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PubMed1987

Epidemiologic methods for selective surveillance.

To allow time for problem-solving and staff education aimed at the prevention of future nosocomial infections, it is necessary for infection control practitioners to decrease the quantity of data-gathering activities and increase the quality of data analysis and action based on the data. A system by which certain high-risk patient groups and life-threatening infection sites are monitored by continuous surveillance every month, but other units and sites are selected on a rotating basis for periodic study, has been called "selective surveillance" and used at our 500-bed medical center for eight years. The system is backed by an essential third component: a network of inspections with prevalence studies, prospective studies of medical and surgical procedures, retrospective studies of sites with low endemic rates, and immediate investigations of clusters of infection. Success of this system is based on good daily communication with laboratory and nursing personnel and use of sound epidemiologic methods.

Cross Infection↗
PubMed1988

Epidemiological methods in prevention of blindness.

A major objective of the Prevention of Blindness programme of the World Health Organisation (WHO PBL Programme) is that by the year 1989 National Prevention of Blindness Programmes should be established in 60 developing countries which have a huge excess of avoidable blindness. To date, this has been achieved in 57 developing countries. Centres in a number of academic institutions have been designated "WHO Collaborating Centres for Prevention of Blindness". These are actively supported by the WHO PBL Programme to undertake collaborative survey and research work in developing countries. A principal aim of such work is to generate epidemiologically sound information that could form the bases for rational planning, implementation and proper evaluation of programmes for prevention of blindness. This paper outlines the main epidemiological methods that have been employed recently, by a WHO collaborating centre based at the Institute of Ophthalmology in London, in population based eye surveys and in epidemiological research in a number of developing countries. The key aspects of the methodology are discussed in detail in the context of practical experience. The outcome of the studies are also mentioned briefly. The three distinct types of epidemiological studies discussed are: (1) Population-based sample surveys, (2) Longitudinal cohort (follow-up) studies and (3) Hospital-based case-control studies.

Adult↗
PubMed1996

Genetic epidemiologic methods to screen for matrilineal inheritance in mitochondrial disorders.

We propose a method to screen for the matrilineal inheritance in mitochondrial disorders by comparing the risk of disease in a person whose mother is affected or whose maternal grandmother or aunt or uncle is affected to the risk of disease in a person whose father is affected or whose paternal grandmother or aunt or uncle is affected using a modification of the reconstructed cohort design. Sampling of pedigrees is accomplished via probands and must not be influenced by family history. The cohort of the proband's offspring, and offspring of the proband's siblings, can be analyzed using survival analysis. Cox proportional hazards model, Bonney's [(1986) Biometrics 42:611-625] model, and Liang's [(1991) Genet Epidemiol 8:329-338] model. Mitochondrial transmission can be distinguished from X-linked transmission by examining sex-specific patterns of disease expression in matrilineally transmitted diseases. To illustrate our epidemiologic method, we apply our screening method to pedigrees of two disorders which have been proposed to have a mitochondrial DNA component to their inheritance.

Bipolar Disorder↗
PubMed1999

Male reproduction and environmental and occupational exposures: a review of epidemiologic methods.

Concerns that chemical exposures in the environment have been detrimental to male sexual development and fertility have been heightened by reports of declining sperm counts over the past 50 years. Marked geographic variation has been found in semen quality and in the incidence of testicular cancer and certain urogenital defects. Debate continues over the existence, magnitude and significance of these trends, and how best to evaluate the hypothesis that in utero and childhood exposures to estrogenic compounds may be to blame. Epidemiologic methods for assessing the impact of hazardous substances on male reproductive health have been developed mainly in the area of occupational medicine, and this paper will review the currently recommended methods. These include questionnaires to determine reproductive history and sexual function; reproductive hormone profiles; and semen analyses such as sperm concentration, motility, and morphology. New research tools that show significant promise from the fields of clinical reproductive medicine and reproductive toxicology are discussed as possible additions to epidemiologic studies, including assays of sperm function and genetic integrity, and biomarkers of DNA damage. For population-based studies involving occupational groups or communities with environmental exposures, issues related to the cost, validity, precision and utility of these methods must be carefully considered.

Environmental Exposure↗
PubMed1999

Epidemiological methods for research with drug misusers: review of methods for studying prevalence and morbidity.

Epidemiological studies of drug misusers have until recently relied on two main forms of sampling: probability and convenience. The former has been used when the aim was simply to estimate the prevalence of the condition and the latter when in depth studies of the characteristics, profiles and behaviour of drug users were required, but each method has its limitations. Probability samples become impracticable when the prevalence of the condition is very low, less than 0.5% for example, or when the condition being studied is a clandestine activity such as illicit drug use. When stratified random samples are used, it may be difficult to obtain a truly representative sample, depending on the quality of the information used to develop the stratification strategy. The main limitation of studies using convenience samples is that the results cannot be generalised to the whole population of drug users due to selection bias and a lack of information concerning the sampling frame. New methods have been developed which aim to overcome some of these difficulties, for example, social network analysis, snowball sampling, capture-recapture techniques, privileged access interviewer method and contact tracing. All these methods have been applied to the study of drug misuse. The various methods are described and examples of their use given, drawn from both the Brazilian and international drug misuse literature.

Epidemiologic Methods↗