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PubMed2000

Choice of effect measure for epidemiological data.

The debate concerning the choice of effect measure for epidemiologic data has been renewed in the literature, and it suggests some continuing disagreement between the pertinent clinical and statistical criteria. In this article, some defining characteristics of the main choices of effect measure [risk difference (RD), relative risk (RR), and odds ratio (OR)] for binary data are presented and compared, with consideration of both the clinical and statistical perspectives. Relationships of these measures to the relative risk reduction (RRR) and number needed to treat (NNT) are also discussed. A numerical comparison of models of constant RD, RR, and OR is made to assess when and by how much they might differ in practice. Typically the models show only small numerical differences, unless extreme extrapolation is involved. The RD and RR models can predict impossible event rates, either less than zero or greater than 100%. Each measure has potential theoretical justification. RD and RR may enjoy some advantages for communication of risk, but OR may be preferred for data analysis. A clear distinction should be maintained between the objectives of data analysis and subsequent risk communication, and different effect measures may be needed for each.

Humans↗

PubMed1991

Epidemiologic data on exogenous hormones and hepatocellular carcinoma and selected other cancers.

Epidemiologic data on the use of oral contraceptives and estrogen replacement therapy in relation to cancers of the endometrium, breast, and ovary are briefly reviewed. This is followed by a more detailed review of the epidemiologic literature on hepatic adenomas and primary hepatocellular carcinoma. There is evidence that combined oral contraceptive use increases the risk of hepatocellular carcinoma in developed countries in which rates for this disease are extremely low. Any such elevation is, however, as yet undetectable in countries where hepatitis B virus is endemic and liver cancer rates are high.

Carcinoma, Hepatocellular↗

PubMed1990

Risk assessment for aflatoxin: II. Implications of human epidemiology data.

A review of epidemiology literature revealed that only studies conducted in Africa and Asia included data adequate to permit quantitative assessment of the dose-response relationship between aflatoxin exposure levels and liver cancer rates. Although these studies were judged adequate, their direct use to predict risks in U.S. populations may be questioned since hepatitis B virus (HBV) infections are far more common in the studied areas than in the U.S. Recent research indicates that, if aflatoxin contributes to the development of liver cancer, it almost always does so in the presence of HBV infection. The African/Asian data do not permit us to estimate the potency of aflatoxin in the absence of HBV. Recognizing this, these data can only be used to establish upper limits for the predicted excess lifetime risk for liver cancer in the U.S. When used in conjunction with aflatoxin exposure estimates for the Southeast U.S., these data predict a liver cancer rate, due to aflatoxin alone, far above that actually observed due to all causes; this provides an indication of the conservatism of this approach. Data from the Southeast U.S. may be used to estimate an excess lifetime risk for liver cancer of 2.17 x 10(-6) x (aflatoxin intake, ng/kg/day).

Environmental Exposure↗

PubMed1998

[Pollution and allergy: the epidemiological data].

This area is controversial, mostly because of disagreement between experimental and epidemiological data. Even though modulation of asthma by the level of atmospheric pollution has been well shown by panel and ecological studies, the relationship between pollution and genesis of allergic diseases has not been confirmed by epidemiological studies. Comparison of the frequency of asthma in urban and rural surroundings in general shows, in the urban environment, an advantage of irritation symptoms but not for asthma. In contrast, the prevalence of atopy seems higher in the urban environment, which is perhaps a reflection of a different way of life, like that shown in east-west studies. Several recent investigations showed that at the centre of a development additional respiratory symptoms related to the intensity of automobile traffic, but no relationship was shown with atopy. In the same way, no epidemiological investigation has shown a relationship between automobile pollution and prevalence of atopy. Thus, at present no solid elements exist to support an increase of the frequency of asthma and especially atopy, in a relationship with modern atmospheric pollution, essentially of automobile origin.

Air Pollutants↗

PubMed1998

Causal modeling of epidemiological data on psychiatric disorders.

This paper reviews the logic of causal inference from epidemiological data. I maintain that the clearest causal statements can be made when the philosophical causal principles of association, direction and isolation are upheld in epidemiological research. After reviewing the argument by Holland that only experimental manipulation affords clear causal claims, I examine the utility of structural equation models and longitudinal methods for making causal claims from non-experimental data. This examination leads to the conclusion that mental health epidemiologists should begin to incorporate intervention trials into the last phases of their research programmes when they want to make strong causal claims.

Humans↗

PubMed1991

Epidemiologic data and planning mental health services. A tale of two surveys.

The Epidemiologic Catchment Area Program (ECA) is the most comprehensive community and institutionalized epidemiologic data base currently available for mental health service planning. In this report, the authors compare the ECA with a previous community survey used to plan mental health services--the Stirling County Study--in terms of conceptual framework, research design, results and implementation of service planning. Familiarity with the Stirling County Study can inform users of ECA data regarding the strengths and weaknesses of the ECA data for health services research.

Adolescent↗

PubMedDate not supplied

The changing role of civilian surgeons in conflicts: a meta-analysis of epidemiological data.

Surgical activities in recent conflicts were reviewed based on the published epidemiological data. Ten articles on seven conflicts were identified and reviewed. The surgical activities in these articles were classified into three categories based on their activities: type 1, civilian border camp surgical activities; type 2, military hospitals in military deployment; type 3, civilian hospitals in former Yugoslavia or Palestine camp (most recent conflicts). Comparison of injuries in ratios of head-to-extremities, and critical part-to-extremities, among these three different types of surgical activity showed that type 3 hospitals had a statistically higher number of critical part injuries compared to the other two types of hospital. Type 3 hospitals represent the most recent endemic, regional and indiscriminate killing experiences. The high rates of critical part trauma in studies of recent conflicts show the increasing importance of trauma management skills by civilian surgeons in recent conflicts. Exchange of information among civilian surgeons serving in these difficult and dangerous conditions should be encouraged.

Asia, Southeastern↗

PubMed1987

Analysis of epidemiological data on agonist-antagonist analgesics.

Epidemiological information on the abuse of opioid agonist-antagonists is scanty. Most of the available information relates to pentazocine, the 'oldest' of this class of drugs, and it appears that a sporadic episode of its intravenous abuse in several cities in the United States, is subsiding: reformulation of pentazocine tablets to contain naloxone may have contributed to the decline in this abuse. Apart from a few reports of buprenorphine abuse, there are only occasional accounts of abuse of other drugs in this class. However, the lack of data does not necessarily mean that abuse does not occur and it is essential that epidemiologically sound investigations should be made to explore the existence and extent of any such problem. The interpretation of epidemiological data relating to agonist-antagonist abuse is discussed.

Buprenorphine↗

PubMed1982

Availability of epidemiologic data on humans exposed to animal carcinogens. II. Chemical uses and production volume.

We report further findings of a survey of manufacturers, processors, and importers of chemicals determined by the International Agency for Research on Cancer (IARC) to be animal carcinogens, but whose carcinogenicity in humans was considered uncertain because of inadequate epidemiologic data. We requested epidemiologic studies from the companies marketing or using any of the 75 IARC animal carcinogens in commerce in the United States. Eighteen of the 75 IARC animal carcinogens had volumes listed of 10(6) lb/year or greater, with 8 of the 13 chemicals for which studies had been completed or are in progress in this "high volume" category. The use category with the largest number of chemicals was drugs--19 of the 75 IARC animal carcinogens were in this category. However, none of the 13 chemicals included in epidemiologic studies was a drug. Seven of the 13 chemicals included in studies were used primarily as pesticides. We received little information on dyes and dye intermediates, experimental carcinogens, and drugs, all of which are produced in relatively low volumes; these categories represent 42 of the 75 IARC animal carcinogens. Low volumes and declining usage/production appear to be barriers to performance of epidemiologic studies. Information we received suggests that sometimes the problem of low production volume may be avoided by studying users rather than production workers. Overall, however, we expect few additional epidemiologic studies of the 75 IARC animal carcinogens.

Animals↗

PubMed2006

Applications of artificial intelligence systems in the analysis of epidemiological data.

A brief review of the germane literature suggests that the use of artificial intelligence (AI) statistical algorithms in epidemiology has been limited. We discuss the advantages and disadvantages of using AI systems in large-scale sets of epidemiological data to extract inherent, formerly unidentified, and potentially valuable patterns that human-driven deductive models may miss.

Algorithms↗

PubMed2006

Uveitis in the elderly: epidemiological data from the National Long-term Care Survey Medicare Cohort.

PURPOSE: There is a paucity of population-based data on the epidemiology of uveitis in the elderly. In the past 40 years, only 2 U.S. population-based studies have examined the epidemiology of uveitis. The conclusions of these studies on the burden of uveitis in the elderly differ greatly. In this analysis, we use Medicare claims data to define the population-based incidence and prevalence of uveitis in the United States elderly population. DESIGN: Cohort study. PARTICIPANTS: A cohort of 21644 Medicare beneficiaries drawn for the National Long-term Care Survey, a random sample of U.S. adults 65 years and older, was followed up from 1991 through 1999. METHODS: The International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes specific to uveitis were queried. To decrease the inclusion of uveitis caused by surgery, diagnoses occurring within 3 months of intraocular surgery were excluded. The incidence and prevalence of uveitis by anatomic location was calculated for each year in the study. MAIN OUTCOME MEASURES: The onset of uveitis during a given year and its presence in subsequent years. RESULTS: The cumulative yearly incidence of uveitis ranged from 302/100000 to 424/100000 persons per year and averaged 340.9/100000 persons per year. Anterior uveitis was the most common form of uveitis in this population, with a mean incidence of 243.6 cases per 100000 persons per year. The incidence of posterior uveitis averaged 76.6/100000 and the incidence of panuveitis/endophthalmitis averaged 41.7/100000. Only 2 cases of intermediate uveitis occurred during the study period. The cumulative prevalence of uveitis doubled from 511/100000 in 1991 to 1231/100000 in 1999, with anterior uveitis accounting for most prevalent cases in every year. CONCLUSIONS: The burden of uveitis in the elderly is substantial and is higher than previously thought. Longitudinal analysis of Medicare claims data may provide a useful tool for monitoring uncommon diseases, such as uveitis, in the elderly population.

Aged↗

PubMed1984

Epidemiological data and multistage carcinogenesis.

The purpose of this review has been to demonstrate that a wide range of epidemiological phenomena can be described in terms of simple multistage models of carcinogenesis. The relationship of cancer risk with the different time variables considered corresponds closely with the behaviour predicted by theories of multistage process. Furthermore, the different behaviour associated with different agents enables one to attempt some classification as to how an agent is acting. There is considerable conformity between the tentative classification one might propose for the few agents for which epidemiological data are adequate, and the activity seen experimentally for these agents. The purpose of using multistage models in epidemiology is not simply descriptive. A distant goal would be the use of experimental information on mechanisms of action for the prediction of human risk. Information currently available is clearly insufficient, but the consistency seen between the epidemiological and experimental results suggests that some progress may be possible.

Adolescent↗

PubMed1988

Cancer in migrants to Australia: extending the descriptive epidemiological data.

Australia experienced a large influx of European migrants during the period 1950-1975. The descriptive epidemiological data on cancer rates within the major migrant groups, reviewed here, provide strong evidence of environmental and behavioral influences on the etiology of various cancers. The opportunity to extend the conventional type of data analysis, to include an examination of the effect of duration of residence upon cancer risk, provides further insight into cancer etiology. The possibilities of further exploring the descriptive data are also discussed, and both the desirability and the timeliness of mounting analytical studies of the Southern European migrants to Australia are emphasized.

Australia↗

PubMed1979

[Epidemiologic data on bronchogenic carcinoma (author's transl)].

The Bronchogenic Carcinoma Co-operative Group analyzed the epidemiologic data of 240 cases of bronchogenic carcinoma in a prospective study. When risk factors (exposure to potencial pathogenic substances) were studied, a relationship was noted between the incidence at an early age and the presence of nondifferentiated small cell carcinoma. The number of years of exposure to tobacco had a direct effect on the curative value of the thoracotomy and the survival rate. Forty years of smoking appeared to be borderline for a poor prognosis. Localization of the tumor by bronchoscopy showed a frequency in the left main bronchus (18 percent) more than twice than in the right (8 percent). In 25 percent of the cases the tumor was more peripheral than the subsegmental situation according to the bronchofiberoptic examination. Evaluation of clinical data only showed a lack of correlation between the different symptoms and the various means of evaluation and the prognosis of the disease. For example, a patient with hemoptysis has a statistically higher probability of having an epidermoid tumor and a greater possibility of a successful curative thoracotomy (23 percent as opposed to 17 percent for the rest). The group of incidental cases (9 percent of the total) was analyzed. The degree of resectability was higher as compared with the rest (62 percent against 34 percent) as well as the absence of nondifferentiated small cell type carcinomas.

Adenocarcinoma↗

PubMed1994

On the pathogenesis of multiple sclerosis. A revised model of the cause(s) of multiple sclerosis, especially based on epidemiological data.

Data from an epidemiological study are used to analyse the course of multiple sclerosis. It could be proved that the course of MS is not as haphazard as was often supposed. In general the course is described as being a chronic progressive one, in the majority of patients preceded by a relapsing-remitting period. In contrast to the relapsing-remitting phase the chronic progressive phase of the course does not show marks of being an autoimmune process. From recent data obtained by MRI and NMR spectroscopy it can be concluded that the chronic progression of handicaps in multiple sclerosis is related to neuronal and axonal damage. The relation between these different pathogenetic processes should be the aim of further research.

Adult↗

PubMed1994

[Epidemiological data on severely injured patients; a retrospective study of the period 1985-1989].

OBJECTIVE: To describe the epidemiological data of a group of multiple injured patients. SETTING: University Hospital, Groningen. DESIGN: Retrospective, descriptive. PATIENTS AND METHODS: All multiple injured patients (HTI/ISS > 18), treated from 1985 to 1989 were analysed (932 cases). Age, sex, residence, type of accident, mortality, cause of death, ISS, length of hospital stay and destination after discharge are described. RESULTS: Generally speaking the multiple injured patients investigated were young and male. 75% of the injuries were caused by traffic accidents; occupants of cars run the highest risk of dying. Mortality (22%) is mainly determined by severe head injuries and increases with a higher ISS. The length of hospital stay averaged 22.5 days and compared with situations abroad is short. Half the patients could be discharged to their homes. Those who were transferred to a rehabilitation centre or a nursing home have a high ISS and mainly have severe injuries of the extremities. CONCLUSION: In view of the number of patients who could be discharged to their homes, the ultimate functional results look fair.

Adolescent↗

PubMed1995

Prodromes and precursors: epidemiologic data for primary prevention of disorders with slow onset.

OBJECTIVE: The concepts of prodrome and precursor are used to show how epidemiologic data on age at onset can be used in timing preventive interventions and selecting target populations. METHODS: Data concerning onset of DSM-III major depression and panic disorder were taken from the Epidemiologic Catchment Area Program. Cumulative distributions of ages at onset of diagnosis and onset of precursors are presented, and the concept of attributable risk is introduced. Attributable risk is the maximum proportion of cases that would be prevented if an intervention were 100% effective in eliminating a specific precursor. RESULTS: Illustrative results for depression and panic are presented. Precursors vary in the degree to which they predict onset of the full disorder; 2 or more weeks of sad mood in the year before full-blown depression is a better predictor (relative odds, 7.0) than weight loss or gain (relative odds, 3.0). The formula for population attributable risk was applied to the precursor relative risks and prevalences to estimate the potential success of interventions for specific precursors in preventing the disorder. The precursor attributable risks indicate that sleep problems would identify 47% of the new cases of major depression occurring in the following year, and the question "Are you a nervous person?" would identify 60% of persons with onset of panic disorder in the following year. CONCLUSIONS: This conceptual framework links the early natural history of disorders with the search for syndromes. Knowledge of precursor prevalence and attributable risk, combined with other host characteristics and environmental risk factors, can be used in screening and prevention.

Adolescent↗

PubMed1991

[Occurrence of colds and coughs among adult Danes. Epidemiological data from the DIKE (Danish Institute for Clinical Epidemiology) population study].

The occurrence of upper respiratory symptoms among adult Danes was examined by the use of data from the Danish Health and Morbidity Survey 1986-1987. In this study, 14.0 per cent of 6,672 individuals reported complaints of colds or coughs (CC) during the two-week period preceding the interview. Reporting of CC decreased with age, but there was no sex difference. A multivariate analysis, including a number of suspected exposure variables, showed that CC was reported significantly more frequently (OR 1.42) by individuals also reporting exposure to external health risks in their homes. The reporting of CC was not associated with occupational exposure, psychological stress, spare time physical activity or smoking habits. Using bivariate analysis, it was shown that exposure to external health risks in the home was reported more frequently among women than men. The results indicate, that exposure to external health risks in dwellings contributes significantly to the total morbidity among adult Danes. However, improvement of the validity of information about exposure by means of more objective methods is required.

Adult↗