SEARCH · PubMed Health

Results for “Methodology”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

PubMed1999

[Methodology of diagnostic validation studies. Errors in planning and analysis].

The evaluation of diagnostic tests play an important role in clinical research. Though detailed standards have been developed for treatment evaluation, widely accepted methodological standards in diagnostic test research are still lacking. Following recent methodological research German biostatisticians usually distinguish between 4 types of diagnostic validation studies (Phase I to IV). The diagnostic value of a test can be described by indexes like sensitivity, specificity and predictive values. Sensitivity and specificity are so-called nosological probabilities whereas predictive values describe the probabilities of the disease given a positive or negative test result, respectively. These posterior probabilities depend on the prevalence of the disease in question. The methodological problems that arise in the planning of diagnostic studies differ from those encountered in treatment evaluation. This contribution presents an annotated checklist of the most important faults and shortcomings in the planning and the analysis of diagnostic validation studies. Avoiding these deficiencies may help that the study results are accepted by biostatisticians, clinicians and cost units.

Diagnostic Techniques and Procedures↗

PubMed2003

Assessing elder victimization--demonstration of a methodology.

BACKGROUND: Research on epidemiological assessment of interpersonal violence in younger adults indicates that there are essential components of interview-based queries necessary to maximize the likelihood that episodes of physical and sexual assault will be identified. These include phrasing to prime comprehensive disclosure, combined with extremely behaviorally specific descriptive questions about assault events. Such methodology permits simultaneous assessment of violence perpetrated by intimates or caregivers (i. e., abuse) as well as that perpetrated by strangers (i. e., assault), and is easily conducted via telephone. However, these strategies have not been used to simultaneously measure both abuse and assault in older adults, and some question exists as to the applicability of telephone interview techniques to geriatric populations. METHODS: A total of 106 elder respondents were surveyed, approximately half in person and half via the telephone, to evaluate the feasibility of using a telephone-based structured interview to measure both assault and abuse, as well as to screen for psychopathology in a geriatric population. In order to assure that a sufficient number of crime victims were available to assess the ability of dependent measures to detect a variety of abuse and assault types, approximately half of the group in each interview context was comprised of a victim oversample referred by local police departments, whereas the remainder of each group were randomly selected from local telephone directories. RESULTS: Data indicated that the methodology was successfully adapted to the geriatric population. Rates of lifetime and recent abuse and assault detected by in-person and telephone methods were comparable, and medical problems associated with aging posed no significant problem. CONCLUSIONS: The methodology was acceptable to older adults and very effective in identifying both abuse and assault events, perpetrator status, and psychopathology. Telephone-based interviewing appeared to be a valid alternative to in-person interviews in identifying victimization and psychopathology.

Aged↗

PubMed2004

The production and interpretation of disease mapsA methodological case-study.

BACKGROUND: The study of the spatial variation in disease incidence is a vital component of descriptive epidemiology. The production of attractive and informative disease maps complements any formal statistical analyses of spatial variations and often their visual impact will influence the recipient of the information much more than the accompanying statistics. Like any other graphical display, however, a map can both inform and mislead. METHODS: We describe methodological alternatives and pitfalls for the production of disease maps using data on recent suicides in England and Wales as an illustrative example. RESULTS: Decisions concerning the methods of mapping of suicide rates, including smoothing, choice of grouping criteria and colouring scheme dramatically influence the resulting map and how it might be interpreted by the reader. CONCLUSIONS: This study provides clinicians and other non-specialist research workers an insight into the methodological pitfalls of disease mapping and atlas production and should also act as a methodological framework for a critical appraisal of published maps and atlases.

Cause of Death↗

PubMed2002

ICP-MS multi-element analysis of wine samples - a comparative study of the methodologies used in two laboratories.

A comparison of the performance of the methodologies used in two distinct laboratories (Lab A and Lab B) for multi-element analysis in different wines was carried out. ICP-MS apparatus (quadrupole mass analyzers) of different brands as well as different wine pre-treatments were used. At Lab A, a pre-treatment by UV-irradiation was performed. At Lab B, a micro-concentric nebulizer was used for direct analysis of the wine. Twenty-six elements (Li, V, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Pb) were measured in common at the two labs in three different wine samples (red and white Bordeaux table wines and Port wine) and the results were compared. The two methodologies provided similar LODs and similar precisions, with RSDs of 0.5-5%, for most of the elements. The recovery percentages were 85-120% at Lab A for the three wines, and 78-119% at Lab B for the Bordeaux wines, validating the accuracy of the methods used. Comparable results were obtained at both labs for ten elements (Li, V, Co, Ni, Cu, Zn, Rb, Sr, Ba, and Pb) in the three selected wines; the differences were lower than 10% in most cases. For REEs, the differences observed were slightly higher, but still in the acceptable range due to the sub-ppb levels involved. The results obtained for As and Ga were not comparable, due to methodological influence. A comparison through linear least-squares adjustment indicated that the results obtained by the two labs were linearly correlated (correlation coefficient =0.997) but statistically different as the slope was slightly, but significantly different from one, for a confidence level of 95% (the intercept was statistically identical to zero in any case). In the future, strictly more identical results can be achieved by using a reference wine sample.

Mass Spectrometry↗

PubMed2001

Optimizing analytical methods using sequential response surface methodology. Application to the pararosaniline determination of formaldehyde.

Sequential response surface methodology is a general procedure to re-optimize common analytical methods on the basis of the application of the response surface methodology and of a new approach to the steepest ascent method. This procedure, which is easy to apply, consists of estimating an analytical function relating the response with the experimental parameters by means of a second-degree polynomial. Thus, a 2nd order design covering the total experimental domain is used and when a maximum is obtained, the characteristics of the response surface are confirmed using a new design, which is obtained contracting the first one. In the proposed methodology, Box-Behnken designs are used because they offer advantages in comparison with second order designs more frequently used in the steepest ascent method (central composite designs), i.e. fewer experiments are needed, they are more efficient, they can be moved through the experimental domain and they can even be easily contracted or expanded.

Journal Article↗

PubMed2003

A retrospective evaluation of the feasibility of intrapatient dose escalation as appropriate methodology for dose-ranging studies for combination cytotoxic regimens.

PURPOSE: To investigate the feasibility of intrapatient dose-escalation methodology for dose-ranging studies of conventional cytotoxics in combination. PATIENTS AND METHODS: Case records were identified for patients with ovarian cancer treated first-line with either single-agent carboplatin or carboplatin and paclitaxel in combination and routinely subjected to a 10% dose escalation in carboplatin at each cycle, towards a target day-22 neutrophil count in the range 1.0-1.5x10(9)/l and a platelet count in the range 75-110x10(9)/l, defining adequate dose. 'Entry level' carboplatin doses were in the range AUC 5.1 to AUC 7.4; paclitaxel was given at 175 mg/m(2) as a 3-h infusion throughout. All drugs were administered three-weekly. RESULTS: The distribution of carboplatin maximum tolerated doses (MTDs) indicated a wide interpatient variation, ranging from AUC 5.4 to AUC 9.8. The median MTD in those receiving carboplatin alone (AUC 6.9) was significantly lower than in those treated with carboplatin and paclitaxel (AUC 7.6) ( P=0.01). Also, paclitaxel had both neutrophil- and platelet-protective effects. CONCLUSIONS: The median MTD documented here using intrapatient dose escalation for carboplatin combined with paclitaxel is remarkably similar to that derived from conventional phase I studies. Furthermore, the striking range of carboplatin MTDs recorded in previously untreated patients may have implications for the wider development of management strategies based on the adequacy of treatment, as defined by the modest levels of dose-limiting toxicity encountered. The ready availability of an expanded set of MTD data by this methodology may also provide more compelling evidence about potential pharmacodynamic drug interactions than may be available from conventional phase I combination studies. These retrospective findings clearly justify further prospective evaluation of intrapatient dose-escalation methodology in dose-ranging studies.

Adult↗

PubMed2002

MR imaging of the articular cartilage of the knee with arthroscopy as gold standard: assessment of methodological quality of clinical studies.

The purpose of this study was to assess the methodological quality of articles addressing the value of MR imaging of the knee cartilage with arthroscopy as a standard. Relevant papers were selected after Medline review (MEDLINE database search including the terms "cartilage" "knee", "MR" and "arthroscopy"). Two observers reviewed independently 29 selected articles to determine how each study had met 15 individual standards that had been previously developed to assess the methodological quality of clinical investigations. The following criteria were met in variable percentage of articles including adequate definition of purpose (100%), statistical analysis (90%), avoidance of verification bias (86%), patient population description (83%), reference standard (79%), review bias (79%), study design (66%), inclusion criteria (41%) and method of analysis (41.5%), avoidance of diagnostic-review bias (24%), exclusion criteria (21%), indeterminate examination results (17%), analysis criteria (14%), interobserver reliability (14%) and intraobserver reliability (7%). The assessment of the methodological quality of clinical investigations addressing the value of MR imaging in the evaluation of the articular cartilage of the knee with arthroscopy as the standard of reference demonstrated that several standards were rarely met in the literature. Efforts should be made to rely on clearly defined lesion criteria and to determine reliability of the observations.

Arthroscopy↗

PubMed2002

Neurological diagnosis--aspects of quantitative sensory testing methodology in relation to hand-arm vibration syndrome.

OBJECTIVE: The objectives are to summarise the fundamental neurophysiological base for quantitative sensory testing (QST), and to discuss associated methodological and practical aspects necessary to consider with respect to applicability and reliability as a screening or diagnostic aid for vibration-induced sensory neuropathy. RESULTS: QST is the use of psychophysical techniques to measure the intensity of stimuli needed to produce specific sensory perceptions. The physical components are graded stimuli presented to the skin, eye or ear. The psychological component is mental recognition of the physical stimulus. Sensory modalities are named after the subjective feelings elicited, i.e. touch, pressure, vibration, warmth, cold and thermal pain. Since an exposure to vibration may cause symptoms and signs of sensory neuropathy in the hand and arm, the use of QST as an aid for screening and diagnosis has gained an increasing interest. The "Stockholm Workshop" classification scale for sensorineural stages also requires QST. Further, QST has also spread into many other areas, such as in the screening and diagnosis of peripheral neuropathy or polyneuropathy induced by different types of illness, exposure to toxic substances, compression and nerve entrapment. CONCLUSION: QST is in general easy to perform, usually not associated with pain (except thermal pain), suitable for screening and can readily be conducted in the field. QST is, however, known to be susceptible to the effects of multiple covariates and test methodologies. It is thus important that the relative influence on test results from all significant covariates are identified, and to standardise test methodology accordingly before QST can become a reliable and useful tool for diagnostic and screening purposes in the field of vibration-induced sensory neuropathy. The sensitivity, specificity and reliability of different methods for QST for this type of disorder is still very much unknown. Lack of normative values, standardisation of methods and of a "gold standard" for the presence of sensory neuropathy are some reasons.

Arm↗

PubMed2005

[German Acupuncture Trials (gerac) address problems of methodology associated with acupuncture studies].

OBJECTIVE: Conflicting or ambivalent findings on the effectiveness of body acupuncture in pain treatment are often attributed to flaws in study methodology. The paper describes the methodology used for the German Acupuncture Trials (gerac), which demonstrates that it is possible to design acupuncture studies in accordance with the standards of good clinical practice. METHOD: Approximately 1000 chronic pain sufferers per indication (migraine, tension-type headache, low back pain (cLBP), or gonarthrosis) are randomly allocated to one of three treatment groups (verum acupuncture, sham acupuncture, or established conservative therapy). Patients are blind to the type of acupuncture. All patients receive ten sessions of treatment (two per week) with an option of adding five more treatments in cases of slight but insufficient improvement (number of headache days or von Korff pain score). Participating physicians are in private practice, representing a variety of specialties. All have completed at least a 140-hour training course in acupuncture. Mandatory and optional verum and sham points are predefined. The point selection is individualized according to the criteria of traditional Chinese medicine (TCM). Primary outcome measures are number of headache days per month, von Korff Graded Chronic Pain Scale or Hannover Functional Ability Questionnaire (cLBP), or WOMAC scores (gonarthrosis). Data are assessed by trained telephone interviewers not involved in treatment and blind to types of acupuncture. PRESENT STATUS: Over 500 participating physicians in ten urban areas of Germany. Patient recruitment for cLBP and gonarthrosis was completed in November 2003 and March 2004 respectively. Recruitment for chronic headaches will be completed in autumn 2004. CONCLUSIONS: The gerac trials prove that it is possible to design and carry out acupuncture studies in accordance to stringent standards of methodology and clinical practice. The results will form a basis for the assessment of acupuncture effectiveness in Germany and abroad.

Acupuncture Therapy↗

PubMed2003

A comparison of the whole-body and segmental methodologies of bioimpedance analysis.

Theory supports the use of a segmental methodology (SM) for bioimpedance analysis (BIA) of body water (BW). However, previous studies have generally failed to show a significant improvement when the SM is used in place of a whole-body methodology. A pilot study was conducted to compare the two methodologies in control and overweight subjects. BW of each subject was measured by D(2)O dilution and also estimated from BIA measurements. Bland and Altman analysis was used to compare the two values of BW. The SM resulted in a small but not significantly improved "limits of agreement" of measured and BIA estimated BW (approximately 0.3). This and the results of previous studies suggest that improvements in prediction of BW obtained from application of the SM may be intrinsically small and may not justify the additional effort in application.

Body Water↗

PubMed2006

Novel semi-automated methodology for developing highly predictive QSAR models: application for development of QSAR models for insect repellent amides.

Conventional 3D-QSAR models are built using global minimum conformations or quantum-mechanics based geometry-optimized conformations as bioactive conformers. QSAR models developed using the global minima as bioactive conformers, employing the GFA, PLS and G/PLS methodologies, gave good non-validated r(2) (0.898, 0.868 and 0.922) and performed well on an internal validation test with leave-one-out correlation q(2) (LOO) (0.902, 0.726 and 0.924), leave-10%-out correlation q(2) (L10O) (0.874, 0.728 and 0.883) and leave-20%-out q(2) (L20O) (0.811, 0.716 and 0.907). However, they showed poor predictive ability on an external data set with best predictive r(2) (Pred-r(2)) of 0.349, 0.139 and 0.204 respectively. A novel methodology to mine bioactive conformers, from clusters of conformations with good 3D-spatial representation around pharmacophoric moiety, furnishes highly predictive 3D-QSAR models. The best QSAR model (model A) showed r(2) of 0.989, q(2) (LOO) of 0.989, q(2) (L10O) of 0.980, q(2) (L20O) of 0.963 and Pred-r(2) on eight test compounds of 0.845. The methodology is based on mimicking the multi-way Partial Least Squares (PLS) technique by performing several automated sequential PLS analyses. The poses/shapes of the mined bioactive conformers provide valuable insight into the mechanism of action of the insect repellents. All of the repetitive tasks were automated using Tcl-based Cerius2 scripts.

Algorithms↗

PubMed2006

A methodology for assessing the maximum expected radon flux from soils in northern Latium (central Italy).

Northern Latium (Italy) is an area where the Rn risk rate is potentially high because of the extensive outcropping of Neogene U-rich volcanics and the presence of major active tectonic lineaments. The lack of data on Rn risk rates in that area, which is undergoing major urban and industrial development, has prompted this study. It proposes a methodology to evaluate the maximum potential diffusive Rn flux from soils based on the measurement of (226)Ra, (232)Th and (40)K activities by gamma-ray spectrometry, and the measurement of main soil parameters influencing the Rn emanation. This methodology provides a simple, reliable and low-cost tool for drawing up radon flux maps useful to both public planners and private individuals, who want to operate safely in the study area. The proposed methodology may also be applied to other geographic areas outside the prescribed study area.

Air Pollutants, Radioactive↗

PubMed2005

Non-linear mixed effects modeling - from methodology and software development to driving implementation in drug development science.

Few scientific contributions have made significant impact unless there was a champion who had the vision to see the potential for its use in seemingly disparate areas-and who then drove active implementation. In this paper, we present a historical summary of the development of non-linear mixed effects (NLME) modeling up to the more recent extensions of this statistical methodology. The paper places strong emphasis on the pivotal role played by Lewis B. Sheiner (1940-2004), who used this statistical methodology to elucidate solutions to real problems identified in clinical practice and in medical research and on how he drove implementation of the proposed solutions. A succinct overview of the evolution of the NLME modeling methodology is presented as well as ideas on how its expansion helped to provide guidance for a more scientific view of (model-based) drug development that reduces empiricism in favor of critical quantitative thinking and decision making.

Algorithms↗

PubMed2006

Metalexical awareness: development, methodology or written language? A cross-linguistic comparison.

This study explores the ability to access word boundaries of pre-school children, using an on-line methodology (Karmiloff-Smith, Grant, Sims, Jones, & Cockle (1996). Cognition, 58, 197-219.), which has hardly been used outside English-speaking countries. In a cross-linguistic study in the Netherlands and Norway, four and five-year-old children were asked to repeat the last word every time a narrator stopped reading a story. In total 32 target-words were used, both closed and open class words, and both monosyllabic and disyllabic words. The outcomes in both countries were different from those of the original English study (Karmiloff-Smith et al., 1996): four- and five-year-olds were successful in only about 26% of the cases, whereas the success rate in the former English experiment was 75% for the younger and 96% for the older children. No differences were found between age groups and between open and closed class words. This methodology does reveal the ability to access word boundaries, but probably not because of the ease of the on-line methodology in itself, but rather because literacy introduces new representations of language, even in on-line processing. The outcomes implicate that the ability to mark word boundaries does not seem to be a valid indication of who is ready for reading.

Awareness↗

PubMed1996

Outcome analysis using hazard function methodology.

BACKGROUND: The hazard function is the instantaneous rate of occurrence of a time-related event, such as death. Methods exist to determine the hazard function from clinical outcome (follow-up) data, to identify risk factors for higher hazard, and to generate patient-specific predictions. In this article, hazard function methodology is extended to the arena of healthcare costs. METHODS: Using a compartmental analogue, a hazard function method is introduced to analyze patient-specific distributions of hospital costs, charges, or length of stay when these are truncated by the competing risk of in-hospital death. Another hazard function method is proposed to analyze time-related healthcare costs, exploiting weighted repeated events theory. RESULTS: Successful application of the hospital costs methodology in the hazard function domain is demonstrated for length-of-stay data after coronary artery bypass grafting. A previously reported analysis of variable morbidity from repeated thromboembolic events illustrates the weighted events methods. CONCLUSIONS: Existing hazard function methodology can be extended to analyze healthcare costs, either of a single episode of care or of multiple time-related episodes.

Aged↗

PubMed1994

A field methodology for the control of musculoskeletal injuries.

A methodology is presented for the evaluation of jobs prone to cumulative trauma disorders (CTDs) and manual material handling (MMH) injuries, which combines various tested ergonomics methodologies into a single, coherent programme. This multi-step procedure is based upon the collection of quantitative data that are used to evaluate ergonomic changes with respect to biomechanical risk, perceived comfort, productivity and quality. A method for prioritizing changes, related to cost-benefit analysis, is proposed to guide the selection of ergonomic changes in order to maximize the potential for injury reduction under specified cost constraints. The ten-step methodology has been extensively applied in industry, leading to examples and a case study.

Journal Article↗

PubMed1989

Methodological problems in cross-cultural studies of linguistic relativity.

Bloom (1981) tested a weak version of the linguistic relativity hypothesis (i.e., "Language affects thinking though it does not determine thinking") in a series of cross-cultural experiments. According to Bloom, Chinese lacks two linguistic devices that are present in English and supposed to be critical in performing theoretical thinking. It was found that the Chinese subjects were outperformed by American counterparts in all the tests designed to assess the ability of theoretical thinking. The results were taken as evidence for the weak version of the linguistic relativity hypothesis. A methodological consideration has revealed, however, that all of his experiments except one are uninterpretable because of the lack of necessary control conditions. In addition, three experiments in the present study have demonstrated that the findings in Bloom's sole interpretable experiment were artifacts due to a methodological flaw. Further theoretical considerations reveal the inadequacy of Bloom's basic methodology and the limitation in the effects of linguistic relativity that may be possible at least theoretically.

China↗

PubMed1985

Airborne fiber control in buildings during asbestos material removal by amended water methodology.

Removal of friable asbestos-containing material can cause high levels of airborne contamination. The potential efficacy of control methods recommended by the Environmental Protection Agency (EPA) was evaluated by examination of 503 air samples obtained in 40 removal projects in a number of locations. The EPA methodology with amended water for fiber emission control was utilized on all of the observed removal projects. The projects were also considered to be well controlled and the study cannot be considered representative of common work practices. The EPA amended water methodology, when effectively utilized and administered, can provide a high degree of contamination control. Mean fiber levels in the work area in this study (1.1 f/cm3) were well below those of dry removal (38.9 f/cm3) and control by application by untreated water (28.6 f/cm3). Airborne contamination was higher during bagging debris (3.8 f/cm3) than during material removal from structural surfaces. The range of fiber levels during removal was 0.0 to 37.0 f/cm3 and fibers were detected from initial barrier construction through final cleaning. Contamination was also occasionally detected outside work area containment barriers. Air sampling produced 0.0 counts in areas of obvious contamination by settled dust and debris. Control methodologies, respiratory protection, and decontamination are discussed.

Air Pollutants↗