Background. The effect of hepatitis B virus (HBV) infection on the natural history of human immunodeficiency virus (HIV) disease remains uncertain. Therefore, a retrospective cohort study was ...conducted to examine the influence of HIV-HBV coinfection on AIDS development and overall mortality. Moreover, our results were added to those of previous studies in a literature-based meta-analysis. Methods. Serum samples obtained from HIV-seropositive patients from 1984 through 2003 were retrospectively tested for hepatitis B surface antigen. Multivariable analyses were performed using Poisson and logistic regression models. For meta-analytic purposes, eligible articles were identified and relevant data were abstracted. Pooled estimates of effect were calculated applying fixed and random effects models. Results. The prevalence of chronic HBV infection (documented hepatitis B surface antigen seropositivity for >6 months) among 1729 HIV-positive patients was ∼6%. The multivariable analyses in our primary study revealed no significant impact of concomitant HIV-HBV infection on progression to AIDS and all-cause mortality. However, a meta-analysis performed on data from 12,382 patients enrolled in 11 studies revealed a significant effect of HIV-HBV coinfection on overall mortality (pooled effect estimate, 1.36; 95% confidence interval, 1.12–1.64). The increased rate of death among coinfected individuals was observed in the meta-analyses of studies conducted both before (pooled effect estimate, 1.60; 95% confidence interval, 1.07–2.39) and after (pooled effect estimate, 1.28; 95% confidence interval, 1.03–1.60) commencement of highly active antiretroviral therapy. Conclusions. HIV-HBV coinfection seems to affect all-cause mortality, and strategies to reduce liver damage in patients coinfected with HIV and HBV are justified.
Non-parametric survival analysis has become a very popular statistical method in current medical research. However, resorting to survival analysis when its fundamental assumptions are not fulfilled ...can severely bias the results. Currently, hundreds of clinical studies are using survival methods to investigate factors potentially associated with the prognosis of coronavirus disease 2019 (COVID-19) and test new preventive and therapeutic strategies.In the pandemic era, it is more critical than ever to base decision-making on evidence and rely on solid statistical methods, but this is not always the case. Serious methodological errors have been identified in recent seminal studies about COVID-19: One reporting outcomes of patients treated with remdesivir and another one on the epidemiology, clinical course, and outcomes of critically ill patients.High-quality evidence is essential to inform clinicians about optimal COVID-19 therapies and policymakers about the true effect of preventive measures aiming to tackle the pandemic. Though timely evidence is needed, we should encourage the appropriate application of survival analysis methods and careful peer-review to avoid publishing flawed results, which could affect decision-making.In this paper, we recapitulate the basic assumptions underlying non-parametric survival analysis and frequent errors in its application and discuss how to handle data on COVID-19.
•Earlier application of social distancing interventions reduced Covid-19 mortality.•Concurrent restrictions on gatherings and schools reduced fatalities more effectively.•Timing of interventions is a ...key factor in preventing Covid-19 mortality.•Our findings can assist health policy decisions for upcoming pandemic waves.
To estimate the effect of early application of social distancing interventions on Covid-19 cumulative mortality during the first pandemic wave.
Ecological longitudinal study using multivariable negative binomial regression for panel data. Daily numbers of Covid-19 cases and deaths, and data on social distancing interventions, for the 37 member countries of the Organization for Economic Cooperation and Development (OECD) were analysed.
Covid-19 cumulative mortality over the first pandemic wave varied widely across countries (range, 4.16 to 855 deaths per million population). On average, one-day delay in application of mass gatherings ban was associated with an adjusted increase in Covid-19 cumulative mortality by 6.97% (95% CI, 3.45 to 10.5), whilst a one-day delay in school closures was associated with an increase of 4.37% (95% CI, 1.58 to 7.17) over the study period. We estimated that if each country had enacted both interventions one week earlier, Covid-19 cumulative mortality could have been reduced by an average of 44.1% (95% CI, 20.2 to 67.9).
Early application of mass gatherings ban and school closures in outbreak epicentres was associated with an important reduction in Covid-19 cumulative mortality during the first pandemic wave. These findings may support policy decision making.
Fibrates comprise a class of well-established antilipidemic agents that significantly reduce cardiovascular events. Given the concerns of cancer with fibrate therapy, we undertook a systematic review ...and meta-analysis to investigate the effects of fibrates on cancer outcomes.
We systematically searched Medline, Scopus, SCI Expanded, and the Cochrane Library for studies published up to 2012. We included randomized controlled trials (RCTs) that evaluated a fibrate therapy compared with placebo, had a minimum duration of two years, and reported data on the incidence of and/or deaths from cancer during the trial. Reviews of each study were performed and the relative data were abstracted. Pooled relative risk estimates (RR) and 95% confidence intervals (CIs) were calculated using the inverse variance weighted approach. Subgroup, sensitivity and meta-regression analyses were also conducted.
Seventeen RCTs, involving 44,929 participants with an average follow-up of 5.2 years, contributed to the analysis. The degree of variability between trials was consistent with what would be expected to occur by chance alone. The quantitative synthesis of data retrieved from the RCTs was not indicative of a fibrate effect on cancer incidence (780 fibrate vs 814 control; RR = 1.02, 95% CI 0.92-1.12) or cancer death (385 fibrate vs 377 control; RR = 1.06, 95% CI: 0.92-1.22). When the analysis was restricted to major RCTs, the results did not substantially change. Similarly, we found no evidence of differential effects by length of follow-up or type of fibrate. Insignificant results were also obtained for the role of fibrates in cancers of the respiratory tract, breast, colon, gastrointestinal tract, prostate, genitourinary tract, or in melanoma.
Our findings demonstrate that fibrates have a neutral effect on cancer outcomes. However, it is important to continue monitoring their long-term safety profiles.
Vaccines against SARS-CoV-2 have saved millions of lives and played an important role in containing the COVID-19 pandemic. Vaccination against SARS-CoV-2 is also associated with reduced disease ...severity and, perhaps, with COVID-19 symptom burden. In this narrative review, we present, in a clinically relevant question-and-answer manner, the evidence regarding the association between vaccination against SARS-CoV-2 and long COVID-19. We discuss how the mechanism of action of vaccines could interplay with the pathophysiology of post-COVID-19 condition. Furthermore, we describe how specific factors, such as the number of vaccine doses and the type of SARS-CoV-2 variants, may affect post-COVID-19 condition. We also discuss the role of timing for vaccination in relation to the onset of long COVID-19 symptoms, as it seems to affect the frequency and severity of the condition. Additionally, we describe the potential modifying effect of age, as well as the association of type and level of immune response with long COVID-19. We also describe how system-specific long COVID-19 sequelae, namely neurocognitive-psychologic symptoms and cardiovascular pathology, could be altered by vaccination. Last, we address the question of whether seasonal influenza vaccination has a meaningful impact on the frequency of long COVID-19.
Multiple environmental factors have been associated with the development of inflammatory bowel diseases (IBDs). We performed an umbrella review of meta-analyses to summarize available epidemiologic ...evidence and assess its credibility.
We systematically identified and appraised meta-analyses of observational studies examining environmental factors and risk of IBD (Crohn’s disease CD or ulcerative colitis UC). For each meta-analysis, we considered the random effects estimate, its 95% confidence interval, the estimates of heterogeneity, and small-study effects, and we graded the evidence according to prespecified criteria. Methodologic quality was assessed with AMSTAR (ie, A Measurement Tool to Assess Systematic Reviews) 2.
We examined 183 estimates in 53 meta-analyses of 71 environmental factors related to lifestyles and hygiene, surgeries, drug exposures, diet, microorganisms, and vaccinations. We identified 9 factors that increase risk of IBD: smoking (CD), urban living (CD and IBD), appendectomy (CD), tonsillectomy (CD), antibiotic exposure (IBD), oral contraceptive use (IBD), consumption of soft drinks (UC), vitamin D deficiency (IBD), and non–Helicobacter pylori–like enterohepatic Helicobacter species (IBD). We identified 7 factors that reduce risk of IBD: physical activity (CD), breastfeeding (IBD), bed sharing (CD), tea consumption (UC), high levels of folate (IBD), high levels of vitamin D (CD), and H pylori infection (CD, UC, and IBD). Epidemiologic evidence for all of these associations was of high to moderate strength; we identified another 11 factors associated with increased risk and 16 factors associated with reduced risk with weak credibility. Methodologic quality varied considerably among meta-analyses. Several associations were based on findings from retrospective studies, so it is not possible to determine if these are effects of IBD or the results of recall bias.
In an umbrella review of meta-analyses, we found varying levels of evidence for associations of different environmental factors with risk of IBD. High-quality prospective studies with analyses of samples from patients with recent diagnoses of IBD are needed to determine whether these factors cause or are results of IBD and their pathogenic mechanisms.
Forecasting and operational research: a review Fildes, R; Nikolopoulos, K; Crone, S F ...
The Journal of the Operational Research Society,
09/2008, Letnik:
59, Številka:
9
Journal Article
Recenzirano
Odprti dostop
From its foundation, operational research (OR) has made many substantial contributions to practical forecasting in organizations. Equally, researchers in other disciplines have influenced forecasting ...practice. Since the last survey articles in JORS, forecasting has developed as a discipline with its own journals. While the effect of this increased specialization has been a narrowing of the scope of OR's interest in forecasting, research from an OR perspective remains vigorous. OR has been more receptive than other disciplines to the specialist research published in the forecasting journals, capitalizing on some of their key findings. In this paper, we identify the particular topics of OR interest over the past 25 years. After a brief summary of the current research in forecasting methods, we examine those topic areas that have grabbed the attention of OR researchers: computationally intensive methods and applications in operations and marketing. Applications in operations have proved particularly important, including the management of inventories and the effects of sharing forecast information across the supply chain. The second area of application is marketing, including customer relationship management using data mining and computer-intensive methods. The paper concludes by arguing that the unique contribution that OR can continue to make to forecasting is through developing models that link the effectiveness of new forecasting methods to the organizational context in which the models will be applied. The benefits of examining the system rather than its separate components are likely to be substantial.
Influenza virus continues to cause yearly seasonal epidemics worldwide and periodically pandemics. Although influenza virus infection and its epidemiology have been extensively studied, a new ...pandemic is likely. One of the reasons influenza virus causes epidemics is its ability to constantly antigenically transform through genetic diversification. However, host immune defense mechanisms also have the potential to evolve during short or longer periods of evolutionary time. In this mini-review, we describe the evolutionary procedures related with influenza viruses and their hosts, under the prism of a predator-prey relationship.
Significant cross talk occurs between inflammation and coagulation. Thus, coagulopathy is common in sepsis, potentially aggravating the prognosis. Initially, septic patients tend to exhibit a ...prothrombotic state through extrinsic pathway activation, cytokine-induced coagulation amplification, anticoagulant pathways suppression, and fibrinolysis impairment. In late sepsis stages, with the establishment of disseminated intravascular coagulation (DIC), hypocoagulability ensues. Traditional laboratory findings of sepsis, including thrombocytopenia, increased prothrombin time (PT) and fibrin degradation products (FDPs), and decreased fibrinogen, only present late in the course of sepsis. A recently introduced definition of sepsis-induced coagulopathy (SIC) aims to identify patients at an earlier stage when changes to coagulation status are still reversible. Nonconventional assays, such as the measurement of anticoagulant proteins and nuclear material levels, and viscoelastic studies, have shown promising sensitivity and specificity in detecting patients at risk for DIC, allowing for timely therapeutic interventions. This review outlines current insights into the pathophysiological mechanisms and diagnostic options of SIC.
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