Pippa Simpson

Bio: Pippa Simpson is an academic researcher from Medical College of Wisconsin. The author has contributed to research in topics: Population & Medicine. The author has an hindex of 63, co-authored 463 publications receiving 18397 citations. Previous affiliations of Pippa Simpson include Wayne State University & Virginia Commonwealth University.

Household Food Insecurity Is Associated with Adult Health Status

Abstract: The prevalence of household food security, which reflects adequacy and stability of the food supply, has been measured periodically in the United States and occasionally in high-risk groups or specific regions. Despite a plausible biological mechanism to suggest negative health outcomes of food insecurity, this relation has not been adequately evaluated. This study was conducted in the Lower Mississippi Delta region to examine the association between household food insecurity and self-reported health status in adults. A two-stage stratified cluster sample representative of the population in 36 counties in the Delta region of Arkansas, Louisiana, and Mississippi was selected using list-assisted random digit dialing telephone methodology. After households were selected and screened, a randomly selected adult was interviewed within each sampled household. Data were collected to measure food security status and self-reported mental, physical, and general health status, using the U.S. Food Security Survey Module and the Short Form 12-item Health Survey (SF-12). Data were reported on a sample of 1488 households. Adults in food-insecure households were significantly more likely to rate their health as poor/fair and scored significantly lower on the physical and mental health scales of the SF-12. In regression models controlling for income, gender, and ethnicity, the interaction between food insecurity status and race was a significant predictor of fair/poor health and lower scores on physical and mental health. Household food insecurity is associated with poorer self-reported health status of adults in this rural, high-risk sample in the Lower Mississippi Delta.

The Association of Child and Household Food Insecurity With Childhood Overweight Status

Abstract: CONTEXT. The prevalence of childhood overweight status is increasing. Some have suggested that childhood overweight is associated with food insecurity, defined as limited or uncertain access to enough nutritious food. OBJECTIVES. The purpose of this work was to assess the association of household and child food insecurity with childhood overweight status. METHODS. The National Health and Nutrition Examination Survey 1999–2002 uses a stratified multistaged probability sample and collects a broad array of data from a nationally representative sample of US citizens. All children 3 to 17 years old in this sample are included in these analyses. We measured BMI categorized as at risk for overweight or greater (≥85%) or overweight (≥95%) and household and child food security/insecurity using the US Food Security Scale. RESULTS. When compared with children from food-secure households, children from food-insecure households were more likely to demonstrate significant associations with being at risk for overweight or greater in the following demographic categories: 12 to 17 years, girls, white, and in households with income 4 times the federal poverty level. Household food insecurity is associated with child overweight status in children aged 12 to 17, girls, and children who live in households with incomes >4 times the federal poverty level. Child food insecurity demonstrated the same associations with being at risk for overweight or greater, as did household food insecurity, but associations were also seen in 3- to 5-year-old children, boys, and Mexican American children. Child food insecurity is significantly associated with child overweight status for children aged 12 to 17, girls, white children, and children in families with income ≤100% poverty level. Controlling for ethnicity, gender, age, and family poverty index level, childhood food insecurity is associated with a child being at risk for overweight status or greater, but not overweight status. CONCLUSIONS. Household and child food insecurity are associated with being at risk for overweight and overweight status among many demographic categories of children. Child food insecurity is independently associated with being at risk for overweight status or greater while controlling for important demographic variables. Future longitudinal research is required to determine whether food insecurity is causally related to child overweight status.

Bacteriocin production augments niche competition by enterococci in the mammalian gastrointestinal tract

Abstract: Enterococcus faecalis is both a common commensal of the human gastrointestinal tract and a leading cause of hospital-acquired infections. Systemic infections with multidrug-resistant enterococci occur subsequent to gastrointestinal colonization. Preventing colonization by multidrug-resistant E. faecalis could therefore be a valuable approach towards limiting infection. However, little is known about the mechanisms E. faecalis uses to colonize and compete for stable gastrointestinal niches. Pheromone-responsive conjugative plasmids encoding bacteriocins are common among enterococcal strains and could modulate niche competition among enterococci or between enterococci and the intestinal microbiota. We developed a model of colonization of the mouse gut with E. faecalis, without disrupting the microbiota, to evaluate the role of the conjugative plasmid pPD1 expressing bacteriocin 21 (ref. 4) in enterococcal colonization. Here we show that E. faecalis harbouring pPD1 replaces indigenous enterococci and outcompetes E. faecalis lacking pPD1. Furthermore, in the intestine, pPD1 is transferred to other E. faecalis strains by conjugation, enhancing their survival. Colonization with an E. faecalis strain carrying a conjugation-defective pPD1 mutant subsequently resulted in clearance of vancomycin-resistant enterococci, without plasmid transfer. Therefore, bacteriocin expression by commensal bacteria can influence niche competition in the gastrointestinal tract, and bacteriocins, delivered by commensals that occupy a precise intestinal bacterial niche, may be an effective therapeutic approach to specifically eliminate intestinal colonization by multidrug-resistant bacteria, without profound disruption of the indigenous microbiota.

Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study

Abstract: Objective: To determine the relation between exposure to glycaemia over time and the risk of macrovascular or microvascular complications in patients with type 2 diabetes. Design: Prospective observational study. Setting: 23 hospital based clinics in England, Scotland, and Northern Ireland. Participants: 4585 white, Asian Indian, and Afro-Caribbean UKPDS patients, whether randomised or not to treatment, were included in analyses of incidence; of these, 3642 were included in analyses of relative risk. Outcome measures: Primary predefined aggregate clinical outcomes: any end point or deaths related to diabetes and all cause mortality. Secondary aggregate outcomes: myocardial infarction, stroke, amputation (including death from peripheral vascular disease), and microvascular disease (predominantly retinal photo-coagulation). Single end points: non-fatal heart failure and cataract extraction. Risk reduction associated with a 1% reduction in updated mean HbA 1c adjusted for possible confounders at diagnosis of diabetes. Results: The incidence of clinical complications was significantly associated with glycaemia. Each 1% reduction in updated mean HbA 1c was associated with reductions in risk of 21% for any end point related to diabetes (95% confidence interval 17% to 24%, P Conclusions: In patients with type 2 diabetes the risk of diabetic complications was strongly associated with previous hyperglycaemia. Any reduction in HbA 1c is likely to reduce the risk of complications, with the lowest risk being in those with HbA 1c values in the normal range (

Reconsidering Baron and Kenny: Myths and Truths about Mediation Analysis

Abstract: Baron and Kenny’s procedure for determining if an independent variable affects a dependent variable through some mediator is so well known that it is used by authors and requested by reviewers almost reflexively. Many research projects have been terminated early in a research program or later in the review process because the data did not conform to Baron and Kenny’s criteria, impeding theoretical development. While the technical literature has disputed some of Baron and Kenny’s tests, this literature has not diffused to practicing researchers. We present a nontechnical summary of the flaws in the Baron and Kenny logic, some of which have not been previously noted. We provide a decision tree and a step-by-step procedure for testing mediation, classifying its type, and interpreting the implications of findings for theory building and future research.

Peginterferon alfa-2a plus ribavirin for chronic hepatitis C virus infection.

Abstract: Background Treatment with peginterferon alfa-2a alone produces significantly higher sustained virologic responses than treatment with interferon alfa-2a alone in patients with chronic hepatitis C virus (HCV) infection. We compared the efficacy and safety of peginterferon alfa-2a plus ribavirin, interferon alfa-2b plus ribavirin, and peginterferon alfa-2a alone in the initial treatment of chronic hepatitis C. Methods A total of 1121 patients were randomly assigned to treatment and received at least one dose of study medication, consisting of 180 μg of peginterferon alfa-2a once weekly plus daily ribavirin (1000 or 1200 mg, depending on body weight), weekly peginterferon alfa-2a plus daily placebo, or 3 million units of interferon alfa-2b thrice weekly plus daily ribavirin for 48 weeks. Results A significantly higher proportion of patients who received peginterferon alfa-2a plus ribavirin had a sustained virologic response (defined as the absence of detectable HCV RNA 24 weeks after cessation of therapy) th...

Epidemiologic Classification of Human Papillomavirus Types Associated with Cervical Cancer

Abstract: Background Infection with human papilloma virus (HPV) is the main cause of cervical cancer, but the risk associated with the various HPV types has not been adequately assessed. Methods We pooled data from 11 case–control studies from nine countries involving 1918 women with histologically confirmed squamous-cell cervical cancer and 1928 control women. A common protocol and questionnaire were used. Information on risk factors was obtained by personal interviews, and cervical cells were collected for detection of HPV DNA and typing in a central laboratory by polymerase-chain-reaction–based assays (with MY09/MY11 and GP5+/6+ primers). Results HPV DNA was detected in 1739 of the 1918 patients with cervical cancer (90.7 percent) and in 259 of the 1928 control women (13.4 percent). With the GP5+/6+ primer, HPV DNA was detected in 96.6 percent of the patients and 15.6 percent of the controls. The most common HPV types in patients, in descending order of frequency, were types 16, 18, 45, 31, 33, 52, 58, and 35. A...

Preoperative versus Postoperative Chemoradiotherapy for Rectal Cancer

Abstract: background Postoperative chemoradiotherapy is the recommended standard therapy for patients with locally advanced rectal cancer. In recent years, encouraging results with preoperative radiotherapy have been reported. We compared preoperative chemoradiotherapy with postoperative chemoradiotherapy for locally advanced rectal cancer. methods We randomly assigned patients with clinical stage T3 or T4 or node-positive disease to receive either preoperative or postoperative chemoradiotherapy. The preoperative treatment consisted of 5040 cGy delivered in fractions of 180 cGy per day, five days per week, and fluorouracil, given in a 120-hour continuous intravenous infusion at a dose of 1000 mg per square meter of body-surface area per day during the first and fifth weeks of radiotherapy. Surgery was performed six weeks after the completion of chemoradiotherapy. One month after surgery, four five-day cycles of fluorouracil (500 mg per square meter per day) were given. Chemoradiotherapy was identical in the postoperative-treatment group, except for the delivery of a boost of 540 cGy. The primary end point was overall survival. results Four hundred twenty-one patients were randomly assigned to receive preoperative chemoradiotherapy and 402 patients to receive postoperative chemoradiotherapy. The overall five-year survival rates were 76 percent and 74 percent, respectively (P=0.80). The five-year cumulative incidence of local relapse was 6 percent for patients assigned to preoperative chemoradiotherapy and 13 percent in the postoperative-treatment group (P=0.006). Grade 3 or 4 acute toxic effects occurred in 27 percent of the patients in the preoperative-treatment group, as compared with 40 percent of the patients in the postoperative-treatment group (P=0.001); the corresponding rates of long-term toxic effects were 14 percent and 24 percent, respectively (P=0.01). conclusions Preoperative chemoradiotherapy, as compared with postoperative chemoradiotherapy, improved local control and was associated with reduced toxicity but did not improve overall survival.