We propose the use of multiscale amplitude-modulation frequency-modulation (AM-FM) methods for discriminating between normal and pathological retinal images. The method presented in this paper is tested using standard images from the Early Treatment Diabetic Retinopathy Study (ETDRS). We use 120 regions of 40×40 pixels containing 4 types of lesions commonly associated with diabetic retinopathy (DR) and two types of normal retinal regions that were manually selected by a trained analyst. The region types included: microaneurysms, exudates, neovascularization on the retina, hemorrhages, normal retinal background, and normal vessels patterns. The cumulative distribution functions of the instantaneous amplitude, the instantaneous frequency magnitude, and the relative instantaneous frequency angle from multiple scales are used as texture features vectors. We use distance metrics between the extracted feature vectors to measure interstructure similarity. Our results demonstrate a statistical differentiation of normal retinal structures and pathological lesions based on AM-FM features. We further demonstrate our AM-FM methodology by applying it to classification of retinal images from the MESSIDOR database. Overall, the proposed methodology shows significant capability for use in automatic DR screening.
BackgroundCase‐fatality rates in acute myocardial infarction (AMI) have significantly decreased; however, the prevalence of diabetes mellitus (DM), a risk factor for AMI, has increased. The purposes of the present study were to assess the prevalence and clinical impact of DM among patients hospitalized with AMI and to estimate the impact of important clinical characteristics associated with in‐hospital mortality in patients with AMI and DM.Methods and ResultsWe used the National Inpatient Sample to estimate trends in DM prevalence and in‐hospital mortality among 1.5 million patients with AMI from 2000 to 2010, using survey data‐analysis methods. Clinical characteristics associated with in‐hospital mortality were identified using multivariable logistic regression. There was a significant increase in DM prevalence among AMI patients (year 2000, 22.2%; year 2010, 29.6%, Ptrend<0.0001). AMI patients with DM tended to be older and female and to have more cardiovascular risk factors. However, age‐standardized mortality decreased significantly from 2000 (8.48%) to 2010 (4.95%) (Ptrend<0.0001). DM remained independently associated with mortality (adjusted odds ratio 1.069, 95% CI 1.051 to 1.087; P<0.0001). The adverse impact of DM on in‐hospital mortality was unchanged over time. Decreased death risk over time was greatest among women and elderly patients. Among younger patients of both sexes, there was a leveling off of this decrease in more recent years.ConclusionsDespite increasing DM prevalence and disease burden among AMI patients, in‐hospital mortality declined significantly from 2000 to 2010. The adverse impact of DM on mortality remained unchanged overall over time but was age and sex dependent.
BACKGROUND: A small number of high-need patients account for a disproportionate amount of Medicaid spending, yet typically engage little in outpatient care and have poor outcomes. OBJECTIVE: To address this issue, we developed ECHO (Extension for Community Health Outcomes) Care™, a complex care intervention in which outpatient intensivist teams (OITs) provided care to high-need high-cost (HNHC) Medicaid patients. Teams were supported using the ECHO model™, a continuing medical education approach that connects specialists with primary care providers for casebased mentoring to treat complex diseases. DESIGN: Using an interrupted time series analysis of Medicaid claims data, we measured healthcare utilization and expenditures before and after ECHO Care. PARTICIPANTS: ECHO Care served 770 patients in New Mexico between September 2013 and June 2016. Nearly all had a chronic mental illness, and over three-quarters had a chronic substance use disorder. INTERVENTION: ECHO Care patients received care from an OIT, which typically included a nurse practitioner or physician assistant, a registered nurse, a licensed mental health provider, and at least one community health worker. Teams focused on addressing patients' physical, behavioral, and social issues. MAIN MEASURES: We assessed the effect of ECHO Care on Medicaid costs and utilization (inpatient admissions, emergency department (ED) visits, other outpatient visits, and dispensed prescriptions. KEY RESULTS: ECHO Care was associated with significant changes in patients' use of the healthcare system. At 12 months post-enrollment, the odds of a patient having an inpatient admission and an ED visit were each reduced by approximately 50%, while outpatient visits and prescriptions increased by 23% and 8%, respectively. We found no significant change in overall Medicaid costs associated with ECHO Care. CONCLUSIONS: ECHO Care shifts healthcare utilization from inpatient to outpatient settings, which suggests decreased patient suffering and greater access to care, including more effective prevention and early intervention for chronic conditions.
Age-related macular degeneration (AMD) is the most common cause of visual loss in the United States and is a growing public health problem. The presence and severity of AMD in current epidemiological studies is detected by the grading of color stereoscopic fundus photographs. The purpose of this study was to show that a mathematical technique, amplitude-modulation frequency modulation (AM-FM) can be used to generate multi-scale features for classifying pathological structures, such as drusen, on a retinal image. AM-FM features were calculated for N=120 40x40 regions from 5 retinal images presenting with age-related macular degeneration. The results show that with this technique, drusen can be differenced from normal retinal structures by more than three standard deviations using the AM-FM histograms. In addition, by using different color spaces highly accurate classification of structures of the retina is achieved. These results are the first step in the development of an automated AMD grading system.
Background and objectivesIn the general population, sleep disorders are associated with mortality. However, such evidence in patients with CKD and ESKD is limited and shows conflicting results. Our aim was to examine the association of sleep apnea with mortality among patients with CKD and ESKD.Design, setting, participants, & measurementsIn this prospective cohort study, 180 patients (88 with CKD stage 4 or 5, 92 with ESKD) underwent in-home polysomnography, and sleep apnea measures such as apnea hypopnea index (AHI) and nocturnal hypoxemia were obtained. Mortality data were obtained from the National Death Index. Cox proportional hazard models were used for survival analysis.ResultsAmong the 180 patients (mean age 54 years, 37% women, 39% with diabetes, 49% CKD with mean eGFR 18±7 ml/min per 1.73 m2), 71% had sleep apnea (AHI>5) and 23% had severe sleep apnea (AHI>30). Median AHI was 13 (range, 4–29) and was not significantly different in patients with advanced CKD or ESKD. Over a median follow-up of 9 years, there were 84 (47%) deaths. AHI was not significantly associated with mortality after adjusting for age, sex, race, diabetes, body mass index, CKD/ESKD status, and kidney transplant status (AHI>30: hazard ratio [HR], 1.5; 95% confidence interval [95% CI], 0.6 to 4.0; AHI >15 to 30: HR, 2.3; 95% CI, 0.9 to 5.9; AHI >5 to 15: HR, 2.1; 95% CI, 0.8 to 5.4, compared with AHI≤5). Higher proportion of sleep time with oxygen saturation <90% and lower mean oxygen saturation were significantly associated with higher mortality in adjusted analysis (HR, 1.4; 95% CI, 1.1 to 1.7; P=0.007 for every 15% higher proportion, and HR, 1.6; 95% CI, 1.2 to 2.1; P=0.003 for every 2% lower saturation, respectively). Sleep duration, sleep efficiency, or periodic limb movement index were not associated with mortality.ConclusionsHypoxemia-based measures of sleep apnea are significantly associated with increased risk of death among advanced CKD and ESKD.
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