Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “cost of complexity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 289 records · Page 16Linked to original sources
PubMed2004

Novel hand-held device for exhaled nitric oxide-analysis in research and clinical applications.

Changes in expired nitric oxide (NO) occur in airway inflammation and have proved to be important in the monitoring of inflammatory disease processes such as asthma. We set out to develop a novel hand-held NO-analyzer with a performance comparable to the present more costly and complex chemiluminescence instruments. The new device is based on a specially designed electrochemical sensor, where we have developed a novel sampling and analysis technology, compensating for the relatively slow response properties of the electrochemical sensor technique. A Lowest Detection Limit in NO-analysis from reference gas tests of less than 3 ppb and a response time of 15 seconds together with an average precision in human breath measurements of 1.4 ppb were obtained. We also show an agreement with the existing 'gold standard' FENO measurement technique, within 0.5 ppb in a group of 19 subjects together with a high linearity and accuracy compared to reference gases. The new analyzer enables affordable monitoring of inflammatory airway diseases in research and routine clinical practice.

Asthma↗
PubMed2005

Method validation and measurement of biomarkers in nonclinical and clinical samples in drug development: a conference report.

Biomarkers are increasingly used in drug development to aid scientific and clinical decisions regarding the progress of candidate and marketed therapeutics. Biomarkers can improve the understanding of diseases as well as therapeutic and off-target effects of drugs. Early implementation of biomarker strategies thus promises to reduce costs and time-to-market as drugs proceed through increasingly costly and complex clinical development programs. The 2003 American Association of Pharmaceutical Sciences/Clinical Ligand Assay Society Biomarkers Workshop (Salt Lake City, UT, USA, October 24-25, 2003) addressed key issues in biomarker research, with an emphasis on the validation and implementation of biochemical biomarker assays, covering from preclinical discovery of efficacy and toxicity biomarkers through clinical and postmarketing implementation. This summary report of the workshop focuses on the major issues discussed during presentations and open forums and noted consensus achieved among the participants on topics from nomenclature to best practices. For example, it was agreed that because reliable and accurate data provide the basis for sound decision making, biomarker assays must be validated in a manner that enables the creation of such data. The nature of biomarker measurements often precludes direct application of regulatory guidelines established for clinical diagnostics or drug bioanalysis, and future guidance on biomarker assay validation should therefore be adaptable enough that validation criteria do not stifle creative biomarker solutions.

Biological Assay↗
PubMed1999

Statistical considerations in infant nutrition trials.

Infant nutrition trials usually require developmental follow-up, often to 18 mon, and sometimes beyond reading ability at age 7 yr. They are therefore logistically complex and costly, and should be conducted to a high statistical standard. With examples, we focus on: good practice in nutrition trials and the goal of a common protocol; how to set plausible trial targets and to work out trial size accordingly; statistical observations on assessing visual maturation; and methods of randomization, including the method known as minimization, which can be adapted to select more appropriately a comparison cohort of breast-fed infants. We end with discussion of analysis and reporting standards, including the give-aways (or tell-tale signs) to be on the look out for. A Cochrane Collaboration for systematic review of randomized trials of infant nutrition is proposed.

Child↗
PubMed2005

Advances in therapeutic approaches to ulcerative colitis and Crohn's disease.

Advances (from 2004 to 2006) in the use of conventional agents include the molecular mechanisms of action, which have implications for monitoring (azathioprine and thioguanosine triphosphate) and chemoprevention (mesalamine and peroxisome proliferator activated receptor gamma). Advances in biotherapy include new data on monoclonal antibodies (infliximab in ulcerative colitis, adalimumab, certolizumab pegol, fontolizumab, selective anti-adhesion molecules, and others), antisense oligonucleotides, the development of small molecules, and cell-gene therapy (including helminth ova, leukocytapheresis, stem cell transplantation, and probiotic intestinal mucosal delivery systems). However, management of inflammatory bowel disease is about more than drug therapy, dose, and timing. The goals remain induction of remission, limitation of side effects, modification of the pattern of disease, and avoidance of complications. With the cost and complexity of biotherapy, inflammatory bowel disease is emerging as a specific subspecialty.

Colitis, Ulcerative↗
PubMed1989

Late follow-up of 781 patients undergoing percutaneous transluminal coronary angioplasty or coronary artery bypass grafting for an isolated obstruction in the left anterior descending coronary artery.

Seven hundred eighty-one patients with isolated left anterior descending coronary atherosclerosis treated with either coronary artery bypass grafting or percutaneous transluminal coronary angioplasty between January 1980 and December 1984 were studied to determine late survival and event-free survival. Follow-up was complete in 775 patients (99.4%). Actuarial survival at 5 years was 98% for surgical patients and 95% for angioplasty patients (p = 0.02). Five-year event-free survival (freedom from myocardial infarction, bypass grafting, angioplasty, and death) was 93% for surgical patients and 62% for angioplasty patients. This study suggests that the higher initial cost and complexity of bypass surgery may be justified by superior long-term results.

Angioplasty, Balloon, Coronary↗
PubMed1994

Dual-balloon progressive coronary dilatation catheter: design and initial clinical experience.

As newer interventional devices continue to enter the marketplace, balloon angioplasty remains the standard by which all devices are judged with regard to both safety and efficacy. It has been observed that predilating a stenosis with a small balloon followed by dilatation with an optimally sized larger balloon creates a more controlled arterial injury, reduces complications, and thus improves success rates. Exchanging two balloons for each lesion, however, increases the complexity and cost of the procedure in addition to increasing the amount of time required and the amount of radiation exposure. Therefore an "over-the-wire" dual-balloon catheter was developed with a small distal balloon and a larger proximal balloon on a 2.9F shaft to allow progressive coronary dilatation with a single device, without necessitating a balloon catheter exchange. The device was used successfully in 45 of 47 patients (78 lesions). The two failures were related to an inability to cross the lesion in one and failure of the device in the other. Twenty-one patients (47%) underwent a multivessel procedure. There were 29 left anterior descending/diagonal, 17 circumflex/marginal, 20 right coronary artery/posterior descending artery, and 10 vein graft lesions. The device was successfully delivered in the native anatomy to 12 distal, 27 mid, and 27, proximal lesions of which nine were osteal, for a procedural success rate of 97%. The mean stenosis was reduced from 80.7 +/- 11.5% to 15.2 +/- 11.9%. There were no major dissections, only 9 (11.2%) minor dissections, and no myocardial infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Upright tilt testing in evaluating syncope: a comprehensive literature review.

BACKGROUND: Upright tilt testing is widely utilized for the evaluation of syncope. Recently, there have been concerns about the specificity and the lack of standard methodology for this test. The purpose of this study was to summarize the methodologies of upright tilt testing in patients with syncope of unknown origin, the responses in control subjects, and the reproducibility and selection of therapy. METHODS: We used MEDLINE to search English language articles from 1966 to June 30, 1992. Studies were included for content review if they met our inclusion criteria. Data were extracted from each article by two trained reviewers using a predesigned data collection instrument. RESULTS: Thirty-three articles were included for review. There was considerable variability in the methodologies of tilt testing. Overall positive responses were reported in 49% of patients in passive-only studies as compared with 66% of patients in studies using isoproterenol with tilt testing. The percentage of positive responses increased with increasing angle of testing for studies using isoproterenol. There was no relationship between the percentage of positive responses and the maximum dose of isoproterenol. When we compared the results of passive studies that tested patients for 60 minutes at 60 degrees with the results of isoproterenol studies that tested patients at 60 degrees, the positive rate for passive-only studies was 54% as compared with 52% for the isoproterenol studies. The percentage of positive response in control subjects with passive studies was 8.9% (range 0% to 100%), and with isoproterenol 27% (range 0% to 65%). Other groups of patients showed a wide range of positive responses (range 0% to 83%). Reproducibility ranged from 71% to 87%. Upon retesting while the patient was receiving therapy, 90% of 115 positive patients were negative. Eighty-nine percent of 105 positive patients who were receiving therapy and followed for a mean time of 12 months were free of syncope. CONCLUSIONS: This review strongly suggests that isoproterenol may not have an effect on stimulating vasovagal syncope during upright tilt testing. We recommend protocols of passive tilt testing procedures at 60 degrees for 45 to 60 minutes since the overall specificity is higher with this method. The use of isoproterenol during tilt testing adds to the cost and complexity of the test, is associated with a higher rate of false-positive responses, leads to potential complications, and, thus, should be avoided.

Humans↗
PubMed1976

Period analysis of the electroencephalogram.

A program is described which utilizes the Digital Equipment Corporation LINC-8 computer with 4K of memory to process the electrical activity of the brin into a set of meaningful statistics. The program provides an efficient methol of obtaining spectoral information concerning the EEG without the associated cost or complexity of conventional power spectrum techniques. The combination of utilization of a small laboratory computer with an easily programmable method provides an approach for automated EEG analysis which is within the financial and technical scope of most small hospital EEG laboratories;

Computers↗
PubMed1978

Evoked potential measurement and analysis on a small laboratory computer.

A program is described for the collection and subsequent analysis of somatosensory evoked potentials using a LINC-8 computer. The program allows simple evoked-potentials analysis in centers where a small laboratory computer may be available but sophisticated instrumentation such as a computer of average transients is not available. This program provides an efficient method of easily obtaining information concerning the conduction pathways of the nervous system as well as the cerebral function; the program can be implemented on small laboratory computers which most hospitals currently own, without the associated cost or complexity of additional hardware in the laboratory. Combining utilization of a small laboratory computer with an easily programmable method provides an approach for evoked potential analysis which is well within the financial and technical scope of most neurophysiology laboratories.

Computers↗
PubMed1992

An automated method for the analysis of trabecular bone structure.

Trabecular structure as well as bone mass is important in studies of bone disease and fracture. An automated method for the direct analysis of two-dimensional trabecular micro-anatomy and its application to human iliac crest bone biopsies is described. Compared with established methods which require expensive equipment and complex software, costs have been reduced and availability increased by using an image analyzer driven by a microcomputer. Routine histological sections are accepted and an editing function enables the removal of artifacts. An elastic window allows field expansion for large specimens. The program enables the rapid assessment of the bone volume and trabecular surface from the intact image, followed by image skeletonization and the deduction of the trabecular length, number, character, and spacing together with the number of trabecular junctions and discontinuities; the trabecular width is calculated indirectly. Images may be stored to disk or printed as permanent records for diagnostic or research purposes.

Biopsy↗
PubMed1994

Effectiveness of infertility treatments: choice and comparative analysis.

Choice of infertility treatments usually depends on a balance of the chances of conceiving with or without treatment, and with more or less complex and costly treatments, and on other factors such as duration of infertility and the woman's age. Pregnancies often occur independent of treatment and prospective controlled trials are needed. Comparability between reported results requires pregnancy and birth rates to be calculated in a time-specific or cycle-specific way. Cumulative rates are preferable to account for the usual tendency of fecundity to fall progressively. This review focuses on such published data in order to assess the relative effectiveness of treatments, both conventional and assisted conception methods. The main conclusions are: (1) The only treatments that can achieve a normal chance of pregnancy are the ovulation induction methods in cases of oligomenorrhea/amenorrhea, and the assisted conception methods for other female causes and unexplained infertility. (2) Tubal/pelvic infective damage and endometriosis require new severity classifications which are sensitive to functional potential before and after surgery, and in vitro fertilization (IVF) would often be indicated as the primary choice. (3) Duration of unexplained infertility determines the need and therefore benefit of any of the treatments used, of which the assisted conception methods are by far the most effective. (4) Interpretation of reported results of treatments for 'male factor' infertility is critically affected by the diagnostic accuracy of defining sperm dysfunction. (5) In cases of well-defined sperm dysfunction there is little or no therapeutic benefit to the chance of natural conception, nor by intrauterine insemination; there is moderate success by IVF, but no proven benefit over standard IVF by any micromanipulative method except probably intracytoplasmic sperm injection.

Female↗
PubMed1986

A simple, computer-assisted assay to detect isotype-specific regulation of human immunoglobulin synthesis.

A simple, reliable, and computer-assisted assay has been developed to quantitate isotype-specific regulation of human immunoglobulin synthesis in vitro. The assay utilizes three separate human lymphoblast or myeloma cell lines, which secrete human immunoglobulins IgA, IgG, and IgE. Culture supernatants from 96-well tissue culture plates are then assayed for IgA, IgG, and IgE by a solid-phase enzyme-linked immunosorbent assay (ELISA) on a microtiter plate. Data collection and analysis is performed with the aid of computer programs designed for this assay. This assay has several advantages over other immunoglobulin regulation assays: no radioisotopes are used, thereby reducing cost and complexity; results are directly collected and quantified by computer analysis; the entire assay is completed in 3 days; reliability and reproducibility are increased by the use of established human cell lines; and co-culturing all three immunoglobulin-producing cell lines provides convenient internal controls for isotype specificity.

Cell Line↗
PubMed1992

Use of a scanning laser three-dimensional digitizer to evaluate dimensional accuracy of dental impression materials.

A steel die was machined to represent a dental arch with teeth prepared for complete crowns. Impressions and casts were made from the die, and critical dimensions were measured by two methods--one using micrometers and the other a scanning laser three-dimensional (3-D) digitizer. The digitizer recorded measurements were more precise than the micrometer's and virtually eliminated operator error because the acquisition of data was automatic. The digitizer could also be useful for high-precision analyses of the dimensional accuracy of dental impression materials, but the cost and complexity of the instrument makes it less desirable for low-precision work.

Calibration↗
PubMed1991

Enhanced survival of IFN-alpha augmented IL-2 therapy of pulmonary metastases: efficacy comparable to interleukin-2 and lymphokine activated killer cells.

Recently, we reported enhanced tumor reduction using recombinant interferon-alpha A/D (IFN) combined with interleukin-2 (IL-2). Similar synergism affecting survival was assessed in treatment of both early and advanced pulmonary metastases. This combination was compared with the current "standard" IL-2 and lymphokine activated killer (LAK) therapy in the treatment of early and advanced pulmonary metastases. C57BL/6 mice injected via tail vein with the weakly immunogenic methylcholanthrene-induced murine fibrosarcoma MCA-106 were treated intraperitoneally with IL-2 (50,000 units b.i.d.), IFN (50,000 units q.d.), LAK (2.5-10 x 10(7)), or various combinations of above. Treatment of both early Day 3 and advanced Day 10 metastases using IL-2/IFN reduced metastases and prolonged survival over both controls and IL-2 alone. It was superior to IFN, LAK, and IFN/LAK. Addition of LAK to IL-2/IFN demonstrated no added benefit. Although no mortality was observed during treatment of Day 3 metastases, treatment of Day 10 advanced pulmonary metastases for 9 days with IL-2/IFN resulted in early deaths (33%) without visible tumor, indicating possible toxicity of treatment. These results show survival benefit of IL-2/IFN over IL-2, IFN, or LAK treatment in the therapy of early and advanced pulmonary metastases, albeit with added toxicity. Its relative simplicity and comparable efficacy to the more complex and costly IL-2/LAK provide important advantages for potential clinical applications.

Animals↗
PubMed1977

The biologic bases for using hair and nail for analyses of trace elements.

Sampling of human beings for trace element content can be a complex and costly procedure. The use of hair and nails simplifies the process and it is for this reason that such samples are extensively used. The primary consideration, however, is not how easily the samples can be collected nor even how accurately trace elements can be measured in hair and nails; rather, it is what do the values mean, i.e., to what extent does the measured level reflect the concentration and/or activity of the element in other parts of the body? The structure and histogenesis of hair and nails are discussed in relation to mechanisms by which trace elements are incorporated into these tissues. Problems of contamination in vivo are also considered. A résumé of current literature is presented, considering the trace elements that are appropriate for measurement in samples of human hair and nail and some of the problems involved in analysis.

Animals↗
PubMed1990

Automated three-dimensional finite element modelling of bone: a new method.

Three-dimensional finite element stress analysis of bone is a key to understanding bone remodelling, assessing fracture risk, and designing prostheses; however, the cost and complexity of predicting the stress field in bone with accuracy has precluded the routine use of this method. A new, automated method of generating patient-specific three-dimensional finite element models of bone is presented--it uses digital computed tomographic (CT) scan data to drive the geometry of the bone and to estimate its inhomogeneous material properties. Cubic elements of a user-specified size are automatically defined and then individually assigned the CT scan-derived material properties. The method is demonstrated by predicting the stress, stain, and strain energy in a human proximal femur in vivo. Three-dimensional loading conditions corresponding to the stance phase of gait were taken from the literature and applied to the model. Maximum principal compressive stresses of 8-23 MPa were computed for the medial femoral neck. Automated generation of additional finite element models with larger numbers of elements was used to verify convergence in strain energy.

Adult↗
PubMed1991

Advances in coronary interventional techniques.

The practice of catheter interventional techniques for coronary artery disease is just 14 years old. Many approaches are being applied, including balloon and rotational angioplasty devices, atherectomy catheters, lasers, and stents. Considerable efforts are being made developing, marketing and comparing these technologies. Restenosis is demanding more attention amongst clinical and basic scientists. The pathophysiology of this frequent and irksome complication is still poorly understood. A number of trials are comparing strategies of PTCA against medicine and surgery. In the United States, the Bypass Angioplasty Revascularization Investigation (BARI) of PTCA versus surgery for patients with multivessel disease has nearly completed patient entry; the preliminary results are eagerly awaited. Patients in nearly all countries are benefiting from these new technologies. Their development and evaluation has been most active in North America, Europe and Japan but many of them are being clinically applied in nearly all countries. Their cost and complexity present special challenges for funding, training and evaluation.

Angioplasty, Balloon↗
PubMed1985

Specificity, sensitivity, and prevalence in the design of randomized trials: a univariate analysis.

The number of cases needed to conduct a randomized trial is related to the sensitivity and specificity of a measurement indicative of a condition, to the prevalence of the condition, to the expected benefit of therapy (or other basis for change), and to the statistical precision desired. Sample size calculations frequently ignore sensitivity and specificity (at least qualitatively) probably because no simple formula is provided in the literature. Such a formula is included here. As an example, the number of patients required for a randomized clinical trial was calculated for a clinical outcome (nonfatal myocardial infarction or coronary artery disease death) used to detect atherosclerotic heart disease and is compared to the sample sizes required for each of three noninvasive diagnostic studies (exercise ECG ST depression, exercise LVEF reduction, and thallium myocardial imaging) performed for the detection of atherosclerotic heart disease. We calculated that the sample size should be much smaller when these diagnostic studies are employed compared to the clinical outcome, thereby offering the potential for reduced cost and complexity of a randomized clinical trial.

Adult↗