Each of these sectors contributes to the four basic components of surveillance, which are (collection), (analysis), (dissemination) and (response). A Remote Surveillance Trailer in Sutter CA is a prime example of a surveillance system that utilizes these components. Because surveillance systems vary widely in methodology, scope, and objectives, features that are important to one system may be less important to another. Efforts to improve certain attributes, such as the ability of a system to detect a health event (sensitivity), can be detrimental to other attributes, such as simplicity or timeliness.
Therefore, the success of an individual monitoring system depends on the right balance of characteristics, and the robustness of an evaluation depends on the evaluator's ability to evaluate these characteristics with respect to system requirements. In an effort to adapt to these objectives, any evaluation approach must be flexible. With this in mind, the guidelines that follow describe many measures that can be applied to surveillance systems, with the clear understanding that not all measures will be appropriate for all systems. ORGANIZATION OF THIS DOCUMENT This document begins with a summary of the tasks involved in carrying out an evaluation, followed by sections describing each element of the evaluation. The first of these sections addresses the public health importance of the disease or health condition under surveillance. The second provides a framework for describing the components of a surveillance system.
The following sections focus on the attributes of a surveillance system (simplicity, flexibility, acceptability, sensitivity, positive predictive value, representativeness, and timeliness) and demonstrate how these combine to affect the utility and cost of a system. The document concludes with an analysis of the resources needed to operate the monitoring system and with sections detailing the conclusions and recommendations. The utility can be affected by all the attributes of surveillance. Increased sensitivity may provide a greater opportunity to identify epidemics and understand the natural course of an adverse health event in a community. The improvement of punctuality makes it possible to start control and prevention activities sooner.
The increase in positive predictive value allows public health officials to focus on productive activities. A representative surveillance system will better characterize the epidemiological characteristics of a health event in a defined population. Systems that are simple, flexible, and acceptable also tend to be more useful. SYSTEM ATTRIBUTES Task The simplicity of a surveillance system refers both to its structure and to its ease of operation.
Surveillance systems must be as simple as possible and, at the same time, meet their objectives. Methods: multiple levels of reporting (e.g.Definition of flexibility Flexibility is probably best judged retrospectively, by looking at how a system responded to a new demand. For example, when acquired immunodeficiency syndrome (AIDS) emerged in 1981, the notifiable diseases reporting system existing in state health departments was used to report cases, and AIDS surveillance has been adapted to the rapid advance of knowledge about the disease, its diagnosis and its risk factors. Another example is the ability of the gonorrhea monitoring system to include special surveillance of penicillinase-producing Neisseria gonorrhoeae.
Discussion Unless efforts have been made to adapt a system to another disease, it can be difficult to evaluate flexibility of that system. In the absence of practical experience, the design and operation of a system can be analyzed. In general, simpler systems will be more flexible: fewer components will need to be modified when adapting the system for use in another disease. Acceptability definition Acceptability reflects the willingness of individuals and organizations to participate in the surveillance system.
Methods: Timely reporting Some of these measures can be obtained by analyzing the diseases or conditions to be diagnosed, reflecting the skill of the care providers and the sensitivity of the diagnostic tests; and the system, and the resources available for evaluation. Measuring sensitivity in a surveillance system requires a) the validation of the information collected by the system and b) the collection of information external to the system to determine the frequency of the condition in a community (. From a practical point of view, when evaluating sensitivity (assuming that most of the reported cases are correctly classified), the main emphasis is placed on estimating the proportion of the total number of cases in the community that the system detects. Discussion A surveillance system that does not have high sensitivity can still be useful for monitoring trends, as long as the sensitivity remains reasonably constant.
Issues related to the sensitivity of surveillance systems often arise when changes in the incidence of the disease are observed. Changes in sensitivity can be precipitated by events such as increased knowledge of a disease, the introduction of new diagnostic tests, and changes in the method of carrying out surveillance. Searching for these surveillance devices is often an initial step in investigating an outbreak. Predictive value (positive definition) The PVP reflects the sensitivity and specificity of the case definition and the prevalence of the condition in the population (table). PVP increases with increasing specificity and prevalence.
Definition of Representativeness Multiple sources of data: For example, representativeness can be examined through special studies that show that data quality is an important part of representativeness. Much of the analysis in this document focuses on identifying and classifying cases. However, most surveillance systems are based on more than just counting cases. Information that is commonly collected includes the demographic characteristics of affected individuals, details about the health event, and notification of the presence or absence of potential risk factors. The quality, usefulness, and representativeness of this information depend on its completeness and validity.
To generalize the results of surveillance data to the general population, the data from a surveillance system must reflect the characteristics of the population that are important to the goals and objectives of that system. These characteristics generally relate to time, place and person. An important result of evaluating the representativeness of a surveillance system is the identification of population subgroups that can be systematically excluded from the notification system. This process allows for appropriate modification of data collection and a more accurate projection of the incidence of the health event in the target population.
Until now, attribute analysis has focused on information collected about cases, but in many surveillance systems, morbidity and mortality rates are calculated. The denominators for these rate calculations are usually obtained from a completely independent data system maintained by another agency, e.g.Attention should be paid to the comparability of categories (for example, definition of punctuality). Timeliness reflects the speed or delay between the stages of a surveillance system. Methods The timeliness of a surveillance system should be evaluated based on the availability of information for disease control, either for immediate control initiatives or for long-term program planning.
For example, a study on a surveillance system for shigella infections indicated that the typical case of shigellosis was brought to the attention of health officials 11 days after the onset of symptoms, a period sufficient for secondary and tertiary transmission to occur. This suggests that the level of timeliness was not satisfactory for effective disease control (. Conversely, when there is an extended latency period between exposure and the onset of the disease, the rapid identification of cases of illness may not be as important as the rapid availability of exposure data to serve as a basis for interrupting and preventing exposures that lead to the disease. In another period, public health agencies use surveillance data to track progress towards the 1990 National Goals and to plan for the Goals for the Year 2000.
Efforts to increase sensitivity, PVP, timeliness and representativeness tend to increase the cost of a surveillance system, although efficiency savings with automation may offset some of these costs (1). As sensitivity and PVP approach 100%, a surveillance system is more likely to be representative of the monitored population. However, as sensitivity increases, PVP may decrease. Efforts to increase sensitivity and PVP tend to make the surveillance system more complex, which can reduce its acceptability, timeliness and flexibility. For example, a study comparing surveillance initiated by the health department (active) with that initiated by the provider (passive) did not improve timeliness, despite increased sensitivity (.
Sentinel surveillance is a specific, focused approach to monitoring specific diseases or health conditions. in a selected subset of the population. Instead of collecting data from the entire population, sentinel surveillance involves gathering information from a group representative of health centers, regions, or individuals who are considered to be at high risk of contracting the disease of interest or when resources are too limited to test entire populations. An example of this is described in the Gonococcal Isolate Surveillance Project (GISP), which has been monitoring antimicrobial resistance (AMR) trends in Neisseria gonorrhoeae since 1986 in selected clinics and laboratories in the U.S.
UU. Public health surveillance is what represents the first phase of the general approach to public health. It is a system for collecting patient records and data that helps in the study of infectious diseases. The World Health Organization (WHO) and the CDC are the two main agencies that use this type of system; however, there are other public health institutions that collect data from state and local health departments for analysis and interpretation. Its purpose is to promote the best use of public health resources through the development of effective and efficient surveillance systems.
Although the total volume of surveillance has increased in recent years, surveillance for human immunodeficiency virus (HIV) infection, tuberculosis, and vaccine-preventable diseases has fallen dramatically (Michael Osterholm, state epidemiologist and head of the Minnesota Department of Health, personal communication, November 1999). A representative surveillance system accurately describes a) the occurrence of a health event over time and b) its distribution in the population by place and person. Finally, existing databases, such as those created through routine susceptibility testing, provide another opportunity for surveillance. When evaluating PVP, the main emphasis is placed on confirming cases reported through the surveillance system. The timeliness of a surveillance system must be evaluated based on the availability of information for disease control, either for immediate control initiatives or for long-term program planning.
Since a disease surveillance system can use several of these methodologies in any location or jurisdiction, it is important to coordinate data flows and public health response protocols. Examining the percentage of unknown or blank responses to the elements of surveillance forms or questionnaires is simple. Disease surveillance systems encompass a variety of methodologies designed to monitor and track health events, each adapted to specific contexts and purposes. In addition, the pharmaceutical industry carries out antimicrobial surveillance to demonstrate the activity of a drug compared to that of other agents.
Examples of diseases being monitored include influenza, COVID-19 and its variants, HIV, AIDS and whooping cough.
