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PubMed2005

Methodological issues in clinical trials of drug and behavior therapies.

Trials that compare drug and behavior therapies or evaluate combination therapy raise special methodological issues. This article reviews these methodological issues and, where possible, offers guidelines for addressing them. Sources of bias in the selection and recruitment of participants and in the measurement of treatment outcomes are discussed. In addition, methodological problems presented by the differing structures of behavior and drug therapy, by confounding variables, such as allegiance effects, differential expectations and preferences for drug or behavior therapy, and differential adherence with drug or behavior therapy also are reviewed. Issues in the selection of appropriate control groups are also discussed.

Behavior Therapy↗

PubMed2005

A screening methodology for the identification and ranking of infrastructure vulnerabilities due to terrorism.

The extreme importance of critical infrastructures to modern society is widely recognized. These infrastructures are complex and interdependent. Protecting the critical infrastructures from terrorism presents an enormous challenge. Recognizing that society cannot afford the costs associated with absolute protection, it is necessary to identify and prioritize the vulnerabilities in these infrastructures. This article presents a methodology for the identification and prioritization of vulnerabilities in infrastructures. We model the infrastructures as interconnected digraphs and employ graph theory to identify the candidate vulnerable scenarios. These scenarios are screened for the susceptibility of their elements to a terrorist attack, and a prioritized list of vulnerabilities is produced. The prioritization methodology is based on multiattribute utility theory. The impact of losing infrastructure services is evaluated using a value tree that reflects the perceptions and values of the decisionmaker and the relevant stakeholders. These results, which are conditional on a specified threat, are provided to the decisionmaker for use in risk management. The methodology is illustrated through the presentation of a portion of the analysis conducted on the campus of the Massachusetts Institute of Technology.

Journal Article↗

PubMed1994

QT dispersion: problems of methodology and clinical significance.

QT dispersion is defined as the difference in QT interval between the different leads of the surface 12-lead ECG. This may provide an indirect measure of the underlying inhomogeneity of myocardial repolarization, which is believed to be important in arrhythmogenesis. Methodology for determining QT dispersion varies significantly between studies, and the results of these studies need to be interpreted in light of the methodology used. Although QT dispersion is developing into an important research tool, as yet it has no established role in clinical practice. Once standardization of methodology is achieved a clinical role may emerge, particularly in the assessment of patients before and after intervention aimed at reduction of arrhythmia risk.

Anti-Arrhythmia Agents↗

PubMed2002

Methodological issues in Web-based research.

PURPOSE: To examine methodological issues associated with using the Internet and World Wide Web for scientific research, namely, issues related to the nature of the sample, the testing environment and environmental factors, privacy, and confidentiality, and response rates. METHODS: Reviews of literature and personal observation and experience. FINDINGS: Web-based research provides many advantages such as access to specific, sometimes difficult-to-find populations, speed of data access, and decreased costs for data collection and data entry. Such benefits are likely to increase as more nurse scientists use the Web for research purposes. CONCLUSIONS: Nurse researchers who use this technology must consider the methodological problems associated with Web-based methods. The research potential exists, but the methodological issues discussed in this paper are real and, if not addressed, they can seriously affect the validity of study findings.

Internet↗

PubMed2002

A new foundation for methodological triangulation.

PURPOSE: To show how triangulation with qualitative and quantitative methods can help confirm a theory to a greater degree than can either method alone. CONSTRUCT: Coherence view of theory structure and confirmation. Evidence helps confirm a theory if the theory is the most coherent way of accounting for the evidence, and one theory is more coherent than another insofar as it leaves fewer unanswered questions (and fewer unquestioned answers). METHODS: The method of this theoretical essay is analytic. Analysis of the debate over methodological triangulation reveals presuppositions about theory structure and confirmation. Well-known arguments in the philosophy of science are presented to show that the presuppositions are false. The arguments provide evidence for the construction of an alternative, coherence model of theory structure and confirmation. FINDINGS: Three consequences of the analysis are: (a) qualitative and quantitative methods do not produce theories with different structures; (b) qualitative and quantitative methods help to confirm theory in the same ways; and (c) used together, qualitative and quantitative methods can confirm a theory to a greater degree than the use of either method alone. CONCLUSIONS AND IMPLICATIONS: A coherence of model of theory structure and confirmation supports a version of the blending view of methodological triangulation. Triangulation can provide completeness, abductive inspiration, and confirmation. This version of blending provides principles for resolving issues of methodological dominance and order, and it indicates how different methods can disconfirm theory.

Humans↗

PubMed1999

Assessing research methodology training needs in emergency medicine.

OBJECTIVE: To determine the perceptions of emergency medicine (EM) academic faculty leaders and other academic emergency physicians regarding importance and knowledge of specific research methodology content areas and training priorities. METHODS: The authors conducted a confidential mail survey of 52 EM academic chairs, 112 residency directors, 116 research directors, and 400 randomly selected other members of the Society for Academic Emergency Medicine (SAEM). Respondents rated the importance of knowledge about each of 12 content areas for enhancing research productivity, rated their own knowledge of these areas, and identified training priorities. Standard descriptive statistics were used to characterize the study population; subgroup differences were examined by nonparametric statistics. RESULTS: 551 (81%) of those sampled returned surveys. Most (90%) respondents thought that knowledge about all selected content areas was important for enhancing research productivity; however, 7-37% (depending on the topic) reported little knowledge or experience in specific areas. Research directors reported highest overall knowledge levels (p < 0.001), followed by chairs, residency directors, and other SAEM members. Top training priorities (identified by all subgroups) included study planning (70%), problem identification/hypothesis construction (41%), and proposal writing (38%). CONCLUSIONS: These data support the continued need to offer broad training in research methodology, but suggest that greater emphasis be given to concepts involved in initiating and planning a study and to strengthening research proposal writing skills. These results should be of interest to academic departments who must address their own training needs, and help support the development of research methodology curricula on regional and national levels to advance the state of research in the specialty of EM.

Attitude of Health Personnel↗

PubMed1999

Cigarette smoking and periodontitis: methodology to assess the strength of evidence in support of a causal association.

Identification of the cause of the development and progression of periodontitis has received extensive attention, with notable advances over the past decade in clinical, microbiological, immunological, biochemical, and behavioral knowledge. However, it is still largely unknown which factors lead to the conversion of non-destructive forms of periodontal disease into destructive forms and disease progression. Chronic adult periodontitis is believed to be influenced by an interaction of host defense and environmental factors. Although these variables have been studied extensively, no study has employed randomized controlled prospective human or randomized controlled community intervention designs, methodologies necessary to prove a variable to be a cause of periodontitis. Owing to the absence of literature employing rigorous experimental design, this article assesses systematically observational, cross-sectional and longitudinal studies to examine the potential causal association between cigarette smoking and periodontitis. The methodology of Sir Bradford Hill's criteria for causation was used as the framework. Results suggest that cigarette smoking is causally associated with periodontitis. That is, cigarette smoking is consistently associated with an increased prevalence/severity of periodontitis and is suspected on theoretical grounds of playing a causal role. Hill's criteria provide a useful methodology to better understand the pathogenesis of periodontal diseases and may be applied to study the pathogenesis of other dental diseases as well.

Adult↗

PubMed2004

Visual evaluation in vivo of 'complexion radiance' using the C.L.B.T. sensory methodology.

PURPOSE: The aim of this study was to develop a new technique enabling visual evaluation in vivo of 'complexion radiance' based on sensory analysis, and to apply this methodology to a practical case. METHODS: This evaluation, conducted by trained assessors, was based on a visual analysis in vivo of the following seven descriptors, clearly defined by consensus: a red-pink, olive, beige, and light-pink skin coloring (C), as well as the luminosity (L), brightness (B), and transparency (T) of each subject's facial skin. The scoring of perceived skin descriptor intensity was made possible with the help of structured and analogical scales. Once the assessors were considered to be accurate and repeatable, a method was designed to evaluate a cosmetic product's effect on complexion radiance. The study was conducted on 20 healthy female subjects, between 20 and 35 years of age, who met the 'dull complexion' criteria. Product 'A' (Oligo 25, Laboratoires Vichy, Asnieres, France), formulated to improve 'complexion radiance,' was applied by each subject for 28 days, once a day in the morning, in a homogeneous fashion over the entire face, using a standard quantity and a specific way of massaging the product in. The clinical parameters were evaluated at T0, T+1 h, and at T+28 days. This test was a non-comparative open study and each subject served as her own reference. RESULTS: One hour after its application, product A produced an immediate significant effect by decreasing the complexion's 'olive' skin cast and improving its 'light-pink' coloring, its 'luminosity,' and 'brightness.' The data concerning the long-term effect of product A following 28 days of application showed that there was significant improvement in these first four descriptors, while the 'beige' skin coloring was ultimately diminished in addition. CONCLUSION: This in vivo C.L.B.T. trade mark sensory methodology is a technique enabling the visual evaluation of a product's multi-factorial claim that it improves 'the complexion's radiance.' It made it possible to show, in a reliable and repeatable fashion, the efficacy of a cosmetic product in improving the 'radiance of the complexion' of members of a test panel. This methodology also substantiated the immediate and long-term effects produced by product A, which made the skin pinker and less sallow, more luminous, more uniform (skin coloring), more regular (skin texture), and then lighter. To conclude, five descriptors out of the seven determining complexion radiance were improved.

Analysis of Variance↗

PubMed2005

Cutaneous colorimetric evaluation of serum concentrations of bilirubin in healthy term neonates: a new methodological approach.

BACKGROUND: In recent years, many non-invasive instruments have been used to examine the correlation between transcutaneous bilirubin (TcB) measurements and serum concentrations of bilirubin (SB) in newborns with a view to reducing the need for blood samples. However, their exact role has not been univocal. The aim of the present study was to determine whether non-invasive measurement of skin colour combined with appropriate clinico-statistical methodology can be used to better quantify SB in the first days of life. METHODS: The study group consisted of 49 healthy term breast-fed newborns. Skin colour was measured with a Minolta CR-300 colorimeter and measurements were made in the first 12 h of life, at 48 h and in 13 babies at 96 h. To determine changes in SB from variations in skin colour between birth and 48 h (and also 96 h in 13 cases), a multivariate linear regression model was designed. To test the generalisation power of the regression model, we examined its predictive power for SB a third time (96 h; 13/49 cases) with respect to the previous two times. RESULTS: The model made it possible to recognise increases in SB accurately with a mean absolute error 0.99 mg/dL with a good generalisation power. CONCLUSIONS: The methodological model proposed here made it possible to accurately recognise increases in SB with respect to an initial value. Provided the methodological protocol is observed, TcB can therefore be used in the screening and follow-up of neonatal jaundice.

Algorithms↗

PubMedDate not supplied

Exploitation of high-yields in hard-rock aquifers: downscaling methodology combining GIS and multicriteria analysis to delineate field prospecting zones.

Based on research work in the Truyère River catchment of the Massif Central (Lozère Department, France), a methodology has been developed for delineating favorable prospecting zones of a few square kilometers within basement areas of several hundred, if not thousand, square kilometers for the purpose of sitting high-yield water wells. The methodology adopts a functional approach to hard-rock aquifers using a conceptual model of the aquifer structure and of the functioning of the main aquifer compartments: the alterites (weathered and decayed rock), the underlying weathered-fissured zone, and the fractured bedrock. It involves an economically feasible method of mapping the thickness and spatial distribution of the alterites and the weathered-fissured zone, on which the long-term exploitation of the water resource chiefly depends. This method is used for the first time in hydrogeology. The potential ground water resources were mapped by GIS multicriteria analysis using parameters characterizing the structure and functioning of the aquifer, i.e., lithology and hydrogeological properties of the substratum, nature and thickness of the alterites and weathered-fissured zone, depth of the water table, slope, fracture networks and present-day tectonic stresses, and forecasted ground water quality. The methodology involves a coherent process of downscaling that, through applying methods that are increasingly precise but also increasingly costly, enables the selection of sites with diminishing surface areas as the work advances. The resulting documents are used for ground water exploration, although they can also be applied to the broader domain of land-use management.

Conservation of Natural Resources↗

PubMed2000

Comparison of whole body and segmental bioimpedance methodologies for estimating total body water.

We compared the whole body (WB) and segmental bioelectrical impedance analysis (BIA) methodologies in a group of healthy adults (n = 25). It has been suggested that the segmental methodology may overcome the difficulty in generating a single algorithm to predict total body water (TBW) in all groups whether healthy or not. We measured TBW, using D2O dilution, and WB and segmental BIA parameters. Cole-Cole analysis was used to determine the impedance at the characteristic frequency (Zc). The correlation between TBW (by D2O dilution) and segmental BIA measures (multiple regression, r = 0.90, p < 0.001, SEE = 3.1 L) was not significantly higher than the correlation between TBW (D2O dilution) and WB BIA measures (simple regression, r = 0.85, p < 0.001, SEE = 3.6 L). Others have observed this "lack of improvement" in a group of healthy subjects. The true value of the segmental BIA methodology may lie in applications involving groups with altered distributions of segmental and compartmental fluid.

Adult↗

PubMed2004

A methodology to determine margins by EPID measurements of patient setup variation and motion as applied to immobilization devices.

Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared with traditional margins prescribed during treatment. This method was applied to a patient cohort receiving external beam head and neck radiotherapy under an IRB approved protocol. Although the full study involved the use of an EPID-based method to assess the impact of (1) simulation technique, (2) immobilization, and (3) surgical intervention on inter- and intrafraction variations of individual and population-based CTV-to-PTV margins, the focus of the paper is on the technique. As an illustration, the methodology is utilized to examine the influence of two immobilization devices, the UON thermoplastic mask and the Type-S head/ neck shoulder immobilization system on margins. Daily through port images were acquired for selected fields for each patient with an EPID. To analyze these images, simulation films or digitally reconstructed radiographs (DRR's) were imported into the EPID software. Up to five anatomical landmarks were identified and outlined by the clinician and up to three of these structures were matched for each reference image. Once the individual based errors were quantified, the patient results were grouped into populations by matched anatomical structures and immobilization device. The variation within the subgroup was quantified by calculating the systematic and random errors (sigma(sub) and sigma(sub)). Individual patient margins were approximated as 1.65 times the individual-based random error and ranged from 1.1 to 6.3 mm (A-P) and 1.1 to 12.3 mm (S-I) for fields matched on skull and cervical structures, and 1.7 to 10.2 mm (L-R) and 2.0 to 13.8 mm (S-I) for supraclavicular fields. Population-based margins ranging from 5.1 to 6.6 mm (A-P) and 3.7 to 5.7 mm (S-I) were calculated for the corresponding skull/cervical field and 9.3 to 10.0 mm (L-R) and 6.3 to 6.6 mm (S-I) for the supraclavicular fields, respectively. The reported CTV-to-PTV margins are comparable to a value 7-15 mm based on traditional Mayo margins, but in some cases exceed the default values established in RTOG Head and Neck studies. The data suggests that the population-based margins provide sufficient coverage for the majority of the patients. However, the population-derived margins are excessive for some patients and insufficient for others, suggesting that a re-evaluation of current treatment margins for individual patients is warranted. Finally, this methodology provides direct evidence of treatment variation and thus can demonstrate with confidence, the superiority of one technique over another.

Algorithms↗

PubMed2006

Applicability of ACR breast dosimetry methodology to a digital mammography system.

Determination of mean glandular dose (MGD) to breast tissue is an essential aspect of mammography equipment evaluations and exposure controls. The American College of Radiology (ACR) Quality Control Manual outlines the procedure for MGD determination in screen-film mammography based upon conversions of entrance skin exposures (ESEs) measured with an ionization chamber (IC). The development of digital mammography has increased with the demand for improved object resolution and tissue contrast. This change in image receptor from screen-film to a solid-state detector has led to questions about the applicability of the ACR MGD methodology to digital mammography. This research has validated the applicability of the ACR MGD methodology to digital mammography in the GE digital mammography system Senographe 2000D. MGD was determined using light output measurements from thermoluminescent dosimeters (MGDTL), exposure measurements from an IC (MGD(IC)) and conversion factors from the ACR Mammography Quality Control Manual. MGD(TL) and MGD(IC) data indicate that there is a statistically significant difference between the two measurements with the Senographe 2000D. However, the applicability of the ACR's methodology was validated by calculating MGD at various depths in a 50/50 breast phantom. Additionally, the results of backscatter measurements from the image receptors of both mammography modalities indicate there is a difference (all P values < 0.001) in the radiation backscattered from each image receptor.

Algorithms↗

PubMed1996

Comparison of methodologies for synergism testing of drug combinations against resistant strains of Pseudomonas aeruginosa.

The purpose of this study was to determine if synergism was maintained for various combinations of beta-lactams with an aminoglycoside against four clinical strains and one laboratory strain of Pseudomonas aeruginosa which were resistant, according to the MICs, to the beta-lactams and/or aminoglycoside. The results from both the checkerboard and killing curve methodologies were compared. The laboratory strain (ATCC 27853) was manipulated in vitro by serial passage onto agar containing increasing concentrations of each antibiotic to select for resistance. One clinical isolate (R61) was also serially passed to raise the MIC of piperacillin from 128 to 1,024 micrograms/ml. The fractional inhibitory concentration indices for all isolates indicated indifference for all combination therapies, with values ranging from 0.6 to 3. In contrast, killing curve results for all isolates demonstrated synergism with drug concentrations at either one-fourth or one-half the MIC for each organism. The MIC of piperacillin for the laboratory-manipulated clinical isolate R61 was 1,024 micrograms/ml, and synergism was still observed with concentrations of one-half the MIC of piperacillin and amikacin. For clinical isolate R166, which was beta-lactam and tobramycin resistant, synergism continued to be demonstrated with concentrations of tobramycin (1/16 MIC) in combination with piperacillin and cefepime at 1/2 the MIC. The results of this study indicate that against P. aeruginosa, synergism is observed in spite of resistance to beta-lactams and/or aminoglycosides. Synergism appears to be maintained even at very high MICs (piperacillin, 1,024 micrograms/ml; tobramycin, 128 micrograms/ml) with drug concentrations within achievable therapeutic ranges. With current definitions of synergism there was a complete lack of correlation between the results obtained by the checkerboard and killing curve methodologies, with the fractional inhibitory concentration indices showing indifference and killing curves resulting in synergism. The methodologies and definitions of synergism or antagonism are variable and not standardized and should be reevaluated.

Aminoglycosides↗

PubMed1978

Comparison of miniaturized multitest systems with conventional methodology for identification of Enterobacteriaceae from foods.

Four miniaturized multiple test systems were compared with tube methodology used to identify Enterobacteriaceae encountered in foods. Identification aids supplied with each system were used to assign names to isolates at the species level. For the 129 strains tested, the Minitek system demonstrated a 96.9 percent agreement with reactions in tubed media. The Inolex, Analytab, and PathoTec test systems exhibited 94.3, 93.8, and 92.7 percent agreement, respectively. Analytab identified 96.1 percent of the isolates to the species level, whereas the Minitek, PathoTec, and Inolex systems were able to identify 78.3, 32.6, and 27.1 percent, respectively. The results indicate that the Analytab and Minitek systems are acceptable substitutes for the tube methodology routinely employed in identifying enterics from foods. Although the PathoTec system might be used to screen isolates for their identity, neither the presently available PathoTec nor the Inolex systems should be substituted for current methodology when definitive identification of foodborne organisms is required.

Bacteriological Techniques↗

PubMed1998

Detection of resistance to amphotericin B among Cryptococcus neoformans clinical isolates: performances of three different media assessed by using E-test and National Committee for Clinical Laboratory Standards M27-A methodologies.

Although reliable detection of resistance in vitro is critical to the overall performance of any susceptibility testing method, the recently released National Committee for Clinical Laboratory Standards M27-A methodology for susceptibility testing of yeasts discriminates poorly between resistant and susceptible isolates of Candida spp. We have previously shown that both substitution of antibiotic medium 3 for RPMI 1640 medium in the microdilution variant of the M27-A method and use of the E-test agar diffusion methodology permit detection of amphotericin B-resistant Candida isolates. To determine the relevance of these observations to Cryptococcus neoformans, we have evaluated the performances of both the M27-A and the E-test methodologies with this yeast using three different media (RPMI 1640 medium, antibiotic medium 3, and yeast nitrogen base). As with Candida, we found that only antibiotic medium 3 permitted consistent detection of resistant isolates when testing was performed in broth by the M27-A method. When testing was performed by the E-test agar diffusion method, both RPMI 1640 medium and antibiotic medium 3 agar permitted ready detection of the resistant isolates. Reading of the results after 48 h of incubation was required for testing in broth by the M27-A method, while the MIC could be determined after either 48 or 72 h when the agar diffusion method was used.

Amphotericin B↗

PubMed1996

Comparing survey data on functional disability: the impact of some methodological differences.

STUDY OBJECTIVE: To examine the impact of some differences in survey methodology on the prevalence of functional disability in population based surveys of the elderly. DESIGN AND METHODS: Nine surveys of Dutch people aged 55 years and older were compared to investigate the differences in the methods of data collection (proxy questioning, yes/no; interview versus self administered questionnaire) and construction of the questionnaire (wording of introductory text, activities, and response categories). The effect of these differences on prevalences in three domains of functional disability--activities of daily living, mobility, and communication--were studied. Both univariate analyses and multivariate logistic regression were used to quantify the methodological influences. RESULTS: No effect of proxy questioning could be shown. Self administered questionnaires yielded higher prevalences of disability than interviewer administered questionnaire--in particular for mobility (odds ratio (OR) 1.4, 95% confidence interval (95% CI) 1.3, 1.6) and communication (OR = 1.7, 95% CI 1.5, 1.9), resulting in prevalence differences of 9 and 11 percentage points respectively. Seemingly minor differences in the structure and wording of the questionnaires resulted in major differences (up to 15.6 percentage points) in prevalence estimates of functional disability. These differences were associated with the severity level of the disability indicated by the wording of the questions. CONCLUSIONS: Differences in survey methodology have a substantial effect on the prevalence estimates of disability in the elderly. These differences should be taken into account when making international comparisons and studying time trends based on survey data.

Activities of Daily Living↗

PubMed2001

Methodological quality and reporting of ethical requirements in clinical trials.

OBJECTIVES: To assess the relationship between the approval of trials by a research ethics committee (REC) and the fact that informed consent from participants (ICP) was obtained, with the quality of study design and methods. DESIGN: Systematic review using a standardised checklist. MAIN MEASURES: Methodological and ethical issues of all trials published between 1993 and 1995 in the New England Journal of Medicine, the Lancet, the Journal of the American Medical Association and the British Medical Journal were studied. In addition, clinical trials conducted in Spain and published by at least one Spanish author during the same period in any other journal were also included. RESULTS: We studied the published articles of 767 trials and found the following indicators of lower methodological quality to be independent predictors for failure to disclose REC approval or ICP: absence of concealment of allocation, lack of justification for unblinded trials, not using a treatment for the patients in the control group, absent information on statistical methods, not including sample size estimation, not establishing the rules to stop the trial, and omitting the presentation of a baseline comparison of groups. CONCLUSION: Trials of higher methodological and scientific quality were more likely to provide information about their ethical aspects.

Bibliometrics↗