What is a TB prevalence survey?
The prevalence of TB disease is the number of TB cases that exist in the population at a given point in time. It is reported as the total number of prevalent cases in a country, or as the number of prevalent cases for a given unit of population (for example, the number of cases per 100 000 population).
Why is the TB prevalence survey important?
- To obtain a direct measurement of the absolute burden of disease caused by TB.
- To measure trends in the burden of disease caused by TB
- To highlight invaluable information that can be gained from a survey, beyond both a single point-estimate of the burden of TB and measurement of trends
- Results can be used alongside an in-depth analysis of surveillance data and programmatic data, as the basis for a comprehensive update of estimates of disease burden (incidence and mortality as well as prevalence)
What are the objectives of the prevalence survey?
- To measure the prevalence of bacteriologically-confirmed pulmonary TB, among the adult population
- To identify the extent to which people with TB or those with symptoms suggestive of pulmonary TB have already sought care from health-care providers and, if so, with which types of care provider
- To identify reasons for lack of contact with services provided by or in collaboration with the NTP among people with TB or those with symptoms suggestive of pulmonary TB
- To update all population-based estimates of the burden of disease (measured in terms of incidence, prevalence and mortality) using results from the prevalence survey in combination with in-depth assessment of surveillance and programmatic data and other survey data.
- To assess whether the burden of disease caused by TB has fallen since the last survey.
- To provide a baseline for future measurement of trends in the burden of disease caused by TB.
Who is eligible for the survey?
Those aged 15 years and above, who will be required to voluntarily sign a consent form; asked a few questions about themselves and their health; invited for a free of charge chest X-ray at a given site and if necessary asked to give two sputum samples for TB examination.
Why should I take part in the survey?
- The survey offers free TB testing, free TB diagnosis, and free TB treatment
- Any ailments or disease found through testing will be recommended for further medical care
- Findings from the survey at community level will inform the government’s national TB control efforts
How are survey participants protected?
- All participant information will be kept confidential and not shared with unauthorized persons
- Participants will be shielded from effects of radiation through protective clothing, in particular women of child bearing age
- Those found to have any form of disease will be referred for proper care. In particular, TB patients will be referred for proper care
- Participants will be provided with feedback and information on their conditions
- Participants have a right to decline to answer any questions or withdraw from survey at anytime
How will the survey be conducted?
- Communities will be visited by survey staff, county representatives and community representatives to provide information on the survey
- The survey staff and local community representatives will visit households to collect information
- The survey staff and local community representatives will again visit households to collect information and invite participants to visit a mobile clinic for free testing and diagnosis
- At the mobile clinic, participants will be screened for TB through chest X-ray and collection of sputum specimen
- Results will be relayed through all county governments structures
What is the purpose of the interview?
The interview in a TB prevalence survey consists of a set of standardized questionnaires that collect data to answer specific questions. Answers are recorded using standard forms or tools. For example, the enumeration or census form allows the demographic characteristics of all members of a community to be captured and allows the prevalence survey team to know whether those individuals who give consent are representative of the whole population in terms of age and sex.
Why would a chest X-ray be done?
Chest X-rays are done to look for abnormalities of the heart, lungs, bones, or blood vessels in the chest. Chest X-rays are done using a very small dose of radiation; no significant health risk is recognized by the radiation dose used for taking an X-ray. Radiation exposure from one chest X-ray is equivalent to a few days of average natural exposure from the environment (sunlight, etc).
What if you would not like to undergo chest X-ray for any reason?
You can tell your interviewer or X-ray staff that you would not like to undergo an X-ray examination. Any person can decline the chest X-ray, even without disclosing the reason.
What is informed consent?
Informed Consent is given by a competent individual who has received the necessary information, has adequately understood the information and after considering the information has arrived at a decision, without coercion, undue influence or inducement or intimidation. Informed consent must be obtained from all participants before they take part in the prevalence survey.
Should consent be asked separately for each of the procedures (interview,X-ray, sputum collection)?
This is not essential, but all procedures should be clearly described in the information sheet. Participation is voluntary and participants have the right to withdraw from the survey at any stage with no need for explanations, or refuse survey procedures (e.g. X-rays, sputum examination). Refusal to participate in the survey or specific survey procedures should not compromise the rights of any participant in accessing health care or other community services.
What ethical principles apply to TB prevalence surveys?
- Do no harm/beneficence – This refers to the ethical obligation to maximize benefits and minimize harm.
- Respect for persons – This principle is crystallized in the concept of informed consent.
- Treat populations and individuals fairly – This principle requires the equitable distribution of the burdens and the benefits of participation in the survey.