Predation effects on mean time to extinction under demographic stochasticity

Methods for predicting the probability and timing of a species' extinction are typically based on a combination of theoretical models and empirical data, and focus on single species population dynamics. Of course, species also interact with each other, forming more or less complex networks of interactions. Models to assess extinction risk often lack explicit incorporation of these interspecific interactions. We study a birth and death process in which the death rate includes an effect from predation. This predation rate is included via a general nonlinear expression for the functional response of predation to prey density. We investigate the effects of the foraging parameters (e.g. attack rate and handling time) on the mean time to extinction. Mean time to extinction varies by orders of magnitude when we alter the foraging parameters, even when we exclude the effects of these parameters on the equilibrium population size. In particular we observe an exponential dependence of the mean time to extinction on handling time. These findings clearly show that accounting for the nature of interspecific interactions is likely to be critically important when estimating extinction risk.Comment: 11 pages, 4 figures; Typos removed. For further discussion about the paper go to http://purl.org/net/extinctio

Prescriber continuity and medication availability in older adults with cardiometabolic conditions

Background: Many older adults have multiple conditions and see multiple providers, which may impact their use of essential medications. Objective: We examined whether the number of prescribers of these medications was associated with the availability of medications, a surrogate for adherence, to manage diabetes, hypertension or dyslipidemia. Methods: A retrospective cohort of 383,145 older adults with diabetes, hypertension or dyslipidemia in the US Medicare program living in 10 states. The association between the number of prescribers of cardiometabolic medications in 2010 and medication availability (proportion of days with medication on hand) in 2011 was estimated via logistic regression, controlling for patient demographic characteristics and chronic conditions. Results: Medicare beneficiaries with diabetes, hypertension and/or dyslipidemia had an average of five chronic conditions overall, obtained 10–12 medications for all conditions and most often had one prescriber of cardiometabolic medications. In adjusted analyses, the number of prescribers was not significantly associated with availability of oral diabetes agents but having more prescribers is associated with increased medication availability in older Medicare beneficiaries with dyslipidemia or hypertension. Conclusion: The incremental addition of new prescribers may be clinically reasonable for complex patients but creates the potential for coordination problems and informational discontinuity over time. Health systems may want to identify complex patients with multiple prescribers to minimize care fragmentation

Implementation of automated reporting of estimated glomerular filtration rate among Veterans Affairs laboratories: a retrospective study

Abstract Background Automated reporting of estimated glomerular filtration rate (eGFR) is a recent advance in laboratory information technology (IT) that generates a measure of kidney function with chemistry laboratory results to aid early detection of chronic kidney disease (CKD). Because accurate diagnosis of CKD is critical to optimal medical decision-making, several clinical practice guidelines have recommended the use of automated eGFR reporting. Since its introduction, automated eGFR reporting has not been uniformly implemented by U. S. laboratories despite the growing prevalence of CKD. CKD is highly prevalent within the Veterans Health Administration (VHA), and implementation of automated eGFR reporting within this integrated healthcare system has the potential to improve care. In July 2004, the VHA adopted automated eGFR reporting through a system-wide mandate for software implementation by individual VHA laboratories. This study examines the timing of software implementation by individual VHA laboratories and factors associated with implementation. Methods We performed a retrospective observational study of laboratories in VHA facilities from July 2004 to September 2009. Using laboratory data, we identified the status of implementation of automated eGFR reporting for each facility and the time to actual implementation from the date the VHA adopted its policy for automated eGFR reporting. Using survey and administrative data, we assessed facility organizational characteristics associated with implementation of automated eGFR reporting via bivariate analyses. Results Of 104 VHA laboratories, 88% implemented automated eGFR reporting in existing laboratory IT systems by the end of the study period. Time to initial implementation ranged from 0.2 to 4.0 years with a median of 1.8 years. All VHA facilities with on-site dialysis units implemented the eGFR software (52%, p Conclusions The VHA did not have uniform implementation of automated eGFR reporting across its facilities. Facility-level organizational characteristics were not associated with implementation, and this suggests that decisions for implementation of this software are not related to facility-level quality improvement measures. Additional studies on implementation of laboratory IT, such as automated eGFR reporting, could identify factors that are related to more timely implementation and lead to better healthcare delivery.</p

Social vulnerability is associated with more stomas after surgery for uncomplicated diverticulitis

Background: Previous research has demonstrated disparities in surgical management of diverticulitis based on various patient characteristics, including race. Recent investigation suggests environmental factors may also play a prominent role in patient outcomes. The Center for Disease Control and Prevention's Social Vulnerability Index (SVI) is emerging as a useful tool for studying this effect and may better characterize social determinants of health among colorectal pathology. Methods: This was a retrospective review of patients in the Healthcare Cost and Utilization Project Florida State Inpatient Database (2006–2014), matched by ZIP code to their corresponding SVI. Patients admitted through the emergency department with a primary diagnosis of diverticulitis were included. The rate of stoma creation amongst patients undergoing non-elective surgery for uncomplicated diverticulitis was compared by SVI. Results: Of the 4,212 patients in this study who underwent colectomy, 2,310 (54.8%) received a stoma. Compared to those with low vulnerability, highly vulnerable patients were more likely to receive a stoma (p = 0.014). In multivariable logistic analysis, increasing vulnerability was independently associated with increased odds of stoma creation (OR 1.08, p<0.001). Female sex (OR 0.86, p = 0.027), nonwhite race (OR 0.63, p<0.001), and minimally invasive surgical approach (OR 0.41, p<0.001) were associated with decreased odds of stoma creation. Conclusions: High social vulnerability was associated with stoma creation amongst patients who underwent non-elective surgery for uncomplicated diverticulitis. Contrarily, nonwhite race was associated with decreased rate of stoma creation, highlighting the importance of using more comprehensive metrics of patient vulnerability such as SVI, rather than race, in disparities research