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Biomedical subjects

John A Colwell

Publications and source records attributed to John A Colwell.

10 recordsLinked to original sources
PubMed2006

Aspirin for the primary prevention of cardiovascular events.

There is significant evidence that low-dose aspirin is effective in preventing the first myocardial infarction in men and ischemic stroke in women. There is also an increased risk for major gastrointestinal tract hemorrhage and a suggestive, but nonsignificant, increase in the risk for hemorrhagic stroke. If there is a history of ulcer disease or upper-gastrointestinal tract bleeding, Helicobacter pylori should be eradicated (if present) and a proton pump inhibitor used with aspirin therapy. In conclusion, the benefits of low-dose aspirin (75-162 mg/day) in the prevention of myocardial infarction in men and thrombotic stroke in women generally outweigh the risks of serious bleeding in adults with a coronary heart disease risk >1% per year or >1% in 10 years.

Journal Article↗
PubMed2006

Aspirin for the primary prevention of cardiovascular events.

There is significant evidence that low-dose aspirin is effective in preventing the first myocardial infarction in men and ischemic stroke in women. There is also an increased risk for major gastrointestinal tract hemorrhage and a suggestive, but nonsignificant, increase in the risk for hemorrhagic stroke. If there is a history of ulcer disease or upper-gastrointestinal tract bleeding, Helicobacter pylori should be eradicated (if present) and a proton pump inhibitor used with aspirin therapy. In conclusion, the benefits of low-dose aspirin (75-162 mg/day) in the prevention of myocardial infarction in men and thrombotic stroke in women generally outweigh the risks of serious bleeding in adults with a coronary heart disease risk >1% per year or >1% in 10 years.

Aspirin↗
PubMed2004

Antiplatelet agents for the prevention of cardiovascular disease in diabetes mellitus.

Patients with diabetes mellitus (DM) have accelerated atherothrombotic disease of coronary, cerebral, leg, and other vessels. The major cause of death is cardiovascular, and the risk for a myocardial infarction (MI) in a patient with DM who has never had a MI is the same as a nondiabetic individual who has already had one. In this paper, we review the major reasons for a prothrombotic state in patients with DM: alterations in the intrinsic coagulation and fibrinolytic systems and many abnormalities of platelet function. Increased platelet thromboxane production as well as activation of platelet receptors for fibrinogen and or adenosine diphosphate (ADP) are often present, and can be treated with aspirin (acetylsalicylic acid) and/or receptor blockers. Review of the major primary prevention trials in DM indicates that a significantly reduced risk for MI or major cardiovascular events may be obtained by enteric-coated aspirin, 81-325 mg/day. There is emerging consensus that this is recommended strategy in adult (aged >30 years) patients with DM who are at high vascular risk. Surveys suggest that this includes virtually every patient with type 2 DM in the US, as well as many patients with complicated type 1 DM. These recommendations are also appropriate for secondary prevention. Data supporting the use of clopidogrel as an alternative drug in the case of aspirin allergy or other contraindications are reviewed. Evidence is presented in support of using aspirin plus clopidogrel in acute coronary syndromes (ACS), and a meta-analysis of six trials of platelet glycoprotein (GP) IIb/IIIa inhibitors and aspirin in diabetic patients with ACS establishes this regimen as an effective choice. Although bleeding episodes are more common with combined antiplatelet therapy for ACS than for aspirin alone, the benefit of a significant reduction in 30-day mortality appears to outweigh the risk of major bleeding. It is concluded that major advances in our understanding of the prothrombotic state in DM have been made. Evidence from controlled clinical trials supports the use of enteric-coated aspirin, 81-325 mg/day, as a primary and a secondary prevention strategy in adults with DM with high vascular risk. In ACS, combination therapy with aspirin plus clopidogrel or alternatively, aspirin plus a platelet GP IIb/IIIa inhibitor is supported by prospective trial data. These approaches should be added to the other multifactorial preventive strategies directed at lowering the risk for major vascular events in patients with DM.

Cardiovascular Diseases↗
PubMed2003

The platelet in diabetes: focus on prevention of ischemic events.

Accelerated atherosclerosis and the increased risk of thrombotic vascular events in diabetes may result from dyslipidemia, endothelial dysfunction, platelet hyperreactivity, an impaired fibrinolytic balance, and abnormal blood flow. There is also a correlation between hyperglycemia and cardiovascular (CV) events. The importance of platelets in the atherothrombotic process has led to investigation of using antiplatelet agents to reduce CV risk. A meta-analysis conducted by the Antiplatelet Trialists' Collaboration demonstrated that aspirin reduced the risk of ischemic vascular events as a secondary prevention strategy in numerous high-risk groups, including patients with diabetes. Based on results from placebo-controlled randomized trials, the American Diabetes Association recommends low-dose enteric-coated aspirin as a primary prevention strategy for people with diabetes at high risk for CV events. Clopidogrel is recommended if aspirin allergy is present. There is occasionally a need for an alternative to aspirin or for additive antiplatelet therapy. Aspirin in low doses inhibits thromboxane production by platelets but has little to no effect on other sites of platelet reactivity. Agents such as ticlopidine and clopidogrel inhibit ADP-induced platelet activation, whereas the platelet glycoprotein (Gp) IIb/IIIa complex receptor antagonists block activity at the fibrinogen binding site on the platelet. These agents appear to be useful in acute coronary syndromes (ACSs) in diabetic and nondiabetic patients. A combination of clopidogrel plus aspirin was more effective than placebo plus standard therapy (including aspirin) in reducing a composite CV outcome in patients with unstable angina and non-ST segment elevation myocardial infarction. In a meta-analysis of six trials in diabetic patients with ACSs, intravenous GpIIb-IIIa inhibitors reduced 30-day mortality when compared with control subjects. Results from controlled prospective clinical trials justify the use of enteric-coated low-dose aspirin (81-325 mg) as a primary or secondary prevention strategy in adult diabetic individuals (aged >30 years) at high risk for CV events. Recent studies support the use of clopidogrel in addition to standard therapy, as well as the use of GpIIb-IIIa inhibitors in ACS patients.

Aspirin↗
PubMedDate not supplied

Evidence of nephropathy and peripheral neuropathy in US adults with undiagnosed diabetes.

PURPOSE: Nearly one third of diabetes cases in the United States is undiagnosed, with mounting evidence that complications accrue even before clinical diagnosis. We wanted to determine whether persons with undiagnosed diabetes have signs of nephropathy and peripheral neuropathy. METHODS: We examined the prevalence of positive screening tests for nephropathy and peripheral neuropathy in adults aged > or = 40 years with undiagnosed diabetes using secondary analysis of survey and examination data from the population-based United States National Health and Nutrition Examination Survey 1999-2002. We defined a positive screening test for nephropathy as a spot urine albumin-creatinine ratio > 30.0 mg/g, representing at least microalbuminuria. We defined > or = 1 insensate area on Semmes-Weinstein monofilament testing as a positive finding for neuropathy. Undiagnosed diabetes was defined as a combination of no history of diagnosed diabetes and a measured fasting glucose > or = 126 mg/dL. We used SUDAAN for chi2 and regression analyses. RESULTS: The prevalence of a positive test when screening for nephropathy among those with undiagnosed diabetes was 26.5% compared with 7.1% in those with no diabetes (chi2, P <.01). After adjusting for age and diagnosed or undiagnosed hypertension, the association of undiagnosed diabetes with nephropathy persisted (odds ratio = 2.35; 95% confidence interval, 1.38-4.01). For peripheral neuropathy, 21.5% with undiagnosed diabetes had positive screening tests compared with 10.1% with no diabetes (chi2, P <.01); however, this effect was not significant after adjustment for age. There was no significant difference in positive screening tests for nephropathy or neuropathy when comparing those with undiagnosed and diagnosed diabetes. CONCLUSIONS: A significant proportion of adults with undiagnosed diabetes have signs of nephropathy and peripheral neuropathy. These findings may influence policies about early screening for diabetes.

Adult↗