Clinical Briefs By Louis Kuritzky, MD
Clinical Briefs
By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville. Dr. Kuritzky is a consultant for Sucampo Pharmaceuticals, Takeda, Boehringer Ingelheim; and is a consultant and on the speaker's bureau for Novo Nordisk, Lilly, Daiichi Sankyo, Forest Pharmaceuticals, Cephalon, Novartis, and Sanofi Aventis.
OSA in patients with acute MI
Source: Lee CH, et al. Obstructive sleep apnea in patients admitted for acute myocardial infarction. Prevalence, predictors, and effect of microvascular perfusion. Chest 2009; 135:1488-1495.
Obstructive sleep apnea (OSA) is inextricably linked with adverse cardiovascular events including stroke, MI, hypertension (HTN), and arrhythmia. A putative mechanism links OSA with CVD: The persistent sympathetic overdrive necessary to stimulate engagement of ventilation in persons with frequent apnea/hypopnea while effective in sustaining respiratory activity is toxic to the cardiovascular system. The OSA-CVD relationship may not be uni-directional. For instance, although atrial fibrillation is a much more potent risk factor for stroke than HTN, many more patients have HTN than have atrial fibrillation; therefore, the number of patients who present with stroke on the basis of HTN greatly surpasses those induced by atrial fibrillation. Lee et al studied subjects presenting with acute MI (AMI) to determine the prevalence of OSA.
The study group comprised 105 adult men with uncomplicated AMI, all of whom underwent overnight polysomnography. Essentially two-thirds (65.7%) of all subjects had OSA-positive sleep studies, with the presence of diabetes being a significant risk factor.
Successful treatment of OSA with CPAP has been shown to reduce CV morbidity. Whether treatment of OSA in a population that has recently sustained an MI will reduce events is unknown. On the other hand, since OSA is a well-established risk factor for future CV events, its early identification should be a priority. These prevalence data should encourage more energetic OSA case ascertainment in persons who have sustained coronary events.
High-risk colon cancer subjects and CT colonography
Source: Regge D, et al. Diagnostic accuracy of computed tomographic colonography for the detection of advanced neoplasia in individuals at increased risk of colorectal cancer. JAMA 2009;301:2453-2461.
The most recently released colon cancer screening guidelines from the American Cancer Society (2008) support an increased diversity of appropriate screening tools, including, for the first time since ACS guideline inception, CT colonoscopy (CTC). The largest (n ≥ 6000) head-to-head comparison of CTC with "traditional" (optical) colonoscopy (OTC) found similar colon lesion detection rates with both methods. While such data are reassuring for general screening, no prior trial has compared CTC to OTC in higher-risk populations.
Regge et al studied 973 subjects deemed to be high-risk for colon cancer on the basis of either a positive family history, prior colonic adenoma, or positive FOBT. Each subject underwent CTC and colonoscopy on the same day.
Using OTC as the gold standard, the sensitivity of CTC for advanced neoplasia (defined as adenoma > 6 mm) was 85%, and specificity was 88%; sensitivity of CTC was better for the most concerning lesions (> 10 mm): 91%.
Because some patients prefer the option of CTC to OTC, and because evaluation of populations with CTC is associated with less risk of adverse events (e.g., perforation and bleeding) than OTC, these results support a role for CTC.
Predicting the development of type 2 diabetes
Source: Tabak AG, et al. Trajectories of glycaemia, insulin sensitivity, and insulin secretion before diagnosis of type 2 diabetes. Lancet 2009;373: 2215-2221.
In typical prediabetic populations studied to date, approximately 5%-10% progress to diabetes each year. Because diabetes is preventable in the prediabetic state through diet, exercise, pharmacotherapy, or their combination, it would be useful to identify at-risk individuals even before they manifest impaired fasting glucose (IFG) or impaired glucose tolerance (IGT).
The Whitehall II study is a prospective occupational cohort study of British civil servants. Study subjects without diabetes at baseline (n = 6538) had periodic measurement of fasting glucose, oral glucose tolerance tests, insulin resistance, and b-cell function for as long as 13 years. At a median of 9.7 years of follow-up, 505 had developed diabetes.
There was a distinct curvilinear increase seen in fasting glucose, 2-hour post-load glucose, insulin resistance, and b-cell functional loss noted 3-5 years before the onset of frank diabetes; subjects who did not develop diabetes showed no such steep curvilinear changes.
The presence of IFG and/or IGT heralds the onset of diabetes. These observations suggest that by monitoring trends in markers of glucose dysregulation, clinicians might be able to identify persons at risk of developing diabetes even earlier than the currently accepted metrics for prediabetes afford.
Obstructive sleep apnea (OSA) is inextricably linked with adverse cardiovascular events including stroke, MI, hypertension (HTN), and arrhythmia.Subscribe Now for Access
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