Evaluating risk factor assumptions: a simulation-based approach

<p>Abstract</p> <p>Background</p> <p>Microsimulation models are an important tool for estimating the comparative effectiveness of interventions through prediction of individual-level disease outcomes for a hypothetical population. To estimate the effectiveness of interventions targeted toward high risk groups, the mechanism by which risk factors influence the natural history of disease must be specified. We propose a method for evaluating these risk factor assumptions as part of model-building.</p> <p>Methods</p> <p>We used simulation studies to examine the impact of risk factor assumptions on the relative rate (RR) of colorectal cancer (CRC) incidence and mortality for a cohort with a risk factor compared to a cohort without the risk factor using an extension of the CRC-SPIN model for colorectal cancer. We also compared the impact of changing age at initiation of screening colonoscopy for different risk mechanisms.</p> <p>Results</p> <p>Across CRC-specific risk factor mechanisms, the RR of CRC incidence and mortality decreased (towards one) with increasing age. The rate of change in RRs across age groups depended on both the risk factor mechanism and the strength of the risk factor effect. Increased non-CRC mortality attenuated the effect of CRC-specific risk factors on the RR of CRC when both were present. For each risk factor mechanism, earlier initiation of screening resulted in more life years gained, though the magnitude of life years gained varied across risk mechanisms.</p> <p>Conclusions</p> <p>Simulation studies can provide insight into both the effect of risk factor assumptions on model predictions and the type of data needed to calibrate risk factor models.</p

Routine Laboratory Results and Thirty Day and One-Year Mortality Risk Following Hospitalization with Acute Decompensated Heart Failure

INTRODUCTION: Several blood tests are performed uniformly in patients hospitalized with acute decompensated heart failure and are predictive of the outcomes: complete blood count, electrolytes, renal function, glucose, albumin and uric acid. We sought to evaluate the relationship between routine admission laboratory tests results, patient characteristics and 30-day and one-year mortality of patients admitted for decompensated heart failure and to construct a simple mortality prediction tool. METHODS: A retrospective population based study. Data from seven tertiary hospitals on all admissions with a principal diagnosis of heart failure during the years 2002-2005 throughout Israel were captured. RESULTS: 8,246 patients were included in the study cohort. Thirty day mortality rate was 8.5% (701 patients) and one-year mortality rate was 28.7% (2,365 patients). Addition of five routine laboratory tests results (albumin, sodium, blood urea, uric acid and WBC) to a set of clinical and demographic characteristics improved c-statistics from 0.76 to 0.81 for 30-days and from 0.72 to 0.76 for one-year mortality prediction (both p-values <0.0001). Three dichotomized abnormal laboratory results with highest odds ratio for one-year mortality (hypoalbuminaemia, hyponatremia and elevated blood urea) were used to construct a simple prediction score, capable of discriminating from 1.1% to 21.4% in 30-day and from 11.6% to 55.6% in one-year mortality rates between patients with a score of 0 (1,477 patients) vs. score of 3 (544 patients). DISCUSSION: A small set of abnormal routine laboratory results upon admission can risk-stratify and independently predict 30-day and one-year mortality in patients hospitalized with acute decompensated heart failure

Antibody agonists trigger immune receptor signaling through local exclusion of receptor-type protein tyrosine phosphatases

Antibodies can block immune receptor engagement or trigger the receptor machinery to initiate signaling. We hypothesized that antibody agonists trigger signaling by sterically excluding large receptor-type protein tyrosine phosphatases (RPTPs) such as CD45 from sites of receptor engagement. An agonist targeting the costimulatory receptor CD28 produced signals that depended on antibody immobilization and were sensitive to the sizes of the receptor, the RPTPs, and the antibody itself. Although both the agonist and a non-agonistic anti-CD28 antibody locally excluded CD45, the agonistic antibody was more effective. An anti–PD-1 antibody that bound membrane-proximally excluded CD45, triggered SHP2 phosphatase recruitment, and suppressed systemic lupus erythematosus and delayed-type hypersensitivity in experimental models. Paradoxically, nivolumab and pembrolizumab, anti–PD-1 blocking antibodies used clinically, also excluded CD45 and were agonistic in certain settings. Reducing these agonistic effects using antibody engineering improved PD-1 blockade. These findings establish a framework for developing new and improved therapies for autoimmunity and cancer

Pharmacological activity of the hydroalcoholic extract from Hovenia dulcis thunberg fruit and the flavonoid dihydromyricetin during hypercholesterolemia induced in rats

Cerebrovascular accidents and coronary artery disease are the leading causes of cardiovascular mortalities in Brazil and high levels of LDL cholesterol are one of the main risk factors. In this context, several plant extracts and natural substances have shown promise as cholesterol-lowering. The objective of this study was to evaluate the potential of the hydroalcoholic extract of the fruit of H. dulcisand of dihydromyricetin in cholesterol reduction in hypercholesterolemic rats. Forty-two Wistar male rats were distributed into seven groups of six animals that received diets supplemented with 1% cholesterol and 0.3% cholic acid, with the exception of the control group, which received conventional diets. Animals were treated with oral suspensions containing: atorvastatin 1.0 mg/kg; H. dulcisextract at 50.0 and 100.0 mg/kg and dihydromyricetin at 25.0 and 50.0 mg/kg vehicle (control group). The following biochemical markers were evaluated; total cholesterol, HDL-C, LDL-C, triglycerides, AST, ALT, and alkaline phosphatase. The hypercholesterolemic diet was effective in inducing hypercholesterolemia, increasing total cholesterol by 112.7% relative to the control group. The treatments with two doses of the extract proved to be promising hypocholesterolemic agents, as they were able to substantially reduce total cholesterol and LDL-C, without significantly altering triglycerides, hepatic transaminases, and alkaline phosphatase, thereby encouraging the studies with the plant H. dulcis. The groups treated with the flavonoid dihydromyricetin, although they showed a significant reduction in total cholesterol and LDL-C, and found increases in triglycerides and hepatic transaminases, which is unwanted in the context of hypercholesterolaemia

Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters

“Super-blooms” of cyanobacteria that produce potent and environmentally persistent biotoxins (microcystins) are an emerging global health issue in freshwater habitats. Monitoring of the marine environment for secondary impacts has been minimal, although microcystin-contaminated freshwater is known to be entering marine ecosystems. Here we confirm deaths of marine mammals from microcystin intoxication and provide evidence implicating land-sea flow with trophic transfer through marine invertebrates as the most likely route of exposure. This hypothesis was evaluated through environmental detection of potential freshwater and marine microcystin sources, sea otter necropsy with biochemical analysis of tissues and evaluation of bioaccumulation of freshwater microcystins by marine invertebrates. Ocean discharge of freshwater microcystins was confirmed for three nutrient-impaired rivers flowing into the Monterey Bay National Marine Sanctuary, and microcystin concentrations up to 2,900 ppm (2.9 million ppb) were detected in a freshwater lake and downstream tributaries to within 1 km of the ocean. Deaths of 21 southern sea otters, a federally listed threatened species, were linked to microcystin intoxication. Finally, farmed and free-living marine clams, mussels and oysters of species that are often consumed by sea otters and humans exhibited significant biomagnification (to 107 times ambient water levels) and slow depuration of freshwater cyanotoxins, suggesting a potentially serious environmental and public health threat that extends from the lowest trophic levels of nutrient-impaired freshwater habitat to apex marine predators. Microcystin-poisoned sea otters were commonly recovered near river mouths and harbors and contaminated marine bivalves were implicated as the most likely source of this potent hepatotoxin for wild otters. This is the first report of deaths of marine mammals due to cyanotoxins and confirms the existence of a novel class of marine “harmful algal bloom” in the Pacific coastal environment; that of hepatotoxic shellfish poisoning (HSP), suggesting that animals and humans are at risk from microcystin poisoning when consuming shellfish harvested at the land-sea interface

Rationale and methods of the multicenter randomised trial of a heart failure management programme among geriatric patients (HF-Geriatrics)

<p>Abstract</p> <p>Background</p> <p>Disease management programmes (DMPs) have been shown to reduce hospital readmissions and mortality in adults with heart failure (HF), but their effectiveness in elderly patients or in those with major comorbidity is unknown. The Multicenter Randomised Trial of a Heart Failure Management Programme among Geriatric Patients (HF-Geriatrics) assesses the effectiveness of a DMP in elderly patients with HF and major comorbidity.</p> <p>Methods/Design</p> <p>Clinical trial in 700 patients aged ≥ 75 years admitted with a primary diagnosis of HF in the acute care unit of eight geriatric services in Spain. Each patient should meet at least one of the following comorbidty criteria: Charlson index ≥ 3, dependence in ≥ 2 activities of daily living, treatment with ≥ 5 drugs, active treatment for ≥ 3 diseases, recent emergency hospitalization, severe visual or hearing loss, cognitive impairment, Parkinson's disease, diabetes mellitus, chronic obstructive pulmonary disease (COPD), anaemia, or constitutional syndrome. Half of the patients will be randomly assigned to a 1-year DMP led by a case manager and the other half to usual care. The DMP consists of an educational programme for patients and caregivers on the management of HF, COPD (knowledge of the disease, smoking cessation, immunizations, use of inhaled medication, recognition of exacerbations), diabetes (knowledge of the disease, symptoms of hyperglycaemia and hypoglycaemia, self-adjustment of insulin, foot care) and depression (knowledge of the disease, diagnosis and treatment). It also includes close monitoring of the symptoms of decompensation and optimisation of treatment compliance. The main outcome variables are quality of life, hospital readmissions, and overall mortality during a 12-month follow-up.</p> <p>Discussion</p> <p>The physiological changes, lower life expectancy, comorbidity and low health literacy associated with aging may influence the effectiveness of DMPs in HF. The HF-Geriatrics study will provide direct evidence on the effect of a DMP in elderly patients with HF and high comorbidty, and will reduce the need to extrapolate the results of clinical trials in adults to elderly patients.</p> <p>Trial registration</p> <p>(ClinicalTrials.gov number, <a href="http://www.clinicaltrials.gov/ct2/show/NCT01076465">NCT01076465</a>).</p

Bacterial Biodiversity-Ecosystem Functioning Relations Are Modified by Environmental Complexity

Peer reviewedPublisher PD