Study of Risk Factors Associated with Peripheral Arteriopathy in Japanese-Brazilians from Bauru (SP)

Background

Cardiovascular diseases are the major cause of morbidity and mortality in developed and emerging countries. Their main etiology, atherosclerosis, is a disseminated disease that affects the coronary, cerebral and peripheral territories. The peripheral arterial disease (PAD), as well as its consequences, indicates the involvement of the coronary territory. Therefore, its better understanding enables proper treatment, delaying local and long-term complications, reducing the cost to the health system.

Objective

This study estimates the percentage of PAD in Japanese-Brazilians from Bauru (SP), recognized by the high prevalence of metabolic disorders such as hypertension (43%), diabetes mellitus (33%) and hypercholesterolemia (60%), and examines the association with risk biomarkers.

Methods

This cross-sectional population study evaluated 1,330 Japanese-Brazilians of both genders aged ≥ 30 who underwent a complete physical examination, anthropometric measurements, laboratory tests and ankle-brachial index (ABI). Participants with ABI ≤ 0.90 were diagnosed as having PAD. After applying the exclusion criteria, 1,038 individuals were part of the analysis. We used Poisson regression to analyze associations with PAD.

Results

The mean age was 56.8 years and the percentage of PAD was 21.1%, equal among the genders. PAD was associated with smoking (PR 2.16 [1.33 to 3.48]) and hypertension (PR 1.56 [1.12-2.22]).

Conclusion

The percentage of PAD in Japanese-Brazilians was similar to other populations of adverse cardiometabolic profile (US PARTNERS and POPADAD). The independent association of PAD with smoking and hypertension, but not with other classical risk factors, may depend on the very high frequencies of metabolic disorders in this population.     

Association of Peripheral Arterial and Cardiovascular Diseases in Familial Hypercholesterolemia

Background

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disease characterized by an elevation in the serum levels of total cholesterol and of low-density lipoproteins (LDL- c). Known to be closely related to the atherosclerotic process, FH can determine the development of early obstructive lesions in different arterial beds. In this context, FH has also been proposed to be a risk factor for peripheral arterial disease (PAD).

Objective

This observational cross-sectional study assessed the association of PAD with other manifestations of cardiovascular disease (CVD), such as coronary artery and cerebrovascular disease, in patients with heterozygous FH.

Methods

The diagnosis of PAD was established by ankle-brachial index (ABI) values ≤ 0.90. This study assessed 202 patients (35% of men) with heterozygous FH (90.6% with LDL receptor mutations), mean age of 51 ± 14 years and total cholesterol levels of 342 ± 86 mg /dL.

Results

The prevalences of PAD and previous CVD were 17% and 28.2 %, respectively. On multivariate analysis, an independent association between CVD and the diagnosis of PAD was observed (OR = 2.50; 95% CI: 1.004 - 6.230; p = 0.049).

Conclusion

Systematic screening for PAD by use of ABI is feasible to assess patients with FH, and it might indicate an increased risk for CVD. However, further studies are required to determine the role of ABI as a tool to assess the cardiovascular risk of those patients.     

Effects of age, sex and smoking on ankle-brachial index in a Finnish population at risk for cardiovascular disease

BACKGROUND

Smoking is a well-known risk factor for peripheral arterial disease (PAD). Data regarding differences in the prevalence of PAD between sexes are somewhat controversial. In addition, most studies indicate that the prevalence of PAD increases with age in both sexes. In the present study, the effects of sex, age and smoking on the ankle-brachial index (ABI) in a Finnish cardiovascular risk population were investigated.

OBJECTIVES

To investigate the relationship between the ankle-brachial index, and age, sex and smoking in a Finnish population at risk for cardiovascular disease.

METHODS

All men and women between 45 and 70 years of age living in a rural town (Harjavalta, Finland; total population 7700) were invited to participate in a population survey (Harmonica study). Patients with previously diagnosed diabetes or vascular disease were excluded. In total, 2856 patients were invited to participate in the study. From these subjects, a cardiovascular risk population was screened. Complete data were available from 1028 persons. ABI (the ratio between the posterior tibial or dorsalis pedis artery and brachial artery pressures) was measured, and questionnaires were used to detect smoking status and relevant medical history. Only current smoking status was taken into account.

RESULTS

The mean ABI for the entire study population was 1.10 (range 0.56 to 1.64). Current smokers had a lower mean ABI (1.06; P<0.001). There was no statistically significant difference in ABI values among age groups, although the majority of patients with ABI values below 0.9 were older than 60 years of age. There was no statistically significant difference in ABI between sexes.

CONCLUSION

As previously reported, the present study shows the significant effect of smoking in the development of PAD. No statistically significant difference was found among age groups, but the tendency was toward lower ABIs in the oldest age groups. Sex had a minimal effect on the ABI.     

Abdominal circumference and recurrent hospitalizations may affect the clinical outcome of patients with acute heart failure

BACKGROUND:

In patients with heart failure, low body mass index has been associated with increased mortality. The hypothesis for the present study was that asymptomatic peripheral artery disease (PAD) could have an effect on the in-hospital mortality of patients admitted with acute heart failure.

METHODS:

The effect of PAD (documented by ankle-brachial index [ABI]) on in-hospital mortality was examined among 143 patients who were admitted with acute heart failure (mean [± SD] age 75±12 years; 76 women and 67 men). The mean body mass index was 29.5±7.4 kg/m², the mean ABI was 0.9±0.2 and the mean abdominal circumference was 107.7±22.5 cm.

RESULTS:

Nine patients died (one man and eight women; P=0.02). Forty patients had PAD (documented by an ABI of lower than 0.9); among them, five patients (12.5%) died, while among the 103 patients who did not have PAD (ABI of 0.9 or greater), four patients (3.9%) died (P=0.05). No statistically significant difference was observed in the body mass index of patients who died compared with those who survived (27.14±7.93 kg/m² versus 29.79±7.56 kg/m², respectively) (P=0.38). Patients who died had a lower abdominal circumference (94.87±26.96 cm versus 109.25±20.29 cm) (P=0.05). Recurrent hospitalizations were more prevalent among patients who died (six patients were readmitted and four of them died [66%], while only five patients died among 133 patients who were not rehospitalized [3.8%]; P=0.001). In a multiple regression analysis, abdominal circumference and rehospitalization had an independent impact on in-hospital mortality, while PAD did not.

CONCLUSIONS:

In-hospital mortality of patients admitted with acute heart failure is dependent on abdominal circumference and recurrent hospitalizations. PAD does not affect the in-hospital clinical outcome.     

Peripheral arterial disease: Lack of awareness in Canada

BACKGROUND:

Peripheral arterial disease (PAD) is a common manifestation of systemic atherosclerosis and is associated with a high risk of stroke, myocardial infarction and cardiovascular death. PAD also fosters major morbidity by causing claudication, functional impairment, disability and amputation. PAD is largely unrecognized and under-treated compared with other cardiovascular diseases. The public health impact of PAD, as a contributor to Canadian national rates of heart attack, stroke, amputation, death and disability, will be challenging to address if the public is unaware of this common cardiovascular disease.

OBJECTIVE:

To assess public knowledge of PAD in Canada.

METHODS:

A cross-sectional, population-based telephone survey of 501 adults 50 years of age and older (mean age 64.4 years) was conducted using random digit dialing. The survey assessed demographics and risk factors of the study population and knowledge of PAD causes and consequences.

RESULTS:

Survey respondents reported a high prevalence of atherosclerotic risk factors including high blood pressure (43%), high blood cholesterol (37%), diabetes (12%) and smoking history (18% current and 49% former smokers). Only 36% of respondents reported familiarity with PAD, which was significantly lower than other cardiovascular diseases or risk factors. Knowledge of perceived consequences of PAD was low and knowledge gaps were more pronounced in older, less educated and lower income respondents.

CONCLUSIONS:

The Canadian public is largely unaware of PAD as a prevalent systemic manifestation of atherosclerosis and its associated morbidity and mortality. National PAD awareness programs should be instituted to increase PAD knowledge to levels comparable with other cardiovascular diseases and risk factors.     

Oscillometric measurement of ankle-brachial index

INTRODUCTION

Peripheral arterial disease is a coronary risk equivalent; a low ankle-brachial index (ABI) is indicative of systemic vascular disease, and should place a patient in the high-risk category. Few physicians measure ABI because it is technically challenging and time consuming. Oscillometric blood pressure monitors are readily available and easy to use. The use of a simple method of documenting ABI was assessed and compared with the conventional method.

METHODS

The oscillometric ABI (OABI) was measured for normal volunteers, patients attending a cardiovascular risk clinic (Cardiovascular Risk Factor Reduction Unit [CRFRU] at the University of Saskatchewan, Saskatoon) and patients referred to a vascular laboratory (vasc lab). The latter group had Doppler ABI (DABI) measurements and served to validate OABI. An Omron HEM 711C oscillometric system (Omron Canada Inc) with appropriate cuff size for arm and leg circumference was used.

RESULTS

The mean ± SEM OABI was 1.13±0.08 in normal volunteers (n=26), 1.10±0.10 in CRFRU patients (n=11, P not significant) and 1.03±0.14 in vasc lab patients (n=57, P<0.05 compared with normal volunteers). No difference was found between sexes, and there was no correlation with age. In the vasc lab group, the correlation with DABI was 0.71 (P<0.05). The sensitivity of OABI to detect DABI of less than 0.9 was 0.71, and the specificity was 0.89. OABI was found to be less sensitive at detecting low values in patients with nonpalpable pulses on physical examination.

CONCLUSION

The OABI is feasible and operator-independent, but does not detect low ABI efficiently. If OABI is abnormal, low DABI is likely. The OABI is less likely to detect disease in patients with nonpalpable peripheral pulses. Such patients are better referred directly to a vascular laboratory for DABI testing.     

Ankle-Brachial index by oscillometry: A very useful method to assess peripheral arterial disease in diabetes

Background:

Peripheral Arterial Disease (PAD) remains the least recognized form of atherosclerosis. The Ankle-Brachial Index (ABI) has emerged as one of the potent markers of diffuse atherosclerosis, cardiovascular (CV) risk, and overall survival in general public, especially in diabetics. The important reason for the lack of early diagnosis is the non-availability of a test that is easy to perform and less expensive, with no training required.

Objectives:

To evaluate the osillometric method of performing ABI with regard to its usefulness in detecting PAD cases and to correlate the signs and symptoms with ABI.

Materials and Methods:

Two hundred diabetics of varying duration attending the clinic for a period of eight months, from August 2006 to April 2007, were evaluated for signs, symptoms, and risk factors. ABI was performed using the oscillometric method. The positives were confirmed by Doppler evaluation. An equal number of age- and sex-matched controls, which were ABI negative, were also assessed by Doppler. Sensitivity and Specificity were determined.

Results:

There were 120 males and 80 females. Twelve males (10%) and six females (7.5%) were ABI positive. On Doppler, eleven males (91.5%) and three females (50%) were true positives. There were six false negatives from the controls (three each). The Sensitivity was 70% and Specificity was 75%. Symptoms and signs correlated well with ABI positives. Hypertension was the most important risk factor.

Conclusions:

In spite of the limitations, the oscillometric method of performing ABI is a simple procedure, easy to perform, does not require training and can be performed as an outpatient procedure not only by doctors, but also by the paramedical staff to detect more PAD cases.     

Prevalence of lower extremities peripheral arterial disease among Egyptian ischemic patients attending cardiac rehabilitation unit

Background

Atherosclerosis is progressive and diffuse pathological disorders which can simultaneously affect multiple vascular beds. Diagnosing Lower extremities peripheral arterial disease (PAD) in patients with Coronary artery disease (CAD) admitted to cardiac rehabilitation program can help to tailor exercise regimen to fit these patients, in addition, early treatment and/or intervention may help to control progression of the disease.

Long-term outcome of infrapopliteal catheter-based intervention for critical limb ischemia

CONTEXT:

Percutaneous treatment of tibioperoneal occlusive disease is associated with decreased morbidity compared with bypass surgery. The long-term patency and limb salvage rates are not well documented.

AIMS:

To evaluate the long-term outcome of endoluminal interventions for tibioperoneal lesions.

METHODS:

A retrospective study was performed to determine the outcomes of patients undergoing infrapopliteal catheter-based intervention for critical limb ischemia. Collected data included demographics, comorbidities, clinical presentation, pre- and postintervention noninvasive vascular measurements (segmental pressure and waveforms, and ankle-brachial index [ABI]), type of intervention, limb loss rate, patient follow-up and need for surgical revascularization. Statistical analysis was performed with the two-tailed t test. P<0.05 was considered significant; results were reported as mean ± SD. Cox regression analysis and Kaplan-Meier limb survival analysis were performed to demonstrate freedom from amputation over time.

RESULTS:

Thirty-five patients underwent intervention from 2003 to 2008; technical success was achieved in 26 patients (75%). Arterial segmental pressure studies revealed a significant increase in ABI – preprocedure ABI was 0.62±0.24 versus a postintervention ABI of 0.81±0.29 (P=0.02). The limb salvage rate was 63% during the follow-up period. Limb salvage was better for patients who underwent isolated infrapopliteal intervention versus combined above and below the knee intervention.

CONCLUSION:

Percutaneous interventions for tibioperoneal occlusive disease offer an acceptable limb salvage rate and may be the preferred initial treatment for critical limb ischemia.     

Efficacy of multi-detector coronary computed tomography angiography in comparison with exercise electrocardiogram in the triage of patients of low risk acute chest pain

Objectives

To compare the safety and diagnostic efficacy of coronary computed tomography angiography (CTA) with exercise electrocardiography (XECG) in triaging patients of low risk acute chest pain.

Background

Noninvasive assessment of coronary stenosis by CTA may improve early and accurate triage of patients presenting with acute chest pain to the emergency department (ED).

Methods

Low risk patients of possible acute coronary syndrome (ACS) were included in the study. The patients in CTA arm with significant stenosis (≥50%) underwent catheterization, while those with no or intermediate stenosis (<50%) were discharged from ED and followed up periodically for six months for major adverse cardiovascular events (MACE). The same protocol was applied for XECG arm. Outcomes included: safety and diagnostic efficacy.

Results

A total of 81 (41 CTA and 40 XECG) patients were enrolled. In this study CTA was observed to be 100% sensitive and 95.7% specific in diagnosing MACE in low risk patients of chest pain presenting to the ED, with a PPV of 94.7% and an NPV of 100%.The overall diagnostic efficacy was 97.6%. XECG was observed to be 72.7% sensitive and 96.6% specific in diagnosing MACE with a PPV of 88.9% and NPV of 90.3% in low risk chest pain patients presenting to the ED. The overall diagnostic accuracy was 90%.

Conclusion

CTA is an excellent diagnostic tool in ED patients with low risk of ACS, with minimum time delay as compared to XECG, and also is safe for triaging such patients.     

Comparison of the diagnostic accuracy of ischemia-modified albumin and echocardiography in patients with acute chest pain

BACKGROUND:

Several imaging tests and biomarkers have been proposed for the identification of patients with unstable angina among those presenting to the emergency department with acute chest pain. Preliminary data suggest that ischemia-modified albumin (IMA) may represent a potentially useful biomarker in these patients.

OBJECTIVE:

To compare IMA and echocardiography in excluding unstable angina in patients with acute chest pain.

METHODS:

Thirty-three patients (mean [± SD] age 59.8±10.8 years; 28 men) presenting to the emergency department with acute chest pain lasting <3 h suggestive of acute coronary syndrome, with normal or non-diagnostic electrocardiograms, and creatine kinase MB and troponin levels within the normal range, were included in the present study.

RESULTS:

After further diagnostic evaluation, five patients (15.2%) were diagnosed with unstable angina. The sensitivity, specificity, positive predictive value and negative predictive (NPV) value of echocardiography for diagnosing unstable angina was 60.0%, 89.3%, 50.0% and 92.6%, respectively. The area under the ROC curve for diagnosing unstable angina based on the serum IMA levels was 0.193 (95% CI 0.047 to 0.339; P<0.05). Based on ROC curve analysis, serum IMA levels ≥31.95 IU/mL yielded the optimal combination of sensitivity and specificity for diagnosing unstable angina. The sensitivity, specificity, positive predictive value and NPV of serum IMA levels ≥31.95 IU/mL for diagnosing unstable angina was 40.0%, 28.6%, 9.1% and 72.7%, respectively.

CONCLUSIONS:

Measurement of serum IMA levels appears to represent a useful tool for excluding unstable angina in patients presenting to the emergency department with acute chest pain. Moreover, IMA shows an NPV that is comparable with echocardiography.     

Percutaneous transluminal angioplasty of the popliteal artery without the use of stents: A review of 116 consecutive procedures

PURPOSE

To evaluate the safety and efficacy of percutaneous transluminal angioplasty (PTA), without the use of stents, for the treatment of popliteal artery stenosis.

METHODS

From March 1997 to December 2003, 116 consecutive PTAs of the popliteal artery were performed in 98 patients. All patients underwent preoperative and postoperative colour duplex scans and preoperative angiography. In all cases, the superficial femoral artery was patent and without significant stenosis. Follow-up patency was assessed by clinical examination and colour duplex scanning in all patients.

RESULTS

There was no perioperative mortality. Primary patency after two years was 86% for intermittent claudication (IC) patients and 54% for critical limb ischemia (CLI) patients. Secondary patency rates were 98% for IC patients versus 92% for CLI patients after one year, 94% for IC patients versus 83% for CLI patients after two years and 69% for IC patients versus 7% for CLI patients after five years (P<0.001).

CONCLUSION

Popliteal artery PTA is safe and efficient, especially in IC patients with single lesions.     

Poor ‘real-life’ negative predictive value of cross-sectional imaging in obstructive jaundice

BACKGROUND:

Cross-sectional imaging remains the first-line test for obstructive jaundice despite high miss rates for pancreatobiliary tumours. Improvements in resolution and slice thickness of spiral computed tomography/magnetic resonance imaging/magnetic resonance cholangiopancreatography promised to increase accuracy.

OBJECTIVE:

To assess whether the post-test probability of neoplasm is truly altered by the presence or absence of a mass on computed tomography/magnetic resonance imaging in obstructive jaundice.

METHODS:

The institutional endoscopic ultrasound (EUS) database was retrospectively reviewed to stratify patients presenting to EUS over a two-year period for obstructive jaundice (suspicious for malignancy) according to their pre-EUS imaging results. The primary analysis involved the calculation of the positive predictive value and negative predictive value (NPV) of imaging with 95% binomial CIs. Test performance of EUS/fine-needle aspiration (FNA) was also calculated. Final diagnosis was determined by positive cytology/histology; negative EUS was supplemented by clinical follow-up.

RESULTS:

The positive predictive value (n=51) and NPV (n=53) of pre-EUS imaging was 98% (95% CI 90% to 100%) and 9% (95% CI 3% to 21%), respectively (accuracy 53%), with post-test suspicion of malignancy similar between imaging-positive and -negative groups. EUS demonstrated a mass in 96% of imaging-positive cases versus 85% in imaging-negative cases (exact P=0.09). Malignant or suspicious FNA cytology was obtained with EUS in 92% of the imaging-positive group, and 62% of the imaging-negative group (75% of subgroup with FNA) (P<0.001).

CONCLUSION:

Lack of a definite mass on pre-EUS imaging had low NPV, and was clearly not sufficiently accurate or reassuring in this clinical setting. In suspicious obstructive jaundice, EUS with FNA has a high diagnostic yield regardless of the findings of pre-EUS cross-sectional imaging and, as such, EUS may be a more reasonable first-line test in this high-suspicion setting.     

Prevalence and treatment patterns of lower extremity peripheral arterial disease among patients at risk in ambulatory health settings

Background

Lower extremity peripheral arterial disease (PAD) is underdiagnosed and undertreated in Canada, although data are limited. We sought to measure PAD prevalence and treatment patterns in ambulatory settings.

Methods

Five trained undergraduate pharmacy students screened subjects > 50 years of age in 10 community pharmacies and 4 physician offices in northern and central Alberta. We assessed cardiovascular risk factors, cardiovascular disease (CVD), and use of evidence-based therapies; administered the Edinburgh Claudication Questionnaire; and measured the ankle-brachial index (ABI). Patients with definite claudication but ABI > 0.90, or patients with ABI > 1.30 were referred to the study vascular medicine physician for further assessment. PAD was defined as an ABI ≤ 0.90 at the initial community screening or an exercise ABI of ≤ 0.90 and 20% lower than the resting ABI, or toe-brachial index of ≤ 0.70.

Results

We recruited 361 patients (65.1 ± 9.5 years old, 55% female, 85% white) between July 1 and November 30, 2008. Sixteen subjects had PAD (prevalence 4.4%; 95% confidence interval [CI], 2.3-6.5), and all were previously unaware that they had PAD. Nine patients (2.5%) had PAD only, 7 (1.9%) had both PAD and CVD, 87 (24%) had CVD only, and 259 (72%) had neither PAD nor CVD. Use of antiplatelet agents (44%), angiotensin blockade (56%), or statins (44%) was low in patients with newly diagnosed PAD and without other CVD.

Conclusions

About 1 in 20 ambulatory persons > 50 years of age screened had PAD. All cases of PAD that we found were previously undiagnosed, and there was a large treatment gap for those without concomitant CVD.     

One-year costs associated with cardiovascular disease in Canada: Insights from the REduction of Atherothrombosis for Continued Health (REACH) registry

BACKGROUND AND OBJECTIVES:

To provide a contemporary estimate of the economic burden of atherothrombosis in Canada, annual cardiovascular-related hospitalizations, medication use and associated costs across the entire spectrum of atherothrombotic disease were examined.

METHODS:

The REduction of Atherothrombosis for Continued Health (REACH) registry enrolled 1964 Canadian outpatients with coronary artery disease, cerebrovascular disease or peripheral arterial disease (PAD), or three or more cardiovascular risk factors. Baseline data on cardiovascular risk factors and associated medication use, and one-year follow-up data on cardiovascular events, hospitalizations, procedures and medication use were collected. Annual hospitalization and medication costs (Canadian dollars) were derived and compared among patients according to the presence of established atherothrombotic disease at baseline, specific arterial beds affected and the number of affected arterial beds.

RESULTS:

Average annualized medication costs were $1,683, $1,523 and $1,776 for patients with zero, one, and two or three symptomatic arterial beds, respectively. Average annual hospitalization costs increased significantly with the number of beds affected ($380, $1,403 and $3,465, respectively; P<0.0001 for overall linear trend). Mean hospitalization costs for patients with any coronary artery disease, any cerebrovascular disease and any PAD were $1,743, $1,823 and $4,677, respectively. After adjusting for other clinical factors, PAD at baseline was independently associated with a significant increase in hospitalization costs.

CONCLUSION:

Costs associated with vascular-related hospitalizations and interventions for Canadian patients increased with the number of affected arterial beds, and were particularly high for patients with PAD and/or polyvascular disease. These contemporary data provide insight into the economic burden associated with atherothrombotic disease in Canada, and highlight the need for increased preventive strategies to lessen the burden for patients and society.     

Prediction of Advanced Fibrosis in Nonalcoholic Fatty Liver Disease: An Enhanced Model of BARD Score

Background/Aims

The BARD score is a model to detect advanced liver fibrosis in nonalcoholic fatty liver disease (NAFLD) patients. The aims of this study were to identify additional factors and then to build an enhanced version of the BARD score.

Methods

One hundred seven patients with biopsy-proven NAFLD were enrolled retrospectively. Logistic regressions were performed to identify independent risk factors for advanced liver fibrosis (stage 3 or 4). An enhanced model of the BARD score (BARDI score) was built and evaluated with a receiver operating characteristic (ROC) curve.

Results

In multivariate analysis, age (odds ratio [OR], 0.89; p=0.04), aspartate aminotransferase/alanine aminotransferase ratio (OR, 1.73; p<0.01), and international normalized ratio (INR) (OR, 8.85; p<0.01) were independently significant factors. The BARDI score was created by adding the INR to the BARD. The area under the ROC curve of the BARDI score was significantly larger than that of the BARD score (0.881 vs 0.808, p<0.01). A BARDI score of 3 or more showed a positive predictive value (PPV) of 51.0% and a negative predictive value (NPV) of 96.0%.

Conclusions

The BARDI score had an improved PPV over the BARD score and maintained an excellent NPV. Further study is warranted for its external validation and comparison with other models.     

Identifying type 1 and type 2 diabetic cases using administrative data: a tree-structured model

Background:

To date, few administrative diabetes mellitus (DM) registries have distinguished type 1 diabetes mellitus (T1DM) from type 2 diabetes mellitus (T2DM).

Objective:

Using a classification tree model, a prediction rule was developed to distinguish T1DM from T2DM in a large administrative database.

Methods:

The Medical Archival Retrieval System at the University of Pittsburgh Medical Center included administrative and clinical data from January 1, 2000, through September 30, 2009, for 209,647 DM patients aged ≥18 years. Probable cases (8,173 T1DM and 125,111 T2DM) were identified by applying clinical criteria to administrative data. Nonparametric classification tree models were fit using TIBCO Spotfire S+ 8.1 (TIBCO Software), with model size based on 10-fold cross validation. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of T1DM were estimated.

Results:

The main predictors that distinguished T1DM from T2DM are age <40 years; International Classification of Disease, 9th revision, codes of T1DM or T2DM diagnosis; inpatient oral hypoglycemic agent use; inpatient insulin use; and episode(s) of diabetic ketoacidosis diagnosis. Compared with a complex clinical algorithm, the tree-structured model to predict T1DM had 92.8% sensitivity, 99.3% specificity, 89.5% PPV, and 99.5% NPV.

Conclusion:

The preliminary predictive rule appears to be promising. Being able to distinguish between DM subtypes in administrative databases will allow large-scale subtype-specific analyses of medical care costs, morbidity, and mortality.     

Screening for Diabetic Retinopathy Using Computer Vision and Physiological Markers

Background

Hyperglycemia and diabetes result in vascular complications, most notably diabetic retinopathy (DR). The prevalence of DR is growing and is a leading cause of blindness and/or visual impairment in developed countries. Current methods of detecting, screening, and monitoring DR are based on subjective human evaluation, which is also slow and time-consuming. As a result, initiation and progress monitoring of DR is clinically hard.

Methods

Computer vision methods are developed to isolate and detect two of the most common DR dysfunctions—dot hemorrhages (DH) and exudates. The algorithms use specific color channels and segmentation methods to separate these DR manifestations from physiological features in digital fundus images. The algorithms are tested on the first 100 images from a published database. The diagnostic outcome and the resulting positive and negative prediction values (PPV and NPV) are reported. The first 50 images are marked with specialist determined ground truth for each individual exudate and/or DH, which are also compared to algorithm identification.

Results

Exudate identification had 96.7% sensitivity and 94.9% specificity for diagnosis (PPV = 97%, NPV = 95%). Dot hemorrhage identification had 98.7% sensitivity and 100% specificity (PPV = 100%, NPV = 96%). Greater than 95% of ground truth identified exudates, and DHs were found by the algorithm in the marked first 50 images, with less than 0.5% false positives.

Conclusions

A direct computer vision approach enabled high-quality identification of exudates and DHs in an independent data set of fundus images. The methods are readily generalizable to other clinical manifestations of DR. The results justify a blinded clinical trial of the system to prove its capability to detect, diagnose, and, over the long term, monitor the state of DR in individuals with diabetes.