Recommendations
of a Working Group of the World
Health Organization (WHO) and the Europe Region of the International
Union Against Tuberculosis and Lung Disease (IUATLD) for uniform
reporting on tuberculosis cases.
Published in the European Respiratory Journal (1996 ; 9:1097-1104)
Report prepared by Hans L. Rieder1,
John M. Watson2, Mario
C. Raviglione3, Michael
Forssbohm4, Giovanni
Battista Migliori5,
Valérie Schwoebel6,
A. Gordon Leitch7,
Jean-Pierre Zellweger8
1 International Union Against Tuberculosis and Lung Disease,
Paris, France
2 Public Health Laboratory Service Communicable Disease Surveillance
Centre, London, United Kingdom
3 Tuberculosis Programme, World Health Organization, Geneva,
Switzerland
4 German Central Committee against Tuberculosis (DZK) / Public
Health Office, Wiesbaden, Germany
5 Fondazione Salvatore Maugeri, Clinica del Lavoro e della
Riabilitazione, Care and Research Institute, Tradate, Italy
6 European Centre for the Epidemiological Monitoring of AIDS,
Saint-Maurice, France
7 Chalmers Hospital, Royal Victoria Chest Clinic and Tuberculosis
Service, Edinburgh, United Kingdom
8 Swiss Association against Tuberculosis, Berne, Switzerland
Correspondence:
Hans L. Rieder, M.D., M.P.H.
Chief, Tuberculosis Section of IUATLD
Reichenbachstr. 15
3004 Bern - Switzerland
tel +41 31 / 301 5201
fax +41 31 / 301 8286
Reprint requests:
Global Tuberculosis Programme
World Health Organization
1211 Geneva 27 - Switzerland
or
International Union Against Tuberculosis and Lung Disease
68, Boulevard Saint-Michel
75006 Paris - France
Members of the Working Group:
J. Martinez Benazet, Oriol Ramis-Juan (Andorra); Marina Safarian
(Armenia); Jean Paul Klein (Austria) Farman M. Abdullayev (Azerbaijan);
Jacques Prignot, M. Uydebrouck, Paul Vermeire, Jean-Marie Verstraeten,
M. Wanlin (Belgium); Dizdarevi Zehra (Bosnia & Herzegowina); P. Minchev
(Bulgaria); Ira Gjenero Margan, Rajko Pardon (Croatia); D. Dankova, Ludek
Trnka (Czech Republic); Gunnar Pallisgaard (Denmark); Eero Tala, Kari
Liippo, Juhani Eskola (Finland); Colette Moyse, Valérie Schwoebel
(France); Michael Forssbohm (Germany); Nearchos E. Yatromanolakis (Greece);
Dezsö Kozma, Imre Vadász (Hungary); Thorsteinn Blöndall
(Iceland); Luke Clancy, Paul Kelly (Ireland); Daniel Chemtob, Daniel
Weiler (Israel); Giovanni Battista Migliori, Maria Luisa Moro (Italy);
A.D. Djunusbekov (Kazakhstan); Rishard Zalesky (Latvia); Georges Molitor
(Luxemburg); Hugo Agius-Muscat, Ann Galea Baron (Malta); Dmitrii O. Sain
(Moldova); Jaap Veen, N.A. Kalisvaart (Netherlands); Kjell Bjartveit,
Einar Heldal (Norway); Jerzy Leowski (Poland); Maria L. Antunes (Portugal);
Emil Corlan (Romania); A.G. Khomenko (Russia); A. Bajan, Juraj Trenkler
(Slovak Republic); Jurij orli (Slovenia); Jose Alcaide (Spain);
Victoria Romanus (Sweden); Jean-Pierre Zellweger (Switzerland); Jane
Leese, A. Gordon Leitch, John Watson (United Kingdom); O. Djuri , V.
Vu uini (Yugoslavia); Hans L. Rieder, International Union Against Tuberculosis
and Lung Disease (France); Pierre Chaulet, Mario C. Raviglione, World
Health Organization (Switzerland).
Keywords: tuberculosis, surveillance, Europe
Running head: Surveillance of tuberculosis in Europe
Abstract
Consensus based recommendations have been developed by a
Working Group, comprising representatives of governmental and nongovernmental
organizations in the European Region of the World Health Organization
and the International Union Against Tuberculosis and Lung Disease, on
uniform reporting of tuberculosis surveillance data in the countries
of Europe.
A uniform case definition and a minimum set of variables
for reporting on each case have been agreed which, when collated on a
national basis, will allow comparison of the epidemiology of tuberculosis
in different European countries.
The Working Group recommends that the case definition includes definite cases
where the diagnosis has been confirmed by culture (or supported by microscopy
findings in countries where diagnostic culture facilities are not available)
and other than definite cases based on a clinical diagnosis of
tuberculosis combined with the intention to treat with a full course
of anti-tuberculosis therapy. Both definite and other than
definite cases should be notified by physicians and, in addition,
laboratories should be required to report definite cases.
The minimum set of variables to be collected on each case
of tuberculosis should include date of starting treatment, place of residence,
date of birth, gender, and country of origin to characterise the patient.
Recommended disease-specific variables include site of disease, bacteriologic
status (microscopy and culture), and history of previous antituberculosis
chemotherapy.
The minimum set of variables should be collated on all patients
and should be as complete as possible. Additional variables may be collected
for individual, local or national purposes, but, in general, completeness
of reporting on cases is likely to be better if the information requested
is kept to a minimum.
Timely reporting of cases is essential for appropriate public
health action. Cases should be reported to the health authority at the
local and/or regional level within one week of starting treatment. Individual
case based information should be reported to the national level by the
local or regional level. Feedback to reporters is essential. At the national
level, preliminary quarterly reports should be produced and final reports
should be published annually. Public health surveillance has been defined
as the ongoing systematic collection, analysis, and interpretation of
outcome-specific data, closely integrated with the timely dissemination
of these data to those responsible for preventing and controlling disease
or injury [1]. The epidemiology of tuberculosis may be monitored by surveillance
of incident cases, prevalent cases, risk of infection with Mycobacterium
tuberculosis complex (derived from tuberculin skin test prevalence
surveys), and deaths from tuberculosis. In practice the most readily
accessible and informative indicator of tuberculosis morbidity is the
number of incident cases.
This report is a direct extention of recommendations made
earlier by a European working group in 1990 [2]. Data on tuberculosis
notifications in western and eastern Europe have recently been analysed
[3, 4]. During the compilation of data it was noted that differences
in case definitions between various countries made comparison difficult.
Similar difficulties with case definitions hampered further analysis
of tuberculosis control in relation to international migration in Europe
[5]. That analysis recommended common principles for surveillance of
tuberculosis in European countries and agreed a minimum data set [5 ].
This paper delineates these common principles and specifies the variables
in the common data set which will allow European countries to collect
comparable data as recommended elsewhere [6] and also to respond to matters
of public concern. Although the paper emphasises the rationale for collecting
only a small number of variables relating to each case of tuberculosis,
the system could easily be expanded to gather more detailed information,
customised to the needs of individual countries.
It should be emphasised that, while surveillance is an integral
part of monitoring the effectiveness of interventions, this paper does
not address monitoring of treatment programme performance.
Aims and objectives of surveillance
Surveillance of tuberculosis should serve two major purposes.
It should enable an accurate picture to be obtained of the course of
the tuberculosis epidemic in a community over time and permit timely
intervention if the observed trend deviates from what is expected. Secondly,
the characterisation of cases should be sufficiently detailed to allow,
in conjunction with appropriate population figures, the identification
of groups in the community at particularly high risk of tuberculosis
so that interventions and resources can be targeted more efficiently.
Tuberculosis surveillance has local, national, and international
functions. At the local level it is important so that the public health
authorities can ensure that
o appropriate treatment services are offered to the individual;
o contact tracing is carried out;
o local outbreaks are recognised;
o the local epidemiology is monitored.
At the national level the emphasis is different. Surveillance
enables the public health authority to:
o monitor the epidemiology of the disease in the country,
including trends over time, and variations in incidence in population
subgroups;
o take the first step in the process of monitoring the success
of the national treatment programme for tuberculosis;
o monitor the effectiveness of specific tuberculosis control
and prevention measures.
At the international level, the objectives are to monitor
the epidemiology of the disease in the entire European region, including
trends over time and inter-country comparisons, and to identify high
incidence population groups which may be common to several countries
with a view to co-ordinating efforts in tuberculosis control at an international
level.
The principles guiding tuberculosis surveillance programmes
should include:
o information on cases should be collected locally;
o a range of information sources should be utilised so as
to maximise the ascertainment of cases, e.g., clinicians, laboratories,
pharmacies, social security organisations, etc, provided linking is possible
to avoid double counting;
o a minimum data set for collection of information on cases
should be utilised;
o standard case definitions should be used for the purposes
of reporting to the national centre;
o data on individual cases should be collated nationally
to permit detailed analyses of reported cases and, where appropriate,
linking of case registers to other appropriate disease registers;
o patient confidentiality should be strictly maintained.
In this document, data collected locally are discussed only
in relation to national data collection. In particular, items which might
be relevant for management of individual patients or for contact tracing
are excluded from discussion if they have no potential bearing on national
or European-wide public health policy. Such omissions should not be interpreted
as representing the Working Group's position as to their necessity, but
rather as an acceptance of widely divergent needs at local level beyond
the scope of this paper.
Review of current surveillance systems in Europe
The Working Group reviewed current activities in tuberculosis
surveillance in European countries. The results of this survey, summarised
in table 1 (available in the original article), show that an overwhelming
majority of countries base their reporting system on a case definition
of tuberculosis. In only a few countries are cases reported anonymously,
and reporting is almost universally mandatory, at least by physicians,
but often by both physicians and laboratories. Age, gender, site of disease,
and bacteriological status are almost uniformly required reporting variables
on cases, and many countries additionally request information on country
of birth and history of previous treatment. With few, but important,
exceptions, the information collected locally or regionally, is also
collated nationally.
Case definition
To allow comparability both within and between countries,
a uniform definition of a notifiable case of tuberculosis is essential.
Different countries require different categories of disease to be reported.
The lowest common denominator recommended for uniform reporting in countries
where level II laboratories [8] are routinely available is a case of
tuberculosis in which M. tuberculosis complex has been identified
by culture.
A definite case of tuberculosis is a case with culture
confirmed disease due to M. tuberculosis complex.
Reporting is also be required of other than definite cases
which meet both of the following conditions: 1) a clinician's judgement
that the patient's clinical and/or radiological signs and/or symptoms
are compatible with tuberculosis, and 2) a clinician's decision to treat
the patient with a full course of antituberculosis treatment.
Definite and other than definite cases should
be reported separately to permit an international comparison of definite
cases and their proportion among all cases.
Definite (and, where applicable, other than definite)
cases of pulmonary tuberculosis should be divided into smear-positive
and smear-negative cases based on direct microscopic smear examination
of spontaneously produced or induced sputum. Cases which are positive
on microscopy of bronchoalveolar or gastric lavage material only should
not be considered to be sputum smear-positive. Such cases may still qualify
for definite or other than definite cases depending on
culture results and other criteria.
Data collection
Data on individual tuberculosis cases should be collected
at local level and they should be made accessible on an ongoing basis
to national government authorities. Most countries in Europe have legal
provisions for mandatory reporting by physicians. Nevertheless, busy
physicians may forget, or otherwise neglect, to report cases of tuberculosis
[7], and the legal requirement to report cannot usually be enforced.
A few countries have gained experience by additionally requesting level
II laboratories (capable of identification of M. tuberculosis complex,
[8]) to report each isolate of M. tuberculosis complex. There
are fewer such laboratories than there are physicians potentially seeing
cases making direct involvement of the laboratories with the work of
the public health authorities more feasible. Cases reported by laboratories
can be followed up with physicians to obtain the required demographic
characteristics of the patient and relevant disease-specific information.
The Working Group thus recommends that national health authorities make
both physicians and laboratories subject to mandatory reporting of tuberculosis.
Provisions must be made to eliminate duplicate reports and account for
subsequent changed diagnoses.
Surveillance may also be strengthened by the provision of
information from pharmacies on prescriptions of antituberculosis drugs
as for example in Norway [9].
Timeliness and flow of reporting
Like other infectious diseases, cases of tuberculosis should
be reported promptly after identification. Although annual summary reports
of tuberculosis will usually suffice to indicate major changes in the
epidemiology of tuberculosis, preliminary national statistics should
be published at least quarterly. In the United States it was the continuous
assessment of weekly reports which showed in September 1985 an unprecedented
failure of tuberculosis to decline. This permitted the publication of
an alert about the re-emergence of tuberculosis in the United States
[10].
Local / regional level
All patients started on anti-tuberculosis medication should
be notified by their physician to the local health authority within one
week. For this initial report, information on full name, birth date,
and gender of the patient, presumptive diagnosis, date of starting treatment,
and name and address of the reporting physician suffices to ensure that
contact tracing in collaboration with the physician is properly initiated
where indicated. In countries which have established a continuous reporting
system, local health authorities should forward the information to the
national authorities with or without name, depending on the country's
legal requirements.
Local health authorities should seek further information
from the physician reporting the case, often by means of an extended
reporting form (an example of such a form is shown in figure 1, available
in the original article). This information should be returned to the
local health authority within a maximum of three months following report
of a suspect, providing sufficient time to definitively classify a suspect
as a notifiable case of tuberculosis.
Laboratories identifying M. tuberculosis complex should,
simultaneously with their report to the physician requesting the examination,
provide information on the bacteriological findings to the local health
authority, together with name and address of the physician, full name,
birth date, and gender of the patient, to permit them to definitively
classify a case reported by the physician or to follow up with the physician
concerned on a case hitherto not reported.
From local / regional to national level
The unit of reporting is the local / regional health authority
which will mostly be found at the district / regional (provincial) level.
Local health authorities are responsible for keeping track of suspect
cases. Depending on resources and expertise available, local health authorities
have the responsibility for collecting information and definitively classifying
cases, including linking information from different sources (laboratories,
physicians), completing missing information and eliminating duplicate
reporting as far as possible. They should forward individual (non-aggregate)
information to the national authorities, with or without name or other
identifier, depending on the country's legal requirements. This information
can be sent to the national authorities on an ongoing basis, or at least
quarterly. In the absence of sufficient resources at the local level,
nominal (or suitably coded) data would have to be forwarded to the national
health authorities to exclude duplications and allow the classification
of cases.
National level
Data from the local / regional level should be aggregated
at least quarterly for publication of preliminary statistics. At the
national level, final annual summary reports by calendar year will usually
be sufficient. Ideally, analysis should be carried out by year of starting
treatment, provided the calendar year is closed at the end of the first
quarter in the subsequent year, to allow sufficient time for verifying
the case.
A summary of the flow for reporting tuberculosis suspects
and cases is provided in figure 2 (available in the original article).
Essential variables
Essential variables include information characterizing the
case by time, place, and person, as well as details of site of disease,
bacteriological status and whether the patient was previously treated.
An example of a reporting form providing the minimal information that
is requested from each European country is shown in figure 1 (available
in the original article). These variables are described and discussed
in the following paragraphs.
Time
Date of starting treatment
Ideally, to obtain accurate estimates of incidence, the date
of onset of disease should be known, but this is not usually practical.
The date of diagnosis is the next obvious date but this may often be
difficult to fix in time so it is recommended that the date of starting
treatment for tuberculosis constitutes a reasonable proxy and this
should be recorded in all cases. The date of starting treatment is defined
as the date when the physician is sufficiently confident of his diagnosis
to initiate appropriate treatment for tuberculosis. For pulmonary tuberculosis
this will usually be the time when a positive sputum smear result is
obtained from the laboratory or, in sputum smear-negative cases, when
the clinician has gathered sufficient clinical and/or radiological evidence
for the diagnosis to justify starting treatment. When the date of starting
treatment is unavailable, the date of notification of the case may be
substituted. For cases never receiving treatment, for example post mortem
diagnoses, the date of diagnosis should be substituted.
Place
Place of residence
The place of residence of a tuberculosis patient is
essential for public health action, and also provides at the national
level after appropriate aggregation (by county or region/province) information
on differences in disease frequency in different areas of the country.
The place of residence should be where the patient was living at the
time treatment was started. In cases of homeless people, migrants, and
detainees, the place of residence within the country during of the previous
three months might be used, or any other solution might be sought as
appropriate for individual countries. For European comparison, aggregation
by country will usually suffice.
Person
Age, gender, and country of birth
Date of birth to allow the calculation of age at the
time of starting treatment and gender are variables that should
be known for each patient.
In culturally heterogenous societies, tuberculosis incidence
may vary greatly in different ethnic groups. In view of the increasing
importance of tuberculosis in European countries among immigrants and
other foreigners, the Task Force on Tuberculosis Control and International
Migration identified country of birth as an additional variable
that should be collected routinely [5]. In some countries ethnicity,
citizenship, or citizenship of parents may be of more importance than
country of birth in characterizing the demographics of tuberculosis patients.
Disease-specific variables
Site of disease
Site of disease should be recorded in all patients. Because
patients may have multiple sites of disease, it is recommended that at
least two sites, a major and a minor site, when applicable, be recorded.
Because disease site classification may differ in different countries,
the following sites are recommended for use, because they will allow
further aggregation as needed in a particular country:
o Pulmonary: Pulmonary is defined as tuberculosis
of the lung parenchyma and the tracheo-bronchial tree only. It is proposed
that pulmonary tuberculosis, if present, should always be listed as the
major site whatever other site may additionally be affected. Extrapulmonary
tuberculosis is then defined as tuberculosis affecting any site other
than pulmonary as defined.
o Pleural: Pleural tuberculosis is defined here as
extrapulmonary tuberculosis and is tuberculous pleurisy only, with or
without effusion
o Lymphatic: Lymphatic tuberculosis includes tuberculosis
involving the lymphatic system. Because of the intrathoracic manifestations
of tuberculosis in children and patients with HIV infection, lymphatic
tuberculosis is preferably further differentiated into intrathoracic
and extrathoracic lymphatic tuberculosis
- intrathoracic: Intrathoracic lymphatic tuberculosis
- extrathoracic: Lymphatic tuberculosis other than intrathoracic
lymphatic tuberculosis
It is proposed here that if tuberculosis in children involves
both the lung parenchyma and a lymphatic component the case should be
classified as major site pulmonary and minor site intrathoracic lymphatic
tuberculosis
o Bone / Joint: Tuberculosis of the bones and / or
joints should be subdivided into:
- tuberculosis of the spine
- tuberculosis of bones / joints other than spine
o Central nervous system (CNS): Tuberculosis of the
central nervous system should be subdivided into:
- tuberculous meningitis
- tuberculosis of the CNS other than meningitis
o Genitourinary: Tuberculosis of the genitourinary
system, including tuberculosis of kidney, ureter, bladder, and male and
female genital tract.
o Peritoneal / digestive tract: Peritoneal / digestive
tract tuberculosis includes tuberculosis of the peritoneum with or without
ascites and tuberculosis of the digestive tract.
o Other: Other extrapulmonary sites, including laryngeal
tuberculosis, should be aggregated here and, for country-specific analyses,
might specifically be named.
o Disseminated: Disseminated tuberculosis includes
tuberculosis of more than two organ systems or miliary tuberculosis.
If one of the affected sites is the lung parenchyma, the case should
be classified as having both pulmonary and disseminated tuberculosis.
Miliary tuberculosis, e.g., is thus classified as pulmonary and disseminated.
Where M. tuberculosis complex has been isolated from blood, the
disease site should be designated disseminated
To facilitate reporting of disease site in aggregate form
at European level, cases should be classified into three groups, i.e., pulmonary
tuberculosis only, pulmonary and extrapulmonary, and extrapulmonary
tuberculosis only.
Bacteriological status
Information on bacteriological status must always be included.
The result of culture (negative or positive for M. tuberculosis complex,
not done, or pending) and the source specimen must be recorded by the
physician and if positive also by the laboratory. Whenever possible further
differentiation of isolates into M. tuberculosis, M. bovis,
or M. africanum should also be reported. Similarly, the result
of direct microscopic examination (negative or positive for acid-fast
bacilli, or examination not done) must be reported. Histological examination
with evidence of acid-fast bacilli should be considered as positive microscopy
and recorded accordingly. The specimen from the major site or, if negative
or not attempted, from the minor site that provided a positive result
should be recorded to clearly classify the case (e.g., sputum smear-positive,
culture-confirmed pulmonary tuberculosis or biopsy smear-negative, culture-confirmed
lymphatic tuberculosis). Cases with pulmonary tuberculosis should be
reported when aggregating the data as sputum smear-positive and culture-only
positive cases.
Recurrent or new disease
Before starting treatment for tuberculosis it is important
to establish 1) that the patient has active tuberculosis; 2) whether
the patient has previously had tuberculosis and, if so, 3) what treatment
for tuberculosis has previously been given. The first two questions are
of both epidemiological and clinical concern and the third question is
of clinical relevance since the answer to it will determine the most
appropriate treatment of the present episode of tuberculosis.
For public health purposes, it is essential to report all
cases of tuberculosis which are diagnosed by physicians. For epidemiological
purposes where trends in incidence are of special interest it must be
made clear whether a notified case has or has not had previous tuberculosis.
Care must be taken to ensure that chronic cases and intermittently absconding
and returning patients are not repeatedly notified. The answer to the
following questions should resolve these issues: The first question asks
whether the patient has ever had tuberculosis diagnosed before. If the
answer is yes, the second question seeks the year of the previous episode,
and, if available, the month. A third question determines whether the
patient has had previous chemotherapy and if the answer is yes whether
it was considered adequate or not. This will allow classification of
such cases into relapse and recurrence with or without previous chemotherapy
and so improve the definition of cases.
Other variables
Other variables may be collected for specific analyses. Experience
shows that information on individual cases is usually more complete the
fewer variables are requested. The information that is recommended for
routine collection as outlined above should be 95% or more complete for
each individual variable. Information which is substantially incomplete
is of limited value. For example, information derived from only 60 per
cent of patients may not be representative of all tuberculosis patients.
To increase the specificity of the case definition of other
than definite cases, information on tuberculin skin test results in cases
without culture confirmation and information on results of chest radiographs
may be appended [11].
In countries experiencing a considerable problem of tuberculosis
among those with a country of birth other than the current country of
residence, a further subdivision by legal status, i.e., by citizenship,
and among foreigners grouping into migrant workers, refugees / asylum
seekers, and other foreigners may further help to better characterise
patients. Duration of residence within the country for foreign-born patients
might also be useful information. Not required at the international level,
but potentially useful for national assessment, is an ascertainment of
the number of cases in which the diagnosis was not made until after death.
Specifically designed surveys should be used to answer more
complex questions; physicians are only likely to collaborate and provide
the requested information if it is simple, concise, and of immediate
obvious general interest. Such surveys may be designed to gather information
on prevalence of alcohol and drug-dependence, homelessness, and other
variables of special interest in tuberculosis control.
Analysis and reporting
Public health authorities owe it to reporting laboratories
and physicians to regularly analyze, interpret, and publish collected
surveillance data. In the case of tuberculosis, such reports should be
published on an annual basis. Data should be analysed by calendar year,
based on the date the physician reported commencement of treatment or
in the absence of such information the date the case was first notified
at local level.
Conclusions
This document represents a consensus of technical recommendations
to European Governments on how to structure their tuberculosis surveillance
systems with a view to standardisation which would allow international
comparisons in Europe. The interpretation of standardised surveillance
figures must include an appreciation of the data quality from individual
countries.
The majority of European countries responding to the questionnaire
collect all information considered essential for surveillance in this
report to allow uniform reporting of tuberculosis cases at a European
level. Most systems currently in place will thus need only minor modifications
to allow collation at the European level.
The members of the Working Group, the World Health Organization,
and the Europe Region of the International Union Against Tuberculosis
and Lung Disease consider it essential to obtain regular surveillance
data on tuberculosis from national governments, to make international
comparative analyses of these data, and to distribute them to participating
member states. It is only by doing so that changes in trends or patient
characteristics nationally or internationally can be detected at an early
stage.
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