Five key epidemiological indicators are used to achieve the goal of providing factual, objective, reliable and comparable information on drugs and drug addiction at European level. These indicators have been developed by the EMCDDA in close collaboration with the Reitox network, experts across Europe and with other international organisations competent in the field of drugs and drug addiction.

The five key epidemiological indicators are:

  • Prevalence and patterns of drug use (GPS)
  • Problem drug use (PDU)
  • Treatment demand indicator (TDI)
  • Drug-related deaths and mortality (DRD)
  • Drug-related infectious diseases (DRID)

Prevalence and patterns of drug use (GPS)

GPS helps with understanding patterns of use, risk perceptions, social and health correlates, as well as the consequences of the use of illicit drugs. This indicator makes use of a number of tools including data from general and school population drug surveys, as well as innovative new approaches such as wastewater-based drug epidemiology, and targeted surveys, including web surveys.

National surveys aim to research attitudes and use of psychoactive substances among:

  • general population aged 15-64 years old;
  • high school students (grades 8-12);
  • university students;
  • prisoners.

The regional studies are mainly aimed at researching the attitudes and use of psychoactive substances among school students (grades 5-7) and high school students (grades 8-12).

Problem drug use (PDU)

PDU collects data on the prevalence and incidence of problem drug use at national and local level. The indicator, which has recently been revised mainly due to the changing drug situation, focuses on “recurrent drug use that is causing actual harms (negative consequences) to the person (including dependence, but also other health, psychological or social problems), or is placing the person at a high probability/risk of suffering such harms”.

According to the national definition, problem drug use is associated with a high intensity and risky pattern of use of opioids, stimulants in the past 12 months. Because of the increasing importance of cannabis use in recent years, the definition was expanded to high-risk drug use, which refers to a high intensity and risky pattern of opioid, stimulant, and cannabis use in the past 12 months.

Risky patterns of use are mostly associated with injecting and/or daily or near-daily drug use.

Treatment demand indicator (TDI)

Information on the number of people entering treatment for a drug problem provides insight into general trends in problem drug use and also offers a perspective on the organisation and uptake of treatment facilities. In Bulgaria, information on the indicator has been collected since 1994, with Sofia and Varna being the first cities to provide data.

Since 2003, the collection of data, their processing and analysis has been carried out by the NFP.

By 2008 data was collected only through the questionnaire for patients with drug problems (MULTI CITY), filled in by persons working with the patients – medical doctors, nurses, psychologists, social workers while observing all measures for confidentiality of personal data.

Since the beginning of 2009 an internet based electronic version has been operating at the National Information System for treatment demand related to drug use in Bulgaria (I-MIS) – online filling in questionnaires.

Since 2011 a Reporting Form has been used on treated patients with drug related problems, based on the medical centres, which do not participate in I-MIS, submit aggregated data on issues defined in the electronic version of the system. During the same year the medical centres in prison in the Republic of Bulgaria were covered by the system.

The national system for treatment demand includes inpatient and outpatient centres, opioid substitution treatment programmes and treatment units in prison.

Drug-related deaths and mortality (DRD)

Drug-related mortality is a complex phenomenon, which accounts for a considerable percentage of deaths among young people in many European countries. The EMCDDA, in collaboration with national experts, has defined an epidemiological indicator with two components at present: deaths directly caused by illegal drugs (drug-induced deaths) and mortality rates among problem drug users.

The National Register of Mortality uses information from the National Statistical Institute, which together with the “Medical Activities” directorates in the regional health inspectorates (RHI) collects, processes and distributes data on deaths by cause using the four-digit ICD-10 rubrics.

The source of information for the statistical data on the cause of death is the paper death notification document. A copy of the document is submitted to the RHI for coding.

After coding of the cause of death by specially trained doctors, the documents are submitted to the territorial statistical bureaus for entering the information into the Internet System “Demography” and supplementing the statistical information on the cause of death.

The Special Register of Mortality uses information from the forensic medicine and deontology clinics and forensic toxicological laboratories, which perform chemical analyses of biological samples of deceased persons.

Drug-related infectious diseases (DRID)

The sharing of injecting equipment increases the risk of transmitting and acquiring blood-borne infections, such as HIV and hepatitis B and C viruses (HBV and HCV), and invasive bacterial infections. These drug-related infectious diseases (DRID) constitute a high morbidity and mortality burden among people who inject drugs (PWID). Drug use before and during sex is also linked to increased risk for HIV, HCV and bacterial sexually transmitted infections. The EMCDDA works with the DRID expert network to monitor the prevalence, incidence and risk factors for drug-related infectious diseases in Europe, and to document the coverage of effective interventions.