A two-dimensional discrete delay-differential system model of viremia.

A deterministic model is proposed to describe the interaction between an immune system and an invading virus whose target cells circulate in the blood. The model is a system of two ordinary first order quadratic delay-differential equations with stipulated initial conditions, whose coefficients are eventually constant, so that the system becomes autonomous. The long-term behavior of the solution is investigated with some success. In particular, we find two simple functions of the parameters of the model, whose signs often, but not always, determine whether the virus persists above a nonzero threshold in the circulation or heads toward extinction.

Disparities in Colorectal Cancer Screening in Latinos and Non-Hispanic Whites.

INTRODUCTION: Colorectal cancer is the second leading cause of cancer deaths in Latinos in the U.S., but it is unclear, from previous research, whether Latinos have differing rates of colorectal cancer screening methods from those of non-Hispanic Whites. METHODS: This study used electronic health records from 686 community health centers across 21 states in the Accelerating Data Value Across a National Community Health Center of the National Patient-Centered Clinical Research Network. Records from English-preferring Latinos, Spanish-preferring Latinos, and non-Hispanic Whites aged 50-75 years were included. A total of 5 outcomes were compared between 2012 and 2017 to provide a comprehensive view of colorectal cancer screening: (1) any colorectal cancer screening, (2) stool-based screening, (3) annual rates of stool testing, (4) any referral for lower gastrointestinal endoscopy, and (5) endoscopy referral among patients with a positive stool-based screening. RESULTS: In this study (N=204,243), Spanish-preferring Latinos had higher odds of any colorectal cancer screening (OR=1.44, 95% CI=1.23, 1.68) and stool-based testing (OR=1.82, 95% CI=1.55, 2.13) than non-Hispanic Whites. English- and Spanish-preferring Latinos had lower odds of having ever had a referral for endoscopy in the study period than non-Hispanic Whites (English: OR=0.23, 95% CI=0.15, 0.34; Spanish: OR=0.55, 95% CI=0.40, 0.74), even with a positive stool-based screening (English: OR=0.14, 95% CI=0.06, 0.33; Spanish: OR=0.33, 95% CI=0.19, 0.57). CONCLUSIONS: In a multistate network of community health centers, Latino patients aged >50 years were more likely to receive stool-based screening tests for colorectal cancer than non-Hispanic Whites but were less likely to receive endoscopy referrals than non-Hispanic Whites, even when experiencing a positive stool-based screening test. Initiatives to improve Latino colorectal cancer outcomes should encourage indicated referrals for lower gastrointestinal endoscopy.

Implications of American College of Cardiology/American Heart Association (ACC/AHA) Cholesterol Guidelines on Statin Underutilization for Prevention of Cardiovascular Disease in Diabetes Mellitus Among Several US Networks of Community Health Centers.

BACKGROUND: Little is known about statin underutilization among diabetes mellitus patients cared for in community health centers, which tend to serve socioeconomically disadvantaged populations. Implications of the American College of Cardiology/American Heart Association (ACC/AHA) guidelines on preexisting gaps in statin treatment in this population are unclear. METHODS AND RESULTS: We included 32 440 adults (45% male, 63% nonwhite, 29% uninsured/Medicaid) aged 40 to 75 years with diabetes mellitus who received care within 16 community health center groups in 11 states in the Community Health Applied Research Network during 2013. Statin prescribing was analyzed as a function of concordance with the National Cholesterol Education Program Adult Treatment Panel 2001 and ACC/AHA 2013 guidelines. More patients' treatments were concordant with the ACC/AHA (52.8%) versus the National Cholesterol Education Program Adult Treatment Panel (36.2%) guideline. Female sex was associated with lower concordance for both (odds ratio [OR] 0.90, CI 0.85-0.94; and OR 0.84, CI 0.80-0.88, respectively). Being insured, an Asian/Pacific Islander, or primarily Spanish speaking were associated with greater concordance for both guidelines: 35.5% (11 526/32 440) were concordant with neither guideline, the majority (79.7%) having no statin prescribed; 28.2% (9168/32 440) were concordant with ACC/AHA but not the National Cholesterol Education Program Adult Treatment Panel. 8.7% of these patients had a low-density lipoprotein cholesterol >160 mg/dL despite having a moderate- or high-intensity statin prescribed. And 11.6% (3772/32 440) were concordant with the National Cholesterol Education Program Adult Treatment Panel but not with ACC/AHA. Most of these patients had a low-density lipoprotein cholesterol between 70 and 99 mg/dL with no or a low-intensity statin prescribed. CONCLUSIONS: Opportunities exist to improve cholesterol management in diabetes mellitus patients in community health centers. Addressing care gaps could improve cardiovascular disease prevention in this high-risk population.

Colorectal Cancer Screening Rates at Community Health Centers that Use Electronic Health Records: A Cross Sectional Study.

BACKGROUND: This study was conducted to validate use of electronic health record (EHR) data for measuring colorectal cancer (CRC) screening rates at community health centers (CHCs). METHODS: Electronic health records were queried to assess screening via colonoscopy, flexible sigmoidoscopy, or fecal occult blood testing (FOBT) in 2011. RESULTS: Multiple iterations were required to maximize query accuracy. Manual chart reviews, stratified by screening modality, confirmed query results for 112 of 113 (99.1%) reviewed colonoscopies, 110 of 110 (100%) reviewed FOBTs, and 111 of 120 (92.5%) unscreened patients. At participating CHCs, CRC screening rates ranged from 9.7% to 67.2% (median, 30.6%). Adherence to annual FOBT ranged from 3.3% to 59.0% (median, 18.6%). Most screening was done by colonoscopy. CONCLUSIONS: Colorectal cancer screening varies substantially across CHCs. Electronic health record data can validly measure CRC screening, but repeated assessments of programming accuracy are required. Community health centers may need support to measure quality using EHR data and increase screening.

Colorectal cancer screening at community health centers: A survey of clinicians' attitudes, practices, and perceived barriers.

OBJECTIVE: Colorectal cancer (CRC) screening rates remain lower among some racial/ethnic groups and individuals with low income or educational attainment who are often cared for within community health centers (CHCs). We surveyed clinicians in a network of CHCs to understand their attitudes, practice patterns, and perceived barriers to CRC screening. METHODS: A clinician survey was conducted in 2013 within the Community Health Applied Research Network (CHARN). RESULTS: 180 clinicians completed the survey (47.9% response rate). Participants had an average of 11.5 (SD: 9.8) years in practice, 62% were female, and 57% were physicians. The majority of respondents somewhat agreed (30.2%) or strongly agreed (57.5%) that colonoscopy was the best screening test. However, only 15.8% of respondents strongly agreed and 32.2% somewhat agreed that colonoscopy was readily available for their patients. Fecal immunochemical testing (FIT), a type of fecal occult blood test (FOBT), was viewed less favorably; 24.6% rated FIT as very effective. CONCLUSIONS: Although there are no data showing that screening colonoscopy is superior to FIT, CHC clinicians believe colonoscopy is the best CRC screening test for their patients, despite the high prevalence of financial barriers to colonoscopy. These attitudes could be due to lack of knowledge about the evidence supporting long-term benefits of fecal occult blood testing (FOBT), lack of awareness about the improved test characteristics of FIT compared to older guaiac-based FOBT, or the absence of systems to ensure adherence to regular FOBT screening. Interventions to improve CRC screening at CHCs must address clinicians' negative attitudes towards FIT.

"Not a kidney or a lung:" research challenges in a network of safety net clinics.

BACKGROUND AND OBJECTIVES: To gain a better understanding of the facilitators and barriers to creating a practice-based research network (PBRN) of safety net clinics, we conducted a qualitative study within our network of safety net health centers. METHODS: Utilizing snowball sampling, we conducted interviews with 19 of our founding stakeholders and analyzed these interviews to draw out common themes. RESULTS: The results showed four barriers to research in our network: lack of research generated from clinician questions, lack of appropriate funding, lack of clinician time, and lack of infrastructure. We discuss these results and suggest that inadequate funding for practice-based research, particularly in the health care safety net, is a unifying theme of these four barriers. CONCLUSIONS: Our results suggest that the national funding strategy for research relevant to underserved populations and all of primary care must undergo a fundamental shift. We discuss the features of possible models to meet this need.

Lessons learned and challenges ahead: report from the OCHIN Safety Net West practice-based research network (PBRN).

INTRODUCTION: We recently completed a strategic planning process to better understand the development of our 5-year-old practice-based research network (PBRN) and to identify gaps between our original vision and current progress. Although many of our experiences are not new to the PBRN community, our reflections may be valuable for those developing or reshaping PBRNs in a changing health care environment. LESSONS LEARNED: We learned about the importance of (1) shared vision and commitment to a unique patient population; (2) strong leadership, mentorship, and collaboration; (3) creative approaches to engaging busy clinicians and bridging the worlds of academia and community practice; and (4) harnessing data from electronic health records and navigating processes related to data protection, sharing, and ownership. CHALLENGES AHEAD: We must emphasize research that is timely, relevant, and integrated into practice. One model supporting this goal involves a broader partnership than was initially envisioned for our PBRN--one that includes clinicians, researchers, information architects, and quality improvement experts partnering to develop an innovation center. This center could facilitate development of relevant research questions while also addressing "quick-turnaround" needs. CONCLUSIONS: Gaps remain between our PBRN's initial vision and current reality. Closing these gaps may require future creativity in building partnerships and finding nontraditional funding sources.

Maintaining diversity in an artificially propagated population.

Populations may suffer unexpected loss or distortion of biodiversity as a consequence of strategies employed in artificial propagation programs. The Trinity River Fish Hatchery may have inadvertently experienced this while attempting to preserve diversity in a return time within a Chinook salmon population. We develop a model for this system and prove that the long-term distribution of return types converges and that it is strongly tied to the management strategy. Given estimates of heritabilities for return type and differential survival rates, an estimate of this long-term distribution can be computed easily.