Obstructive Sleep Apnea: Oral Appliances

SOURCE: Hamoda MM, et al. Chest 2018;153:544-553.

Continuous positive airway pressure (CPAP) has been the traditional recommended intervention for obstructive sleep apnea for more than three decades. Unfortunately, limitations on the ultimate application of CPAP to treat obstructive sleep apnea include expense and (for many) poor tolerability. Among the alternative interventions are oral appliances, typically divided into two categories: tools that stabilize the tongue in a forward position, and tools that stabilize the mandible in a forward position. The recently FDA-approved device that employs an electrical current to activate oropharyngeal musculature with improved tongue muscular tone is not included in this review.

Using technical metrics for success, such as degree of improvement of the apnea-hypopnea index, CPAP has been shown to outperform oral appliances. On the other hand, patient-centered outcomes (sleepiness, quality of life, and driving performance) have been found to be equally well-improved by oral appliances as CPAP. Perhaps the most important bottom line is that many patients find compliance with CPAP difficult, and the limited data on oral devices suggest significantly greater compliance with them than with CPAP.

Aside from efficacy and tolerability, cost may be the ultimate deal maker (or breaker). Mandibular advancement devices that may be created at home by the patient cost as little as $30. While dental experts may offer more complex, sophisticated oral appliances, success attained with simple do-it-yourself home kits is quite appealing for many. Fortunately, the diversity of treatment options currently available should stimulate optimism that the consequences of obstructive sleep apnea can be improved successfully in most patients.


Influenza Increases Rate of Myocardial Infarction

SOURCE: Kwong JC, et al. N Engl J Med 2018;378:345-353.

It is obvious that influenza is an important cause of morbidity and mortality. Exploration of the causes of death related to influenza is a bit more complicated. Reporting on influenza epidemics usually includes the single broad category “influenza and pneumonia,” since that category tracks directly with incident cases of influenza each year.

But even with that clarification, the proportion of patients who succumb to influenza pneumonia vs. those who incur bacterial pneumonia (typically Staph) subsequent to pneumonia vs. all other incident pneumonias that occur concomitantly with flu season is not readily discernible. The association between cardiovascular event rates and influenza has been recognized since the 1930s, but few direct studies of rates of myocardial infarction in patients with acute influenza have been performed.

To that end, Kwong et al reported that in a study of subjects with laboratory-confirmed influenza (n = 19,045), myocardial infarction rates were six-fold higher in the “risk interval” (i.e., seven days after influenza identification) than in the “control interval” (i.e., one year immediately before and after the risk interval). Although other viral infections, such as respiratory syncytial virus, also were associated with increased risk for myocardial infarction, of the viruses studied, influenza incurred the greatest relative risk increase.


Promising News About Zika Vaccine

SOURCE: Modjarrad K, et al. Lancet 2018;391:563-571.

Zika virus infection during pregnancy can cause microcephaly and other serious neurologic defects. Protection from infection with Zika virus has been demonstrated in animal studies using a formalin-inactivated Zika virus vaccine derived from a 2015 Puerto Rican virus strain, similar to the 2015 Brazilian Zika virus strain. In preclinical trials in mice and nonhuman primates, two doses of vaccine (day 1 and day 29) produced high antibody levels within two weeks after the second dose.

Modjarrad et al reported on the first study in humans, using an aluminum hydroxide adjuvant Zika virus vaccine. Zika seronegative adults (n = 67) were randomized to Zika vaccine or placebo. Intramuscular vaccine was administered on day 1 and day 29. Efficacy was determined by the percent seroconversion (i.e., attainment of a microneutralization titre of ≥ 1:10).

By day 57, seroconversion had occurred in 92% of vaccine recipients. Tolerability of the vaccine was good, with only mild-moderate adverse events reported. These results compare well with trials of Japanese encephalitis virus and yellow fever virus that have used the same seroconversion status as a surrogate for protection from infection. Clinicians look forward to confirmation of vaccine efficacy in a large population.