Análisis bibliométrico de las desigualdades en n salud en españa (1980-1994)

A bibliometrical analysis of all available studies on Spanish health inequalities (health status and use and access to health services) for the period 1980-1994 has been carried out. The main objective of the study is to specify the subject, geographic origin, place of edition and temporal distribution of all studies found. Using databases, direct consultation on libraries, and direct consultation with Public Health specialists, direct sources of information as well as sources of difficult access have been investigated. Located studies have been classified in three subjects: reviews and conceptual studies, empirical studies on Spain, empirical studies in cities, regions or Autonomous Communities. The majority of the 233 studies located are empirical, have not been published in books or journals, and they have been conducted in two Autonomous Communities (Catalonia and Valencian Community). Since the period 1986-1988 a clear increase in the number of studies as well as in their formal publication has been observed.     

Postmarketing Studies: Benefits and Risks

OBJECTIVE: To consider the benefits and risks of large postmarketing outcomes studies, as demonstrated by studies of the statin drugs. METHODS: Literature review. RESULTS: The risks were that the statin studies had a strong coat-tail effect. Each new study was beneficial to all statins as well as the one studied. Economic analyses based on the results of the postmarketing studies concluded that the drugs were not cost-effective. Long-term postmarketing studies were slow to be put into perspective and did not immediately influence other researchers or clinicians. During that time, the sponsoring companies shouldered opportunity costs as well as the actual costs of the studies. The risk that one drug company would use another company's results instead of investing in their own research did not materialize. The benefits were that the studies definitively showed that the drugs and the lowering of lipids were safe and efficacious. The studies also expanded the indications for the drugs, generated goodwill in the medical and research communities for the sponsors, allowed sponsors to include specific claims in their advertisements, generated follow-up studies, spawned economic analyses that sparked interest in the medical and lay press, and had a major impact on clinicians' use of the drug. CONCLUSION: The risks and benefits of postmarketing studies may depend on the company's time perspective. In the short term, the risks may outweigh the benefits. Only companies that have a longer perspective may find it beneficial to undertake large postmarketing studies.     

Preference-based outcome measures in cost-utility analyses. A 20-year overview

OBJECTIVES: The study evaluated the extent to which quality-adjusted life-years (QALYs) and healthy-years equivalents (HYEs) were used in cost-utility studies over the past 20 years (1981-2000) as well as possible changes in the quality of journals reporting cost-utility studies. METHODS: Cost-utility studies were identified through an electronic search. For each study the journal name, date of publication, article's language and research origin, and the journal's impact factor were recorded. RESULTS: The number of published cost-utility studies increased in the last 20 years but has leveled off in 1997. Most studies were performed in the United States and were published in English. All studies except one used QALYs as an outcome measure. The mean journal's impact factor has changed slightly over the years. CONCLUSIONS: Cost-utility studies would possibly gain more popularity if they were used as a vehicle in the decision-making process regarding healthcare budgets and were more visible in the scientific literature.     

Assessing disease risk in genome-wide association studies using family history

We show how to use reports of cancer in family members to discover additional genetic associations or confirm previous findings in genome-wide association (GWA) studies conducted in case-control, cohort, or cross-sectional studies. Our novel family history-based approach allows economical association studies for multiple cancers, without genotyping of relatives (as required in family studies), follow-up of participants (as required in cohort studies), or oversampling of specific cancer cases (as required in case-control studies). We empirically evaluate the performance of the proposed family history-based approach in studying associations with prostate and ovarian cancers, using data from GWA studies previously conducted within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The family history-based method may be particularly useful for investigating genetic susceptibility to rare diseases for which accruing cases may be very difficult, by using disease information from nongenotyped relatives of participants in multiple case-control and cohort studies designed primarily for other purposes.     

New models for large prospective studies: is there a better way?

Large prospective cohort studies are critical for identifying etiologic factors for disease, but they require substantial long-term research investment. Such studies can be conducted as multisite consortia of academic medical centers, combinations of smaller ongoing studies, or a single large site such as a dominant regional health-care provider. Still another strategy relies upon centralized conduct of most or all aspects, recruiting through multiple temporary assessment centers. This is the approach used by a large-scale national resource in the United Kingdom known as the "UK Biobank," which completed recruitment/examination of 503,000 participants between 2007 and 2010 within budget and ahead of schedule. A key lesson from UK Biobank and similar studies is that large studies are not simply small studies made large but, rather, require fundamentally different approaches in which "process" expertise is as important as scientific rigor. Embedding recruitment in a structure that facilitates outcome determination, utilizing comprehensive and flexible information technology, automating biospecimen processing, ensuring broad consent, and establishing essentially autonomous leadership with appropriate oversight are all critical to success. Whether and how these approaches may be transportable to the United States remain to be explored, but their success in studies such as UK Biobank makes a compelling case for such explorations to begin.     

Etiologic and prevention effectiveness intervention studies in occupational health

In this article a basic distinction is made between etiologic and prevention effectiveness intervention studies. Etiologic intervention studies focus on elucidating causes of disease, while the purpose of prevention effectiveness intervention studies is to study methods of prevention. The design requirements for each of these studies are very different: etiologic intervention studies usually need large study populations, large exposure contrasts, ascertainment of exposure, as well as health outcome. Ideally, randomization and blinding should also be applied. Effective preventive strategies may, on the other hand, be identified in small study populations with exposure as the only outcome measure, and randomization and blinding may be superfluous. At present, intervention studies are in great demand, and often there is a wish that etiologic questions as well as prevention effectiveness be addressed in the same study. We argue that this should not be done without careful consideration of possible conflicting design aspects. © 1996 Wiley-Liss, Inc.     

Analytical, practical and regulatory issues in prevention studies

Prevention studies, as distinguished from studies investigating treatments for established disease, present some distinct challenges. Perhaps the most extensive experience with preventive agents is in the area of infectious diseases; vaccines have been extremely effective in preventing many such diseases. Vaccines have been, and continue to be, studied in other disease areas such as certain cancers, but as yet have not achieved success outside of infectious disease prevention. One obvious and important feature of prevention studies is that they enroll healthy individuals; thus such studies require particularly high standards for the safety of those enrolled (and those who might ultimately receive the product being tested). Prevention studies often need to be quite large, as the types of diseases most important to prevent tend to be uncommon. Large studies usually require simplified approaches; to ensure high quality of data on the key variables it may be necessary to compromise on the amount of data collected, frequency of data collection, and other aspects of trial design. The reliability of randomization and blinding may be especially important in these large studies, as bias could easily overwhelm the small effects that are usually sought. Often, biomarkers thought to indicate developing but as yet subclinical disease, will be important to evaluate; whether such markers can serve as primary endpoints in prevention studies has been a contentious issue in many contexts. Studies in older populations, such as those at risk for Alzheimer's Disease, raise challenges such as accounting for competing risks, and considering potential interactions of preventive agents with multiple medications often used by the elderly.     

A literature review: the cardiovascular effects of exposure to extremely low frequency electromagnetic fields

The effects of exposure to extremely low frequency (ELF) electromagnetic fields (EMFs) on human cardiovascular parameters remain undetermined. Epidemiological studies have utilized dosimetry estimations of employee workplace exposure using altered heart rate variability (HRV) as predictive of certain cardiovascular pathologies. Laboratory studies have focused on macrocirculatory indicators including heart rate, HRV and blood pressure. Few studies have been conducted on the response of the microcirculatory system to EMF exposure. Attempts to replicate both epidemiological and laboratory studies have been mostly unsuccessful as study design, small sample populations and confounding variables have hampered progress to date. Identification of these problems, in the current context of international exposure guideline re-evaluation, is essential for future EMF studies. These studies should address the possible deleterious health effects of EMFs as well as the detection and characterization of subtle physiological changes they may induce. Recommendations for future work include investigating the macro- and microcirculatory relationship and the use of laboratory geomagnetic shielding.     

Is epidemiology implicating extremely low frequency electric and magnetic fields in childhood leukemia?

We have reviewed epidemiological studies examining the association between residential exposure to extremely low frequency electric and magnetic fields (ELF-EMF) and childhood leukemia. We have excluded studies focusing on electrical appliances, because it is difficult to consolidate transient exposure from multiple sources and equally difficult to control information bias. We have identified 24 studies of residential exposure to ELF-EMF and childhood leukemia. About half of these studies were reported as positive and the remaining as null. For each of the studies reported as positive, however, one or more sources of bias could not be confidently excluded. Moreover, studies which were methodologically more sound, or benefited from high quality registry data, were more frequently null than other investigations. We conclude that the empirical evidence in support of an association between ELF-EMF and childhood leukemia is weak.     

Current view of epidemiologic study designs for occupational and environmental lung diseases

Epidemiologic studies long have played a role in the understanding of the effects of the general environment and various occupational exposures on the occurrence of acute and chronic diseases of the lung. This article is an overview of epidemiologic study designs that have particular relevance to studies of environmental and occupational lung disease. The application of times-series designs in the context of epidemiologic studies is discussed, as such designs have become widely used in studies of health effects ambient air pollution. The article emphasizes recent developments in the application of case-control study designs, many of which have had particular applications in epidemiologic studies related to environmental and occupational lung disease. These case-control designs offer efficient and valid alternatives for studies that in the past might have been conducted as more costly and time-consuming cohort studies.     

The search for SNPs, CNVs, and epigenetic variants associated with the complex disease of male infertility

Understanding the genetic basis of idiopathic male infertility has long been the focus of many researchers. Numerous recent studies have attempted to identify relevant single nucleotide polymorphisms (SNPs) through medical re-sequencing studies in which candidate genes are sequenced in large numbers of cases and controls in the search for risk or causative polymorphisms. Two major characteristics have limited the utility of the re-sequencing studies. First, reported SNPs have only accounted for a small percentage of idiopathic male infertility. Second, SNPs reported to have an association with male infertility based on gene re-sequencing studies often fail validation in follow-up studies. Recent advances in the tools available for genetic studies have enabled interrogation of the entire genome in search of common, and more recently, rare variants. In this review, we discuss the progress of studies on genetic and epigenetic variants of male infertility as well as future directions that we predict will be the most productive in identifying the genetic basis for male factor infertility based on our current state of knowledge in this field as well as lessons learned about the genetic basis for complex diseases from other disease models.     

Plant foods versus compounds in carcinogenesis; observational versus experimental human studies

The protective role of plant foods and its constituents in cancer prevention is under renewed debate since the results of recent observational studies on colorectal cancer as well as large-scale human experimental studies on colorectal adenoma recurrence are disappointing. However, most short-term experimental human studies do show that plant foods favourably modulate potential cancer-preventive mechanisms. Which methodological pitfalls may explain the inconsistencies within and between different study designs? What are the advantages and limitations of the different study approaches? Observational studies do have the advantage to study the population at large with ultimate disease as the study endpoint. These studies are limited by the difficulty to estimate intake of individual compounds by questionnaires and the lack of biological markers of relevant exposure. Controlled experimental short-term studies in humans rely on biological markers of disease as intermediate endpoints. Relatively low sensitivity and specificity of these markers may complicate extrapolation of results. In the case of long-term and large-scale human intervention studies with disease endpoints, issues such as time, dose and duration of intervention, compliance and choice of the study population influence the interpretation of results. An integrated approach combining designs, and implementing new techniques to identify biomarkers, may clarify the role of plant foods in carcinogenesis.     

Methodological quality of pharmacogenetic studies: issues of concern

Pharmacogenetic studies investigate association between genetic variants(double dagger) and drug efficacy and toxicity. Regardless of the extent of current knowledge regarding the human genome(double dagger) and relatively low genotyping costs, the value of pharmacogenetic studies in improving understanding of variable drug response remains contentious. Failure to replicate initial significant findings in subsequent studies is one reason for this and problems with methodological quality has been cited as contributing to this lack of replication. Here, concerns raised in the literature regarding the methodological quality of genetic association studies in general are discussed with particular consideration given to how applicable they are to the conduct and reporting of pharmacogenetic studies. Some of these issues such as sample size and quality of genotypes(double dagger) have been given significant attention in the literature already whereas others, such as dealing with missing genotypes and assumptions regarding mode of inheritance, have been discussed very little. Issues of quality believed to be uniquely relevant to pharmacogenetic studies are also considered. These discussions close with an assessment of how well the issues are dealt with in pharmacogenetic studies published over recent years and, overall, methodological quality is found to be poor. A checklist is provided of issues to be addressed whenever a future pharmacogenetic study is embarked upon. Referring to this checklist will improve the chances of replication and instil confidence in the integrity of future pharmacogenetic studies. It will also serve as a tool in assessing methodological quality of studies included in a systematic review of pharmacogenetic studies.     

The search for SNPs,CNVs, and epigenetic variants associated with the complex disease of male infertility

Understanding the genetic basis of idiopathic male infertility has long been the focus of many researchers. Numerous recent studies have attempted to identify relevant single nucleotide polymorphisms (SNPs) through medical re-sequencing studies in which candidate genes are sequenced in large numbers of cases and controls in the search for risk or causative polymorphisms. Two major characteristics have limited the utility of the re-sequencing studies. First, reported SNPs have only accounted for a small percentage of idiopathic male infertility. Second, SNPs reported to have an association with male infertility based on gene re-sequencing studies often fail validation in follow-up studies. Recent advances in the tools available for genetic studies have enabled interrogation of the entire genome in search of common, and more recently, rare variants. In this review, we discuss the progress of studies on genetic and epigenetic variants of male infertility as well as future directions that we predict will be the most productive in identifying the genetic basis for male factor infertility based on our current state of knowledge in this field as well as lessons learned about the genetic basis for complex diseases from other disease models.     

Drinking water contaminants and adverse pregnancy outcomes: a review

Concern for exposures to drinking water contaminants and their effects on adverse birth outcomes has prompted several studies evaluating chlorination disinfection by-products and chlorinated solvents. Some of these contaminants are found to be teratogenic in animal studies. This review evaluates 14 studies on chlorination disinfection by-products such as trihalomethanes (THMs) and five studies on chlorinated solvents such as trichloroethylene (TCE). The adverse birth outcomes discussed in this review include small for gestational age (SGA), low birth weight, preterm birth, birth defects, spontaneous abortions, and fetal deaths. Because of heterogeneities across the studies in the characterization of birth outcomes, the assessment and categorization of exposures, and the levels and mixtures of contaminants, a qualitative review was conducted. Generally, the chief bias in these studies was exposure misclassification that most likely underestimated the risk, as well as distorted exposure-response relationships. The general lack of confounding bias by risk factors resulted from these factors not being associated with drinking water exposures. The studies of THMs and adverse birth outcomes provide moderate evidence for associations with SGA, neural tube defects (NTDs), and spontaneous abortions. Because fewer studies have been conducted for the chlorinated solvents than for THMs, the evidence for associations is less clear. Nevertheless, the findings of excess NTDs, oral clefts, cardiac defects, and choanal atresia in studies that evaluated TCE-contaminated drinking water deserve follow-up.     

Short term effect of urban air pollution on respiratory insufficiency due to chronic obstructive pulmonary disease. Synthesis of studies published from 1962 to January 2000

This review presents a synthesis of studies published from 1962 to 2000 on the relations between air pollution and chronic obstructive pulmonary disease (COPD): 12 ecological epidemiological studies, 6 epidemiological panel studies, and 11 controlled human exposure trials. The controlled trials, ecological time-based epidemiological studies and panels are examined successively followed by a discussion of their methodology and results. The controlled trials either do no highlight effects or show effects having no clinical significance since variations are similar to physiological variability. For epidemiological studies reporting individual data, the results point to a particle effect (two studies). This effect of particles is found in ecological studies which also describe an impact of ozone, sometimes of sulfur dioxide and less often of nitrogen dioxide. In conclusion, patients suffering from COPD are generally regarded as a group sensitive to air pollution, as suggested by the results of numerous ecological epidemiological studies. Rare individual studies provide a few arguments supporting this assumption.     

Algorithm for application of the "ethical guidelines for epidemiological research" and taxonomy of public health research

BACKGROUND: "Ethical Guidelines for Epidemiological Research" took effect in July 2002, with a moral duty of all researchers to comply when conducting epidemiological studies although it is not legally binding. Public health research entails various forms of studies including not only epidemiological studies but also attention to psychological, societal and economic aspects, which are outside of the jurisdiction of the guidelines. Hence, confusion may arise among members of Japanese Society of Public Health as to whether the study they conduct falls within the definition of epidemiological research. The author discusses legal interpretations of the guidelines arising in the course of translation work as part of government-funded project, "Dissemination of the 'Ethical Guidelines for Epidemiological Research' via Internet (principal investigator: Toru Doi)" and argues that a case-method approach would be best suited to enhance understanding by researchers with diverse, non-legal backgrounds. METHODS: The author proposes an algorithm for classification of studies as to whether the guideline applies, and applies it to all original articles published in the Japanese Journal of Public Health (JJPH) in one year (March 2002 thru February 2003). The rationale for classification is discussed from the strict legal viewpoint in each case. RESULTS: Sixteen out of 46 original articles published in JJPH for one year were classified as epidemiological studies to which the guidelines apply. Those classified otherwise were psychological studies (10), epidemiological studies not targeting specific diseases and are exempt form the guidelines (3), purely methodological studies (4), economics studies (3), fact-finding or opinion surveys with no hypothesis testing (2), as well as studies authorized by law (4) or using unlinkable anonymous data only (4), all of which are exempt from the guidelines. Reference to ethical considerations in the methodology section as required by the instructions for authors was generally well performed in epidemiological studies although some shortcomings were noted. DISCUSSIONS: The guidelines affect approximately a third of original articles published in the JJPH. The ratio of applicable to non-applicable articles was roughly 1 to 2. This gives both authors and reviewers confusion as to whether articles are subject to the guidelines and would require ethical approval. This case-method approach using actual articles readily available to members should help unnecessary confusion and enhance appropriate application of the guidelines. (366 words).     

Bias resulting from the use of 'assay sensitivity' as an inclusion criterion for meta-analysis

Assay sensitivity has been proposed as a criterion for including psychiatric clinical outcome studies in meta-analyses. The authors assess the performance of assay sensitivity as a method for determining study appropriateness for meta-analysis by calculating expected standard drug vs placebo effect sizes for various combinations of high quality and flawed studies. In the absence of flawed studies, expected effect sizes are close to unbiased only when sample sizes are very large. In the presence of flawed studies, expected effect sizes tend to be substantially biased except under simultaneous conditions of high power, a large proportion of flawed studies, and a population standard vs placebo effect size of flawed studies considerably lower than that of high quality studies. The authors conclude that this method is not robust and can lead to serious bias. Unless it can be shown that specific conditions hold, assay sensitivity should not be used to make quality judgments of studies.     

Improvement of work environment]

As a result of a literature review on methodology and the effectiveness of work-environment oriented workplace stress reduction, it is suggested that improvement of the work environment is effective in reducing workers' job stressors and psychological and physiological stress reaction, from a limited number of controlled studies including RCT, as well as a number of case studies and before-after comparison studies. An expert-guided, supervisor and worker participated approach also seems effective. The author proposes five practical steps toward an effective improvement of the work environment based on the review. Remaining topics include the need for more well-designed studies, investigation of the relationship between intervention type and outcome, as well as modifying effects according to social situations, and instruments for implementation.