Mathematical modelling of internal HIV dynamics

We study a mathematical model for the viral dynamics of HIV in an infected individual in the presence of HAART. The paper starts with a literature review and then formulates the basic mathematical model. An expression for R0, the basic reproduction number of the virus under steady state application of HAART, is derived followed by an equilibrium and stability analysis. There is always a disease-free equilibrium (DFE) which is globally asymptotically stable for R0 1 then some simulations will die out whereas others will not. Stochastic simulations suggest that if R0 > 1 those which do not die out approach a stochastic quasi-equilibrium consisting of random uctuations about the non-trivial deterministic equilibrium levels, but the amplitude of these uctuations is so small that practically the system is at the non-trivial equilibrium. A brief discussion concludes the paper

A stochastic model for internal HIV dynamics

In this paper we analyse a stochastic model representing HIV internal virus dynamics. The stochasticity in the model is introduced by parameter perturbation which is a standard technique in stochastic population modelling. We show that the model established in this paper possesses non-negative solutions as this is essential in any population dynamics model. We also carry out analysis on the asymptotic behaviour of the model. We approximate one of the variables by a mean reverting process and nd out the mean and variance of this process. Numerical simulations conclude the paper

Association of Ambulatory Hemodynamic Monitoring With Clinical Outcomes in a Concurrent Matched Control Analysis.

Importance: In a randomized clinical trial, heart failure (HF) hospitalizations were lower in patients managed with guidance from an implantable pulmonary artery pressure sensor compared with usual care. It remains unclear if ambulatory monitoring could also improve long-term clinical outcomes in real-world practice. Objective: To determine the association between ambulatory hemodynamic monitoring and rates of HF hospitalization at 12 months in clinical practice. Design, Setting, and Participants: This case-control study of Medicare beneficiaries used claims data collected between June 1, 2014, and March 31, 2016. Medicare patients who received implants of a pulmonary artery pressure sensor were identified from the 100% Medicare claims database. Each patient who received an implant was matched to a control patient by demographic features, history of HF hospitalization, and number of all-cause hospitalizations. Propensity scoring based on comorbidities (arrhythmia, hypertension, diabetes, pulmonary disease, and renal disease) was used for additional matching. Data analysis was completed from July 2017 through January 2019. Exposures: Implantable pulmonary artery pressure monitoring system. Main Outcomes and Measures: The rates of HF hospitalization were compared using the Andersen-Gill method. Days lost owing to events were compared using a nonparametric bootstrap method. Results: The study cohort consisted of 1087 patients who received an implantable pulmonary artery pressure sensors and 1087 matched control patients. The treatment and control cohorts were well matched by age (mean [SD], 72.7 [10.2] years vs 72.9 [10.1] years) and sex (381 of 1087 female patients [35.1%] in each group), medical history, comorbidities, and timing of preimplant HF hospitalization. At 12 months postimplant, 616 HF hospitalizations occurred in the treatment cohort compared with 784 HF hospitalizations in the control cohort. The rate of HF hospitalization was lower in the treatment cohort at 12 months postimplant (hazard ratio [HR], 0.76 [95% CI, 0.65-0.89]; P \u3c .001). The percentage of days lost to HF hospitalizations or death were lower in the treatment group (HR, 0.73 [95% CI, 0.64-0.84]; P \u3c .001) and the percentage of days lost owing to all-cause hospitalization or death were also lower (HR, 0.77 [95% CI, 0.68-0.88]; P \u3c .001). Conclusions and Relevance: Patients with HF who were implanted with a pulmonary artery pressure sensor had lower rates of HF hospitalization than matched controls and spent more time alive out of hospital. Ambulatory hemodynamic monitoring may improve outcomes in patients with chronic HF

Clinical outcomes and healthcare expenditures in the real world with left ventricular assist devices - The CLEAR-LVAD study

BACKGROUND: Several distinctly engineered left ventricular assist devices (LVADs) are in clinical use. However, contemporaneous real world comparisons have not been conducted, and clinical trials were not powered to evaluate differential survival outcomes across devices. OBJECTIVES: Determine real world survival outcomes and healthcare expenditures for commercially available durable LVADs. METHODS: Using a retrospective observational cohort design, Medicare claims files were linked to manufacturer device registration data to identify de-novo, durable LVAD implants performed between January 2014 and December 2018, with follow-up through December 2019. Survival outcomes were compared using a Cox proportional hazards model stratified by LVAD type and validated using propensity score matching. Healthcare resource utilization was analyzed across device types by using nonparametric bootstrap analysis methodology. Primary outcome was survival at 1-year and total Part A Medicare payments. RESULTS: A total of 4,195 de-novo LVAD implants were identified in fee-for-service Medicare beneficiaries (821 HeartMate 3; 1,840 HeartMate II; and 1,534 Other-VADs). The adjusted hazard ratio for mortality at 1-year (confirmed in a propensity score matched analysis) for the HeartMate 3 vs HeartMate II was 0.64 (95% CI; 0.52-0.79, p\u3c 0.001) and for the HeartMate 3 vs Other-VADs was 0.51 (95% CI; 0.42-0.63, p \u3c 0.001). The HeartMate 3 cohort experienced fewer hospitalizations per patient-year vs Other-VADs (respectively, 2.8 vs 3.2 EPPY hospitalizations, p \u3c 0.01) and 6.1 fewer hospital days on average (respectively, 25.2 vs 31.3 days, p \u3c 0.01). The difference in Medicare expenditures, conditional on survival, for HeartMate 3 vs HeartMate II was -$10,722, p \u3c 0.001 (17.4$17,947, p \u3c 0.001 (26.1% reduction). CONCLUSIONS: In this analysis of a large, real world, United States. administrative dataset of durable LVADs, we observed that the HeartMate 3 had superior survival, reduced healthcare resource use, and lower healthcare expenditure compared to other contemporary commercially available LVADs

Applications of stochastic and ordinary differential equations to HIV dynamics

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

136-37: Health-related quality-of-life in patients with leadless pacemaker

Purpose: Leadless pacemakers (LPs) are miniaturized, fully self-contained devices percutaneously implanted in the right ventricle using a femoral vein approach. The multicenter LEADLESS II clinical trial has demonstrated that both pre-specified safety and effectiveness endpoints for the NanostimTM LP were met. This study assessed the health-related quality-of-life (HRQoL) in these LP patients and its corresponding changes over time. Method: Patients\u27 HRQoL were assessed using the EuroQol EQ-5D, a preference-based instrument from which utility values could be generated on the basis of item responses and an established EuroQol algorithm. EQ-5D utilities were measured on a cardinal scale of 0–1, where 0 indicates death and 1 indicates full health; with higher utilities representing better HRQoL. We included the 468 patients from the LP IDE Study who had complete EQ-5D item responses at 4 time points including: pre-discharge, weeks 2, 6 and 12, respectively. Patients\u27 baseline EQ-5D utilities (before the LP implant) were not collected; hence, a systematic review of US single-chamber pacemaker studies was conducted to obtain the mean baseline utility value to be used as the reference point for comparison. Proportional changes in EQ-5D utilities at different time points, compared with the baseline utility, were estimated and tested using Analysis of Variance. Effect sizes were calculated to evaluate the magnitude of these changes, independent of sample size effects. Summary: Mean patient age was 75 (±12) years, 37% were female and 91% were white. As shown in Table 1, mean baseline EQ-5D utility, based on literature review, was 0.73. Mean EQ-5D utility at pre-discharge was 0.81, and increased to 0.84, 0.85 and 0.84 at weeks 2, 6, and 12, respectively (p \u3c 0.01). Compared with the baseline utility, the EQ-5D utility increased by 10.3% at pre-discharge, then by 14.7%, 16.7% and 14.7% at weeks 2, 6 and 12, respectively (p \u3c 0.01). A moderate to high effect size of 0.55 was achieved at week 2, followed by a sustained improvement over the 12-week period (Table 1). Table 1. EQ-5D utility values and changes over time Mean SD Utility Change(%, compared with baseline) Effect Size¥(compared with baseline) Baseline* 0.7300 Pre-discharge 0.8053 0.2219 10.31%§ 0.3393 Week 2 0.8375 0.1964 14.73%§ 0.5476 Week 6 0.8522 0.1833 16.73%§ 0.6666 Week 12 0.8375 0.1781 14.73%§ 0.6038 * Baseline utility was obtained from a systematic review of single-chamber pacemaker studies in the US, which was 0.73. ¥ Effect size (ES) measures the magnitude of the utility changes, independent of sample size effect, where: ES ≥ 0.8: large effect; 0.8 ≥ ES ≥ 0.5: moderate to high effect; 0.5 ≥ ES ≥ 0.2: low to moderate effect; ES ≤ 0.2: low effect. § All % utility changes were statistically significant, compared with baseline utility. Conclusions: These data indicate that implantation of the NanostimTM LP is accompanied with improved HRQoL immediately after implant and the improvement was sustained over time