative benchmark and/or your own local data.
1. Home Office (2008) National and regional estimates of the prevalence of opiate use and/or crack cocaine use 2006/07: a summary of key findings. London: The Stationery Office
2. Health Protection Agency (2008) Shooting up - infections among injecting drug users in the United Kingdom 2007. An update: October 2008. London: Health Protection Agency
This page was last updated: 02 March 2012
- Needle and syringe programmes
- Commissioning needle and syringe programmes
- Specifying needle and syringe programmes
- Determining local service levels for needle and syringe programmes
- Assumptions used in estimating a population benchmark
- The commissioning and benchmarking tool
- Ensuring corporate and quality assurance