Alexia Antczak-Bouckoms

Meta-analysis of multiple outcomes by regression with random effects

Earlier work showed how to perform fixed-effects meta-analysis of studies or trials when each provides results on more than one outcome per patient and these multiple outcomes are correlated. That fixed-effects generalized-least-squares approach analyzes the multiple outcomes jointly within a single model, and it can include covariates, such as duration of therapy or quality of trial, that may explain observed heterogeneity of results among the trials. Sometimes the covariates explain all the heterogeneity, and the fixed-effects regression model is appropriate. However, unexplained heterogeneity may often remain, even after taking into account known or suspected covariates. Because fixed-effects models do not make allowance for this remaining unexplained heterogeneity, the potential exists for bias in estimated coefficients, standard errors and p-values. We propose two random-effects approaches for the regression meta-analysis of multiple correlated outcomes. We compare their use with fixed-effects models and with separate-outcomes models in a meta-analysis of periodontal clinical trials. A simulation study shows the advantages of the random-effects approach. These methods also facilitate meta-analysis of trials that compare more than two treatments.

Evaluation of the Costs and Relative Effectiveness of Alternative Strategies for the Removal of Mandibular Third Molars

Decision analysis is used to compare the cost and disability of alternative treatment strategies for asymptomatic mandibular third molars. The analysis shows that extracting only those third molars that remain impacted and become pathologically involved is always associated with less expected cost and disability than prophylactic removal of asymptomatic wisdom teeth.

Multiple-outcomes Meta-analysis of Treatments for Periodontal Disease

The results of periodontal therapy vary by disease severity, outcome measure, and method of data analysis. Several clinical trials and a subsequent meta-analysis have demonstrated that, for teeth with severe disease, surgery decreases probing depth (PD) and increases attachment level (AL) more than non-surgical treatment. For other disease levels, the choice of therapy depends on the outcome measure. When clinical trials use two or more outcome measures (such as PD and AL), investigators ordinarily analyze each outcome separately. When the correlations are incorporated among the outcomes, a meta-analysis can use generalized-least-squares (GLS) regression to analyze multiple outcomes jointly. We applied the GLS multiple-outcomes model in a meta-analysis of 5 trials comparing surgical and non-surgical periodontal treatments, each assessing the outcomes PD and AL one year after treatment. The clinical conclusions are similar to those reported earlier, but our estimates of the relative benefits of surgical and non-surgical treatment should be more accurate, because the GLS method takes into account correlation between AL and PD. When correlations between the two outcomes rise, as they do with increasing severity of disease, the GLS estimates depart from those derived from separate analyses of PD and AL.

A review of clinical research in orthodontics

The orthodontic journals should provide valid and reliable information that helps clinicians make appropriate decisions about patient care. The nature of the published literature has not been categorized. The American Journal of Orthodontics and Dentofacial Orthopedics (formerly the American Journal of Orthodontics) was reviewed for the years 1976, 1981, and 1986, to determine the frequency of clinical articles, the topics reported, the study designs used to obtain information, the senior author affiliation, and the major funding sources. This review demonstrates that more than half the articles in this Journal report data on patients, with the majority focusing on the evaluation or description of therapeutic interventions. Academic institutions contribute the majority of the clinical research, although only a few student theses are published. The major support for this work continues to be from departmental resources with little external funding. Despite the introduction of powerful research designs such as randomized clinical trials, these methods have not been widely adopted for orthodontic clinical research. The case report (study containing fewer than 10 patients with no control nor comparison group) continues to be the most frequently published format. Clinicians should become aware of the inherent weakness in the research designs generally used and recognize the limited information that can be obtained from such methods. Support for this research needs to be greatly expanded if the more powerful type of study required to provide valid and reliable clinical information is to be continued.

Introduction: Using Medical Registries and Data Sets for Technology Assessment

The rising costs of health care and interest in the evaluation of health services and systems have sparked an increased need for technology assessment. A variety of available methods of assessment are described in the Institute of Medicines book Assessing Medical Technologies (1). Although such methods as the randomized controlled trial (RCT) are widely accepted and used, obtaining information by such methods often takes a considerable amount of time, expense, and sophistication in study design. These costs suggest that a broader range of methods for collecting information about health care technologies should be considered. A vast resource of data collected on patients, ranging from a providers practice records to national data sets, might be useful for technology assessment if it could be properly appraised.

Assessing the Effectiveness of Ambulatory Cardiac Monitoring for Specific Clinical Indications: Introduction

This introduction and the three essays that follow examine ambulatory cardiac monitoring for specific clinical indications. They also examine the ways in which evidence from the literature may be synthesized through the framework of decision analysis to guide its appropriate use and identify areas in which more research is needed. The essays discuss ambulatory cardiac monitoring for evaluation of syncope in the elderly; detection of silent ischemia after a myocardial infarction; and selection of antiarrhythmic drugs for malignant ventricular arrhythmias.

Ambulatory Cardiac Monitoring for the Evaluation of Antiarrhythmic Agents

This decision-analysis model assesses ambulatory cardiac monitoring (ACM), ACM followed by exercise testing, and electrophysiologic studies (EPS) in the evaluation and selection of antiarrhythmic agents in postinfarct patients with malignant arrhythmias. With existing data, we find no consistent advantage for one method of drug testing over another, although ACM appears to require fewer resources than does EPS. More patients qualify for EPS, but this fact does not increase the proportion of patients for whom a drug can be identified. These methods may test different aspects of arrhythmia activity and drug response, and sequential use may provide additional benefits. Such benefits must be determined empirically.

Technology assessment in the Veterans Administration Dental Longitudinal Study.

Of the 52 studies emanating from the Veterans Affairs Dental Longitudinal Study, 6 were identified as technology assessments. Three of these studies evaluated dental radiographs used for the diagnosis of oral lesions. Two studies compared alternative technologies for the replacement of missing teeth, and one reported the effects of NSAIDs on alveolar bone loss. Four additional articles are discussed that provide data that will be useful in future assessments of dental technologies.

Technology Assessment in the Normative Aging Study

This review of publications based on data from the Veterans Affairs Normative Aging Study identified four articles that were considered assessments of health care technologies. Three evaluated methods for research on body composition, the fourth studied ventricular size in patient with presenile dementia. Several additional articles are discussed that provided data on baseline values or risk factors for disease that might be useful in generating hypotheses to be tested in later assessments of technologies.

Using Medical Registries and Data Sets for Technology Assessment: An Overview of Seven Case Studies

In this concluding article, we summarize the major ways that seven registries and data sets have been used for technology assessment in the published literature. The registries fell into three groups according to the original purpose of the registry. Within each group, we note the types of contributions that researchers using the registries made to technology assessment.