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Search Results: 1 - 10 of 228196 matches for " Karen R. Steingart "
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Is Scale-Up Worth It? Challenges in Economic Analysis of Diagnostic Tests for Tuberculosis
David W. Dowdy ,Adithya Cattamanchi,Karen R. Steingart,Madhukar Pai
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1001063
Abstract:
Serological Testing Versus Other Strategies for Diagnosis of Active Tuberculosis in India: A Cost-Effectiveness Analysis
David W. Dowdy,Karen R. Steingart,Madhukar Pai
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1001074
Abstract: Background Undiagnosed and misdiagnosed tuberculosis (TB) drives the epidemic in India. Serological (antibody detection) TB tests are not recommended by any agency, but widely used in many countries, including the Indian private sector. The cost and impact of using serology compared with other diagnostic techniques is unknown. Methods and Findings Taking a patient cohort conservatively equal to the annual number of serological tests done in India (1.5 million adults suspected of having active TB), we used decision analysis to estimate costs and effectiveness of sputum smear microscopy (US$3.62 for two smears), microscopy plus automated liquid culture (mycobacterium growth indicator tube [MGIT], US$20/test), and serological testing (anda-tb ELISA, US$20/test). Data on test accuracy and costs were obtained from published literature. We adopted the perspective of the Indian TB control sector and an analysis frame of 1 year. Our primary outcome was the incremental cost per disability-adjusted life year (DALY) averted. We performed one-way sensitivity analysis on all model parameters, with multiway sensitivity analysis on variables to which the model was most sensitive. If used instead of sputum microscopy, serology generated an estimated 14,000 more TB diagnoses, but also 121,000 more false-positive diagnoses, 102,000 fewer DALYs averted, and 32,000 more secondary TB cases than microscopy, at approximately four times the incremental cost (US$47.5 million versus US$11.9 million). When added to high-quality sputum smears, MGIT culture was estimated to avert 130,000 incremental DALYs at an incremental cost of US$213 per DALY averted. Serology was dominated by (i.e., more costly and less effective than) MGIT culture and remained less economically favorable than sputum smear or TB culture in one-way and multiway sensitivity analyses. Conclusions In India, sputum smear microscopy remains the most cost-effective diagnostic test available for active TB; efforts to increase access to quality-assured microscopy should take priority. In areas where high-quality microscopy exists and resources are sufficient, MGIT culture is more cost-effective than serology as an additional diagnostic test for TB. These data informed a recently published World Health Organization policy statement against serological tests. Please see later in the article for the Editors' Summary
Field assessment of a model tuberculosis outbreak response plan for low-incidence areas
Laura Freimanis Hance, Karen R Steingart, Christine G Hahn, Lisa Pascopella, Charles M Nolan
BMC Public Health , 2007, DOI: 10.1186/1471-2458-7-307
Abstract: We designed a semi-structured questionnaire and interviewed all key stakeholders involved in the response. We used common themes to assess validity of and identify gaps in the plan. A subset of participants provided structured feedback on the plan.We interviewed 11 public health and six community stakeholders. The assessment demonstrated that (1) almost all of the main response activities were reflected in the plan; (2) the plan added value by providing a definition of a tuberculosis outbreak and guidelines for communication and evaluation. These were areas that lacked written protocols during the actual outbreak response; and (3) basic education about tuberculosis and the interpretation and use of genotyping data were important needs. Stakeholders also suggested adding to the plan questions for evaluation and a section for specific steps to take when an outbreak is suspected.An interactive field assessment of a programmatic tool revealed the value of a systematic outbreak response plan with a standard definition of a tuberculosis outbreak, guidelines for communication and evaluation, and response steps. The assessment highlighted the importance of education and training for tuberculosis in low-incidence areas.Tuberculosis (TB) is a treatable disease that causes considerable morbidity and mortality throughout the world, accounting for nearly nine million new cases and two million deaths in 2005 alone [1]. Controlling TB requires integrated public health and medical systems that serve the entire population. The United States has witnessed decreasing TB incidence since 1992, with 2006 marking the lowest number of cases (13,779 cases, 4.6 per 100,000 population) ever reported in this country [2]. Although the idea of eliminating TB in the U.S. (TB case rate < 1 per 1,000,000 population by 2010) had been discussed for decades [3,4], the recent decline in TB, after a brief resurgence in the mid-1980s to early 1990s, has given new impetus to this possibility [5,6].Areas o
Commercial Serological Tests for the Diagnosis of Active Pulmonary and Extrapulmonary Tuberculosis: An Updated Systematic Review and Meta-Analysis
Karen R. Steingart,Laura L. Flores,Nandini Dendukuri,Ian Schiller,Suman Laal,Andrew Ramsay,Philip C. Hopewell,Madhukar Pai
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1001062
Abstract: Background Serological (antibody detection) tests for tuberculosis (TB) are widely used in developing countries. As part of a World Health Organization policy process, we performed an updated systematic review to assess the diagnostic accuracy of commercial serological tests for pulmonary and extrapulmonary TB with a focus on the relevance of these tests in low- and middle-income countries. Methods and Findings We used methods recommended by the Cochrane Collaboration and GRADE approach for rating quality of evidence. In a previous review, we searched multiple databases for papers published from 1 January 1990 to 30 May 2006, and in this update, we add additional papers published from that period until 29 June 2010. We prespecified subgroups to address heterogeneity and summarized test performance using bivariate random effects meta-analysis. For pulmonary TB, we included 67 studies (48% from low- and middle-income countries) with 5,147 participants. For all tests, estimates were variable for sensitivity (0% to 100%) and specificity (31% to 100%). For anda-TB IgG, the only test with enough studies for meta-analysis, pooled sensitivity was 76% (95% CI 63%–87%) in smear-positive (seven studies) and 59% (95% CI 10%–96%) in smear-negative (four studies) patients; pooled specificities were 92% (95% CI 74%–98%) and 91% (95% CI 79%–96%), respectively. Compared with ELISA (pooled sensitivity 60% [95% CI 6%–65%]; pooled specificity 98% [95% CI 96%–99%]), immunochromatographic tests yielded lower pooled sensitivity (53%, 95% CI 42%–64%) and comparable pooled specificity (98%, 95% CI 94%–99%). For extrapulmonary TB, we included 25 studies (40% from low- and middle-income countries) with 1,809 participants. For all tests, estimates were variable for sensitivity (0% to 100%) and specificity (59% to 100%). Overall, quality of evidence was graded very low for studies of pulmonary and extrapulmonary TB. Conclusions Despite expansion of the literature since 2006, commercial serological tests continue to produce inconsistent and imprecise estimates of sensitivity and specificity. Quality of evidence remains very low. These data informed a recently published World Health Organization policy statement against serological tests. Please see later in the article for the Editors' Summary
Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review
Karen R Steingart,Megan Henry,Suman Laal,Philip C Hopewell,Andrew Ramsay,Dick Menzies,Jane Cunningham,Karin Weldingh,Madhukar Pai
PLOS Medicine , 2007, DOI: 10.1371/journal.pmed.0040202
Abstract: Background The global tuberculosis epidemic results in nearly 2 million deaths and 9 million new cases of the disease a year. The vast majority of tuberculosis patients live in developing countries, where the diagnosis of tuberculosis relies on the identification of acid-fast bacilli on unprocessed sputum smears using conventional light microscopy. Microscopy has high specificity in tuberculosis-endemic countries, but modest sensitivity which varies among laboratories (range 20% to 80%). Moreover, the sensitivity is poor for paucibacillary disease (e.g., pediatric and HIV-associated tuberculosis). Thus, the development of rapid and accurate new diagnostic tools is imperative. Immune-based tests are potentially suitable for use in low-income countries as some test formats can be performed at the point of care without laboratory equipment. Currently, dozens of distinct commercial antibody detection tests are sold in developing countries. The question is “do they work?” Methods and Findings We conducted a systematic review to assess the accuracy of commercial antibody detection tests for the diagnosis of pulmonary tuberculosis. Studies from all countries using culture and/or microscopy smear for confirmation of pulmonary tuberculosis were eligible. Studies with fewer than 50 participants (25 patients and 25 control participants) were excluded. In a comprehensive search, we identified 68 studies. The results demonstrate that (1) overall, commercial tests vary widely in performance; (2) sensitivity is higher in smear-positive than smear-negative samples; (3) in studies of smear-positive patients, Anda-TB IgG by enzyme-linked immunosorbent assay shows limited sensitivity (range 63% to 85%) and inconsistent specificity (range 73% to 100%); (4) specificity is higher in healthy volunteers than in patients in whom tuberculosis disease is initially suspected and subsequently ruled out; and (5) there are insufficient data to determine the accuracy of most commercial tests in smear microscopy–negative patients, as well as their performance in children or persons with HIV infection. Conclusions None of the commercial tests evaluated perform well enough to replace sputum smear microscopy. Thus, these tests have little or no role in the diagnosis of pulmonary tuberculosis. Lack of methodological rigor in these studies was identified as a concern. It will be important to review the basic science literature evaluating serological tests for the diagnosis of pulmonary tuberculosis to determine whether useful antigens have been described but their potential has not been
Correction: Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review
Karen R Steingart,Megan Henry,Suman Laal,Philip C Hopewell,Andrew Ramsay,Dick Menzies,Jane Cunningham,Karin Weldingh,Madhukar Pai
PLOS Medicine , 2007, DOI: 10.1371/journal.pmed.0040254
Abstract:
It’s Not Just the Money: Why Consumers Do Not Purchase Pharmacist-Provided Services  [PDF]
Patricia R. Freeman, Mikael Jones, Karen Blumenschein
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.56067
Abstract:

The reimbursement model for pharmaceutical care remains a barrier to successful widespread implementation of pharmacist-provided services. In some instances, community pharmacists have been successful in obtaining direct compensation for services from patients; however, evidence suggests that lack of patient demand for pharmacist-services may ultimately undermine the campaign for widespread third-party payment. The purpose of this study is to conduct a secondary analysis of data indicating consumer/patients’ rationale for not purchasing pharmacist-provided disease management services when offered the opportunity to do so in community pharmacies. Our review of the data indicates that while financial concerns are clearly important in consumer demand for pharmacist-provided services, other considerations exist. The consumer/patient belief that pharmacist-provided services are duplicative or that these services are not needed are significant barriers to overcome. Intensive education and marketing campaigns are needed to sway consumer opinion on the value of pharmacist-provided services.

Pulverization provides a mechanism for the nucleation of earthquakes at low stress on strong faults
Karen R. Felzer
Frontiers in Earth Science , 2014, DOI: 10.3389/feart.2014.00020
Abstract:
C*-algebras of minimal dynamical systems of the product of a Cantor set and an odd dimensional sphere
Karen R. Strung
Mathematics , 2014,
Abstract: Let \beta : S^n \to S^n, for n = 2k + 1, k \geq 1, be one of the known examples of a non-uniquely ergodic minimal diffeomorphism of an odd dimensional sphere. For every such minimal dynamical system (S^n, \beta) there is a Cantor minimal system (X, \alpha) such that the corresponding product system (X x S^n, \alpha x \beta) is minimal and the resulting crossed product C*-algebra C(X x S^n) \rtimes_{\alpha x \beta} \mathbb{Z} is tracially approximately an interval algebra (TAI). This entails classification for such C*-algebras. Moreover, the minimal Cantor system (X, \alpha) is such that each tracial state on C(X x S^n) \rtimes_{\beta} \mathbb{Z} induces the same state on the K_0-group and such that the embedding of C(S^n) \rtimes_{\beta} \mathbb{Z} into C(X x S^n) \rtimes_{\alpha x \beta} \mathbb{Z} preserves the tracial state space. This implies C(S^n) \rtimes_{\beta} \mathbb{Z} is TAI after tensoring with the universal UHF algebra, which in turn shows that the C*-algebras of these examples of minimal diffeomorphisms of odd dimensional spheres are classified by their tracial state spaces.
A Pragmatic Approach to Coping with Matrix Effects during ICP-MS Analysis of Trace Elements in Silicate Rocks and Calibration of REE Interferences  [PDF]
C. Michael B. Henderson, Paul R. Lythgoe, Karen J. Theis
Journal of Geoscience and Environment Protection (GEP) , 2019, DOI: 10.4236/gep.2019.73005
Abstract: Operating an Agilent 7700X ICP-MS spectrometer under robust plasma conditions (1550 W) with a He-filled octopole collision cell and analysing solutions (<2000 μg·g?1 total dissolved solids) still suffered analyte peak suppression due to matrix effects. International reference rocks BCR-1, BHVO-1, AGV-1, G-2 and BCR-2 all showed count rate reductions for 36 elements (mass range 7Li to 238U) averaging ~10% but with no dependence on isotope mass. Use of an internal standard (103Rh) and/or using a ten-fold dilution of sample solutions reduced these effects but problems with reduced count rates combined with larger errors for some elements introduced other problems. The best approach was to normalise the count rates for each element in the other samples against those for BCR-1 as an external standard; thus the count suppression due to the matrix effect is corrected for each individual element. This approach provides standardization “traceability” in line with the ERM ISO/IEC requirement. Experiments are also reported on quantifying the proportions of Ba and selected REE oxide/hydroxide components versus parent isotopes (XO/X and XOH/X). This information is essential for correcting peak interferences on higher mass number REE for the rock samples, and equations are developed to use measured CeO/Ce and CeOH/Ce ratios to predict such values for any other member of the REE suite. Concentrations obtained show excellent agreement with recommended values for the international reference materials especially for the REE. Robust data are also provided for two other standard rocks: nepheline syenite STM-1 and quartz syenite CAAS-1; the latter shows exceptional enrichments of Zr, REE, Th, and U.
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