South West Public Health Observatory
	The impact of drug misuse on health in the South West, 1996-2001

Methods

back              Problem drug misuse

Regional Drug Misuse Database (RDMD)

The RDMDs were established by the Department of Health in 1989 and replaced the Home Office Addicts Index in 1997. Every region in England has a database and similar arrangements exist in Scotland, Wales and Northern Ireland. The RDMDs were renamed the National Drug Treatment Monitoring System (NDTMS) in April 2001. Data are now collected on the number in treatment on an annual basis.

Further details on the information contained in the database may be found in Appendix 1.

Each record on the database represents one notification by any agency. In order to distinguish between notifications and persons a unique case number was assigned to each record, based on matching initials, date of birth and gender. An anonymised copy of the database was made for the data years 1996/97 to 2000/01 [1] and various analyses were undertaken using SPSS and S-Plus. Data selection criteria were devised to differentiate new cases from repeat cases. In order to examine workload it was useful to be able to combine new and repeat cases. In order to calculate annual incidence rates of those newly presenting for treatment, and age, gender and substance trends, it was more appropriate to examine new cases per annum.

The database comprises the population of notified problem drug users; hence it is not appropriate to utilise sample-based methodology. Descriptive statistics were used, based on frequency distributions and cross-tabulations. Prevalence estimates have been calculated, using:

1.         capture-recapture methods via log-linear modelling [2]

2.         treatment-demographic method [3]

3.         treatment coverage method ⁱⁱⁱ

Results are reported on age, gender, children, living circumstances, substances and methods used. Information was also available on sharing drug equipment, age of first use and age of drugs first becoming problematic. Analyses were made of the numbers of new and repeat cases over the five years. Geographical comparisons have been made, looking at the DAT area of the referring agency and the DAT area of residence of the drug user. Rates of annual incidence were calculated, for the South West and for each DAT area.

Department of Health (DH)

The DH website holds the reports from the Regional Drug Misuse Databases. ^6,7 Results are presented from these reports related to trends and rates, for comparison of the South West region with other regions and England as a whole.

Methadone prescriptions

The volume of methadone prescriptions gives an indication of trends in the use of substitute medication, instead of using heroin. The NHS Executive South West Regional Office provided data. Results are reported on numbers of prescriptions per month, for each Health Authority (HA) in the South West, for two years from 1998.

back             Population and mortality

National Statistics (ONS)

The National Statistics website (http://www.statistics.gov.uk) provided information on population changes, drug related deaths, ^20,21 and the Neighbourhood Statistics section provided useful local authority data. The DH provided data relating to the population of HAs and regions.

Where rates have been calculated, they have been based on the 15–44 year old population. As stated previously, 95% of the population of problem drug users are between 15 and 44 years of age, so it is common practice to calculate rates based on this age range, rather than the population as a whole.

National Programme for Substance Misuse Deaths (np-SAD)

The St.George's Hospital study ²² has been gathering data on substance misuse deaths since 1997. All coroners send the study returns and annual reports have been produced, with regional and HA breakdowns.

Information is available from both the ONS and np-SAD regarding deaths from all drugs including prescribed medication, not just illicit drugs. We have not considered in detail deaths associated with the misuse of prescribed medication or over-the-counter drugs, except for comparison with the proportion of deaths from illicit drugs.

Results are presented for each HA, along with local authority areas with significantly higher or lower death rates than national norms.

back              Infectious diseases

Public Health Laboratory Service (PHLS) and Communicable Disease Surveillance Centre (CDSC)

The Public Health Laboratory Service and Communicable Disease Surveillance Centre websites provide national and regional figures for infectious diseases. ^24,25,26

Results are presented on the national trends in HIV/AIDS and Hepatitis A, B, C, as they relate to problem drug misuse, and compared with the South West region.

back              Overdoses and psychiatric admissions

Hospital Episode Statistics (HES [4]

This DH database holds information on all hospital admissions, according to International Classification of Diseases (ICD10) diagnostic criteria. The Department of Social Medicine at Bristol University also holds the database and provided tabulations for various drug-related diagnoses, particularly admissions for overdoses of narcotics and psychiatric admissions related to drug misuse. The Medical Sciences Department at Bath University has also obtained a HES extract related to overdoses and they undertook further analyses. Results are reported for five years 1995/96 to 1999/2000 for HAs, the South West region, and nationally.

back              Families of problem drug misusers

Within the time scale of the project we were unable to collect information on the impact of drug misuse on children and families in areas of the South West. More detailed information on the nature and scale of family difficulties associated with drug misuse would be available from case note searching, but time constraints made this prohibitive. We have been able to provide some limited data on children, where this was recorded in the RDMD. Social Services were approached but it was apparent that whilst there is computerised information on children at risk, or in care, as well as information on drug misusers receiving help, there is no overlap of information.

Similarly, regarding the transmission of infection to neonates, or neonatal addiction, there are ICD10 codes relating to these conditions. What little information was available from HES was omitted because of the lack of specificity of the data. It was not possible to distinguish drug effects damage to the foetus or neonate, from any other potential sources of harm. Study of maternity and neonatal records would be more useful and some results from the maternity drug user clinic in Bristol are presented.

back              Other

Various sources and studies have been used and information extracted for the South West. These include the British Crime Survey, Department of Environment accident studies and Beachwatch.

back             Social deprivation

We have not attempted to examine the relationship between problem drug use and social deprivation, because of the incomplete nature of area of residence data.