Machine Learning Applied to Cholesterol-Lowering Pharmacotherapy: Proof-of-Concept in High-Risk Patients Treated in Primary Care.

Objectives: Machine learning has potential to improve the management of lipid disorders. We explored the utility of machine learning in high-risk patients in primary care receiving cholesterol-lowering medications. Methods: Machine learning algorithms were created based on lipid management guidelines for England [National Institute for Health and Care Excellence (NICE) CG181] to reproduce the guidance with >95% accuracy. Natural language processing and therapy identification algorithms were applied to anonymized electronic records from six South London primary care general practices to extract medication information from free text fields. Results: Among a total of 48,226 adult patients, a subset of 5630 (mean ± standard deviation, age = 67 ± 13 years; male:female = 55:45) with a history of lipid-lowering therapy were identified. Additional major cardiometabolic comorbidities included type 2 diabetes in 13% (n = 724) and hypertension in 32% (n = 1791); all three risk factors were present in a further 28% (n = 1552). Of the 5630 patients, 4290 (76%) and 1349 (24%) were in primary and secondary cardiovascular disease prevention cohorts, respectively. Statin monotherapy was the most common current medication (82%, n = 4632). For patients receiving statin monotherapy, 71% (n = 3269) were on high-intensity therapy aligned with NICE guidance with rates being similar for the primary and secondary prevention cohorts. In the combined cohort, only 46% of patients who had been prescribed lipid-lowering therapy in the previous 12 months achieved the NICE treatment goal of >40% reduction in non-high-density lipoprotein cholesterol from baseline pretreatment levels. Based on the most recent data entry for patients not at goal the neural network recommended either increasing the dose of statin, adding complementary cholesterol-lowering medication, or obtaining an expert lipid opinion. Conclusions: Machine learning can be of value in (a) quantifying suboptimal lipid-lowering prescribing patterns, (b) identifying high-risk patients who could benefit from more intensive therapy, and (c) suggesting evidence-based therapeutic options.

Evolving Patterns of Hyperfluorescent Fundus Autofluorescence Accompany Retinal Atrophy in the Rat and Mimic Atrophic Age-Related Macular Degeneration.

PURPOSE: Complex two-dimensional (2D) patterns of hyperfluorescent short-wave fundus autofluorescence (FAF) at the border of geographic atrophy (GA) can predict its expansion in patients with late non-exudative "dry" AMD. However, preclinical models do not phenocopy this important feature of disease. We sought to describe the spatiotemporal changes in hyperfluorescent FAF patterns that occur following acute oxidative stress, potentially in association with GA expansion. METHODS: Sprague Dawley rats (n = 54) received systemic sodium iodate (25-45 mg/kg, n = 90 eyes) or saline (n = 18 eyes) and underwent serial full fundus imaging by confocal scanning laser ophthalmoscopy, including blue FAF and delayed near-infrared analysis. Composite images of the fundus were assembled, and the 2D patterns were described qualitatively and quantitatively. A subset of eyes underwent tissue analysis, and four underwent optical coherence tomography (OCT) imaging. RESULTS: Reproducibly changing, complex patterns of hyperfluorescent FAF emerge at the borders of toxin-induced damage; however, in the absence of GA expansion, they percolate inward within the region of retinal pigment epithelium loss, evolving, maturing, and senescing in situ over time. Unexpectedly, the late FAF patterns most closely resemble the diffuse tricking form of clinical disease. A five-stage classification system is presented. CONCLUSIONS: Longitudinal, full-fundus imaging of outer retinal atrophy in the rat eye identifies evolving, complex patterns of hyperfluorescent FAF that phenocopy aspects of disease. TRANSLATIONAL RELEVANCE: This work provides a novel tool to assess hyperfluorescent FAF in association with progressive retinal atrophy, a therapeutic target in late AMD.

Spontaneously occurring fundus findings observed using confocal scanning laser ophthalmoscopy in wild type Sprague Dawley rats.

PURPOSE: Non-invasive in vivo imaging is an increasingly used component of pre-clinical research. However, to reliably interpret data, it may be necessary to identify and document pre-existent findings prior to initiating long-term or intensive protocols, particularly where toxicity or efficacy is under investigation. Here we report here spontaneously occurring findings from the Sprague Dawley (SD) rat eye using multi-modal confocal scanning laser ophthalmoscopy (cSLO). METHODS: As part of ongoing studies, with the goal of excluding animals with abnormalities from further investigation, a total of 165 wild type SD rats (312 eyes) were assessed using cSLO imaging at baseline prior to initiating experiments to detect, describe, and determine the prevalence of spontaneous fundus findings. RESULTS: Using fundus autofluorescence (FAF) as the primary screening modality, over 30% of analyzed eyes possessed some fundus finding that differed from the normal composite reference image. Unexpectedly, 100% of eyes demonstrated a diffuse hyperfluorescent region in the posterior pole that was ultimately considered normal, and formed part of the reference. Evaluated by three independent reviewers, five groups of FAF abnormalities were defined, based primarily on shape and size of the lesion. Of these, the most extensive lesions were further analyzed using infrared reflectance (IR) and red free (RF) imaging. White light and autofluorescent microscopy of excised tissue confirmed that the extensive lesions were derived from abnormalities in both the isolated retina and posterior eyecups. CONCLUSIONS: Given the newly described hyperfluorescent glow that appears in all eyes, and the high basal rate of spontaneous lesions in the outbred SD rat, we suggest that investigators be aware of the variants of normal, and that baseline in vivo screening be considered prior to initiating intensive or expensive investigation.

Intact endothelial autophagy is required to maintain vascular lipid homeostasis.

The physiological role of autophagic flux within the vascular endothelial layer remains poorly understood. Here, we show that in primary endothelial cells, oxidized and native LDL stimulates autophagosome formation. Moreover, by both confocal and electron microscopy, excess native or modified LDL appears to be engulfed within autophagic structures. Transient knockdown of the essential autophagy gene ATG7 resulted in higher levels of intracellular (125) I-LDL and oxidized LDL (OxLDL) accumulation, suggesting that in endothelial cells, autophagy may represent an important mechanism to regulate excess, exogenous lipids. The physiological importance of these observations was assessed using mice containing a conditional deletion of ATG7 within the endothelium. Following acute intravenous infusion of fluorescently labeled OxLDL, mice lacking endothelial expression of ATG7 demonstrated prolonged retention of OxLDL within the retinal pigment epithelium (RPE) and choroidal endothelium of the eye. In a chronic model of lipid excess, we analyzed atherosclerotic burden in ApoE(-/-) mice with or without endothelial autophagic flux. The absence of endothelial autophagy markedly increased atherosclerotic burden. Thus, in both an acute and chronic in vivo model, endothelial autophagy appears critically important in limiting lipid accumulation within the vessel wall. As such, strategies that stimulate autophagy, or prevent the age-dependent decline in autophagic flux, might be particularly beneficial in treating atherosclerotic vascular disease.

Fundus autofluorescence (FAF) non-invasively identifies chorioretinal toxicity in a rat model of retinal pigment epithelium (RPE) damage.

INTRODUCTION: Traditional methods of pre-clinical ocular toxicology require that multiple cohorts of animals be sacrificed over time for terminal histological analysis. By contrast, in vivo techniques capable of following the same cohort prospectively have the potential to be efficient and cost-saving. We therefore asked if fundus autofluorescence (FAF), a non-invasive imaging technique, could detect damage to the posterior pole. Results were compared against electroretinography (ERG), another in vivo technique. The systemic toxin sodium iodate (NaIO3) was used to induce retinal pigment epithelium (RPE) damage. METHODS: FAF images (488/510nm excitation/emission) were obtained using a commercially available confocal scanning laser ophthalmoscope (cSLO; Heidelberg, HRAII) and were described qualitatively and quantitatively. NaIO3, over a dose range of 5 to 45mg/kg, or saline, was injected via tail vein in 6-10week old Sprague Dawley rats, and FAF images obtained at baseline and days 3, 7 and 14 thereafter and compared against the ERG response amplitude. RESULTS: Compared against baseline, there was no change in the FAF or ERG responses in the control, 5 or 15mg/kg NaIO3 groups. At 30mg/kg, responses fell into two groups. Half the animals developed small patches of abnormal FAF with modest reductions in the ERG amplitude; the other half developed large areas of damage and had severely reduced ERG responses. At 45mg/kg, all eyes developed extensive areas of abnormal FAF and the ERG was non- or minimally recordable. The en face size of the FAF patches was inversely correlated with the b-wave amplitude. DISCUSSION: This study demonstrates that FAF can detect chorioretinal toxicity in vivo in the rat eye, and that the findings correlate with the ERG. Such in vivo testing can enhance the detection of ocular toxicity.

Delayed near-infrared analysis permits visualization of rodent retinal pigment epithelium layer in vivo.

Patches of atrophy of the retinal pigment epithelium (RPE) have not been described in rodent models of retinal degeneration, as they have the clinical setting using fundus autofluorescence. We hypothesize that prelabeling the RPE would increase contrast and allow for improved visualization of RPE loss in vivo. Here, we demonstrate a new technique termed "delayed near-infrared analysis (DNIRA)" that permits ready detection of rat RPE, using optical imaging in the near-infrared (IR) spectrum with aid of indocyanine green (ICG) dye. Using DNIRA, we demonstrate a fluorescent RPE signal that is detected using confocal scanning laser ophthalmoscopy up to 28 days following ICG injection. This signal is apparent only after ICG injection, is dose dependent, requires the presence of the ICG filters (795/810 nm excitation/emission), does not appear in the IR reflectance channel, and is eliminated in the presence of sodium iodate, a toxin that causes RPE loss. Rat RPE explants confirm internalization of ICG dye. Together with normal retinal electrophysiology, these findings demonstrate that DNIRA is a new and safe noninvasive optical imaging technique for in vivo visualization of the RPE in models of retinal disease.