When are medication side effects due to the nocebo phenomenon?
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Attitude to Health↗
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Results for “Effect Modifier, Epidemiologic”
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Maternal cigarette smoking, regular use of multivitamin/mineral supplements, and risk of fetal death: the 1988 National Maternal and Infant Health Survey.
Data from the 1988 National Maternal and Infant Health Survey were used to examine whether regular use of multivitamin/mineral supplements could modify the relation between maternal smoking and fetal death. Maternal smoking was defined as the self-reported average number of cigarettes smoked after recognition of pregnancy. Regular supplement use was defined as use of multivitamin/mineral supplements for at least 3 days per week during the 3 months before and/or after recognition of pregnancy. The sample comprises 12,465 singleton pregnancies, including 9,402 livebirths and 3,063 fetal deaths. Odds ratios were derived from logistic regression analyses after adjustment for a number of demographic and reproductive variables. Major findings are that 1) smoking increased the risk of fetal death; 2) regular supplement use either before or after recognition of pregnancy did not affect the risk of fetal death in the absence of maternal smoking; 3) odds ratios for fetal death among smoking women who regularly used supplements were generally smaller than those for women who did not regularly use supplements but who smoked a comparable number of cigarettes; and 4) a significant negative excess risk due to interaction was observed among women who regularly used supplements before recognition of pregnancy and smoked 20 or more cigarettes a day. These findings suggested that regular multivitamin/mineral supplement use might reduce the risk of fetal death associated with maternal smoking.
Adult↗
Diagnostic test ordering in the evaluation of febrile children. Physician and environmental factors.
OBJECTIVE: To assess the independent effects of physician and environmental factors on test ordering. METHODS: We prospectively studied 6191 consecutive visits by nonadmitted febrile (rectal temperature > or = 38.0 degrees C) children less than 18 years of age to a children's hospital emergency department from March through November 1989. Multiple logistic regression analysis was used to control for the mutually confounding effects of patient, physician, and environmental factors and to assess attending staff-trainee interactions (effect modification). RESULTS: Patients evaluated by hospital-based subspecialists were significantly more likely to undergo tests than patients evaluated by community-based physicians (odds ratio [OR] for undergoing at least one test, 1.13; 95% confidence interval [CI], 1.04 to 1.23; OR for complete blood cell count, 1.28; 95% CI, 1.12 to 1.46). Children seen by physicians with more than 10 years of experience were significantly less likely to undergo tests than those seen by their more junior colleagues, but this effect was modified substantially by trainee presence and level. For example, when children were seen by a physician with more than 10 years of experience and no trainee was involved, the OR for undergoing at least one test was 0.81 (95% CI, 0.73 to 0.91). If the same physician saw the same patient with a junior trainee, the OR for undergoing at least one test was 1.08 (95% CI, 0.95 to 1.24). Patients seen between July and November were significantly more likely to undergo at least one test than those seen between March and June (OR, 1.28; 95% CI, 1.20 to 1.36). CONCLUSIONS: Attending staff, trainee, and seasonal effects on test ordering have important implications for febrile children and their families, for clinical training and supervision, and for health care costs.
Adolescent↗
Serum cotinine level and incident hearing loss: a case-control study.
BACKGROUND: A growing body of literature suggests an association between cigarette smoking and hearing loss. OBJECTIVE: To assess the relation between levels of serum cotinine, a biomarker of exposure to tobacco smoke, and incident hearing loss. DESIGN: A cross-sectional, incident, case-control study of participants selected from a population-based cohort. SETTING: Testing was conducted at the Beaver Dam Community Hospital, Beaver Dam, Wis. PARTICIPANTS: A total of 197 participants with incident hearing loss and 394 control participants, aged 53 to 75 years, selected from the 2800 participants of the 5-year follow-up examination of the population-based Epidemiology of Hearing Loss Study, 1998-2000. MAIN OUTCOME MEASURE: Incident hearing loss. The incidence of hearing loss was defined as a pure-tone average of thresholds at 500, 1000, 2000, and 4000 Hz greater than 25-dB hearing level in either ear at follow-up among those without hearing loss at baseline. RESULTS: No significant associations were found between serum cotinine levels and incident hearing loss. CONCLUSIONS: These results were not consistent with a previous report, which found cross-sectional associations between prevalent hearing loss and current smoking and environmental tobacco smoke exposure in the home. Longer-term longitudinal studies of smoking and/or serum cotinine levels and the subsequent development of hearing loss may help clarify these associations.
Aged↗
Occupational disability related to back pain: application of a theoretical model of work disability using prospective cohorts of manual workers.
BACKGROUND: A new model of work disability was developed based on the assumption that four different groups of workers are present at the beginning of a prospective epidemiologic study: one group of workers without back pain, and three groups of workers with back pain and a gradient of work disability. The goal of this research was to verify if these groups comprise workers at different levels of risk of occurrence of complete work disability related to back injury. METHODS: Prospective cohorts of manual workers (n=578) were followed for 1 year to document the risk of occurrence of complete disability related to back injury. RESULTS: The results showed that the workers who presented with back pain without work disability at the beginning of the study were at less risk compared to all the other workers in the cohort. Moreover, an effect modification was found between the workers who initially presented with back pain without work disability and a past history of compensation for back injury, adding credence to the non-similarity of these workers to the others. CONCLUSIONS: Based on these results, further studies should focus on improving the knowledge of the characteristics of these workers leading to a better understanding of how to prevent occupational low-back pain.
Adult↗
Exploratory or analytic meta-analysis: should we distinguish between them?
Meta-analysis has been defined as a study and "statistical analysis which combines or integrates the results of several independent studies." Included in this definition are other terms, such as systematic overviews, pooling data, pooling study results, and quantitative literature reviews. Like any study, the questions being asked will influence the design and the method of analysis of the meta-analysis. Since a meta-analysis is a study based on a literature review, it is inherently observational rather than experimental in nature. This idea is supported by the fact that the meta-analyst has limited control over the availability of studies or the information collected and reported in the individual studies. Meta-analysis has been applied to clinical trials and epidemiology. At first glance the potential for bias appears greater in epidemiology than in clinical trials. But this may depend on the question being asked. If randomized clinical trials are limited to improving an estimate of effect or testing a hypothesis in a relatively homogeneous set of effect sizes, the clinical trial will tend to be less prone to bias than a comparable set of epidemiologic studies. In this context, the issue of combinability may dominate the meta-analysis. We refer to this type of meta-analysis as an "analytic" meta-analysis. On the other hand when the goal is to resolve controversy, or pose and answer new questions the main concern of the meta-analysis is to explain the variation in the effect sizes. We refer to this application of a meta-analysis as an "exploratory" meta-analysis. In this second type of meta-analysis the characteristics of the different studies become the focus of the analysis. This leads to the idea that protocols for a meta-analysis should reflect its goals and how the results are to be used. Finally, we will consider whether there is a role of meta-analysis in the field of drug development.
Bias↗
Exploring the role of contextual factors in disability models.
PURPOSE: The objective of this paper is to define and categorize the types of relationships that contextual factors have within models of disability according to the WHO International Classification of Disability, Functioning, and Health (ICF) conceptual scheme. METHOD: A conceptual analysis building on the disability literature specifies the causal relationships for contextual factors in relation to the association between activity limitation and participation using a person with arthritis as an example. RESULTS: From a statistical point of view, in relation to disability process, contextual factors can act as an independent factor, confounding factor, moderating factor, and mediating factor. How the role of a particular contextual factor is specified depends on the researcher's hypothesized disability framework and research goals. Moderating and mediating contextual factors are of particular importance in disability model specification. Various sub-types of moderating contextual factors are also identified. CONCLUSION: This paper provides a framework for the conceptualization of contextual factors in the examination of disability models. This framework has implications in constructing conceptual models as well as for setting up analytical plans. In light of the increasing awareness and application of the ICF model, we intend this work to stimulate additional discussion on this topic.
Activities of Daily Living↗
Comparison of effect estimates from a meta-analysis of summary data from published studies and from a meta-analysis using individual patient data for ovarian cancer studies.
To determine the relative merits of two quantitative methods used to estimate the summary effects of observational studies, the authors compared two methods of meta-analysis. Each quantified the relation between oral contraceptive use and the risk for ovarian cancer. One analysis consisted of a meta-analysis using summary data from 11 published studies from the literature (MAL) in which the study was the unit of analysis, and the second consisted of a meta-analysis using individual patient data (MAP) in which the patient was the unit of analysis. The authors found excellent quantitative agreement between the summary effect estimates from the MAL and the MAP. The MAP permits analysis 1) among outcomes, exposures, and confounders not investigated in the original studies, 2) when the original effect measures differ among studies and cannot be converted to a common measure (e.g., slopes vs. correlation coefficients), and 3) when there is a paucity of studies. The MAL permits analysis 1) when resources are limited, 2) when time is limited, and 3) when original study data are not available or are available only from a biased sample of studies. In public health epidemiology, data from original studies are often accessible only to limited numbers of research groups and for only a few types of studies that have high public health priority. Consequently, few opportunities for pooled analysis exist. However, from a policy view, MAL will provide answers to many questions and will help in identifying questions for future investigation.
Bias↗
Influence of the behaviour pattern on the nocebo response of healthy volunteers.
The occurrence of a nocebo effect after placebo administration to healthy volunteers in a Phase I trial was analysed according to their type of personality (Bortner Rating Scale). More subjects with a behaviour pattern A (competitive and aggressive) (50%) described subjective side effects of the placebo than type B subjects (17%, P = 0.03). The volunteers who had nocebo effect had a higher Bortner score (BS) than did placebo non-responsive subjects (P = 0.05). The BS was 205 for paramedical staff, 189 for medical and dentistry students, 173 for non-science students and 161 for science students (P < 0.04). The nocebo response was not statistically correlated with professional status. These results suggest that volunteer's type of personality might influence the reporting of subjective symptoms after placebo, and therefore impair the evaluation of new drugs in Phase I clinical trials.
Adult↗
Phase specific analysis of herpes zoster associated pain data: a new statistical approach.
Herpes zoster or shingles is a frequent occurrence in both elderly individuals and immunocompromised hosts. The pain associated with herpes zoster is the most debilitating complication of the disease. It can be described as acute pain and post-herpetic neuralgia or zoster associated pain (ZAP). The latter definition encompasses pain from the onset of disease through its resolution and provides a convenient analytic tool for evaluation of antiviral therapy. A heuristic examination of ZAP historical data suggests the existence of three phases of pain resolution: the acute, subacute and chronic phases. The subacute and chronic phases comprise the post-herpetic neuralgia (PHN) stage. Common analytic methods, such as a Kaplan-Meier survival function or a Cox's model, have been used to assess the pain. However, such approaches do not adequately allow for phase comparison. Notably, in the clinical trial setting the comparison of specific treatment effects on the latter stages of pain are of the greatest medical relevance since this is the most debilitating phase of the illness. In order to incorporate the phase-specific information in the modelling of time to cessation of ZAP, we assumed the hazard function was a stepwise constant. Utilizing the full likelihood function, we obtained the maximum likelihood estimate for the transition times (that is, change-points), and other parameters of medical importance. The standard error of the change-point estimates were obtained through a bootstrapping method. The asymptotic properties of the parameter estimates are also discussed. Hence, the rates of pain resolution across all phases can be examined in order to precisely define the existence of multiple phases. In addition, the covariates effect can be examined across phases and populations, thereby allowing us to translate potential efficacy of a standard therapy to different populations. These results can be utilized in the design of clinical trials or in targeting the outcome for a specific phase while controlling for the effect of other variables.
Acute Disease↗
Urinary incontinence and age at the first and last delivery: the Norwegian HUNT/EPINCONT study.
OBJECTIVE: This study was undertaken to investigate the association between maternal age at the first and last delivery, and urinary incontinence later in life. STUDY DESIGN: In the Norwegian EPINCONT study (a substudy of HUNT 2), cross-sectional data on incontinence from 11,397 women aged 20 to 64 years was linked with prospectively obtained data on exposures from the Medical Birth Registry of Norway. Bivariate and multivariate methods were applied. RESULTS: Women 25 years or younger at their first delivery had a lower risk of incontinence than their older counterparts (23% vs 28%, P < .01). No significant effect of maternal age at the first delivery was found in women with actual age 50 to 64 years. Adjusting for confounders did not change any results. Age at the last delivery was less associated with incontinence. CONCLUSION: Being older than 25 years at the first delivery was associated with incontinence. The effect attenuated with actual age.
Adult↗
Coffee drinking: the rationale for treating it as a potential effect modifier of carcinogenic exposures.
Clinical and epidemiological studies on cancer etiology seldom treat coffee drinking as a potential effect modifier. Yet caffeine exerts significant effects upon a large variety of physiologic, cellular and molecular systems. Caffeine, 'the world's most popular drug', is also a fundamental research tool, widely used in clinical studies on drug metabolism, and in experimental studies on cell cycle checkpoints, DNA repair, and apoptosis, among many other. Caffeine can profoundly alter cell cycle checkpoint function and several mechanisms of DNA repair, as well as carcinogen metabolism. The impact of caffeine on cell cycle checkpoint function occurs in spite of it being nonmutagenic in traditional mutagenesis assays. A complex body of biologic evidence suggests that caffeine-containing beverages can both enhance and antagonise potentially carcinogenic exposures. However, most pathways leading to the ultimate effects in human beings remain unknown. It is unclear whether any of the hundreds of compounds contained in coffee and tea exert a direct and significant carcinogenic effect per se in any human tissue at usual conditions of use. Reasons exist to consider that coffee may sometimes be an indirect, positive confounder. The study of interactions between caffeine-containing beverages and environmental agents in well defined groups of healthy and diseased people could yield new insights into checkpoint signal transduction and other mechanisms of carcinogenesis. Information on the use of caffeine-containing beverages should more often be integrated in studies on the role of gene-environment interactions in the pathogenesis of cancer.
Coffee↗
Hospitals and health services enterprises as social systems.
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Attitude of Health Personnel↗
Epidemiological studies on genetic polymorphism: study design issues and measures of occurrence and association.
As with other epidemiological studies, the design and analysis of a study including genetic polymorphisms generally involve relating a particular disease or health outcome to a particular exposure or genetic trait, while assessing the presence of systematic error, controlling random error and assessing effect modification (interaction) with other exposures or traits. In studies of determinants and mechanisms of disease, markers of genetic polymorphism are generally treated either as exposure variables or as effect modifiers. In epidemiological studies the study base can be completely enumerated, and the cases can be identified as either incident or prevalent cases (incidence and prevalence studies). Alternatively, the study may involve cases of the disease (or condition) under investigation and a control group sampled from the study base that generated the cases (incidence and prevalence case-control studies). Most available studies on metabolic polymorphism and cancer risk are incidence case-control studies. Their major methodological problem is the selection of controls, which may be an important source of bias. Another important limitation of many available studies is the small sample size, which may be inadequate for assessing statistical interaction when the metabolic polymorphism is treated as an effect modifier.
Case-Control Studies↗
Understanding research synthesis (meta-analysis).
Synthesis of research findings has long been a part of reviewing and summarizing a field of study. Public health decisions are made on the available evidence. We summarize the approaches to research synthesis that draw on the best available evidence and the use of quantitative summaries through meta-analysis. We focus on observational studies. Heterogeneity offers the potential to observe a relation across study populations and circumstances. We emphasize the benefits of heterogeneity in overviews and the need to explore and describe the sources of heterogeneity. Random effects approaches to combining data are recommended, and the use of regression approaches is emphasized. Excluding studies with extreme results may bias a research synthesis and underestimate the true variance of the results, thus contributing to misleading inference. Thorough searching is the best guard against publication bias. We conclude with guidelines for combining epidemiological studies.
Analysis of Variance↗
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.
Bias↗
Placebos and placebo effects in medicine: historical overview.
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Effect Modifier, Epidemiologic↗
Nonspecific effects in longitudinal studies: impact on quality of life measures.
A variety of factors may influence outcome measures in longitudinal studies, including placebo, Hawthorne, or natural history effects. Quality of life (QoL) measures are particularly subject to these phenomena. This 2-month postal survey was set up to examine the extent of nonspecific effects in a treatment (vitamin supplementation) group (n = 180), a placebo group (n = 180), as part of a stratified, randomized controlled trial, and two control groups (n = 768 each). Quality of life was measured using the SF36. The placebo effect had a significant impact on improving physical, mental, and pain dimensions (p = 0.02 to 0.04), and the Hawthorne effect was significant (p = 0.03 to 0.009) for psychological dimensions. Although the impact of natural history was not significant, it tended to worsen all QoL dimensions. Vitamin supplementation had no effect on QoL. These results demonstrate the importance of placebo and Hawthorne effects and suggest that they may be responsible for misleading results or reductions in the power of controlled trials.
Adult↗