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PubMed1985

Intralaboratory comparison of drug susceptibility testing of Mycobacterium tuberculosis by BACTEC and conventional methodology.

The BACTEC radiometric method of drug susceptibility testing of Mycobacterium tuberculosis is a reliable and rapid diagnostic tool in clinical mycobacteriology. However, large scale comparative studies have also shown that the level of agreement with standard methodology was less satisfactory with strains resistant to ethambutol and streptomycin than with strains resistant to rifampin and to isoniazid. Since disagreement with drug resistance strains is far more frequent than with drug susceptible strains, it was felt that only the comparison of a large number of resistant strains would be needed to further refine this new technique. The analysis of BACTEC-derived data for isoniazid and rifampin shows that the level of agreement with conventional methodology falls well within accepted limits. Statistical analysis of the radiometric versus conventional comparisons shows no significant differences between the two methods in the case of isoniazid, rifampin, and ethambutol (3 mg/L). Streptomycin and two other ethambutol concentrations tested showed lower levels of agreement and significant statistical differences with conventional methodology.

Anti-Bacterial Agents↗

PubMed1996

Methodological issues in psychopathology research.

We present an overview of methodological issues involved in conducting psychopathology research, including conceptual, analytic, and interpretive considerations. Research issues germane to structured diagnostic interviewed, comorbidity of mental disorders, and ascertainment and sampling are reviewed. Further, the problem of specificity (with respect to disorder, to differential deficit, and to time) is discussed. Specific issues concerning risk vs protective factors, conducting research with special populations, and the continuity of abnormal and normal functioning are highlighted. Finally, various analogue strategies (human subclinical syndromes, experimental study of "pathological" processes in normals, animal models, and computer simulations) are critiqued. Our review documents many of the impressive methodological developments that have emerged in this field, and we hope our review stimulates additional research that exploits recent methodological advances.

Animals↗

PubMed1997

Methodologic evaluation of the radiology cost-effectiveness literature.

PURPOSE: To evaluate the methodologic quality of cost-effectiveness and cost-benefit analyses reported in the radiology literature. MATERIALS AND METHODS: Original investigations of cost-effectiveness and cost-benefit analysis were identified from an on-line search of the radiology literature from 1989 to 1995. The articles were evaluated for adherence to minimum methodologic standards for economic analysis research. Major criteria assessed were (a) provision of comparative options, (b) statement of perspective of analysis, (c) presentation of cost data, (d) measurement of outcomes, (e) use of a summary measure of economic efficiency, and (f) performance of sensitivity analysis. Minor criteria assessed were inclusion of (a) source of cost data, (b) long-term costs, (c) discounting, and (d) incremental computation of the summary measure. RESULTS: Forty-four economic analysis articles were identified. The median numbers of major and minor principles adhered to were three and one, respectively. Five studies used all six major criteria, and three used all 10 criteria. The median number of criteria adhered to did not increase during the study period. CONCLUSION: Adherence to methodologic standards in the radiology cost-effectiveness literature is not optimal. There are several examples from radiology journals, however, where such standards are met.

Bibliometrics↗

PubMed1994

Modeling methodology for vascular input impedance determination and interpretation.

The significance of pulse wave reflections in the pulmonary vascular system is elaborated using a new method to determine the broadband frequency response of input impedance up to frequencies of 100 Hz. A simple data model, based on the signal construct of a wavelet, is used to generalize and reconcile the common approaches to vascular frequency response estimation so that an accurate response can be calculated from physiological waveforms. Input impedance interpretation is accomplished using a structural and functional modeling methodology. To identify internal structural system properties, the methodology of inverse scattering is used to relate observed pulse wave echoes in the frequency response to a longitudinal distribution of reflection sites of anatomic significance. To identify functional interactions with pulmonary vascular wave mechanics, a time series analysis methodology is proposed to describe vascular interactions using a generalized principle of superposition. The methods of determination and interpretation are applied to a sample pressure-flow data set from the pulmonary circulation of a lamb experiencing vascular-ventilatory interaction. The example suggests that the frequency response is consistent with a discrete longitudinal distribution of reflection sites that may be affected by the ventilator.

Animals↗

PubMed2005

Cost-effectiveness analysis of prenatal diagnosis: methodological issues and concerns.

With increasing concerns regarding rapidly expanding health care costs, cost-effectiveness analysis (CEA) provides a methodology to assess whether marginal gains from new technology are worth the increased costs. In the arena of prenatal diagnosis, particular methodological and ethical concerns include whether the effects of such testing on individuals other than the patient are included, how termination of pregnancy is included in the models, redundancy of screening and diagnostic methods, and how screening may reassure or cause anxiety in patients depending on their results. The existing literature has demonstrated cost-effectiveness of screening and diagnosis of neural tube defects, Down syndrome, and cystic fibrosis in the general population. Screening for genetic disorders which have a higher prevalence among particular groups has also been shown to be cost effective, including diseases such as hemoglobinopathies and Tay-Sachs disease. Understanding the methodology and salient issues of CEA is critical for researchers, editors and clinicians to accurately interpret results of the growing body of cost-effectiveness studies in prenatal diagnosis.

Cost-Benefit Analysis↗

PubMed1997

Association between the angiotensinogen 235T-variant and essential hypertension in whites: a systematic review and methodological appraisal.

Recently, an allelic variant of the angiotensinogen gene (AGT 235T) has been associated with increased risk of hypertension. However, this finding has not been confirmed by all investigators. A meta-analysis was performed to examine the association between the AGT 235T-allele and hypertension in whites and to identify potential reasons for the controversial results. All relevant articles published between 1992 and 1996 were identified through multiple sources. The studies were methodologically appraised, and the frequency of the AGT 235T-allele was extracted. The 235T-allele frequency was pooled using the common odds ratio (OR) estimator by Mantel-Haenszel. Homogeneity was assessed using the Breslow-Day test. Together these studies present data on 5493 patients. The AGT 235T-allele was significantly associated with hypertension (OR: 1.20; 95% [CI]: 1.11 to 1.29; P<.0001). This association increased in studies with positive family history (OR: 1.42; 95% CI: 1.25 to 1.61, P<.0001), recruitment of cases from referral centers (OR: 1.39; 95% CI: 1.20 to 1.62, P<.0001), and more severe hypertension (OR: 1.34; 95% CI: 1.22 to 1.47, P<.0001). However, the presence of methodological problems in all studies gives rise to serious concerns regarding bias and confounding. Despite a statistically significant, albeit weak, association between the AGT 235T variant and hypertension that has been confirmed through sensitivity analysis, this finding has to be interpreted with caution, as the methodological weaknesses of the individual studies are likely to have biased the outcome of the meta-analysis. Clearly, more rigorous methods need to be applied in association studies on the genetics of human hypertension.

Alleles↗

PubMed2005

Genetic association studies in stroke: methodological issues and proposed standard criteria.

BACKGROUND AND PURPOSE: A large number of candidate gene association studies have attempted to identify genes implicated in stroke, but there have been few replicable and robust associations reported. SUMMARY OF REVIEW: The skantness of replicable associations partly relates to poor study design. Important methodological considerations include adequate sample size, the selection of appropriate controls, careful clinical phenotyping using standardized classification systems, and determining associations with stroke subtypes as well as stroke as a whole. The use of intermediate phenotypes, particularly carotid intima-media thickness and MRI white matter hyperintensities, appears promising. It is essential that positive associations are replicated in independent populations, and appropriate methodology is used in such studies. To be of use for others, association studies should meet certain standards. In particular, genetic association studies should enable replication studies and meta-analyses. CONCLUSIONS: This article discusses key methodological aspects and suggests standard criteria for candidate gene studies in stroke.

Biomedical Research↗

PubMedDate not supplied

School-based methylphenidate placebo protocols: methodological and practical issues.

Around 1990, psychologists and educators began to notice increasing use of methylphenidate by students. Diagnosis of attention-deficit/hyperactivity disorder by family physicians and pediatricians was most commonly based on brief behavioral descriptions by parents and, infrequently, by use of rating scales. At that time, the present researchers began to explore the development of a school-based, methodologically sound, and inexpensive method of assessing the efficacy of stimulant medications, which would ensure reasonable compliance by teachers, parents, and students in monitoring the effects of medications and placebos. This article focuses on the methodological issues involved in choosing instruments to monitor behavior, once a comprehensive evaluation has suggested trials on Ritalin. Case examples illustrate problems of teacher compliance in filling out measures, supplying adequate placebos, and obtaining physician cooperation, and with the practical issue of providing adequate data without overwhelming the time and resources of participants. Emerging school-based methodologies are discussed with recommendations for future efforts.

Attention Deficit Disorder with Hyperactivity↗

PubMedDate not supplied

Risk assessment methodology: maximum tolerated dose and two-stage carcinogenesis models.

The Committee on Risk Assessment Methodology of the Board on Environmental Studies and Toxicology of the National Academy of Sciences has considered issues related to the use of the maximum tolerated dose (MTD) in carcinogenesis bioassays and of 2-stage models of carcinogenesis. In each case, the goal has been to consider whether sufficient information is available to lead to a change in current methodology used by regulatory agencies in assessing risk. The majority of the committee favored retention of the MTD but recommended that lower doses also be used for cancer bioassays and, if the results are positive, performance of additional mechanistic studies aimed at improved extrapolation to environmentally relevant concentrations. The minority recommended that additional preliminary studies be done in order to obtain information about the highest dose relevant to extrapolation to humans for use in the cancer bioassay. Two-stage carcinogenesis models were found to be an excellent approach to increase understanding but required an extensive toxicological data base beyond that available for most chemicals. These deliberations have highlighted the value of increased understanding of the basic mechanisms of action of potential cancer-causing chemicals in order to advance the methodology of risk assessment.

Animals↗

PubMedDate not supplied

Exploration of a bayesian updating methodology to monitor the safety of interventional cardiovascular procedures.

Appropriate methods for monitoring of the safety of medical devices introduced into clinical practice have been elusive to develop and implement. A novel approach is the application of Bayesian updating, which incorporates existing knowledge regarding event rates into the estimation of risk. This framework has been shown in other domains to be data efficient and to address some of the limitations of conventional statistical methods. In this article, the authors propose a methodologic framework for developing initial prior probability distributions in risk-stratified patient groups and a mechanism for incorporating accumulating procedure safety experience. In addition, they use this methodology to retrospectively analyze the clinical outcomes of 309 patients undergoing an infrequent interventional cardiology procedure, rotational atherectomy. These exploratory analyses demonstrate the feasibility of Bayesian updating applied to medical device safety evaluation and indicate that the methodology is capable of generating stable estimates of risk in a variety of patient risk groups.

Atherectomy, Coronary↗

PubMedDate not supplied

Impact of model, methodological, and parameter uncertainty in the economic analysis of vaccination programs.

Guidelines for economic evaluations insist that the sensitivity of model results to alternative parameter values should be thoroughly explored. However, differences in model construction and analytical choices (such as the choice of a cost-effectiveness or cost-benefit framework) also introduce uncertainty in results, though these are rarely subjected to a thorough sensitivity analysis. In this article, the authors quantify the effect of model, methodological, and parameter uncertainty, taking varicella vaccination as an example. They used 3 different models (a static model, a dynamic model that only looks at the effect of vaccination on varicella, and a dynamic model that also assesses the implications of vaccination for zoster epidemiology) and 2 forms of analysis (cost-benefit and cost-utility). They also varied the discount rate and time frame of analysis. Probabilistic sensitivity analyses were performed to estimate the impact of parameter uncertainty. In their example, model and methodological choice had a profound effect on estimated cost-effectiveness, but parameter uncertainty played a relatively minor role. Under cost-utility analysis, the probabilistic sensitivity analysis suggested that there was a near certainty that vaccination dominates no vaccination, or the other way around, depending on model choice and perspective. Under cost-benefit analysis, vaccination always appeared to be attractive. Thus, the authors clearly show that model and methodological assumptions can have greater impact on results than parameter estimates, although sensitivity analyses are rarely performed on these sources of uncertainty.

Adolescent↗

PubMed2005

An assessment of the methodological quality of research published in The American Journal of Sports Medicine.

BACKGROUND: Evidence-based medicine has become a popular topic in academic medicine during the past several decades and more recently in orthopaedics and sports medicine. HYPOTHESIS: Articles published in The American Journal of Sports Medicine have shown an improvement in methodological quality in 2001-2003, compared with 1991-1993. STUDY DESIGN: Systematic review. METHODS: All articles published in The American Journal of Sports Medicine during the periods 1991-1993 and 2001-2003 were reviewed and classified by type of study. The use of pertinent methodologies such as prospective data collection, randomization, blinding, and controlled studies was noted for each article. The frequency of each article type and the use of evidence-based techniques were compared across study periods. RESULTS: Case series and descriptive studies decreased during the study period, from 27.4% to 15.3% (P = .00003) and from 11.9% to 5.6% (P = .001), respectively, of articles published. Prospective cohort studies increased from 4.7% to 14.1% (P = .000005), and randomized, prospective clinical trials increased from 2.7% to 5.9% of articles (P = .04). More studies tested an explicit hypothesis (P = .0000002), used prospective data collection (P = .000003), and used blinding (P = .02), and more studies identified a funding source (P = .004). CONCLUSIONS: Overall, there was a shift toward more prospective and randomized research designs published in The American Journal of Sports Medicine during 2001-2003 compared to 1991-1993, demonstrating an improvement in the methodological quality of published research.

Case-Control Studies↗

PubMed2003

Siting MSW landfills on Lesvos island with a GIS-based methodology.

The siting of Municipal Solid Waste (MSW) landfills in Greece is a difficult process due to land resource limitations, the country's mountainous, insular and primarily water permeable terrain as well as an exacerbated public opposition (NIMBY syndrome). A GIS-based methodology is presented here with the goal to identify and rank the candidate landfill sites for the entire island of Lesvos. The initial step of the methodology comprises a GIS-based spatial analysis that uses 10 criteria, by excluding all areas unsuitable for any waste disposal activity. The pre-selected areas are then further assessed by fieldwork and candidate landfill sites are determined. The candidate sites are ranked using 19 criteria with predefined weight coefficients on a 0 to 10 grading scale. The weight coefficients are estimated for each criterion using the Analytic Hierarchy Process (AHP), while the grading scheme is based on pre-defined guidelines. An overall suitability index is produced for each candidate site allowing comparison and best case selection. A case study for the island of Lesvos is presented here, in which eight candidate landfill sites were finally selected and ranked. Social factors highly determined the ultimate selection of the site in Lesvos, since the third rather than the first site suggested by the methodology, was finally approved by local authorities.

Decision Making↗

PubMed1989

Emerging methodologies for assessment of complex mixtures: application of bioassays in the Integrated Air Cancer Project.

The assessment of complex mixtures of environmental pollutants requires new interdisciplinary strategies. Integration of bioassay methodologies into these strategies is an important tool that provides direct evidence of the toxicity of a mixture. Short-term genetic bioassays are now widely used in the cancer assessment of complex mixtures. New and emerging interdisciplinary methodologies for assessing complex mixtures using bioassays are illustrated by the U.S. EPA's Integrated Air Cancer Project (IACP). The goals of this project are to identify the major airborne carcinogens and their emission sources and to improve the methodology and data available for human exposure and risk assessment from airborne carcinogens. The research effort is focused primarily on characterizing the impact of complex mixtures of products of incomplete combustion, including gaseous, semi-volatile, and particle-bound organic species. Short-term genetic bioassays have been integrated into several analysis strategies, including environmental biomonitoring; bioassay-directed fractionation/characterization; transformation studies; source apportionment; and exposure, dosimetry, and risk assessment.

Air Pollutants↗

PubMed1997

Evaluation of surveillance programmes for colorectal cancer in ulcerative colitis patients by case-control studies: methodological considerations.

OBJECTIVES: The evaluation of the efficacy of colonoscopy screening in patients with ulcerative colitis for colorectal cancer is associated with methodological difficulties. Case-control studies can, however, be used to determine the efficacy of such a programme and the outline of the methodology in such a programme is presented. METHODS: The randomised controlled trial provides perspective for case-control studies of screening efficacy. Cases are selected from persons who have ulcerative colitis with manifestations of colorectal cancer: for example, those who have died of colorectal cancer or have symptomatic metastases. Controls are selected from persons who have ulcerative colitis, who had been alive when the case died of colorectal cancer, and who had been subject to the risk of dying from, but had not had, colorectal cancer diagnosed when the case was diagnosed with colorectal cancer. The relevant screening history for cases begins with the case's diagnosis of ulcerative colitis and ends with the cases diagnosis of colorectal cancer; that for controls should be comparable to that for cases to avoid bias. Cases and controls are compared with respect to their "exposure" to colonoscopy during their screening histories: the occurrence of any screening, which took place during the period of time that an occult tumour (or an identifiable lesion) may plausibly have been present. CONCLUSION: The proposed methodology can evaluate the efficacy of a screening programme rapidly, practically, and ethically.

Case-Control Studies↗

PubMed1995

Primary care, avoidable hospitalization, and outcomes of care: a literature review and methodological approach.

The purpose of this article is to review the literature on the relationships between primary care, potentially avoidable hospitalizations, and outcomes of care and to develop a methodology to study these relationships. The methodological approach includes developing criteria to select medical conditions, aggregating patient claims files of both ambulatory and acute care records, and delineating episodes of care. A taxonomy of physician visits is proposed that classifies visits on the basis of type of care, type of illness, and linkage to hospital episodes. A structural model of use and outcomes is specified that includes hazard rate models to estimate the likelihood of a potentially avoidable hospitalization, primary care and ad hoc physician visits, and mortality; the latter suggests a modification of the Health Care Financing Administration methodology that includes physician visit variables.

Centers for Medicare and Medicaid Services, U.S.↗

PubMed2000

Multiple sclerosis, disease modifying treatments and depression: a critical methodological review.

BACKGROUND: Major depression affects one in two patients with multiple sclerosis (MS) during the course of their lifetime. This adds to the morbidity associated with the disorder and may contribute to an increased mortality rate because of suicide. Over the past few years, with the advent of disease modifying treatments for MS, a new concern with respect to mood has arisen, namely the possibility that some of these drugs may have depression as a clinically significant side effect. OBJECTIVE: To ascertain whether disease modifying treatments in MS are associated with the development of depression or the worsening of a depressive illness. METHODOLOGY: A MEDLINE and PSYCHLIT search focusing on depression and disease modifying treatments going back to 1993 (the publication date of the results of the first randomised, placebo controlled trial). The methodology pertaining to the assessment of depression is critically reviewed. Furthermore, a critical summary is provided of treatment modalities for the depressed MS patient. RESULTS: There are conflicting data that depression may occur with some disease modifying drugs, particularly interferon beta-1b. However, all studies reveal limitations with respect to the assessment of mood. Some reports, despite omitting details of how mentation was assessed, still comment on the presence or absence of depression. Others suffer from one or more of the following shortcomings: a failure to assess premorbid risk factors for mood disorder; a reliance on one question to assess depression; the utilisation of self report mood rating scales of questionable validity; neglecting to distinguish depression as a symptom from depression as a syndrome (i.e. major depression as defined by the DMS-1V). CONCLUSIONS: Given the many methodological pitfalls inherent in all studies to date, it is premature to conclude that disease modifying drugs are associated with depression. Evidence suggests that treatment of depression, irrespective of a putative association with a disease modifying agent, is frequently effective. This applies to pharmacotherapy or psychotherapy, although the former may be preferred should depression arise during a course of treatment with a disease modifying agent. Multiple Sclerosis (2000) 6 343 - 348

Major Depressive Disorder↗

PubMed1999

Systematic reviews and meta-analysis: a structured review of the methodological literature.

OBJECTIVE: To systematically review methods for systematic review/meta-analysis in order to identify the different methodological and statistical methods that have been proposed. A summary of the main findings is presented here, with emphasis given to health services research topics. METHODS: A thorough systematic search for methodological papers was carried out using a variety of methods, including the use of electronic databases. Approximately 1000 potentially relevant references were identified, a number of them from education, psychology and sociology. RESULTS: After briefly reviewing the procedural methods required to carry out a review, and the basic statistical methods used to combine study estimates, less established methods are discussed. These include methods for dealing with publication bias, meta-regression, meta-analysis of individual patient data, the synthesis of non-randomized evidence alone and in combination with randomized studies. Bayesian modelling and economic evaluation through meta-analysis. Recommendations for meta-analytical practice are given; these are either distilled from previous guidelines, or constructed where there appears to be a broad consensus across the literature. CONCLUSIONS: It is hoped that this review will provide a consistent and comprehensive, but concise, description of the methods available for synthesizing evidence, that it will promote better quality reviews of the results of health services research and identify specific areas which require methodological development.

Bayes Theorem↗