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PubMed1995

Epidemiological measures of participation in community health promotion projects.

BACKGROUND: The paper is concerned with the use of epidemiological methods to measure the rates at which different strata of a defined population participate in community health promotion projects. The specific aim was to estimate the incidence rates of participation in projects sponsored by the Western Australian Health Promotion Foundation (Healthway), separately for sociodemographic and health-related behavioural subgroups. METHODS: Data were drawn from Healthway sponsorship projects in 1992. Each sport, arts and racing project was associated with promotion of a health message and creation of a health promoting environment. The study used a two-stage sampling design. Thirteen of 57 large sponsorship projects and 30 of 129 small projects were selected. In the second stage, respondents were randomly surveyed from among project participants. A total of 4060 respondents aged > or = 10 years was sampled from the 43 selected projects. Population-based incident participants were estimated and were related to person-years at risk. RESULTS: The total participation rate was 4.01 per person-year. The rate was very high at ages 10-14 years and thereafter declined with increasing age. Compared with the least socially disadvantaged 25% of population, the participation rate fell by around one-third in the medium and high disadvantage groups, but exceeded the baseline by a ratio of 1.85 (95% confidence interval: 1.57-2.18) in the most disadvantaged 10% of population. The effect was most pronounced at ages 10-19 years. Participation was higher in those who smoked, drank alcohol unsafely, reported sunburn and reported low consumption of fruit and vegetables. However, participation was reduced in people who were sedentary. CONCLUSIONS: Epidemiological methods can be used to evaluate the distribution of participation of a population in community health promotion projects. The Western Australian Health Promotion Foundation has been successful in reaching disadvantaged youth.

Adolescent↗
PubMed2002

Investigation of a slaughterhouse-related outbreak of Q fever in the French Alps.

The aim of the study presented here was to describe the different epidemiological methods used to investigate an outbreak of Q fever that occurred in the spring of 1996 among inhabitants of Briançon, a small town in the French Alps. Three approaches were used: (i) a comparison between a 2-month exhaustive serological survey among blood donors and a retrospective serological survey performed on frozen plasma collected by the transfusion centre in the spring of 1995; (ii) a serological survey performed in the general population by cluster sampling, using dried blood on blotting paper; and (iii) a case-control study. A total of 29 cases of acute Q fever were diagnosed by physicians during hospitalisations of the patients or ambulatory care. The case-con-trol study suggested that the outbreak resulted from airborne transmission of contaminated sheep waste, which had been left uncovered in the slaughterhouse area. Such transmission may have been facilitated by the nearby heliport. The comparison between the cumulative incidence of Q fever among blood donors during the spring seasons of 1995 and 1996 confirmed the outbreak (0.38% vs. 2.58%, respectively; P<0.0001). Health authorities promptly decided to close the slaughterhouse. The use of complementary epidemiological methods allows investigators to focus on major issues related to an outbreak: timely detection of cases, identification of the source, estimations of incidence, and public health intervention. Rapid recognition and management of outbreaks in the general population of a rural region need to be improved, particularly at a time when airborne agents could be used as biological weapons.

Abattoirs↗
PubMed1998

[Molecular biology methods in epidemiology of tuberculosis].

The spread of tuberculosis often remains undetected and development of disease may occur years after the primary infection. However, tracing chains of transmission is an important task for prevention of new cases, especially for multi-drug-resistant tuberculosis. Today, molecular typing methods have become an important tool for identification and confirmation of epidemiological links between tuberculosis patients in an outbreak situation. Differentiation between strains of Mycobacterium tuberculosis also allows to decide between reactivation because of treatment failure and superinfection. A growing number of typing methods have been developed that differ mainly in their reproducibility and the ability to differentiate between isolates closely related at the molecular level. Based on further standardisation and automation, molecular typing techniques can provide pertinent information for tuberculosis control.

Contact Tracing↗
PubMed1994

Epidemiology of stroke: methods and trends.

Epidemiology is the study of the natural history of disease or injury. For a given disorder, this includes its definition, frequency, severity, course and risk factors. Only population-based rates provide data that can be compared among studies. These rates are the incidence or attack rate, the mortality or death rate, and the prevalence rate. For stroke even these rates are not comparable unless they are age-adjusted to a common base. Risk factors are attributes associated with the occurrence of the disease. Relative risk calculation requires population-based rates or a population cohort followed prospectively. For retrospective case-control comparisons the odds ratio is used as an approximation of relative risk. Mortality rates for stroke are widely available and can give a first estimate of risk by geographic location, age, sex and race. In death data, only the sum of all stroke deaths is sufficiently valid for use, while the components are more often wrong than right, except for subarachnoid hemorrhage. International death rates show considerable variation, the highest rates occurring in the Orient. Rates in many countries declined between the 1950s and 1970s but in others, like Portugal, they increased. Stroke deaths in the United States hae been declining rather steadily since the 1920s and continue to do so to the present.

Age Factors↗
PubMed2000

Psychiatric epidemiology.

Psychiatric epidemiology is considered one of the main scientific foundations of psychiatry. This article reviews methodological issues and major studies in psychiatric epidemiology. Methods such as measures of frequency and association are discussed. Selection, observation, and confounding, the main sources of bias in epidemiological studies, are described. Types of study designs, such as cross-sectional, cohort, and case-control, are detailed. A historical perspective of major population-based and clinical studies is presented. Major findings of the Epidemiologic Catchment Area Study and the National Comorbidity Survey are also included. Finally, future directions in the field are discussed.

Adolescent↗
PubMed1988

Probit analysis applied to the allergen dose-response curve: a method for epidemiologic surveys.

The degree of skin sensitivity to five common allergens (grass, Dermatophagoides pteronyssinus, mugwort, birch, and Parietaria) was determined by the threshold dilution technique in all the skin test reactors of a random sample of 295 schoolchildren (142 male and 153 female subjects, age range 11 to 14 years), and the frequency distribution of responders at each concentration was analyzed by probit analysis. The potency of each allergen was presented in terms of median effective dose (ED50), and comparison between different allergens and between symptomatic and asymptomatic subjects was made by computing the relative potency. The ED50 of the allergens was found to be nearly identical (grass, 13.5; D. pteronyssinus, 12.3; mugwort, 9.6 activity units by RAST (AUR)/ml) with the exception of birch (22 AUR/ml). Grass and D. pteronyssinus demonstrated a lower ED50 in symptomatic subjects (3.3 and 2.8 AUR/ml, respectively) than in asymptomatic subjects (85 and 27 AUR/ml, respectively). The lower fiducial limits of ED50 in symptomatic subjects demonstrated to be a cutoff point, since they included only 5% and 12% of asymptomatic reactors to grass and D. pteronyssinus, respectively. We conclude that probit analysis applied to the distribution of threshold doses of allergen extracts is a useful method to evaluate skin sensitivity in epidemiologic surveys. We believe that the ED50 is a practical and reliable allergy index.

Allergens↗
PubMed2006

TBE incidence versus virus prevalence and increased prevalence of the TBE virus in Ixodes ricinus removed from humans.

Traditionally, the classification of risk areas of tick-borne encephalitis (TBE) is based on the recording of autochthonous cases of the disease. In Germany, an extension of these areas over the years and an increasing virus prevalence in ticks have been observed in recent years. Registration of foci with autochthonous TBE cases, recording of disease incidence and virus prevalence in ticks are all proven epidemiological methods to characterize TBE risk areas. These data are necessary for a scientifically proven recommendation of TBE vaccines, and they need to be updated regularly. These epidemiological methods have advantages and disadvantages with respect to the risk assessment of TBE areas. Despite the fact that these methods are suitable for risk assessment in practice, disease incidence (new cases per year/100,000 inhabitants) and virus prevalence in questing ticks did not correlate. Using nested RT-PCR we were able to demonstrate that the prevalence of TBE virus (TBEV) in ticks removed from humans was significantly higher than in unfed, free-living Ixodes ricinus of the same area. The 561 ticks collected from humans in doctors' surgeries in Bavaria in 2002 were examined by nRT-PCR. The estimated overall virus prevalence in tested ticks was 8.8% (95% CI: 6.45-11.57%). The removed ticks examined were classified according to the sites of exposure of the patients in the individual districts. Peak values were measured in the district of Regen with 20.6% and in the district of Freyung-Grafenau with 18.3%. In recent studies on unfed I. ricinus (nymphs, adults), the average TBEV prevalence in ticks in Bavarian risk areas was between 0.5% and 2%.

Animals↗
PubMed2000

Statistical methods in epidemiology. v. Towards an understanding of the kappa coefficient.

PURPOSE: This paper introduces readers to the problem of measuring interrater agreement in observer variation studies. The most usual statistic to quote is the kappa coefficient which measures agreement having corrected for chance. METHOD: The kappa coefficient for measuring agreement between two observers is introduced. Some pointers are given to determining sample size estimation. RESULTS: Some properties of the kappa coefficient are illustrated by taking examples from the author's teaching experiences. CONCLUSION: The kappa coefficient is recommended for measuring agreement in observer variation studies.

Epidemiology↗
PubMed1996

Epidemiologic concerns for ergonomists: illustrations from the musculoskeletal disorder literature.

Ergonomics and epidemiology are unique fields that share some common interests. Epidemiologic methods are increasingly being utilized in ergonomic studies of the work-related risk factors of musculoskeletal disorders. This multidisciplinary approach requires a shared knowledge base and understanding of the methodology of both disciplines. In this paper, basic epidemiologic concepts are introduced. Examples from the upper extremity musculoskeletal disorder literature are used to illustrate study design issues and to suggest improved study methods. Epidemiologic design problems including selection bias (healthy worker survivor effect), misclassification, and confounding are discussed. Prospective research designs are described as a feasible approach for the study of these disorders. Increased collaboration between ergonomists and epidemiologists is encouraged to improve progress towards the reduction of workplace injuries and illnesses.

Epidemiology↗
PubMed1985

Use of epidemiology in medical specialties: an examination by citation analysis.

Epidemiologic methods have been applied unevenly among medical specialties. Identifying current uses and areas of potential research helps clarify and define the field. Using citation analysis of published data, the patterns of references to and by the American Journal of Epidemiology were examined for 1974-1982; 17,574 citations to and 15,872 citations by that Journal were classified according to the subject category of the referencing or referenced journal. Internal medicine and public health/epidemiology journals accounted for the largest proportion of all citations, followed by journals of immunology, cancer, microbiology, pediatrics, cardiovascular system, virology, tropical medicine, statistics, and obstetrics/gynecology. Few citations to or by the Journal were found in the allergy, anesthesiology, dermatology, geriatrics, hematology, nephrology, orthopedics, otorhinolaryngology, radiology, rheumatology, and urology journals. Examination of citations between clinical and epidemiologic literature suggests that adequate interchange between clinicians and epidemiologists is occurring. Citation analysis results for the American Journal of Epidemiology were significantly correlated (p less than 0.05) with those from a MEDLINE search on epidemiologic methods used in research in 22 clinical specialties. Despite inherent limitations, citation analysis appears to be a useful tool for examining interactions and trends in epidemiology and for identifying fields which may be ripe for new epidemiologic studies.

Bibliographies as Topic↗
PubMed2002

Comparative assessment of genotyping methods for epidemiologic study of Burkholderia cepacia genomovar III.

We analyzed a collection of 97 well-characterized Burkholderia cepacia genomovar III isolates to evaluate multiple genomic typing systems, including pulsed-field gel electrophoresis (PFGE), BOX-PCR fingerprinting and random amplified polymorphic DNA (RAPD) typing. The typeability, reproducibility, and discriminatory power of these techniques were evaluated, and the results were compared to each other and to data obtained in previous studies by using multilocus restriction typing (MLRT). All methods showed excellent typeability. PFGE with SpeI was more reproducible than RAPD and BOX-PCR fingerprinting. The discriminatory power of the methods was variable, with PFGE and RAPD typing having a higher index of discrimination than BOX-PCR fingerprinting. In general, the results obtained by PFGE, BOX-PCR fingerprinting, and MLRT were in good agreement. Our data indicate that different genomic-based methods can be used to type B. cepacia genomovar III isolates depending on the situation and the epidemiologic question being addressed. PFGE and RAPD fingerprinting are best suited to addressing small-scale studies (i.e., local epidemiology), whereas BOX-PCR fingerprinting is more appropriate for large-scale studies (i.e., global epidemiology). In this regard, BOX-PCR fingerprinting can be considered a rapid and easy alternative to MLRT.

Bacterial Typing Techniques↗
PubMed2000

Statistical methods in epidemiology. IV. Confounding and the matched pairs odds ratio.

PURPOSE: This paper introduces readers to the problem of confounding in epidemiology, how it differs from effect modification and how to deal with it statistically. There are several options for dealing with confounding. These include techniques based on matching, on stratification and on regression. This paper reviews the first method, matching and the matched pairs odds ratio. METHOD: For 1:1 pair matching (1 case and 1 matched control), the matched pairs odds ratio is introduced as the ratio of discordant pairs. A method for calculating confidence intervals based on the normal approximation is described. RESULTS: Some properties of the matched pair design are illustrated by taking examples from the authors' own teaching experiences. CONCLUSION: Matching remains a difficult design option in epidemiology. Its 'best' use is for special types of studies such as for those on twin pairs.

Confidence Intervals↗
PubMed2005

Epidemiological reflections of the contribution of anthropology to public health policy and practice.

Academic disciplines like anthropology and epidemiology provide a niche for researchers to speak the same language, and to interrogate the assumptions that they use to investigate problems. How anthropological and epidemiological methods communicate and relate to each other affects the way public health policy is created but the philosophical underpinnings of each discipline makes this difficult. Anthropology is reflective, subjective and investigates complexity and the individual; epidemiology, in contrast, is objective and studies populations. Within epidemiological methods there is the utilitarian concept of potentially sacrificing the interests of the individual for the benefits of maximizing population welfare, whereas in anthropology the individual is always included. Other strengths of anthropology in the creation of public health policy include: its attention to complexity, questioning the familiar; helping with language and translation; reconfiguring boundaries to create novel frameworks; and being reflective. Public health requires research that is multi-, inter- and trans-disciplinary. To do this, there is a need for each discipline to respect the 'dignity of difference' between disciplines in order to help create appropriate and effective public health policy.

Anthropology↗
PubMed1977

Childhood accidents. Three epidemiological studies on the etiology.

Three studies on childhood accidents are presented. The aim was to study the importance of different factors regarding the accidents in question. The following factors have then been taken into consideration: the enviromental hazard, the accident proneness, the supervision and the education. Methodologically the investigations were carried out with an epidemiological technique. One is of a descriptive nature and the other two more analytically oriented. The studies are based on two different 1-year-materials consisting of accidents among children recorded in the emergency departments of Ostersund Hospital and the University Hospital in Uppsala. The results indicate that risk factors in the children's physical milieu played an important role in the occurrence of the accidents: clearly identifiable risk factors in the environment could be connected with 52% of the accidents, whereas some deficiency in supervision was noted in 20%. The investigators could identify a number of specific risk factors. Attempts were made to examine how frequency and type of childhood accidents vary with the population structure and social structure in well-defined housing areas, but the results were hard to evaluate because of methodological problems. The results are presented against the background of a detailed discussion on central methodological problems in epidemiological accident research. It is pointed out in particular that epidemiological methods have clear limitations in attempts at studying the low-frequency events that each individual type of accident in fact comprises. It is of great importance that in future research, side by side with the traditional epidemiological methods, other techniques are tested with the aim of obtaining maximal usable information from a detailed study of individual accidents and their backgrounds.

Accident Proneness↗
PubMed1998

A comparative study on IgG-ELISA, IgM-IFT and Kato-Katz methods for epidemiological purposes in a low endemic area for schistosomiasis.

The high sensitivity and the possibility of automation of the enzyme-linked-immunosorbent-assay (ELISA) has indicated this technique as one of the most useful serological test for epidemiological studies. In the present study, an ELISA for detection of IgG antibodies against adult worm antigens (IgG-ELISA) was investigated for epidemiological purposes, in a rural area of the municipality of Itariri (São Paulo, Brazil). Blood on filter paper (1,180 samples) from about 650 schoolchildren were submitted to ELISA and the data compared to the results of the parasitological method of Kato-Katz and also to the IgM-IFT (immunofluorescence test for IgM antibodies to gut associated antigens). The prevalence rates respectively of 8.5%, 43.0% and 56.2% by the Kato-Katz, IgG-ELISA, and IgM-IFT methods suggest the poor sensitivity of the parasitological method for detection of Schistosoma mansoni eggs in individuals with low worm burden, situation commonly observed in low endemic areas. These results can partially explain the poor degree of agreement between the IgG-ELISA and the Kato-Katz, as suggested by the Kappa index of 0.170. Otherwise, the Kappa index of 0.675 showed substantial agreement between the two serological tests. Some discrepancy of results between the two serological techniques must be better investigated.

Animals↗