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True Risk (true + risk)

Distribution by Scientific Domains

Medical Sciences	71%

Selected Abstracts

Evaluation of Bayesian models for focused clustering in health data

ENVIRONMETRICS, Issue 8 2007
Bo Ma
Abstract This paper examines the ability of Bayesian hierarchical models to recover evidence of disease risk excess around a fixed location. This location can be a putative source of health hazard, such as an incinerator, mobile phone mast or dump site. While Bayesian models are convenient to use for modeling, it is useful to consider how well these models perform in the true risk scenarios. In what follows, we evaluate the ability of these models to recover the true risk under simulation. It is surprising that the resulting posterior parameters estimates are heavily biased. Using the credible intervals for distance decline parameter to assess ,coverage or power' of detecting distance effect, the ,power' decreases with increasing correlation in the background population effect. The inclusion of correlated heterogeneity in models does affect the ability of the models to detect the stronger distance decline scenarios. The uncorrelated heterogeneity seems little affect this ability however. Copyright © 2007 John Wiley & Sons, Ltd. [source]

The epidemiology of inhibitors in haemophilia A: a systematic review

HAEMOPHILIA, Issue 4 2003
J. Wight
Summary., This paper emphasizes the importance of distinguishing between the prevalence, incidence and cumulative incidence of inhibitors in haemophilia A. Incidence and cumulative incidence data will include patients with transient inhibitors or whose inhibitors have been eliminated by treatment. As these will not be included in prevalence data, prevalence studies will tend to give rise to lower figures than incidence studies. As a result, the most accurate estimates of the true risk of inhibitor development comes from prospective studies of newly diagnosed haemophiliacs who are tested regularly for the presence of inhibitors. This paper reports a systematic review of the best available evidence relating to the epidemiology of inhibitors in haemophilia A. Cohort studies, registry data reporting incidence or prevalence of inhibitors in patients with haemophilia A, and prospective studies of factor VIII (FVIII) in the treatment of previously untreated patients which reported the development of inhibitors as an outcome, were included in the review. The overall prevalence of inhibitors in unselected haemophiliac populations was found to be 5,7%. The cumulative risk of inhibitor development varied (0,39%). Incidence and prevalence were substantially higher in patients with severe haemophilia. Studies of patients using a single plasma-derived FVIII (pdFVIII) preparation reported lower inhibitor incidence than those using multiple pdFVIII preparations or single recombinant FVIII preparations. Incidence data should be used to estimate the likely demand for treatments aimed at eliminating inhibitors, whereas the best estimates of the overall burden to the National Health Service (NHS) of treating bleeding episodes in patients with continuing inhibitors will come from prevalence studies. [source]

Needle-tract implantation from hepatocellular cancer: Is needle biopsy of the liver always necessary?

LIVER TRANSPLANTATION, Issue 1 2000
Ryan Takamori
Percutaneous needle biopsies are frequently used to evaluate focal lesions of the liver. Needle-tract implantation of hepatocellular cancer has been described in case reports, but the true risk for this problem has not been clearly defined. We retrospectively reviewed 91 cases of hepatocellular cancer during a 4-year period from 1994 to 1997. Data on diagnostic studies, therapy, and outcome were noted. Of 91 patients with hepatocellular cancer, 59 patients underwent percutaneous needle biopsy as part of their diagnostic workup for a liver mass. Three patients (5.1%) were identified with needle-tract implantation of tumor. Two patients required en bloc chest wall resections for implantation of hepatocellular cancer in the soft tissues and rib area. The third patient, who also received percutaneous ethanol injection of his tumor, required a thoracotomy and lung resection for implanted hepatocellular cancer. Percutaneous needle biopsy of suspicious hepatic lesions should not be performed indiscriminately because there is a significant risk for needle-tract implantation. These biopsies should be reserved for those lesions in which no definitive surgical intervention is planned and pathological confirmation is necessary for a nonsurgical therapy. (Liver Transpl 2000;6:67-72.) [source]

Estimating Returns on Commercial Real Estate: A New Methodology Using Latent-Variable Models

REAL ESTATE ECONOMICS, Issue 2 2000
David C. Ling
Despite their widespreao use as benchmarks of U.S. commercial real estate returns, indexes produced by the National Council of Real Estate Investment Fiduciaries (NCREIF) are subject to measurement problems that severely impair their ability to capture the true risk,return characteristics,especially volatility,of privately held commercial real estate. We utilize latent-variable statistical methods to estimate an alternative index of privately held (unsecuritized) commercial real estate returns. Latent-variable methods have been extensively applied in the behavioral sciences and, more recently, in finance and economics. Unlike factor analysis or other unconditional statistical approaches, latent variable models allow us to extract interpretable common information about unobserved private real estate returns using the information contained in various competing measures of returns that are measured with error. We find that our latent-variable real estate return series is approximately twice as volatile as the aggregate NCREIF total return index, but less than half as volatile as the NAREIT equity index. Overall, our results strongly support the use of latent-variable statistical models in the construction of return series for commercial real estate. [source]

Melanoma in Solid Organ Transplant Recipients

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010
F. O. Zwald
This manuscript outlines estimated risk and clinical course of pretransplant MM, donor-transmitted MM and de novo MM posttransplantation and includes an analysis of risk factors for metastasis, data from clinical studies and current and proposed management. MM in situ and thin melanoma (<1 mm) in the transplant population has similar recurrence and survival estimates to those in the general population. A minimum wait time of 2 years prior to transplantation is suggested for MM with a Breslow depth <1 mm and no clinical evidence of metastasis. More advanced MM may adopt a more aggressive course in transplant recipients. Sentinel lymph node biopsy may be of additional prognostic benefit. Revision of immunosuppression in the management of de novo melanoma in collaboration with the transplant team should be considered. Larger studies utilizing uniform staging criteria or at minimum Breslow depth, are required to assess true risk and outcome of MM in the immunosuppressed transplant population. Emphasis remains on patient education and regular screening to provide early detection of MM. [source]

Incidence of autism spectrum disorders: Changes over time and their meaning,

ACTA PAEDIATRICA, Issue 1 2005
M. Rutter
Abstract Aim: Several reviews have noted a huge increase in the rate of diagnosed autism spectrum disorders. The main aims of this paper are: 1) to use published empirical findings to consider whether the rise reflects a true increase in incidence, as distinct from the consequences of better ascertainment and a broadening of the diagnostic concept; and 2) to consider how epidemiological data may be used to test hypotheses about possible causal influences, using MMR and thimerosal as examples. Methods: Search of the literature for studies with a large epidemiological base population, systematic standardized screening, a focus on an age group for which diagnostic assessments are reliable and valid, and diagnosis by trained professionals using high-quality research assessments. Also, search of a broader literature to consider the evidence from all epidemiological studies with respect to the hypothesized causal effect of MMR and thimerosal on autism spectrum disorders. Results: The true incidence of autism spectrum disorders is likely to be within the range of 30,60 cases per 10,000, a huge increase over the original estimate 40 years ago of 4 per 10,000. The increase is largely a consequence of improved ascertainment and a considerable broadening of the diagnostic concept. However, a true risk due to some, as yet to be identified, environmental risk factor cannot be ruled out. There is no support for the hypothesis for a role of either MMR or thimerosal in causation, but the evidence on the latter is more limited. Conclusion: Progress in testing environmental risk hypotheses will require the integration of epidemiological and biological studies. [source]

Complications of hysterectomy in women with von Willebrand disease

HAEMOPHILIA, Issue 4 2009
A. H. JAMES
Summary., Case reports and small case series suggest that women with von Willebrand disease (VWD) are at a very high risk of bleeding complications with hysterectomy. As the procedure may be beneficial to women who suffer from heavy menstrual bleeding and have completed childbearing, an understanding of the true risks involved is essential for appropriate decision making. To estimate the incidence of bleeding and other complications in women with VWD who undergo hysterectomy. The United States Nationwide Inpatient Sample (NIS) from the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality for the years 1988,2004 was queried for all hysterectomies for non-malignant conditions. Data were analysed based on the NIS sampling design. Bivariate analyses were used to examine the differences between women with and without VWD. Multivariate analysis was used to adjust for potential confounders among women who underwent hysterectomy for heavy menstrual bleeding. 545 of the 1 358 133 hysterectomies were to women with VWD. Women with VWD were significantly more likely to experience intraoperative and postoperative bleeding (2.75% vs. 0.89%, P < 0.001) and require transfusion (7.34% vs. 2.13%, P < 0.001) than women without VWD. One woman with VWD died. While the risk of bleeding complications from hysterectomy in women with VWD is smaller than previously reported, women with VWD did experience significantly more bleeding complications than women without VWD. Nonetheless, for women who have completed childbearing, the risks of hysterectomy may be acceptable. [source]