Clinical Briefs
March 30, 2016 4 minutes read
Ambulatory BP for All
SOURCE: Verdeechia P, et al. J Am Soc Hypertens 2015;9:911-915.
In 2011, the British were the first to include a recommendation that all patients identified with elevated blood pressure in the office undergo 24-hour ambulatory blood pressure monitoring (ABPM) before finalizing the diagnosis. They estimated that routinely employing ABPM would save tens of millions of dollars. In 2015, the United States Preventive Services Task Force evaluated the very same issue, and came to the same conclusion: ABPM should be routinely included as a diagnostic tool before confirming the diagnosis of hypertension. Why should we listen to this new advice?
It has been shown that a substantial minority of patients who demonstrate elevated office blood pressure (OBP), when monitored by ABPM, are determined not to have hypertension at all; rather, they have what is usually called white-coat hypertension, a transient phenomenon seen among patients whose anxiety during medical encounters raises their blood pressure into the hypertensive range. As many as one-third of patients originally diagnosed with hypertension through OBP are ultimately determined to have white-coat hypertension. Fortunately, the epidemiologic data looking at outcomes among patients with white-coat hypertension suggests that cardiovascular outcomes are essentially no different than normotensive patients.
Patients with white-coat hypertension, whether treated or not, typically show declines in blood pressure over time. When unnecessarily treated, they sustain the costs, adverse effects, and consequences of misdiagnosis (i.e., epidemiologic data have shown that simply being diagnosed as hypertensive is associated with lower quality-of-life scores).
ABPM is readily available, has little or no adverse effects, and is not costly (typically around $100-$150). Considering that it could save a patient years of unnecessary treatment, we should follow the advice the British adopted long ago: ABPM for all initially diagnosed hypertensives to confirm the diagnosis.
What’s the Deal with Grapefruit Juice?
SOURCE: Lee JW, et al. Am J Med 2016;129:26-29.
FDA labeling for simvastatin changed several years ago because of the recognition that high doses of simvastatin were associated with a meaningful increase in risk for rhabdomyolysis. Drugs known to interact with the CYP450 hepatic enzyme system — specifically, CYP3A4 — were singled out since CYP3A4 is the primary metabolic pathway for many of the statins. Many patients with dyslipidemia also suffer hypertension, and drugs like amlodipine, which can also influence CYP3A4 metabolism, were promptly added to the list of agents that could potentially interact with simvastatin.
About 3 years ago, new FDA labeling for simvastatin spoke to the issue of grapefruit juice, suggesting patients should avoid large quantities. Why grapefruit juice?
Grapefruit juice has been known for more than a decade to be a prompt, potent, and persistent inhibitor of the CYP3A4 enzyme, and it doesn’t take a lot: As little as 8 oz. of grapefruit juice (or one whole grapefruit) taken with simvastatin 40 mg elevates the simvastatin area under the curve by almost 400%.
In evaluating the effect of grapefruit juice on risk, Lee et al extrapolated from data that link changes in low-density lipoprotein to cardiovascular outcomes. They also suggested that the combination of grapefruit juice with simvastatin would indeed increase simvastatin blood levels, but at the same time would possibly reduce cardiovascular event levels to a degree that would far counterbalance any increased risk of rhabdomyolysis. While their notion is intriguing, in the absence of prospective data corroborating that the simvastatin + grapefruit juice combination is safe and actually reduces cardiovascular events, clinicians would be wise to continue observing labeling restrictions.
Smoking and Low Back Pain
SOURCE: Shiri R, Falah-Hassani K. Am J Med 2016;129:64-73.
Low back pain and its consequences are responsible for the largest single expenditure of disability dollars in the United States. Whereas both the clinician and lay population have a high level of awareness of the consequences of smoking, such as heart disease, lung disease, and various cancers, the relationship between smoking and sciatica is not widely recognized. Of course, when an individual patient encounters a potential or real consequence of smoking (e.g., abnormal chest CT, pneumonia, etc.), he or she sometimes becomes — at least transiently — more motivated to quit. There are even data showing that among otherwise healthy young men who fracture their tibia, healing occurs weeks earlier in non-smokers, providing clinicians a teachable moment when they encounter such a patient. Might we add low back pain to that list?
Shiri and Falah-Hassani reviewed data from 28 studies (n = 20,111) in which sciatica risk was compared between smokers and non-smokers. Overall, current smokers were more than 60% more likely to experience any radicular back pain, and 35% more likely to incur sciatica. Similarly, the odds ratio for back pain-related hospitalization or surgery was elevated to 1.45; encouragingly, former smokers demonstrated only slight risk elevation. This is the latest in a long list of reasons to encourage smoking cessation.
In this section: a better way to measure blood pressure; the magical powers of grapefruit juice; and yet another reason to stop smoking.
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