Case Control Study: From 4 Different Sources
A design for epidemiological studies that matches individuals with a disease or health problem (cases) with others who do not have that condition (controls). Frequently, individuals included in the study are matched for factors such as age, race, socioeconomic status, occupation and area of residence. Comparisons are then made between the two groups.
A study that starts with the identification of persons with the disease (or other outcome variable) of interest, and a suitable control (comparison, reference) group of persons without the disease. The relationship of an attribute to the disease is examined by comparing the diseased and non-diseased with regard to how frequently the attribute is present or, if quantitative, the level of the attribute, in each of the groups.
Research in which ‘cases’ – that is, persons with a particular condition or receiving a particular medication – are compared with a group similar in age, sex distribution and social class, etc. who do not have the condition or who are not receiving the drug.
comparison of a group of people with a disease or condition and a control group of people free from that disease (e.g. people diagnosed with lung cancer and people without lung cancer). The groups are compared in terms of the frequency of *variables in their backgrounds (e.g. cigarette smoking). This method can be used to investigate risk factors for diseases. In the more precise matched pair study each individual with the disease is paired with a control matched on the basis of (say) age, sex, and occupation: this places greater emphasis on the factors for which the pairs have not been matched. Compare cross-sectional study, longitudinal study.
See CONTRACEPTION.... birth control
An observational study in which outcomes in a group of participants that received an intervention are compared with outcomes in a similar group (i.e. the cohort) of participants, either contemporary or historical, that did not receive the intervention. In an adjusted (or matched) cohort study, investigators identify (or make statistical adjustments to provide) a cohort group that has characteristics (e.g. age, gender, disease severity) that are as similar as possible to the group that experienced the intervention.... cohort study
See “cohort study”.... prospective study
A research design used to test hypotheses in which inferences about exposure to the putative causal factor(s) are derived from data relating to characteristics of the persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or other outcome condition of interest, and their characteristics and past experiences are compared with those of other, unaffected persons.... retrospective study
The number of fatal cases of specific disease, divided by total number of known cases and it is usually expressed as percent. Case fatality is one index of disease severity and is of more interest in acute than in chronic disease.... case fatality rate
A study that measures the prevalence of health outcomes or determinants of health, or both and other variables of interest in a population at a point in time or over a short period.... cross-sectional study
Comparison of outcomes between two or more groups of patients who have been intentionally given di?erent treatments or preventative measures, for example, diets. The subjects in the trial should be randomly allocated to the groups, with patients in one group – called controls – receiving no active treatment. If possible, neither patients nor doctors participating in a study should know which patients are receiving what treatment (double blind study/trial). Furthermore, groups should exchange treatments after a prearranged time (crossover study/trial). (See CLINICAL TRIALS; RANDOMISED CONTROLLED TRIAL.)... intervention study
A study designed to examine associations, commonly putative or hypothesized causal relationships. An analytic study is usually concerned with identifying or measuring the effect of risk factors, or is concerned with the health effects of specific exposure(s).... analytic study
Use of natural, indigenous predators or organisms to control medically important insects.... biological control
The set of actions taken to ensure that spending is in line with budgeted amounts and the regulations for spending them.... budgetary control
A partic ular instance of disease; as in a case of typhoid fever. A case is not synonymous with a patient, for the latter is the human being affected with the disease.... case
A meeting of all professionals (often including carers) interested in an individual’s care.... case conference
A continuous process of planning, arranging and coordinating multiple health care services across time, place and discipline for persons with high-risk conditions or complex needs in order to ensure appropriate care and optimum quality, as well as to contain costs.... case management
A method by which a health care provider measures the service needs of the patient population. It may be based on such things as age, medical diagnosis, severity of illness or length of stay.... case mix
Fixed cost for a case. See also “fee for service”.... case payment
A measure of intensity or gravity of a given condition or diagnosis for an older person.... case severity
An in-depth study of an individual, group, institution, organization or programme. The advantage of the case study method is that it allows more intensive analyses of specific empirical details. However, it is difficult to use the results to generalize to other cases.... case study
The control of disease caused by infectious agents or their toxic products. Successes in the 19th and 20th centuries in the treatment and control of communicable diseases such as SMALLPOX, CHOLERA, TUBERCULOSIS, gastrointestinal infections, POLIOMYELITIS and SEXUALLY TRANSMITTED DISEASES (STDS) resulted in an erroneous conception that they no longer posed a serious threat to public health, and certainly not in developed countries. As a consequence, the maintenance of e?ective public health strategies steadily lost out in the competition for resources to the more ‘glamorous’ developments in medicine, such as improved CANCER treatments, HEART surgery, kidney DIALYSIS and organ TRANSPLANTATION. However, in recent decades the dangers of this approach have become increasingly apparent. Rapidly expanding urban populations, more complex lifestyles, new and resurgent infections (some linked to a spread of antibiotic resistance) such as AIDS/HIV and variant CREUTZFELDT-JAKOB DISEASE (CJD), and the ease with which infection can be spread by the enormous growth of long-distance travel and population migrations are severely straining existing public health measures. The supply of clean water, e?ective waste- and sewage-disposal measures, the hygienic production and delivery of food and early detection and subsequent prevention of infectious diseases can no longer be taken for granted. Governments will need to strengthen the provision of workable, properly resourced public health facilities, and developing countries will need ?nancial support and expert help from developed nations to achieve this objective. Timely recognition of new and resurgent infectious diseases requires national and international early-warning mechanisms to ensure rapid investigation and implementation of e?ective control measures. Otherwise, serious breakdowns in public health will occur, and international co-operation is vital to provide and support control measures. (See also COMMUNICABLE DISEASE; NOTIFIABLE DISEASES.)... communicable diseases control
A control group that is observed by investigators at the same time as the treatment group but that was not established using random assignment of participants to control and treatment groups. Differences in the composition of the treatment and control groups may result.... concurrent nonrandomized control
A group of participants that serves as the basis of comparison when assessing the effects of the intervention of interest that is given to the participants in the treatment group. Depending upon the circumstances of the trial, a control group may receive no treatment, a ‘usual’ or ‘standard’ treatment, or a placebo. To make the comparison valid, the composition of the control group should resemble that of the treatment group as closely as possible.... control group
A study concerned with and designed only to describe the existing distribution of variables, without regard to causal or other hypotheses.... descriptive study
All the measures designed to prevent or reduce as much as possible the incidence, prevalence and consequences of disease, such as the control of disease vectors, the removal or reduction of the influence of predisposing factors in the environment, immunization and curative care.... disease control
A study in which conditions are under the direct control of the investigator.... experimental study
A study where the main objective is to explain, rather than merely describe, a situation by isolating the effects of specific variables and understanding the mechanisms of action.... explanatory study
Preliminary study to determine the practicability of a proposed health programme or procedure, or of a larger study, and to appraise the factors that may influence its practicability.... feasibility study
A study in which individuals or populations, selected on the basis of whether they have been exposed to risk, have received a specified preventive or therapeutic procedure, or possess a certain characteristic, are followed to assess the outcome of exposure, the procedure or the effect of the characteristic, e.g. occurrence of disease.... follow-up study
A combination of biological and insecticidal methods of control, e.g. the introduction of predacious fish to breeding places which are also sprayed with insecticides that have minimum effect on the fish.... integrated control
See “synthetic study”.... integrative study
An executive agency of the Department of Health with the prime function of safeguarding the public health. It ensures that branded and non-branded MEDICINES on the UK market meet appropriate standards of safety, quality and e?cacy. The agency applies the strict standards set by the UK Medicines Act (1968) and relevant European Community legislation.... medicines control agency
A National Health Service body intended to combat the increasing threat from infectious diseases and biological, chemical and radiological hazards. Covering England, the agency includes the Public Health Laboratory Service, the National Radiological Protection Board, the Centre for Applied Microbiology and Research, and the National Focus Group for Chemical Incidents.... national infection control and health protection agency
A study in which the investigators do not manipulate the use of an intervention (e.g. do not randomize people to treatment and control groups) but only observe people who are (and sometimes people who are not) exposed to the intervention, and interpret the results.... observational study
A study, generally undertaken by an individual health programme or health planning agency to determine the geographic distribution of the residences of the patients served by one or more health programmes. Such studies help define catchment and medical trade areas and are useful in locating and planning the development of new services.... patient-origin study
A small-scale test of the methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.... pilot study
See “cross-sectional study”.... prevalence study
An investigation that collects original (primary) data from subjects, e.g. randomized controlled trials, observational studies, series of cases, etc. See “secondary data analysis”.... primary study
The sum of all the activities which prevent unwanted change in quality. In the health care setting, quality control requires a repeated series of feedback loops which monitor and evaluate the care of the individual (and other elements in the health care process). These feedback loops involve checking the care being delivered against standards of care, identification of any problems or opportunities for improvement, and prompt corrective action, so that the quality is maintained.... quality control (qc)
A process within society which both formally, through law, and informally, through customs, norms and mores, attempts to influence and order the actions of social groups and their members and thus maintain public order.... social control
A study that does not generate primary data but that involves the qualitative or quantitative consolidation of findings from multiple primary studies. Examples are literature review, meta-analysis, decision analysis and consensus development.... synthetic study
Identification of species and their genetic relationship to one another.... taxonomic study
a combined X-ray and manometry examination of the bladder to look for abnormal function. The bladder is filled slowly with contrast medium using a small urinary catheter and the pressure is monitored during filling and voiding (micturition). X-ray images of the bladder and urethra (see urethrography) are taken. The test is used to differentiate between obstruction to bladder outflow and abnormal involuntary contractions of the muscle in the bladder wall.... bladder pressure study
see social services.... case work
the control of disease due to infectious agents or their toxic products. See Consultant in Health Protection.... communicable disease control
surgical procedures that can be performed in a single day, without the need to admit the patient for an overnight stay in hospital. Modern techniques of surgery and anaesthesia now enable many surgical cases of minor and intermediate degrees of severity to be treated in this way: examples include many breast lesions, dilatation and curettage, and operations for hernia and varicose veins. Special units are established in many hospitals.... day-case surgery
(EPS) an assessment of the electrical system of the heart by means of thin preshaped wires passed into the heart via the femoral vein. An *electrocardiogram is recorded from various points within the heart, and the reaction of the heart to timed electrical stimuli is observed. The information obtained guides treatment of arrhythmia, particularly *radiofrequency ablation.... electrophysiological study
the collection and analysis of data about a group of participants over a period of time, often some years. Compare cross-sectional study. See also cohort study.... longitudinal study
see case control study.... matched pair study
a person with a communicable disease in whom the symptoms and signs are so minimal that either there is no request for medical assistance or the doctor fails to make the diagnosis. The patient usually has partial immunity to the disease, but since the infecting organisms are of normal virulence, nonimmune contacts can be affected with the full manifestations of the illness. The period of infectivity is confined to the shortened duration of the illness (in contrast to a *carrier, in whom the pathogen is present without necessarily causing any ill effect). Alternatively, the subject has had the disease but retains some of the pathogens (e.g. in the throat or bowel) and so acts as a continuing reservoir of infection.... missed case
a test done to assess the peripheral nervous system. It involves activating the nerves electronically with electrical pulses and measuring the responses obtained.... nerve conduction study
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