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 757 records · Page 42Linked to original sources

PubMed1996

A methodological approach for exposure assessment studies in residences using volatile organic compound-contaminated water.

This paper presents a methodological approach for assessing total exposures to volatile organic compounds (VOCs) in residences using contaminated water supplies. This approach is founded on assessment of ingestion, inhalation, and dermal exposures; both long-term (i.e., 12 to 24 hr) low-level exposures and short-term (i.e., approximately 10 min) high-level exposures are considered. The methodology is based on the collection of water samples to establish the identity of the contaminants, maximum source terms, and possible dermal and ingestion exposures; integrated whole-air samples are collected to assess long- and short-term inhalation exposures; whole-air grab samples are used to confirm peak and typical inhalation exposures; and alveolar breath samples are used to confirm exposures and to estimate contaminant concentrations in the blood of the test subjects. While we do not suggest that this methodology should supersede any current investigative approach, this material is primarily offered as a consolidated reference to the many people or organizations who might contemplate a study of this type. Application of this investigative protocol should provide detailed exposure assessment information, while it supplies critical real world data for risk assessment specialists, toxicologists, and modeling experts. Data from a recent field study assessing exposures to trichloroethylene are presented to illustrate the utility and some of the limitations of this strategy.

Administration, Inhalation↗

PubMedDate not supplied

[Against abuse of methodology in psychiatry].

The author argues with methodological requirements of scientific research in psychiatry especially as far as the estimation of the value of new psychotropic drugs is concerned. Periodical withdrawal of the drugs and double blind placebo controlled challenge in endogenous depression and psychosis as well as in pediatric psychiatry and psychogeriatry are considered to be inadmissible. The author warns against the possibility of judicial claim in case of fatal complications in psychiatric patients. The abuse of methodology has been named "methodologization of psychiatry" as compared to the discredited term "politicalization of psychiatry".

Aged↗

PubMed1977

[Methodologic principles of epidemiology].

The author presented the nature of the epidemic process and formulated the methodological principles in epidemiology. In the author's opinion, the main principles were that of evolutionism and of unity (social and biological, continuous and interrupted, general and individual) in the epidemic process. The author is against bringing the special methodology only to the illustration of general materialistic dialectics laws on the example of a definite medical science. Methodological direction of the study, teaching and practice in epidemiology should be realized in organic association with the specific subject of the given science.

Epidemiologic Methods↗

PubMedDate not supplied

Costing methodology in laparoscopic surgery.

This paper provides some basic insights in economic evaluation and costing methodology by means of illustrations in the field of laparoscopic surgery. Some general methodological aspects are discussed, as well as their impact on the calculation of both societal and hospital costs of medical interventions. First, Health Care Technology Assessment is described, and several techniques of economic evaluation in health care are situated in this area. Two fundamental concepts in costing analysis are discussed : opportunity costs and marginal (or incremental) analysis. Furthermore, it is argued that in designing an economic analysis, sufficient attention should be given to delineating the alternative treatment options and to determining the perspective from which the study is performed (patient, hospital, insurer, society,...). Subsequently, it is argued that all price and wage data for activities performed within a certain period should apply to the same time period. Finally, in order to facilitate overview, re-calculation and interpretation of cost data, it is advised to distinguish fixed from variable costs. Different categories of societal costs are described, as well as a number of methodologies for their evaluation. In calculating hospital costs, the costs of all different resources used (e.g. buildings, equipment, staff, materials) must be identified precisely. The issues of annuitising initial investment expenses, calculating operating and maintenance costs, and allocating labour and overhead costs are discussed. Finally, it is argued that, in all studies, it should be investigated whether the results of the economic analysis are robust to the models' assumptions, by means of sensitivity analysis. This paper provides a practical toolkit for medical doctors, to allow a correct understanding and critical analysis of economic literature in the field of laparoscopic surgery.

Cost-Benefit Analysis↗

PubMed1997

Clinical prediction rules. A review and suggested modifications of methodological standards.

BACKGROUND: Clinical prediction rules are decision-making tools for clinicians, containing variables from the history, physical examination, or simple diagnostic tests. OBJECTIVE: To review the quality of recently published clinical prediction rules and to suggest methodological standards for their development and evaluation. DATA SOURCES: Four general medical journals were manually searched for clinical prediction rules published from 1991 through 1994. STUDY SELECTION: Four hundred sixty potentially eligible reports were identified, of which 30 were clinical prediction rules eligible for study. Most methodological standards could only be evaluated in 29 studies. DATA ABSTRACTION: Two investigators independently evaluated the quality of each report using a standard data sheet. Disagreements were resolved by consensus. DATA SYNTHESIS: The mathematical technique was used to develop the rule, and the results of the rule were described in 100% (29/29) of the reports. All the rules but 1 (97% [28/29]) were felt to be clinically sensible. The outcomes and predictive variables were clearly defined in 83% (24/29) and 59% (17/29) of the reports, respectively. Blind assessment of outcomes and predictive variables occurred in 41% (12/29) and 79% (23/29) of the reports, respectively, and the rules were prospectively validated in 79% (11/14). Reproducibility of predictive variables was assessed in only 3% (1/29) of the reports, and the effect of the rule on clinical use was prospectively measured in only 3% (1/30). Forty-one percent (12/29) of the rules were felt to be easy to use. CONCLUSIONS: Although clinical prediction rules comply with some methodological criteria, for other criteria, better compliance is needed.

Decision Support Techniques↗

PubMed1997

Novel methodology for echocardiographic quantification of cardiac shape.

BACKGROUND: Left ventricular (LV) shape is a major determinant of cardiac physiology with important prognostic implications. Current techniques are limited in their ability to characterize shape. Regional curvature analysis is a recently developed method that is free of idealized shape assumptions and is applicable globally or regionally. OBJECTIVE: To measure the change in regional curvature from diastole to systole to determine whether modifications of this methodology can be applied to study LV shape noninvasively, and to compare this method with other shape analysis methods. ANIMALS: Seventeen normal dogs underwent transthoracic echocardiography. LV dimensions were measured at end-diastole and end-systole. LV endocardial outlines were traced from apical four-chamber views. LV short to long axis (D/L) ratios and eccentricity index (E) were calculated. Regional curvatures were determined using customized software. Reproducibility of regional curvature was also determined. MAIN RESULTS: LV regional curvature values were consistent among animals at diastole and systole in all areas. Regional curvature showed divergence in different areas. D/L ratios showed a 7% decrease from diastole to systole, whereas E demonstrated a 10% increase. However, regional curvature exhibited a 39% change, suggesting that this methodology is more sensitive. Duplicate curvature values from same or different cardiac cycles were highly reproducible. CONCLUSIONS: Quantitative regional curvature analysis can be applied with echocardiography to study LV shape. This methodology is more sensitive than current methods, is reproducible and may be applicable to the noninvasive study of shape changes in cardiac disease.

Analysis of Variance↗

PubMed1997

Methodological findings and considerations in measuring colorectal epithelial cell proliferation in humans.

The methodological issues for measuring colorectal epithelial cell proliferation, an intermediate end point for studies of colon neoplasia, in epidemiological studies are deceptively numerous and complex, with few methodological data available. Accordingly, during our experience with measuring colorectal epithelial cell proliferation from nearly 500 participants attending over 1300 study visits over a 6-year period, we recorded data on a variety of measurement variations. Methods investigated included rectal biopsy technique, general histological and labeling procedures [including the tritiated thymidine, 5-bromodeoxyuridine (BrdUrd), and the proliferating cell nuclear antigen (PCNA) immunohistochemical techniques used to label S-phase cells in colonic crypts in rectal biopsy specimens], biopsy scoring procedures, and summary scoring methods. Findings include that the PCNA technique was the simplest, most economical, and least time-consuming. The BrdUrd labeling failure rate was 15% versus < 1% for PCNA. The percentage of labeled cells (labeling index) was highest using PCNA in biopsies processed without prior incubation, intermediate using PCNA in biopsies processed with prior incubation as for BrdUrd, and lowest using BrdUrd. The percentage of labeled cells that were in the upper 40% of the crypt (phi h) was higher using BrdUrd than PCNA; visit-to-visit correlations were higher using PCNA (r = 0.51 versus 0.35), and visit-to-visit variability was lower and between-person variability was higher using PCNA. Intra- and inter-rater reliabilities for the techniques were comparable (PCNA intra-rater r = 0.93, inter-rater r = 0.92). The PCNA technique, compared to the BrdUrd technique, is more feasible and reliable, provides a more accurate estimate of the labeling index, and cell proliferation measures determined with PCNA have statistical properties that are generally more favorable for detecting differences in clinical trials. Thus, the PCNA technique may be preferable to techniques requiring incubation of biopsies. Other methodological findings lead us to recommend that, for larger studies measuring colorectal epithelial cell proliferation on outpatient rectal biopsies, biopsies should be taken 10 cm above the anus using a flexible, preferably jumbo cup, endoscopic forceps through a rigid sigmoidoscope, and histological sections should be 3 microns thick taken 50 microns apart.

Analysis of Variance↗

PubMed1998

[Medical-scientific research in the elderly in The Netherlands; historic milestones and methodological problems].

OBJECTIVE: To describe the methodological development of medical research regarding elderly subjects in the Netherlands. DESIGN: Descriptive. SETTING: Nijmegen University, the Netherlands. METHOD: All research on aging published in the Netherlands Tijdschrift voor Geneeskunde (Dutch Journal of Medicine) starting from its first volume in 1857 up to 1983 was studied. Selected were those articles in which new research methods were introduced. Next, six pioneering researchers in geriatrics were interviewed on the methodological development of geriatric research and on the problems they encountered in their own research. RESULTS: Research started with studies on age-associated diseases such as prostatism, presbyacusis and senile dementia. It was only after a considerable delay that new diagnostic instruments such as electrocardiography and new research designs such as randomized trials found their way into research on elderly patients. The development of a questionnaire on the health of the elderly, the introduction of the concept of activities of daily living and of diagnostic instruments in the field of psychogeriatrics were important steps that made possible current geriatric research. From the outset, researchers encountered methodological problems still relevant in current research and caused by characteristics of geriatric patients: frailty, high prevalence of comorbidity, coexistence of physical, psychological and social problems, and large interindividual differences.

Activities of Daily Living↗

PubMed1998

The content and methodology of research papers published in three United Kingdom primary care journals.

BACKGROUND: With the expansion of academic departments, the National Research and Development initiative, and the Culyer report, United Kingdom (UK) general practice research is undergoing a period of investment and change. AIM: To examine the content and methodological quality of UK-published general practice research, and in particular to focus on the quantity and proportion of studies that were of high methodological quality, namely randomized controlled trials (RCTs). METHOD: We manually searched three UK-published journals over a five-year period: the British Journal of General Practice (BJGP), Family Practice, and the British Medical Journal (BMJ), which has a section devoted to general practice research. Studies were classified according to the International Classification of Health Problems of Primary Health Care (ICHPPC-2). RESULTS: Nearly half of published studies in UK primary care journals were concerned with either organization and administration issues in primary care or social problems (509 studies, 48%). Just over half were either qualitative studies or surveys of opinion or attitudes (528 studies, 50%). The overall number of RCTs was low (67 studies, 6%), and the proportion published has not changed over time (chi 2 for trend = 3.79, df = 1, P = 0.051). In contrast to surgical journals, nearly one-fifth of studies in general practice followed a longitudinal design (186 studies, 18%). CONCLUSIONS: The content and design of published general practice research in the UK is varied and broad. The most robust methodological design should be the aim of all prospective researchers in general practice.

Humans↗

PubMed1998

The dependency of calcium set point on basal plasma calcium in dialysis patients: a better explanation for the discrepancies regarding its link with PTH secretion than methodological differences.

BACKGROUND: The increase of calcium (Ca) set point in uremic hyperparathyroid patients and its decrease with calcitriol therapy are controversial. Besides methodological differences regarding the experimental protocol for obtaining the sigmoidal curve, mainly differences in definitions of maximal PTH (peak or steady value) and of calcium set point itself have been proposed for the discrepant conclusions. However, two other explanations are possible: the various aluminum load of the patients and the dependency of Ca set point upon the basal plasma ionized calcium (PCa). PATIENTS AND METHODS: Therefore the Ca set point was measured in 2 groups of patients on maintenance dialysis never exposed to aluminum, one of 7 patients with normosecretion of PTH (NPT) and the other of 8 patients with hyperparathyroidism (HPT) before and after 3 intravenous administration of 4 microg of alfacalcidol in a week. The sigmoidal curve was established during a zero Ca dialysis, without Ca replacement for the first 90 minutes and with intravenous infusion of 41 mmoles of Ca during the 150 last minutes. The curvilinear decrease of PCa induced a peak of PTH followed by a decrease while PCa was still decreasing up to the 90th minute. Therefore PTHmax was taken both at the peak and at its lower value observed at the 90th minute (steady PTHmax). Experimental determinations of the Ca set point were made using both definitions of Brown and Felsenfeld and both PTHmax values. In basal conditions, while using any of the values given by the same calculation methodology, Ca set point was not different in NPT and HPT patients. After alfacalcidol, no change in plasma PTH nor in Ca set point was observed in HPT patients. In contrast, in NPT patients alfacalcidol induced a significant decrease of plasma PTH concentrations in association with an increase in basal PCa and in Ca set point, whatever the definitions of the latter and of PTHmax. Calcitriol induced changes in Ca set point and basal PCa were correlated. CONCLUSIONS: 1) In normocalcemic dialysis patients never exposed to aluminium hyperparathyroidism is not explained by an increased Ca set point 2) Calcitriol suppressive effect on PTH secretion is neither explained by a decrease in Ca set point. 3) Ca set point as measured in vivo does not reflect an intrinsic characteristic of the parathyroid glands since it varies with basal PCa. Better than methodological differences, this dependency may explain the discrepant conclusions between the various clinical investigations.

Aluminum↗

PubMed1998

[General human pathology and methodology of medicine].

The most important methodological problems of modern medicine, such as sociobiological relationships, the methodological and social aspects of teaching of normalcy, health, and diseases, physiological/pathological ratios, determinism, casualty and etiology, a part and the whole, regional and systemic in the light of the systems approach, diagnosis in the light of conception, etc. To solve these problems is inseparably linked with the assessment and analysis of general theoretic and methodological issues outlined in the "General Human Pathology" (the 2nd edition) by D. S. Sarkisov, M. A. Paltsev, and N. K. Khitrov (Moscow, 1997). The work is a peculiar unit of a paper and a review.

Humans↗

PubMedDate not supplied

[Multicenter trials in the treatment of depression: some methodological issues].

In recent year, multicenter psychopharmacological trials have met an increasing interest since through them it has become easier, in a relatively short time, to collect large samples of patients. Methodological problems common to all psychopharmacological trials may be sharpened in this kind of investigation. Others, that are specifically related to multicenter studies, may also arise. Methodological difficulties addressed in this paper are those related to patients selection procedure, to strategies for data analysis and to issues about design or management of the study. Strictly speaking, the results of a such a trial could only be generalised to patients exhibiting the characteristics of the studied sample. Moreover, before pooling the data obtained at each center, preliminary analyses should demonstrate that centers do not differentiate themselves on the basis of patient characteristics. The new drug has to be compared to both a placebo and a reference compound. In this way, and through the replication of the expected difference between the placebo and the reference drug, the methodological validity of the trial could be ascertained. The treatment with a placebo is warranted by the facts that illness natural course and non specific treatment effects have to be taken into account. Satisfactory levels of inter-rater reliability have to be achieved and maintained through training sessions with the participation of all the centers involved in the trial. Statistical analyses generally focus on the intent to treat sample. However, due to the delayed activity of antidepressant drugs, efficacy analyses could be limited to patients treated at least 14 days. Multivariate analysis of variance is particularly well suited for data analysis but can be invalidated by an excess of dropouts. To overcome this problem, other techniques such as survival analysis and random regression models have been proposed. This latter procedure seems to be particularly promising for analysing data of multicenter trials since it can assess treatment difference while adjusting for inter-center variability.

Antidepressive Agents↗

PubMed1991

The impact of forecasting methodology on the accuracy of national population forecasts: evidence from the Netherlands and Czechoslovakia.

"This study considers the accuracy of national population forecasts of the Netherlands and the Czechoslovak Socialist Republic.... We look at the demographic components employed in each forecast, the procedure to extrapolate fertility and the level at which assumptions for each component are formulated. Errors in total population size, fertility, mortality and foreign migration, and age structure are considered. We discuss trends in errors and methodology since 1950 and compare the situations in the two countries. The findings suggest that methodology has only a very limited impact on the accuracy of national population forecasts."

Czechoslovakia↗

PubMed1993

Vasectomy and prostate cancer risk: methodological review of the evidence.

Two recent studies have reported a significantly elevated risk of prostate cancer among vasectomized men. To assess whether the new results conflict with earlier studies that found no significant overall association, and, if so, whether such a conflict could have a methodological basis, we reviewed the six major epidemiological studies of this topic. Statistical analysis revealed significant (p < 0.01) heterogeneity among the associations in the six studies, attributable to one of the recent studies. Scrutiny of the studies for fulfillment of eight methodological standards for scientific validity revealed that no study completely fulfilled more than four standards, and that all studies were deficient in avoiding detection bias and obtaining accurate vasectomy histories. Our review indicates that the evidence on this topic is indeed conflicting, that the quality of the evidence does not resolve the conflict, and that future studies of this topic, designed to ensure scientific credibility of results, are needed.

Adult↗

PubMed1997

Methodological issues in the evaluation of the quality of public health nursing: a case study of the maternal and child health centres in Hong Kong.

The demand for the evaluation of the quality of patient and client care has increased in public health nursing as in all disciplines of nursing. In Hong Kong this demand led to the development of a collaborative study with the Department of Health to evaluate the quality of public health nursing in the maternal and child health centres. A multiple case study design was developed to undertake the research using both qualitative and quantitative methods of data collection. The findings from the study demonstrated not only implications for clinical practice which have been reported elsewhere, but also methodological issues for the evaluation of care. These findings indicate three major issues for consideration. The first issue is that of the cultural context of care which includes perceptions of care such as demands on the service and expectations of care. The second issue is the use of health data, including both the methods of recordings as well as the sources of data. The final issue is that of the method of data collection, in particular the implications of the use of language in data collection tools. The findings suggest that both the use of professional language and the need for translation have implications for data collection methods. Indeed in the author's view the development of methodologies for the evaluation of care must address culturally specific issues, particularly where English is not the first language of subjects in the study. In addition the use the use of language in the method of data collection highlights more general issues raised by the use of translation in the collection and analysis of qualitative data.

Attitude of Health Personnel↗

PubMedDate not supplied

A methodology for segregating rural-urban mortality estimates.

" This study deals mainly in estimating rural/urban mortality differentials in countries where death registration by place of residence is nonexistent or inadequate. The methodology was applied to Philippine death registration data of 1975 and the result was compared to those estimates obtained by applying Brass, Sullivan and Trussell techniques on the 1978 World Fertility Survey data of children ever born and children still living. Basically, the methodology allocates death registration data to rural and urban areas by applying to each geographic unit several indices of urbanization. This is possible when death registration in developing nations is tabulated by geographic units, such as province, region, state, island, etc. The underlying assumption is that some geographic units are more urbanized than others. The process involves identification of these units and combining them into urban areas. This likewise implies that the remaining areas can be combined as rural." (SUMMARY IN FRE AND ITA)

Asia↗

PubMed1991

Evaluation of the EPI survey methodology for estimating relative risk.

Precision in estimation of relative risks using a standardized sampling method proposed by the WHO Global Programme on AIDS was evaluated using a Monte Carlo model simulating actual populations; the proposed survey design represents a modification of the methodology used by the WHO Expanded Programme on Immunization (EPI) to estimate immunization coverage among children. This study suggests that in actual populations the proposed survey strategy is a reasonable alternative to the use of simple random sampling (SRS) at the second stage of cluster sampling. Although varying such population characteristics as the seroprevalence rate, nonresponse rate, and rate of misclassification of exposure failed to demonstrate a clear advantage of one method over the other, the added cost and difficulty of implementing SRS under field conditions warrant further consideration of the EPI-like methodology for use in estimating relative risks.

Adult↗

PubMedDate not supplied

The relationship between passive smoking and child health: methodologic criteria applied to prior studies.

Most studies investigating the relationship between passive smoking and child health have found a significant effect on respiratory illness and lung function. The wide range of findings is based on diverse types of studies which use multiple criteria for respiratory illness, smoke exposure, and outcome variables. The aim of this review is to examine these studies in an attempt to focus attention on methodological criteria which relate to the strength of the association and likelihood of a causal relationship between passive smoking and child health. We examined 30 studies and judged their strength by examining (1) data collection, (2) surveillance bias, (3) definition of amount of smoking, (4) definition of illness, (5) detection bias, (6) outcome variables, and (7) control for confounding variables. Poor scores were noted in the use of "blinded" data collectors (37 percent of possible score), use of multiple specific outcome variables (51 percent), and definition of the quantity of smoking (56 percent). Good scores were noted in the detection of illnesses (98 percent), recall by study subjects of symptoms of illness (71 percent), control for confounding variables (81 percent), and definition of illnesses (86 percent). The range of scores for the studies was from 44 percent to 89 percent (of the total possible score). While a few well-designed studies demonstrate a significant effect of passive smoking on child health, most studies had significant design problems that prevent reliance on their conclusions. Thus, many questions remain, and future studies should consider important methodological standards to determine more accurately the effect of passive smoking on child health.

Child↗