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Positive airway pressure (PAP) treatment for obstructive sleep apnea (OSA) was linked to reduced respiratory symptoms and nocturnal gastroesophageal reflux (nGER), an Icelandic study found.

After 2 years, full PAP users reported a decrease in both nGER (adjusted odds ratio [aOR] 0.58, 95% CI 0.40-0.86) and wheezing (aOR 0.56, 95% CI 0.35-0.88) compared with non-users, reported researchers led by Thorarinn Gislason, MD, PhD, of the National University Hospital of Iceland in Reykjavik.

And cutting nighttime reflux, regardless of PAP use, was linked to higher odds of a reduction in productive morning cough (aOR 4.70, 95% CI 2.22-9.99) and in chronic bronchitis (aOR 3.86, 95% CI 1.74-8.58), according to the cohort study published in .

Both respiratory and nGER symptoms are more frequent for those experiencing OSA, with researchers citing as a potential cause the greater respiratory exertion required of OSA patients, leading to strain on the gastroesophageal junction.

"Given the high prevalence of OSA, nGER, and respiratory symptoms, more knowledge on their possible causative associations and response to treatment is of significant clinical and public health importance," the group wrote. "This knowledge could ultimately [lead] to more efficient and personalized treatment, possibly changing treatment decisions for a considerable number of OSA patients who often are not offered PAP treatment today, particularly those with a low AHI [apnea-hypopnea index] but respiratory symptoms and nGER."

A mediation analysis suggested that PAP treatment decreased wheezing directly, not by reducing nGER. Those whose nGER didn't go away after 2 years didn't have a reduction in wheeze regardless of level of PAP usage. "Conversely, PAP treatment decreased productive cough mediated through a decrease in nGER," the researchers wrote.

Decreases in nGER (P<0.01) and wheezing (P=0.02) symptoms were greater among full PAP users than those using it only partially or not at all. A similar but statistically nonsignificant trend between the two groups was seen in regards to productive cough.

The Icelandic Sleep Apnea Cohort Study encompassed all 732 patients prescribed PAP at a single academic medical center's respiratory medicine and sleep service from September 2005 through December 2009.

Prior to starting PAP treatment, patients had a type 3 home sleep apnea testing and completed detailed questionnaires. Follow-ups were conducted 2 years after beginning treatment, which included assessments of PAP adherence and a repeat of the baseline measurements. Those with newer PAP machines provided the devices' memory cards for objective usage data, while those with older machines without that feature filled out questionnaires on usage.

Full PAP usage, seen for 366 patients, was defined as objective evidence of device use for at least 4 hours a day on 20 or more days out of the previous 4 weeks or self-reported use for at least 60% of the night on 5 or more nights per week. Those who returned their PAP device within a year after starting use were considered non-users.

The average patient age was 54, and the population was 78.4% male. Researchers reported that full PAP users were slightly older, had a higher BMI, and were less likely to be currently smoking in comparison to partial or non-users.

Researchers noted that the study design did not include an objective measurement for nGER, utilizing questionnaire responses for both nGER and PAP adherence for some patients. This, and a lack of subgroup analysis, potentially limited the findings of the study.

Andrew Varga, MD, of the the Icahn School of Medicine at Mount Sinai in New York City, expressed concern regarding the more subjective measurement methods despite corrective measures like propensity matching analysis, noting that "subjects who went on to become adherent to PAP had a somewhat higher level of baseline apnea severity -- which might suggest they have more to gain symptomatically from treatment of their apnea."

He encouraged further research, telling 乌鸦传媒 in an email that "it may be useful to prescreen and only include subjects who have both OSA and symptoms of [gastroesophageal reflux disease] at baseline. Because there will always be an adherence issue when newly diagnosed individuals are started on PAP, an alternative approach would include selecting individuals already known to be adherent to PAP and withdrawing therapy to determine whether -- and how rapidly -- any of these subjective symptoms return."

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