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PubMed1993

[An epidemiological method for studying the effect of elevated background radiation on the neuropsychic health of children].

The children living in 4 regions of Russia contaminated as a result of the Chernobyl catastrophe were investigated. The control group consisted of the children of 2 regions which did not undergo this influence. The investigations were made 1-3 years after the catastrophe took place. An increase of etiologically non-clear asthenic-vegetative disorders was determined in the regions of radiation contamination. They were observed mainly among the children who had light residual organic cerebral deficiency. The authors cannot exclude the impact of the psychogenic factors.

Accidents, Occupational↗
PubMed1995

Asthma and factory emissions in northern England: addressing public concern by combining geographical and epidemiological methods.

STUDY OBJECTIVE: The prevalence of asthma was assessed to investigate respiratory health effects of airborne emissions from a factory. A geographical information system allowed flexible definition of study areas in terms of their size, distance, and location in relation to the factory. The value of the approach for this type of investigation is focussed on. SETTING: The factory is located in the south western part of a small market town in County Durham. MEASUREMENTS AND MAIN RESULTS: A total of 1573 asthma cases were identified from general practitioner computerised repeat prescribing systems. Population denominators were defined from family health services authority patient registers. The area within 1 km and immediately to the north east of the factory had an age and sex standardised asthma prevalence 24% (confidence interval 4, 44%) in excess of the expected rate (p = 0.01). The increased prevalence was confined to middle aged and elderly adults living in the area between 0.5 and 1 km to the north east of the factory. CONCLUSIONS: The value of combining the skills of geographers and epidemiologists in addressing public health issues is shown, particularly through the use of geographical information systems which proved powerful and effective.

Adolescent↗
PubMed1995

[Comparison of epidemiologic methods in a case-control study of lung cancer and air pollution in Trieste, Italy].

To investigate the relationship between air pollution and histologic type of lung cancer we conducted a case-control study among deceased men in Trieste, Italy. 755 cases of lung cancer and 755 controls were identified through the local autopsy registry. Information on smoking habits, occupation and place of residence was obtained from the subject's next-of-kin. Air pollution at the residence of each subject was estimated from the average value of total particulate at the nearest monitoring station. Spatial models and logistic regression were used to evaluate the effect of residence and air pollution on LC after adjustment for age, smoking habits, likelihood of exposure to occupational carcinogens and social group. The risk of lung cancer increased with increasing level of air pollution for all types of lung cancer combined (P = 0.022), for small cell carcinoma (P = 0.016) and for large cell carcinoma (P = 0.049). Compared with inhabitants of the residential area, residents of the rural area had a relative risk (RR) of 0.6 (95% confidence interval (CI): 0.4-1.0). The RR was 1.5 (1.0-2.2) for residents of the center of the city and 1.4 (1.0-2.1) for residents of the industrial area. In the center of the city the excess risk was almost completely restricted to small cell carcinoma (RR = 2.0) and to large cell carcinoma (RR = 2.6). In the industrial area the risk was increased especially for adenocarcinoma (RR = 2.1). These results provide evidence that air pollution is a moderate risk factor for certain histologic types of lung cancer.

Adenocarcinoma↗
PubMed1975

Evaluation of a measles-smallpox vaccination campaign by a sero-epidemiologic method.

An assessment technique has been devised whereby children from 30 randomly chosen sampling sites are visited within three days of measles-smallpox vaccination and one month later. Vaccination coverage is measured at house visits and immunologic status is determined by collection of early and late blood samples on filter papers from substratified children in priority age-groups, and by looking at vaccination scars. The methodology was employed in a rural area of the Ivory Coast during the maintenance phase of a measles-smallpox vaccination program; 1762 children from 0--72 months old were inspected. Children in the target age groups, 6--24 months, had a vaccination coverage of 53.6% whereas children outside of the target group had a 10.5% coverage. Of 571 target age children, 94.6% had a measles hemagglutination-inhibition antibody titer of less than 1:10 dilution at the first visit, and were presumed susceptible to measles or vaccine. Of 247 substratified children 6--8 months, 98.3% were susceptible to measles before vaccination; 84.3% of 127 vaccinated children in this age-group sero-converted when re-tested. Of 324 children 9--24 months, 91.7% were susceptible before the campaign; 94.7% of 170 vaccinated children in this age-group converted. A positive history of prior measles or prior measles-vaccination was not a good indicator of measles serologic status. The smallpox vaccination major reaction rate was 93.2%; 91.4% of children with a recent vaccination scar sero-converted to measles vaccine. Thus, the smallpox scar read at the second visit proved the best clinical marker for determining both coverage and immunologic effectiveness of the campaign.

Age Factors↗
PubMed1994

Transmission of tuberculosis in New York City. An analysis by DNA fingerprinting and conventional epidemiologic methods.

BACKGROUND: The incidence of tuberculosis and drug resistance is increasing in the United States, but it is not clear how much of the increase is due to reactivation of latent infection and how much to recent transmission. METHODS: We performed DNA fingerprinting using restriction-fragment-length polymorphism (RFLP) analysis of at least one isolate from every patient with confirmed tuberculosis at a major hospital in the Bronx, New York, from December 1, 1989, through December 31, 1992. Medical records and census-tract data were reviewed for relevant clinical, social, and demographic data. RESULTS: Of 130 patients with tuberculosis, 104 adults (80 percent) had complete medical records and isolates whose DNA fingerprints could be evaluated. Isolates from 65 patients (62.5 percent) had unique RFLP patterns, whereas isolates from 39 patients (37.5 percent) had RFLP patterns that were identical to those of an isolate from at least 1 other study patient; the isolates in the latter group were classified into 12 clusters. Patients whose isolates were included in one of the clusters were inferred to have recently transmitted disease. Independent risk factors for having a clustered isolate included seropositivity for the human immunodeficiency virus (HIV) (odds ratio for Hispanic patients, 4.31; P = 0.02; for non-Hispanic patients, 3.12; P = 0.07), Hispanic ethnicity combined with HIV seronegativity (odds ratio, 5.13; P = 0.05), infection with drug-resistant tuberculosis (odds ratio, 4.52; P = 0.005), and younger age (odds ratio, 1.59; P = 0.02). Residence in sections of the Bronx with a median household income below $20,000 was also associated with having a clustered isolate (odds ratio, 3.22; P = 0.04). CONCLUSIONS: In the inner-city community we studied, recently transmitted tuberculosis accounts for approximately 40 percent of the incident cases and almost two thirds of drug-resistant cases. Recent transmission of tuberculosis, and not only reactivation of latent disease, contributes substantially to the increase in tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1984

An epidemiological method applied to practices to measure the representativeness of their prescribing characteristics.

The standardised report of the Prescription Pricing Authority, which is concerned with the prescribing characteristics of practices, was used as an epidemiological tool to evaluate the prescribing representativeness of practices. Study practices were compared with average prescribing results from family practitioner committees, which are specific for the geographical district and month sampled. The method was applied in 40 practices, representing 120 doctors who had been recruited to the third morbidity study in general practice. In these practices 488 items per 1000 people had been prescribed compared with 548 items per 1000 people from the matched values of family practitioner committees. There was a parallel reduction in the net ingredient cost of items per 1000 people--1414 pounds for the practices compared with 1600 pounds for the family practitioner committees. These differences were highly significant. The average net ingredient cost was the same for both groups. Study practices were biased towards reduced prescribing costs for drugs used to treat infections, respiratory diseases, disorders of the nervous system, skin disease, rheumatic disorders, and gastrointestinal problems. The comparison and its interpretation provide a model that may be used by individual practices to evaluate their own prescribing reports.

Aged↗
PubMed1991

Parkinson's disease: an epidemiologic method for distinguishing between symptomatic and neuroprotective treatments.

Recent studies have suggested that deprenyl may exert a neuroprotective influence and thus retard progression of Parkinson's disease (PD). On the other hand, the data do not disprove that deprenyl is primarily another form of symptomatic therapy like levodopa. Longitudinal Gompertzian analysis demonstrates the absence of beneficial alteration of intrinsic or environmental influences on the epidemiology of PD mortality after the introduction of levodopa. Moreover, this method demonstrates the basis for the enhanced survival in PD that resulted from the efficacy of levodopa as symptomatic therapy. If deprenyl becomes standard therapy in PD and exerts a beneficial (neuroprotective) influence on intrinsic and environmental pathogenic mechanisms, this will become evident by a decrease in the PD mortality rate in the United States in men at age 73.4 years and in women at age 79.1 years. The ability to accurately assess the overall impact of new therapies on the general population is increasingly important in an era of upward spiraling health care costs. Longitudinal Gompertzian analysis is a simple method of detecting and distinguishing between symptomatic (competitive) and protective (intrinsic and environmental) influences on disease mortality at the population level after the introduction of new therapies.

Aged↗
PubMedDate not supplied

[Epidemiological methods used in studies in the prevalence of Tourette syndrome].

Tourette syndrome (TS) prevalence was studied since the early 80-ies. Its clinical course is characterised by co-occurrence of motor and vocal tics. Results of previous epidemiological studies were surprisingly divergent: the prevalence varied from 0.5 to 115 cases per 10,000 population. The disease previously recognised as extremely rare and severe is now considered as quite common, with often moderate course. Selected methods used in studies of TS prevalence and analysis of their possible impact on study results are presented. The studies were divided into 3 groups: studies of the hospitalised population, large-scale screenings and studies involving school population, basing on characteristic and size of population, methods of selection of subjects, diagnostic and screening methods used. Studies of the hospitalised population involved patients with most severe symptoms, in different age groups, different methods of final diagnosis confirmation were used. TS prevalence varied from 0.5 up to 15 cases per 10,000 population. Procedures used in large-scale screening studies made possible the elimination of potential selection bias. Large populations were studied using transparent and repetitive confirmation of diagnoses. Their validity was additionally checked in parallel validity studies. TS prevalence was in the range 4.3 to 10 cases per 10,000 population. The highest TS prevalence was obtained in studies involving schoolchildren. Data were gathered from multiple sources: from parents, teachers and children, as well as from classroom observation. Diagnoses were made by experienced clinicians. TS prevalence obtained in school population studies was between 36.2 up to 115 per 10,000 population.

Attention Deficit Disorder with Hyperactivity↗
PubMed1986

A simple epidemiological method for animal trypanosomiasis to provide relevant data for effective financial decision-making.

The epidemiology of bovine trypanosomiasis on Galana Ranch, Kenya was studied for one year (July 1980--June 1981), using measurements from an experimental population of 3 types of Boran cattle. The results were applied to the estimated ranch population at risk, and an attempt was made to measure the potential economic loss due to trypanosomiasis. The potential losses in beef production due to trypanosomiasis in the ranch population at risk at Galana were estimated at around K.Shs. 8900/km2, when the stocking rate was 14.2 Tropical Livestock Units per km2. The estimated potential loss in the total population at risk was approximately K.Shs. 5 million (around US$ 700,000 at 1981 values). These losses can be minimised by good management techniques based on accurate epidemiological information. Results indicated that Orma-type Boran steers are more resistant to trypanosomiasis than Galana-type Boran steers. Although both types showed similar mortality rates, untreated Orma animals which survived showed a similar growth performance to animals maintained under 3-month Samorin prophylaxis. Untreated Galana Borans lost 14% of their body weight when compared with animals maintained under 3-month Samorin. Also, 30% of the untreated Orma Borans never showed trypanosomes in their blood over the study period, while all corresponding Galana Borans showed parasites; this resulted in a lower measured attack rate in Orma cattle. In 1982, a combination of treating only those animals under trypanosome attack, relating the timing of chemotherapy to measured increased trypanosome attack, and the increased utilisation of the trypano-tolerant Orma Borans resulted in an annual saving of around US$ 110,000 in control costs and an increased land usage of approximately 5%.

Age Factors↗
PubMed1995

[A critical review of epidemiological methods for spatial analysis].

Since the 1950's a number of methods have been developed whose aims is to provide enhanced mapping tools, which allow the depiction of the distribution of disease, and thereafter, to assess risks due to environmental factors (or other spatial-defined factors). Our review of statistical-epidemiological methodology for spatial analysis of diseases shall outline the distinction between global tests for clustering (detection of non casual distribution of events in an area) and cluster detection's techniques for the identification and location of abnormal aggregation of disease's cases. In this paper we evaluate each-one of the proposed methods, on general grounds, with regard to whether they meet the aims of the analysis and how successful they are in overcoming problems.

Epidemiologic Methods↗
PubMed2004

Control without separate controls: evaluation of vaccine safety using case-only methods.

Epidemiological methods involving only cases are reviewed in the context of vaccine safety studies. These methods include some ecological methods, case-coverage methods, case-crossover and self-controlled case series methods. The properties of the methods are described using examples from the literature. It is argued that such methods, and in particular the self-controlled case series method, are powerful epidemiologic tools meriting the same attention as more traditional cohort and case-control methods.

Case-Control Studies↗
PubMed2001

Epidemiological methods for studying genes and environmental factors in complex diseases.

Exploration of the human genome presents new challenges and opportunities for epidemiological research. Although the case-control design is quicker and cheaper for study of associations between genotype and risk of disease than the cohort design, cohort studies have been recommended because they can be used to study gene-environment interactions. Although the scientific relevance of statistical interaction is pertinent, the main disadvantage of the case-control design-susceptibility to bias when estimating effects of exposures that are measured retrospectively-does not necessarily apply when studying statistical interaction between genotype and environmental exposure. Because correctly designed genetic association studies are equivalent to randomised comparisons between genotypes, conclusions about cause can be drawn from genetic associations even when the risk ratio is modest. For adequate statistical power to detect such modest risk ratios, the case-control design is more feasible than the cohort design.

Case-Control Studies↗
PubMed1997

Counting the uncatchable? An epidemiological method for counting drug misusers.

Service provision and treatment outcome for problem drug users are receiving increased attention, although both are hindered by the lack of good epidemiological data. A technique of population enumeration called capture recapture methodology (CRM) is currently being advocated for use in populations that are otherwise hard to count. CRM is explained and some of its limitations discussed. Studies that have used this methodology are examined.

Catchment Area, Health↗
PubMed2006

Linking healthcare associated norovirus outbreaks: a molecular epidemiologic method for investigating transmission.

BACKGROUND: Noroviruses are highly infectious pathogens that cause gastroenteritis in the community and in semi-closed institutions such as hospitals. During outbreaks, multiple units within a hospital are often affected, and a major question for control programs is: are the affected units part of the same outbreak or are they unrelated transmission events? In practice, investigators often assume a transmission link based on epidemiological observations, rather than a systematic approach to tracing transmission.Here, we present a combined molecular and statistical method for assessing:1) whether observed clusters provide evidence of local transmission and2) the probability that anecdotally|linked outbreaks truly shared a transmission event. METHODS: 76 healthcare associated outbreaks were observed in an active and prospective surveillance scheme of 15 hospitals in the county of Avon, England from April 2002 to March 2003. Viral RNA from 64 out of 76 specimens from distinct outbreaks was amplified by reverse transcription-PCR and was sequenced in the polymerase (ORF 1) and capsid (ORF 2) regions. The genetic diversity, at the nucleotide level, was analysed in relation to the epidemiological patterns. RESULTS: Two out of four genetic and epidemiological clusters of outbreaks were unlikely to have occurred by chance alone, thus suggesting local transmission. There was anecdotal epidemiological evidence of a transmission link among 5 outbreaks pairs. By combining this epidemiological observation with viral sequence data, the evidence of a link remained convincing in 3 of these pairs. These results are sensitive to prior beliefs of the strength of epidemiological evidence especially when the outbreak strains are common in the background population. CONCLUSION: The evidence suggests that transmission between hospitals units does occur. Using the proposed criteria, certain hypothesized transmission links between outbreaks were supported while others were refuted. The combined molecular/epidemiologic approach presented here could be applied to other viral populations and potentially to other pathogens for a more thorough view of transmission.

Caliciviridae Infections↗
PubMed1995

[The mode of infection of tuberculosis--analysis using molecular epidemiologic methods].

In the 1950's, evidence showed that INH-resistant Mycobacterium tuberculosis organisms were attenuated in both virulence and pathogenicity in animals, and it was postulated that these bacilli might also be attenuated in their virulence to humans. Subsequent studies, however, indicated that all INH-resistant strains should not be considered as being attenuated in their virulence to humans. The general conclusion was that patients excreting INH-resistant organisms are somewhat less infectious to their contacts than patients excreting INH-susceptible organisms. Insertion sequences are suitable tools for the diagnosis and epidemiology of tuberculosis because of the highly variable copy number and variability of insertion sites in the chromosome. This variability allows the subtyping of M. tuberculosis strains by restriction fragment length polymorphism (RFLP) analysis. Patients with the same RFLP pattern constitute an epidemiologically linked cluster. Clustering indicates recent infection and rapid progression to clinical illness. Nearly one thirds of new cases of tuberculosis in San Francisco are the result of recent infection. In Thailand, tuberculosis has now emerged as the most common opportunistic disease associated with HIV infection. Cluster analysis showed the risk of progression to active tuberculosis among individuals infected with HIV. Ther have been numerous outbreaks of multidrug-resistant tuberculosis in the United States. Most of such outbreaks have primarily involved persons infected with HIV, who are thought to have been exposed to the strains in medical or correctional facilities.

AIDS-Related Opportunistic Infections↗