Epidemiologic field units on narcotic-related problems


Concept of epidemiologic field unit
Characteristics of an epidemiologic field unit
Areas of inquiry
Elaboration of areas
Components of a field unit onnarcotics
Exiting data bases
Continuous file
Periodic surveys
Follow-up studies
Qualitative studies
Types of field units


Pages: 17 to 28
Creation Date: 1982/01/01

Epidemiologic field units on narcotic-related problems

A. RICHMAN Professor, Training and Research Unit in Psychiatric Epidemiology, Departments of Psychiatry and Preventive Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
I. ROOTMAN Chief, Health Promotion Studies Unit, Health and Welfare Canada, Ottawa, Ontario, Canada


Much more understanding is needed of the epidemiology of narcotic-related problems. This paper describes a research strategy which is responsive to the heterogeneous nature of such problems. It is suggested that it is feasible and useful to establish, for defined geographic areas, epidemiologic field units which would have continuity be comprehensive and develop programmatically relevant information on a timely basis. The possible areas of inquiry and the components of such a unit are discussed.


A task force on the epidemiology of heroin and other narcotics sponsored by the National Institute on Drug Abuse (NIDA) concluded that: "Heroin use is not a homogeneous phenomenon across the nation: it exists in enclaves; it thrives in certain neighbourhoods, communities and regions, and these enclaves are only partially defined by demographic factors such as age, sex and race. Although a great deal of public attention centres on national prevalence estimates, there is a growing realization that such estimates tend to conceal the clustering characteristic of heroin use" [ 1] .

While there is general agreement with this conclusion in the research community, there is some uncertainty regarding the most appropriate research strategy to deal with it. The purpose of this paper is to describe an approach which seems to us to have considerable merit in resolving some of the problems created by the phenomenon noted by the task force.

Specifically, we suggest that it may be desirable to establish what might be called epidemiologic field units to carry out long-term geographically-based studies of narcoticrelated problems in order to produce programmatically-significant knowledge. This paper will describe the characteristics and functions of one such field unit.

Concept of epidemiologic field unit

The concept of an epidemiologic field unit (EFU) for the study of narcotic-related problems is new. No existing units can be used as models upon which to build. There are, however, some models in related areas including agricultural research stations, epidemic field units, monitoring and surveillance programmes and epidemiologic field units for mental disorders.

Agricultural research stations have been established in many countries in order to bring theory and practice together, to hasten the application of science to current problems of agriculture, to speed up the implementation of new findings and to reduce the gap between basic and applied research. These stations are finely attuned to the immediate needs of its clients, have a proven record of achievement and are considered an instructive example for scientific policy-makers.

Epidemic field units have been located in many parts of the world which have endemic infectious diseases. They were intended to assist in the early identification of change in problems, to develop specific interventions as well as to enhance understanding of basic disease processes.

Monitoring and surveillance programmes have been established to provide prompt warning and early intelligence of changes in the extent and characteristics of specific disorders. These programmes have been based either on the use of existing vital statistics or on specially created systems. Colonies of animals have been used for assessing the spread of viral diseases. In the substance abuse field, information systems such as the drug abuse warning network (DAWN) system in the United States have been developed and used for monitoring the experience of intervention programmes with which substance abusers might come into contact.

Finally, epidemiologic field units have been established in the mental health field. The idea for such units grew out of large-scale community research studies where it became apparent that there was either a need to collate different sources of data, or to assess community changes over longer periods of time.

These examples, none of which alone is sufficient to provide a prototype for a field unit on narcotic-related problems, do provide some clues as to what such a unit might look like.

Characteristics of an epidemiologic field unit

While, in our opinion, it is possible to argue about the desirable characteristics of an epidemiologic field unit on narcotics, among its essential characteristics are: defined geographic area, continuity, comprehensiveness, programmatic relevance and timeliness.

As noted by the NIDA task force [ 1] , there is considerable diversity in patterns of heroin use across the country. This diversity is difficult to capture using standard approaches such as national surveys. Thus, it seems to us that one of the necessary characteristics of a field unit on narcotics is that it focuses on a defined geographic area. Such an area should be of manageable population size--less than a large metropolitan area, yet of sufficient size to have the range of substance-related problems to justify continuing scrutiny. It is not realistic to attempt to select an area on the basis of represen- tativeness or "typicality" since no such "Middletown" exists from which data can be generalized to the national scene.

Since there are relatively rapid changes in patterns of narcotic use over time in communities, continuity is a necessary characteristic of a fled unit on narcotic-related problems. Such continuity allows for the assessment of transitions between stages of drug use and problems that the NIDA task force felt were important in the development of our knowledge of narcotic-related problems [ 1] .

Comprehensiveness is also a necessary characteristic of an epidemiologic fled unit on narcotics because of the increasing observation that the "typical" pattern of narcotic use involves the use of many other types of drugs. It is therefore essential for a field unit to consider the interrelationships of substances used by particular groups, factors which affect patterns of usage over time and the chronology of these patterns of use and problems.

A fourth, but necessary, characteristic of a field unit on narcotics is programmatic relevance. The knowledge obtained through such a unit must be of use to people who have to make policy or programme decisions in the drug problem field. Thus, a major objective of an epidemiologic field unit on narcotics would be to provide information that can assist planners in establishing priorities, targeting populations and groups for interventions, developing intervention strategies and providing feedback to enhance the efficacy of intervention activities.

Finally, timeliness is an essential characteristic of a field unit on narcotics. This is an aspect of programmatic relevance as decision makers often require up-to-date information in order to make the right decisions. Current approaches to epidemiologic research often do not result in such timely information.

Areas of inquiry

Programmatic relevance is an important characteristic of an epidemiologic field unit on narcotic-related problems. This leads to the question of what programmatically relevant questions should such a field unit address. There are eight such questions, or areas of inquiry, which a group of epidemiologists and social scientists working in the drug problem field felt were programmatically relevant [ 2] . Although originally stated in terms of "drug-related problems" the questions could be stated in terms of "narcotic related problems". The areas of inquiry are:

  1. What is the extent and distrbution of narcotic use and narcotic-related problems?

  2. How can changes in the extent, distrbution and pattern of narcotic use and related problems be measured and assessed and monitored early, reliably and efficiently?

  3. What are the factors and processes involved in person-to-person or place-to place spread of narcotic use and related problems, and to changes over time?

  4. What are the programmatically relevant characteristics of persons with various types of narcotic-related problems?

  5. What is the course and outcome of narcotic-related problems of various types and severity?

  6. What are the social, behavioral and biological correlates of narcotic-related problems?

  7. What are the relationships between institutional arrangements and narcoticrelated problems?

  8. What is the impact of policy and programmes on the incidence and prevalence of narcotic-related problems?

These areas are certainly not the only ones that might be specified, but they seem to be sufficiently comprehensive to provide a reasonable framework for the work of an epidemiologic field unit on narcotic-related problems, and they will, therefore, be described in more detail.

Elaboration of areas

  1. Extent and distribution of narcotic use

This questions fundamental to any epidemiologic inquiry, for epidemiology is the study of the distribution of a disease or health condition in a population and of the determinants of that distribution [ 3] . The former is critical to the latter because, as noted by Richman [ 4] , the study of the causes of things must be preceded by the study of the things caused. In addition, simply knowing where conditions are located socially and geographically and their magnitude is useful in determining points of intervention for prevention or treatment. Thus, the question is one that should be pursued on an ongoing basis by researchers in the field of narcotics epidemiology.

The question of what is a narcotic-related problem is, of course, critical to this enterprise; the objective of most national, regional and local organizations working in the field is to prevent or reduce these problems. Defining what is a narcotic-related problem in a totally satisfactory manner is, however, not a simple task. What is defined as a problem depends as much on who is doing the defining as it does on the nature of the phenomenon under consideration.

It is unlikely that we will ever have complete agreement on the definition of "narcotic-related problems". If, however, we were to take prevailing medical and social standards as benchmarks, it would be possible to make reasonable judgements regarding what constitutes a "narcotic-related problem" today, if we consider such problems in terms of "physical, mental and social damage associated with narcotics use". What is being talked about, to use the terminology of the LeDain Commission of Inquiry in to the Non-Medical Use of Drugs [ 5] , are the "dangerous" or adverse consequences of narcotics use. This might include consequences such as death, various forms of illness such as hepatitis, and crime required to maintain an adequate supply of narcotics.

Extent refers to the amount of narcotic use and problems which exist in the population. Measurements of the amount can change because of additions to, or subtractions from, the group who are using or who have problems. The rate of addition or increment is best measured by incidence. Trends or projections of change in extent are crucial for problem definition, for monitoring high-risk groups and for determining points for intervention.

The extent of narcotic use or problems may be assessed in terms of the following indices of morbidity:

Point prevalence (now)

Period prevalence (e.g. 12 months)

Incidence (onset for first time in an individual's life during a specified time period)

Lifetime prevalence (ever use)



Distribution refers to the location of use or problems in personal, social or geographic terms. Distribution includes:


Demographic (e.g. age, sex)

Societal groups (e.g. ethnic, religious)

Special populations (e.g. arrestees, school, military)

Medical treatment or other high-risk groups with social or psychological problems


Region, suburban and urban

Ecological relations (e.g. census tract, micro-geography)


Changes (indirection, amount and rate) over time in incidence and prevalence of use of various types of drug-related problems within the above person and place classifications

  1. Early, reliable and efficient monitoring of changes in the extent, distribution and pattern of narcotic use and related problems

It is essential to have reliable methods for early, rapid provision of valid information on changes in the extent, distribution and types of narcotic use and problems in the community. Such information is important to the local community and to regional and national organizations as it facilitates effective responses within a reasonable period of time and may even permit forecasting of future trends. This information might be provided through direct monitoring or surveillance, or through the use of indirect indicators.

  1. Factors and processes involved in person-to-person or place-to-place spread of narcotic-related problems, and in changes over time

Spreading is one of the most striking features of narcotic-related problems with rapid changes in time and diffusion to new groups and places. The dynamics of this spreading is a crucial area for study because of the implications for prevention which may flow from better understanding of this phenomenon. Mathematic and geographic models of the diffusion of this form of innovation may be particularly helpful in unravelling the mechanisms involved in the spread of narcotic-related problems from person-to person, place-to-place or time-to-time.

  1. Programmatically relevant characteristics of persons with narcotic-related problems

In order for intervention programmes to be effective, they must have accurate and relevant information on certain characteristics of the persons or groups to whom they are directed. Such programmatically relevant characteristics might include previous treatment experiences, sex, social networks, employment status, marital situation and patterns of previous and current use of substances. Identifying these characteristics can give programmes valuable assistance in matching individuals with the most effective approaches as well as in altering programme effort in the appropriate directions.

Included under this area of inquiry would be the development of methods for systematic comparison of the similarities or differences in the personal, clinical or social characteristics of groups with narcotic-related problems.

Such methods are essential for assessing the generality of treatment results or programme intervention, for ensuring that research findings can be compared from time-to-time and from place-to-place and for evaluation of clinical experience in non-experimental situations.

  1. Course and outcome of narcotic-related problems of various types and severity

This area refers to the natural or life history of narcotic-related problems. Knowledge of the course and the outcome can be useful to treatment and prevention programmes by helping to predict in advance the likely sequence and timing of events. This should considerably improve programme planning. Questions such as whether or not persons whose narcotic-related problems are ascertained by treatment entry have different courses and outcomes from those identified by other means are particularly crucial for such purposes. Information on course and outcome is also critical in the identification of possible causal factors.

  1. Correlates of narcotic-related problems

Although "correlates" are not the same as "causes" the study of the former in and of itself is extremely useful both in terms of providing clues about causes and suggesting reasonable courses of intervention. In using our knowledge of correlates for these purposes, however, we must be extremely careful to avoid reaching unwarranted conclusions. For example, correlations of poverty and its manifestations with narcotic dependence did not demonstrate that poverty causes narcotic dependence, nor that reduction in poverty would reduce narcotic-related problems. It is also possible that the method of ascertainment may result in persons with narcotic-related problems having characteristics which are due to the method of identification rather than the cause or consequence of narcotics use. These correlates of ascertainment may not be amenable to intervention, or if they are, the problem may persist unchanged. Nevertheless, if we exercise caution in interpreting correlations there is considerable merit in carrying out systematic studies to determine the social, behavioural and biological correlates of narcotic-related problems, especially in view of the difficulty of conducting the types of prospective studies with random assignment which are required to demonstrate that a correlate is probably a cause.

  1. Relationships between institutional arrangements and narcotic-related problems

Improved understanding of how institutional arrangements are related to the extent and distribution of narcotic-related problems is important because of possible policy implications. For example, research directed at unravelling the relationships of narcotic related problems to law enforcement practices and social values and concerns should be useful.

  1. Impact of policy and programmes on the incidence and prevalence of narcotic related problems

Epidemiologic research techniques and methods frequently lend themselves to assessing the effects of programmes and policies. But it would be a mistake to overlook its potential in the field of narcotic-related problems. As a result, this area of inquiry has been explicitly included. Research in this area might profitably deal with such questions as: What is the impact of legislation on narcotic-related problems? To what extent has intervention resulted in the target population being reached? And what impact have particular programmes had on the extent of narcotic-related problems in the community?

Components of a field unit onnarcotics

The specific activities of a field unit on narcotics, in our opinion, would merit consideration in modular form. Specifically, we suggest that an epidemiologic field unit on narcotics might include the following components or modules:

  1. Analysis of existing data bases;

  2. Maintenance and analysis of a continuous unduplicated file of contacts with intervention agencies;

  3. Periodic surveys of the population and of persons in contact with official agencies;

  4. Follow-up of persons identified in the continuous file or agency surveys;

  5. Qualitative studies of the narcotics scene;

  6. Assessment of interrelations of above components.

Exiting data bases

Work in this module would focus on areas of inquiry (a), (d), (f) and (g).It would involve the analysisandenhancementofavailablestatisticsonnarcoticuseandproblems in the selected community. These data bases might include existing data on morbidity, mortality, homicide, reported crimes, arrests, motor-vehicle accidents and poisonings. The field unit would be concerned with input, regional analyses and enhancing the methodology of data utilization.

With respect to input, the unit would focus on procedures used to obtain, record and check reports at the source. Attention would be directed to the reliability of the data, coverage (gaps and overlaps) of the reporting universe, and variability between agencies in definition, completeness and quality. It would attempt to resolve problems along these dimensions and thereby improve the quality of the data.

The field unit would also attempt to develop regional analyses that are specific for the local community. These analyses would also differentiate sub-populations (for example, school age populations, homeless people etc.). Their interest would be to reduce the distortion and bias produced by aggregating diverse data from diverse sources.

Attempts would also be made to enhance the analyses of data by differentiating events from individuals and developing new methods of presentation which are readily understood but not overly simplified. These attempts may result in collaborative studies with data sources, statistical agencies and potential users.

Useful references in the development of such a module might be World Health Organization (WHO) publications on "Drug abuse reporting systems" [ 6] and "Guidelines for investigating alcohol problems and developing appropriate responses" [ 7] .

Continuous file

This module would focus on all areas of inquiry with the possible exception of (f). It would primarily involve agencies specifically directed to the treatment and rehabilitation of narcotic-dependent persons. It may also involve services where the volume of narcotic-related problems is relatively high and ascertainment of these cases is relatively reliable.

The file itself would consist of an accumulation of records of contacts of narcotic dependent persons with the selected agencies. It would be continuous in that it would include all contacts with the source agencies on a regular basis. It should record at least the following data:

  1. Personal identifying information so as to be able to identify various events reported for an individual over time from different agencies and to provide analysis based on individuals (rather than on events);

  2. The social and demographic characteristics of the individual should include the basic census questions as well as some type of address coding to permit analysis of geographic distributions;

  3. The characteristics of the clinical disorder for which treatment is being given. In treatment agencies this should include diagnosis, type of substance use, frequency, intensity and duration of consumption, correlates or complications of the disorder and history of previous types of intervention:

  4. The nature and type of intervention, referrals elsewhere, and use of clinical or social resources.

The file should be able to accomplish the following objectives:

  1. Provide a picture of treatment utilization in the community, a longitudinal perspective of repeated contacts with one or more agencies overtime;

  2. Identify the extent of resource absorption and characteristics of resource absorbed (i.e. recidivists);

  3. Characterize the relationship between agencies and patients; particularly patient flow within and between agencies;

  4. Identify persons who might be followed in other communities.

Emphasis should be placed on the quality, reliability and validity of the data. Computerization is not necessarily an asset and should not delay the development of tabulations and analyses. Generally, this continuous file would provide substantial information on the small proportion of narcotic-dependent persons who enter treatment agencies. The WHO publication "Core data for epidemiological studies of non-medical drug use" [ 8] may be helpful in designing this module as well as the publication "Drug abuse reporting systems" [ 6] .

Periodic surveys

This module would focus on all areas of inquiry except (e)and (f). It would consist of systematic surveys of intervention agencies not included in the continuous file, as well as population surveys. Its purpose would be to supplement the epidemiologic picture obtained of the "visible tip of the iceberg" with data from sources which allow assessment of the "non-visible" part. The surveys might be repeated to enable trends to be identified.

Perodic surveys of agencies would provide a systematic, cross-sectional perspective of a broader range of agencies (including emergency rooms, in-patient wards, education or welfare agencies) than would the continuous file. The treatment needs of those identified may be quite different from those in treatment in continuous file agencies.

Other WHO publications would be useful in developing this module. These include: "Review of general population surveys of drug abuse" [ 9] , "A methodology for student drug use surveys" [ 10] , and "Drug use among non-student youth" [ 11] .

Follow-up studies

This module is directed primarily to area of inquiry (e)(course and outcome) but also bears on area of inquiry (f)(correlates). Follow-up studies permit people in the community to consider the natural history of disorders, to assess the significance of data obtained from intervention agencies and to form a panel of former patients whose need and use of intervention can be studied intensively and directly.

The primary follow-up studies consist of a first-hand follow-up of groups currently or recently in contact with intervention agencies. This could be done using interviews, postal questionnaires or similar techniques. This follow-up could be initiated at the time of the first contact of the person with the intervention agency. Cohorts could be stratified to include an adequate number of women. Secondary follow-up studies would consist of a follow-up of a group in contact with intervention agencies in the past through contacts recorded in various files. The continuous file of contacts might be one such source.

It should be noted that ethical and confidential requirements must be maintained in such studies. Informed consent permitting later contact for health research could be sought at the time of initial contact with treatment agencies.

In developing this module, WHO publication "A methodology for evaluation of drug dependence treatment and rehabilitation" [ 12] might be useful.

Qualitative studies

This module would focus primarily on area of inquiry (b)but also on areas (g)and (h). It includes the development of a "spotter-sentinel network" and participant observation studies.

The spotter-sentinel network would consist of knowledgeable persons in key locations in the community who would be periodically surveyed regarding characteristics of narcotics use and users. The network might include persons in health, correction facilities, welfare agencies, pharmacies, morticians as well as former users. This widespread network would rapidly provide gross or impressionistic answers to specific questions on drug users with whom the observer may come in contact, and on the nature of the "drug scene".

Participant observation studies would involve systematic observations of the drug scene by persons trained in techniques of ethnomethodology.

The WHO publication "Guidelines for investigating alcohol problems and developing appropriate responses" [ 7] might be useful in developing this module.


This module bears on all of the areas of inquiry and is perhaps the most difficult of the activities of the field unit. It represents an attempt to integrate the other five modules to produce a more systematic, coherent account of the chronology and manifestation of various types of narcotic-related problems in the community. It would involve identifying which part of the spectrum of narcotic problems is described by which module, the leads or lags in data from different modules, and the time sequence and interrelations of the phenomena described in the different modules.

In the city of New York the number of new intensive users began to decrease before a reduction in supply and before a reduction in demand [ 13] . This module would assess the meaning of such interrelations, and attempts might also be made to develop approaches different from those enumerated here [ 14] , [ 15] .

Types of field units

It is not essential that all epidemiologic field units on narcotics are alike. One advantage is that this permits variability depending on local needs, organizational circumstances and funding contingencies.

Field units vary in terms of coverage and intensity of activity. In this respect, a field unitcouldencompassallofthemoduleswhichhavebeendescribedoronlysomeofthem. Similarly, it might conduct all analyses itself or transmit data to a central point for such analyses. Three possible types of field units could:

  1. Collect basic data set material under the supervision of a data manager and transmit it to another centre for analysis;

  2. Collect the data, carry out data analyses within the unit by a researcher with some epidemiologic skills. In addition to collecting basic data set material, this field unit might he involved in enhancing data quality and analyses at the local level;

  3. Encompass all six modules and engage in the full analysis of these data. Such a field unit would develop, pilot and improve the basic data sets and analyses used in the above-mentioned types of units. In addition, this field unit, which requires a well-trained and fully experienced epidemiologist, would develop research projects focused on specific areas of inquiry and would provide the technical knowledge and leadership for the study of narcotics in other field units.

Field units could also vary in organizational relationships. They could exist in dependently of existing agencies, they could be units within an existing agency or they could consist of people drawn from existing agencies. They could also obtain funds from a single source or from numerous sources.

In any particular community, the exact nature of a field unit on narcotics will require assessment of local needs and circumstances. It is important, however, that epidemiologic field units on narcotics be structured so that their technical and research activities have long-term stability and are protected from perodic cruses in organization and management of intervention programmes.


The above description of the possibilities for epidemiologic field units on narcotic related problems is certainly not exhaustive and does not pretend to present a specific, rigid blueprint or action. It is simply intended to suggest that it may be both desirable and feasible to develop such units in some circumstances and to outline some of the considerations which might be involved. The decision to establish such units must then be made after carefully weighing the benefits and costs involved.

The main benefit is that it should help to unravel the complex and changing nature of narcotic use and its consequences and thereby lead to the development of more effective interventions. The costs would vary depending on the number of personnel required, the area to be covered, the mandate and scope of the unit. We would suggest that in most circumstances where there is a serious, ongoing narcotics problem, the benefits would outweigh the costs.


The assistance of National Health Research and Development Program Award Number 6603-1115-48 is acknowledged.



The Epidemiology of Heroin and other Narcotic, J. D. Rittenhouse, ed., National Institute on Drug Abuse Research Monograph 16 (Washington, D.C., Government Printing Office, 1977), p. 247.


I. Rootman and others, A Canadian Strategy for Epidemiologic Research on Drug-Related Problems, Non-Medical Use of Drugs Directorate, Internal Report Series 160 (Ottawa, Health and Welfare Canada, 1975),pp. 2-3.


D. Wigle, "The epidemiological approach ", in Epidemiology of Drug-Related Problems in Canada, Non-Medical Use of Drugs Directorate (Ottawa, Health and Welfare Canada, 1975), pp.1-26.


A. Richman, "Critical concepts in the epidemiology of drug-related problems ", in Epidemiology of Drug-Related Problems in Canada, Non-Medical Use of Drugs Directorate (Ottawa, Health and Welfare Canada, 1975), pp. 29-46.


G. LeDain and others, Final Report: Commission of Inquiry into the Non-Medical Use of Drugs, Commission of Inquiry into the Non-Medical Use of Drugs (Ottawa, Information Canada, 1973), pp. 12-22.


I. Rootman and P. Hughes, "Drug abuse reporting systems ", World Health Organization Offset Publication No. 55 (Geneva, 1980).


I. Rootman and J. Moser, "Guidelines for investigating alcohol problems and developing appropriate responses ", Division of Mental Health, unpublished draft report (World Health Organization Geneva).


P. H. Hughes and others, "Core data for epidemiological studies of non-medical drug use ", World Health Organization Offset Publication No. 56 (Geneva, 1980).


L. Johnston, "Review of general population surveys of drug abuse ", World Health Organization Offset Publication No. 52(Geneva, 1980).


R. Smart and others, "A methodology for student drug use surveys ", World Health Organization Offset Publication No. 50 (Geneva, 1980).


11. R. Smart and others, "Drug use among non-student youth", World Health Organization Offset Publication No. 60 (Geneva, 1981).


12. J. Klett and others, "A methodology for evaluation of drug dependence treatment and rehabilitation", World Health Organization Offset Publication, in press (Geneva, 1981).


13. D. C. des Jarlais and G. S. Uppal, "Heroin activity in New York city 1920-1978", American Journal of Drug and Alcohol Abuse ,vol. 7, Nos. 3 and 4 (1980), pp. 335-346.


14. W.J. Riley, M. O. Wagenfeld and S. Sonnad, " Triangulated investigating: an approach to the estimating of the extent of heroin use ", International Journal of the Addictions, vol .16, No. 1 (1981), pp. 97-108.


15. A. Richman and H. Abbey, "Heroin epidemics-decline and fall of epidemiologic research ", in Proceedings of the Social Statistics Session, Part II, of the American Statistical Association, Boston, Mass. 1976 (Washington, D.C., American Statistical Association, 1976), pp. 711-714.