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Threshold Used (threshold + used)
Selected AbstractsTrends in the start of the wet season over AfricaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2009D. R. Kniveton Abstract A quarter of a century of daily rainfall data from the Global Telecommunications System are used to define the temporal and spatial variability of the start of the wet season over Africa and surrounding extreme south of Europe and parts of the Middle East. From 1978 to 2002, the start of the wet season arrived later in the year for the majority of the region, as time progressed. In some parts of the continent, there was an annual increase in the start date of up to 4 days per year. On average, the start of the wet season arrived 9,21 days later from 1978 to 2002, depending on the threshold used to define the start of the rains (varying from 10,30 mm over 2 days, with no dry period in the following 10 days). It is noted that the inter-annual variability of the start of the wet season is high with the range of start dates varying on average from 116 to 142 days dependent on the threshold used to determine the start date. These results may have important implications for agriculturists on all levels (from the individual farmer to those responsible for regional food supply), as knowledge of potential future climate changes starts to play an increasingly important role in the agricultural decision-making process, such as sowing and harvesting times. Copyright © 2008 Royal Meteorological Society [source] Comparison Insight Bone Measurements by Histomorphometry and ,CT,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2005Daniel Chappard MD Abstract Morphometric analysis of 70 bone biopsies was done in parallel by ,CT and histomorphometry. ,CT provided higher results for trabecular thickness and separation because of the 3D shape of these anatomical objects. Introduction: Bone histomorphometry is used to explore the various metabolic bone diseases. The technique is done on microscopic 2D sections, and several methods have been proposed to extrapolate 2D measurements to the 3D dimension. X-ray ,CT is a recently developed imaging tool to appreciate 3D architecture. Recently the use of 2D histomorphometric measurements have been shown to provide discordant results compared with 3D values obtained directly. Material and Methods: Seventy human bone biopsies were removed from patients presenting with metabolic bone diseases. Complete bone biopsies were examined by ,CT. Bone volume (BV/TV), Tb.Th, and Tb.Sp were measured on the 3D models. Tb.Th and Tb.Sp were measured by a method based on the sphere algorithm. In addition, six images were resliced and transferred to an image analyzer: bone volume and trabecular characteristics were measured after thresholding of the images. Bone cores were embedded undecalcified; histological sections were prepared and measured by routine histomorphometric methods providing another set of values for bone volume and trabecular characteristics. Comparison between the different methods was done by using regression analysis, Bland-Altman, Passing-Bablock, and Mountain plots. Results: Correlations between all parameters were highly significant, but ,CT overestimated bone volume. The osteoid volume had no influence in this series. Overestimation may have been caused by a double threshold used in ,CT, giving trabecular boundaries less well defined than on histological sections. Correlations between Tb.Th and Tb.Sp values obtained by 3D or 2D measurements were lower, and 3D analysis always overestimated thickness by ,50%. These increases could be attributed to the 3D shape of the object because the number of nodes and the size of the marrow cavities were correlated with 3D values. Conclusion: In clinical practice, ,CT seems to be an interesting method providing reliable morphometric results in less time than conventional histomorphometry. The correlation coefficient is not sufficient to study the agreement between techniques in histomorphometry. The architectural descriptors are influenced by the algorithms used in 3D. [source] Identification of colorectal adenomas by a quantitative immunochemical faecal occult blood screening test depends on adenoma characteristics, development threshold used and number of tests performedALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009P. ROZEN Summary Background Faecal occult blood tests (FOBT) are faulted by low sensitivity for advanced adenomatous polyps (AAP). Quantified, immunochemical, haemoglobin (Hb)-specific immunochemical FOBT (I-FOBT) measurements are now used for colorectal screening. Aims To correlate adenoma characteristics to amount of faecal Hb lost and to evaluate sensitivity and specificity for AAP by faecal Hb development threshold used and number of I-FOBTs collected. Methods Three daily I-FOBTs were collected and analysed in 1221 patients scheduled for colonoscopy. Faecal Hb was analysed as ngHb/mL of buffer and the highest result related to colonoscopy findings. Results In 1204 patients without cancer, colonoscopy identified adenomas in 294, 99 with AAPs. Adenoma patients had elevated faecal Hb increasing with advanced histology, size, pedunculated shape and multiplicity (P < 0.001 for all). At 50 ngHb/mL threshold, sensitivity and specificity for AAPs were 54.5% (95%CI 44.7, 64.7) and 88.1% (95%CI 86.2, 90.1) for three tests. At higher thresholds, sensitivity decreased, but was significantly higher with more samples collected. Conversely, specificity increased at higher thresholds, but decreased with more samples. Conclusions Faecal Hb loss from adenomas is significantly associated with size, number and advanced features. Sensitivity and specificity for AAPs are determined by test threshold chosen and number of samples collected; these determine the number of colonoscopies needed for positive tests. [source] The value of medical interventions for lung cancer in the elderly,CANCER, Issue 11 2007Results from SEER-CMHSF Abstract BACKGROUND. Lung cancer is the leading source of cancer mortality and spending. However, the value of spending on the treatment of lung cancer has not been conclusively demonstrated. The authors evaluated the value of medical care between 1983 and 1997 for nonsmall cell lung cancer in the elderly US population. METHODS. The authors used Surveillance, Epidemiology, and End Results (SEER) data to calculate life expectancy after diagnosis over the period 1983 to 1997. Direct costs for nonsmall cell lung cancer detection and treatment were determined by using Part A and Part B reimbursements from the Continuous Medicare History Sample File (CMHSF) data. The CMHSF and SEER data were linked to calculate lifetime treatment costs over the time period of interest. RESULTS. Life expectancy improved minimally, with an average increase of approximately 0.60 months. Total lifetime lung cancer spending rose by approximately $20,157 per patient in real, ie, adjusted for inflation, 2000 dollars from the early 1980s to the mid-1990s, for a cost-effectiveness ratio of $403,142 per life year (LY). The cost-effectiveness ratio was $143,614 for localized cancer, $145,861 for regional cancer, and $1,190,322 for metastatic cancer. CONCLUSIONS. The cost-effectiveness ratio for nonsmall cell lung cancer was higher than traditional thresholds used to define cost-effective care. The most favorable results were for persons diagnosed with early stage cancer. These results suggested caution when encouraging more intensive care for lung cancer patients without first considering the tradeoffs with the costs of this therapy and its potential effects on mortality and/or quality of life. Cancer 2007. © 2007 American Cancer Society. [source] | ||||||||||