Clinical Briefs
March 15, 2017 3 minutes read
Is the Intestinal Microbiome the Culprit in Obesity?
SOURCE: Komaroff AL. The microbiome and risk for obesity and diabetes. JAMA 2017;317:355-356.
Apparently, the gut bacteria — currently called the microbiome — are much more than simple innocent bystanders. There are two primary families of intestinal microbiota: Bacteroidetes and Firmicutes, which comprise approximately 90% of all gut bacteria. Recently, it has been appreciated that the microbiome actually generates proteins, hormones, neurotransmitters, and inflammatory molecules. These products of the microbiome may enter the circulation and produce far-reaching effects.
For instance, obese persons are populated with greater numbers of Firmicutes, which are more efficient in providing energy sources than Bacteroidetes. Confirming the causal role of this relationship, transplantation of gut microbiota from obese mice promptly converts lean mice into obese ones. Equally remarkable, and much more hopeful, is the observation that transplantation of microbiota from lean mice into obese ones produces a favorable effect on weight.
The story is complicated even further by the observation that the microbiome is capable of remodeling: When obese persons consume weight-reducing diets, the disproportion of Firmicutes declines, and it resumes when excess calories are again introduced. We are only beginning to understand the magnitude of the role the microbiome plays in health and disease.
The Dubious Benefits of Urinalysis in Asymptomatic Patients
SOURCE: Bush LM, Vazquez-Pertejo MT. The unintended deleterious consequences of the ‘routine’ urinalysis. Am J Med 2017;130:3-4.
The only population in which treatment of asymptomatic bacteriuria might be beneficial appears to be pregnant women, and even that widely held belief has been challenged recently. Part of the problem of addressing asymptomatic bacteriuria is that often we are dealing with results of a test we may not have thought was really pertinent to the patients well-being (or lack thereof) in the first place. That is, so-called “routine” urinalysis — usually by urine dipstick — may be part of standard protocol for patients presenting with no symptoms even remotely referable to the genitourinary tract.
Were asymptomatic bacteriuria rare, perhaps the problem would not be so vexing. On the contrary, the prevalence in long-term care facility residents may be as high as 25-50% in women and 15-40% in men. When presented with such abnormal results, clinicians often are tempted to treat, hoping to avoid more serious consequences. However, clinical trial data do not demonstrate achieved benefit.
Both the Infectious Diseases Society of America and the American Board of Internal Medicine advise against treatment of asymptomatic bacteriuria in non-pregnant adults. Clinicians would be wise to heed such advice, and perhaps even better, be more selective about seeking urine testing only when clinically pertinent.
Comparing Treatments for Peripheral Artery Disease Patients
SOURCE: Hiatt WR, Fowkes FG, Heizer G, et al. Ticagrelor versus clopidogrel in symptomatic peripheral artery disease. N Engl J Med 2017;376:32-40.
Clopidogrel has demonstrated superiority to aspirin for reducing cardiovascular events in patients with stable vascular disease (i.e., post-myocardial infarction, post-stroke, prevalent peripheral arterial disease). In the CAPRIE trial, patients on clopidogrel experienced an almost 9% lower relative risk of cardiovascular events than patients on aspirin, although the absolute risk reduction was very small (0.5%). At the time of publication of the CAPRIE trial, this presented a dilemma for clinicians, primarily because of cost issues.
Ticagrelor is in the same class of agents as clopidogrel: Both are P2Y12 inhibitors, which lead to reduced platelet aggregation. The success that ticagrelor has achieved in acute coronary syndromes prompted the question of whether ticagrelor might provide greater reduction in cardiovascular events than clopidogrel, since the presence of peripheral arterial disease (whether symptomatic or not) is indicative of coexisting coronary artery disease.
Hiatt et al conducted a randomized, double-blind, placebo-controlled trial of ticagrelor vs. clopidogrel in patients with peripheral arterial disease (n = 13,885). The primary outcome was incident cardiovascular events over 2.5 years.
There was no statistically significant difference in cardiovascular outcomes between the two agents. The additional expense of ticagrelor, plus the fact that it is administered b.i.d in contrast to the q.d. dosing of clopidogrel, suggest that clopidogrel should remain the preferred agent.
In this section: targeting the culprit of obesity; a skeptical look at urinalysis; and comparing treatments for peripheral artery disease.
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