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Wednesday, August 27, 2008
 Latest
Epidemiology Medical and Health News Headlines
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Epidemiology Medical and Health News Headlines
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All Recent Epidemiology Medical News Headlines |
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An augmented data method for the analysis of nosocomial infection data
The analysis of nosocomial infection data for communicable pathogens is complicated by two facts. First, typical pathogens more commonly cause asymptomatic colonization than overt disease, so transmission can be only imperfectly observed through a sequence of surveillance swabs, which themselves have imperfect sensitivity. Any given set of swab results can therefore be consistent with many different patterns of transmission. Second, data are often highly dependent: the colonization status of one patient affects the risk for others, and, in some wards, repeated admissions are common. Here, the authors present a method for analyzing typical nosocomial infection data consisting of results from arbitrarily timed screening swabs that overcomes these problems and enables simultaneous estimation of transmission and importation parameters, duration of colonization, swab sensitivity, and ward- and patient-level covariates. The method accounts for dependencies by using a mechanistic stochastic transmission model, and it allows for uncertainty in the data by imputing the imperfectly observed colonization status of patients over repeated admissions. The approach uses a Markov chain Monte Carlo algorithm, allowing inference within a Bayesian framework. The method is applied to illustrative data from an interrupted time-series study of vancomycin-resistant enterococci transmission in a hematology ward. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Making the most of case-mother/control-mother studies
The prenatal environment plays an important role in many conditions, particularly those with onset early in life, such as childhood cancers and birth defects. Because both maternal and fetal genotypes can influence risk, investigators sometimes use a case-mother/control-mother design, with mother-offspring pairs as the unit of analysis, to study genetic factors. Risk models should account for both the maternal genotype and the correlated fetal genotype to avoid confounding. The usual logistic regression analysis, however, fails to fully exploit the fact that these are mothers and offspring. Consider an autosomal, diallelic locus, which could be related to disease susceptibility either directly or through linkage with a polymorphic causal locus. Three nested levels of assumptions are often natural and plausible. The first level simply assumes Mendelian inheritance. The second further assumes parental mating symmetry for the studied locus in the source population. The third additionally assumes parental allelic exchangeability. Those assumptions imply certain nonlinear constraints; the authors enforce those constraints by using Poisson regression together with the expectation-maximization algorithm. Calculations reveal that improvements in efficiency over the usual logistic analysis can be substantial, even if only the Mendelian assumption is honored. Benefits are even more marked if, as is typical, information on genotype is missing for some individuals. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Gender differences in hiv progression to aids and death in industrialized countries: slower disease progression following hiv seroconversion in women
To evaluate sex differences in human immunodeficiency virus (HIV) disease progression before (pre-1997) and after (1997–2006) introduction of highly active antiretroviral therapy, the authors used data from a collaboration of 23 HIV seroconverter cohort studies from Europe, Australia, and Canada restricted to the 6,923 seroconverters infected through injecting drug use and sex between men and women. Within a competing risk framework, they used Cox proportional hazards models allowing for late entry to evaluate sex differences in time from HIV seroconversion to death, to acquired immunodeficiency syndrome (AIDS), and to each first AIDS-defining disease and death without AIDS. While no significant sex differences were found before 1997, from 1997 onward, women had a lower risk of AIDS (adjusted cumulative relative risk (aCRR) = 0.76, 95% confidence interval (CI): 0.63, 0.90) and death (adjusted hazard ratio = 0.68, 95% CI: 0.56, 0.82) than men did. Compared with men, women also had lower risks of AIDS dementia complex (aCRR = 0.23, 95% CI: 0.07, 0.74), tuberculosis (aCRR = 0.60, 95% CI: 0.39, 0.92), Kaposi's sarcoma (aCRR = 0.27, 95% CI: 0.07, 0.99), lymphomas (aCRR = 0.47, 95% CI: 0.23, 0.96), and death without AIDS (aCRR = 0.74, 95% CI: 0.56, 0.98). Sex differences in HIV disease progression have become larger and statistically significant in the era of highly active antiretroviral therapy, supporting a stronger impact of health interventions among women. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Maternal smoking during pregnancy and children's cognitive and physical development: a causal risk factor?
There remains considerable debate regarding the effects of maternal smoking during pregnancy on children's growth and development. Evidence that exposure to maternal smoking during pregnancy is associated with numerous adverse outcomes is contradicted by research suggesting that these associations are spurious. The authors investigated the relation between maternal smoking during pregnancy and 14 developmental outcomes of children from birth through age 7 years, using data from the Collaborative Perinatal Project (1959–1974; n = 52,919). In addition to adjusting for potential confounders measured contemporaneously with maternal smoking, the authors fitted conditional fixed-effects models among siblings that controlled for unmeasured confounders. Results from the conditional analyses indicated a birth weight difference of –85.63 g associated with smoking of ≥20 cigarettes daily during pregnancy (95% confidence interval: –131.91, –39.34) and 2.73 times' higher odds of being overweight at age 7 years (95% confidence interval: 1.30, 5.71). However, the associations between maternal smoking and 12 other outcomes studied (including Apgar score, intelligence, academic achievement, conduct problems, and asthma) were entirely eliminated after adjustment for measured and unmeasured confounders. The authors conclude that the hypothesized effects of maternal smoking during pregnancy on these outcomes either are not present or are not distinguishable from a broader range of familial factors associated with maternal smoking. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Mobility disability and the urban built environment
Research on the effects of the built environment in the pathway from impairment to disability has been largely absent. Using data from the Chicago Community Adult Health Study (2001–2003), the authors examined the effect of built environment characteristics on mobility disability among adults aged 45 or more years (n = 1,195) according to their level of lower extremity physical impairment. Built environment characteristics were assessed by using systematic social observation to independently rate street and sidewalk quality in the block surrounding each respondent's residence in the city of Chicago (Illinois). Using multinomial logistic regression, the authors found that street conditions had no effect on outdoor mobility among adults with only mild or no physical impairment. However, among adults with more severe impairment in neuromuscular and movement-related functions, the difference in the odd ratios for reporting severe mobility disability was over four times greater when at least one street was in fair or poor condition (characterized by cracks, potholes, or broken curbs). When all streets were in good condition, the odds of reporting mobility disability were attenuated in those with lower extremity impairment. If street quality could be improved, even somewhat, for those adults at greatest risk for disability in outdoor mobility, the disablement process could be slowed or even reversed. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Adult height and the risk of mortality in south korean women
To evaluate the association between adult height as a surrogate marker of childhood circumstances and the risk of mortality, 344,519 South Korean women aged 40–64 years categorized into six height groups were prospectively followed for mortality between 1994 and 2004. In Cox proportional hazards regression with adjustment for behavioral and biologic risk factors, there was an inverse association between height and total mortality; mortality risk decreased 7% for each 5-cm increment in height. The association did not materially change after adjustment for behavioral factors and adulthood socioeconomic factors or after full adjustment for all available covariates. When height-associated risks of death from specific causes were evaluated in a fully adjusted analysis, a 5-cm increment in height was associated with lower risks of death from respiratory diseases, stroke, diabetes mellitus, and external causes (hazard ratios were 0.84 (95% confidence interval (CI): 0.74, 0.96), 0.84 (95% CI: 0.80, 0.88), 0.87 (95% CI: 0.80, 0.96), and 0.88 (95% CI: 0.83, 0.94), respectively) and with a higher risk of death from cancer (hazard ratio = 1.05, 95% CI: 1.02, 1.09). Given that adult height reflects early-life conditions, the independent associations between height and mortality from all causes and specific causes support the view that early-life circumstances significantly influence health outcomes in adulthood. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Nielsen et al. respond to "stress and mortality"
(Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Invited commentary: stress and mortality
In this issue of the Journal, Nielsen et al. (Am J Epidemiol 2008;168:481–91) use data from a large Danish study to provide evidence that self-reported stress is associated with increased all-cause mortality over the next 20 years. The finding is remarkable. In this commentary, the authors explore what is really meant by stress; they argue that it would be naïve to view stress as reported in this way, with some external exposure. It has to be seen through the lens of the participant's personal experience, and this lens is likely to be clouded by personality, coping styles, and the common mental disorders—depression and anxiety. The authors discuss a wider literature concerning similar findings associating depression with mortality, suggesting three broad reasons for the association. First, the findings might be explained by the impact of stress or distress on well-established risk factors for cardiovascular disease and cancer. Second, there might be direct, underlying psychosomatic pathways by which stress or distress can affect immune or autonomic function. Third, there might be common causal pathways—shared genes or early adversities that predict both stress and mortality from other causes independently. The authors suggest that life course epidemiologic research is required to test these competing hypotheses. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Type 2 diabetes mellitus and risk of non-hodgkin lymphoma: a systematic review and meta-analysis
Type 2 diabetes mellitus is associated with altered immune function and chronic inflammation. Both of these immune conditions are implicated in the pathogenesis of non-Hodgkin lymphoma. The authors performed a systematic review to summarize findings from the current literature on the association between history of type 2 diabetes mellitus and risk of non-Hodgkin lymphoma. Ten case-control studies and three prospective cohort studies were included in this review. Meta-analysis found that a history of type 2 diabetes mellitus was positively associated with overall non-Hodgkin lymphoma risk. However, there was significant heterogeneity between studies. Study design was an important source of heterogeneity. The rate ratio between type 2 diabetes mellitus and non-Hodgkin lymphoma was found to be 1.18 (95% confidence interval: 0.99, 1.42) among case-control studies and 1.79 (95% confidence interval: 1.30, 2.47) among the prospective cohort studies. Weaknesses were identified in some of the included studies in the areas of case and control selection, measurement of covariates and non-Hodgkin lymphoma, and confounding control. Although a positive association between type 2 diabetes mellitus and risk of non-Hodgkin lymphoma was suggested, the evidence is inconclusive because of methodological limitations of the included case-control studies. More prospective studies with improved control of confounding are needed to confirm these findings. (Source: American Journal of Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Understanding cardiac output
The cardiac output is the amount of blood that the heart pumps in one minute and is dependent on heart rate, contractility, preload, and afterload. Understanding of the applicability and practical relevance of each of these four components is important when interpreting cardiac output values. Here, we use a simple analogy comparing cardiac output to the speed of a bicycle, to help appreciate better the effects of various disease processes and interventions on cardiac output and its four components. (Source: Critical Care)...
POSTED 08/21/2008 at 11:00 PM --
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Prognostic value of brain natriuretic peptide in acute pulmonary embolism
IntroductionThe relationship between brain natriuretic peptide (BNP) increase in acute pulmonary embolism (PE) and the increase in mortality and morbidity has frequently been suggested in small studies but its global prognostic performance remains largely undefined. We performed a systematic review and meta-analysis of data to examine the prognostic value of elevated BNP for short term all-cause mortality and serious adverse events.
Methods:
The authors reviewed PubMed, BioMedCentral, and the Cochrane database and conducted a manual review of article bibliographies. Using a prespecified search strategy, we included a study if it used BNP or N-Terminal Pro-Brain Natriuretic Peptide (NT-pro BNP) biomarkers as a diagnostic test in patients with documented pulmonary embolism and if it reported death, the primary endpoint of the meta-analysis, in relation to BNP testing. Studies were excluded if they were performed in patients without certitude of PE or in a subset of patients with cardiogenic shock. Twelve relevant studies involving a total of 868 patients with acute PE at baseline were included in the meta-analysis using a random-effects model.
Results:
Elevated BNP levels were significantly associated with short-term all-cause mortality (odds ratio [OR], 6.57; 95% confidence interval (CI), 3.11 to 13.91), with death resulting from pulmonary embolism (OR, 6.10; 95% CI, 2.58 to 14.25), and with serious adverse events (OR, 7.47; 95% CI, 4.20 to 13.15). The corresponding positive and negative predictive values for death were 14% (95%, 11 to 18) and 99% (95% CI, 97 to 100), respectively.
Conclusions:
This meta-analysis indicates that while elevated BNP levels can help to identify patients with acute pulmonary embolism at high risk of death and adverse outcome events, the high negative predictive value of normal BNP levels is certainly more useful for clinicians to select patients with a likely uneventful follow-up. (Source: Critical Care)...
POSTED 08/21/2008 at 11:00 PM --
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Update: measles --- united states, january--july 2008.
Update: measles --- United States, january--july 2008.
MMWR Morb Mortal Wkly Rep. 2008 Aug 22;57(33):893-6
Authors:
Sporadic importations of measles into the United States have occurred since the disease was declared eliminated from the United States in 2000. During January--July 2008, 131 measles cases were reported to CDC, compared with an average of 63 cases per year during 2000--2007. This report updates an earlier report on measles in the United States during 2008 and summarizes two recent U.S outbreaks among unvaccinated school-aged children. Among those measles cases reported during the first 7 months of 2008, 76% were in persons aged <20 years, and 91% were in persons who were unvaccinated or of unknown vaccination status. Of the 131 cases, 89% were imported from or associated with importations from other countries, particularly countries in Europe, where several outbreaks are ongoing. The findings demonstrate that measles outbreaks can occur in communities with a high number of unvaccinated persons and that maintaining high overall measles, mumps, and rubella (MMR) vaccination coverage rates in the United States is needed to continue to limit the spread of measles.
PMID: 18716580 [PubMed - in process] (Source: MMWR Morb Mortal Wkl...)...
POSTED 08/21/2008 at 11:00 PM --
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West nile virus update --- united states, january 1--august 19, 2008.
West nile virus update --- United States, january 1--august 19, 2008.
MMWR Morb Mortal Wkly Rep. 2008 Aug 22;57(33):899-900
Authors:
This report summarizes 2008 West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, August 19, 2008. A total of 28 states have reported 236 cases of human WNV illness to CDC. A total of 137 (58%) cases for which such data were available occurred in males; median age of patients was 48 years (range: 10 months--86 years). Dates of illness onset ranged from January 17 to August 14; two cases were fatal.
PMID: 18716582 [PubMed - in process] (Source: MMWR Morb Mortal Wkl...)...
POSTED 08/21/2008 at 11:00 PM --
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A new association test to test multiple-marker association
As a result of the availability of a very large numbers of single nucleotide polymorphisms, there has been increasing interest in genetic associations involving several closely linked loci. Methods for detection of association between traits and multiple genetic polymorphisms are being rapidly developed, which include the Hotelling's T2 test and the LD contrast (LDC) tests. The Hotelling's T2 test can be considered as a test to compare the means of the genotypic score in cases and controls; while the (LDC) tests can be considered as a test to compare the variance-covariance matrices of the genotypic score in cases and controls. In this article, we propose a likelihood ratio test which simultaneously compares the means and the variance-covariance matrices of the genotypic score in cases and controls. We use simulation studies to evaluate the type I error rate of the proposed test, and compare the power of the test with the Hotelling's T2 test and the LDC tests. The simulation results show that when marginal effects of the disease loci are strong, the proposed test is more powerful than the LDC tests and similar with or slightly less powerful than the Hotelling's T2 test. If there are interaction effects and weak or no marginal effects, the proposed method is more powerful than the Hotelling's T2 test and slightly more powerful than the LDC tests. Genet. Epidemiol. 2008. © 2008 Wiley-Liss, Inc. (Source: Genetic Epidemiology)...
POSTED 08/21/2008 at 11:00 PM --
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Inflammatory and transcriptional roles of poly (adp-ribose) polymerase in ventilator-induced lung injury
IntroductionPoly (ADP-ribose) polymerase (PARP) participates in inflammation by cellular necrosis and nuclear factor-kappaB (NF-kappaB) dependent transcription. The purpose of this study was to examine the roles of PARP in ventilator-induced lung injury (VILI) in normal mice lung.
Methods:
Male C57BL/6 mice were divided into four groups: sham tracheostomized (Sham), lung protective ventilation (LPV), VILI, and VILI with PARP inhibitor PJ34 pretreatment (PJ34+VILI) groups. Mechanical ventilator (MV) settings were peak inspiratory pressure (PIP) 15 cmH2O + positive end-expiratory pressure (PEEP) 3 cmH2O + 90 breaths/min for the LPV group and PIP 40 cmH2O + PEEP 0 cmH2O + 90 breaths/min for the VILI and PJ34+VILI groups. After 2 hours of MV, acute lung injury (ALI) score, wet-to-dry (W/D) weight ratio, PARP activity, and dynamic compliance (CD) were recorded. Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), myeloperoxidase (MPO) activity, and nitrite/nitrate (NOx) in the bronchoalveolar lavage fluid (BALF) and NF-kappaB-DNA binding activity in tissue homogenates were measured.
Results:
The VILI group showed higher ALI score, W/D weight ratio, MPO activity, NOx, and concentration of TNF-alpha and IL-6 along with lower CD than the Sham and LPV groups (p (Source: Critical Care)...
POSTED 08/21/2008 at 11:00 PM --
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Epidemiology, characteristics and distinctiveness of headaches in children from vojvodina, serbia
Neuroepidemiology 2008;31:122-128 (DOI:10.1159/000151513) (Source: Neuroepidemiology)...
POSTED 08/21/2008 at 04:05 AM --
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Body mass index, cholesterol level and poststroke mortality
Neuroepidemiology 2008;31:138 (DOI:10.1159/000151515) (Source: Neuroepidemiology)...
POSTED 08/21/2008 at 04:05 AM --
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Reply to the letter by mascitelli et al.: body mass index, cholesterol level and poststroke mortality
Neuroepidemiology 2008;31:138A (DOI:10.1159/000151516) (Source: Neuroepidemiology)...
POSTED 08/21/2008 at 04:05 AM --
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Environmental epidemiology of essential tremor
Neuroepidemiology 2008;31:139-149 (DOI:10.1159/000151523) (Source: Neuroepidemiology)...
POSTED 08/21/2008 at 04:05 AM --
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Clinical parameters to predict response to interferon in relapsing multiple sclerosis
Neuroepidemiology 2008;31:150-156 (DOI:10.1159/000151524) (Source: Neuroepidemiology)...
POSTED 08/21/2008 at 04:05 AM --
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