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15 March 2011 Annals of Internal Medicine Tip Sheet

Annals of Internal Medicine is published by the American College of Physicians on the first and third Tuesday of every month. These highlights are not intended to substitute for articles as sources of information. For a copy of an article, call 215-351-2653 or e-mail Angela Collom at acollom@acponline.org

1. Hospitals with Low AMI Mortality Rates Share Specific Organizational Characteristics

Mortality rates for patients hospitalized with acute myocardial infarction (AMI) vary by as much as twofold between the highest- and lowest-performing hospitals. Researchers interviewed 158 staff members at 11 hospitals at either the top or bottom five percent of the spectrum to determine the factors associated with better performance in AMI care. While protocols and procedures did not differ among high-and low-performing hospitals, the researchers found distinct differences between organizational approaches. Hospitals with better mortality rates shared an overall vision of excellence that permeated the organization. High-performing hospitals also had more senior management involvement, broad staff presence and expertise in AMI care, better communication and coordination among different types of physicians, and more capacity for problem solving and learning across the organization.

2. New Low-radiation Alternative to CT Angiography Shows Promise in CAD

Approximately 2.3 million coronary computed tomography (CT) angiography examinations are performed each year to diagnose coronary artery disease (CAD) in symptomatic patients. While less invasive than catheter angiography, the procedure still requires a relatively high dose of radiation. Recently, a technique called prospective ECG gating in which radiation is only applied at a predefined point in the cardiac cycle has gained traction, as it can reduce the radiation dose by up to 80 percent. However, whether this test performs as well as angiography in diagnosing disease is uncertain. Researchers analyzed 16 published studies that compared results of prospective ECG-gated CT angiography with those of catheter angiography in a total of 960 patients with suspected coronary artery disease. The research shows that low-dose CT angiography with prospective ECG gating has good specificity and excellent sensitivity for diagnosing symptomatic CAD. The procedure’s excellent negative predictive value, suggests that it could be useful in ruling out CAD in low risk patients. The researchers caution that more studies are needed before widespread use of the technology can be recommended.

3. No Proof that Lower Blood Pressure Targets Improve Outcomes in Chronic Kidney Disease

Currently, experts recommend lower blood pressure targets for chronic kidney disease patients. However, there is question as to whether lower blood pressure targets provide optimal benefits to the patient. Researchers reviewed three trials with a total of 2,272 patients to compare a low (130/80mmHg or less) versus a higher (140/90mmHg or less) target. Overall, the lower target did not prove to be more beneficial than the higher target. However, the lower blood pressure target could provide benefit for patients with protenuria (high concentration of protein in the urine) of more than 300-1000mg/day. Yet, achieving a lower blood pressure target required more anti-hypertension medication and may result in a slightly higher rate of adverse events. The researchers recommend that physicians choose a blood pressure target based on an individualized risk/benefit assessment and patient tolerance and preference.

4. Comparative Effectiveness Study Identifies Meformin as First-line Treatment for Type 2 Diabetes

No Two-drug Combinations Stood Out Above Others

There are eleven unique classes of medications approved to treat hyperglycemia in type 2 diabetes, and patients may require more than one class of medication to achieve blood sugar control. Researchers reviewed 140 randomized controlled trials and 26 observational studies in 166 articles to compare the benefits and harms of several drugs and drug combinations for type 2 diabetes. The drugs and drug classes examined included metformin, second-generation sulfonylureas, thiazolidinediones, meglitinides, dipeptidyl peptidase-4 inhibitors, and glucagon-like peptide-1 receptor agonists alone or in two-drug combinations. According to the published evidence, the researchers concluded that metformin, both on its own and in combination with other medications, had the highest benefit to risk profile. Comparisons of two-drug combinations showed little to no difference in blood sugar reduction, but some combinations increased risk for hypoglycemia and other adverse events.