When Predicting Oral Appliance Treatment Response Based on CPAP Pressure, Ethnicity May Be a Factor

By Peter Blais, RPSGT

A study in the Journal of Clinical Sleep Medicine suggests there may be differences among ethnicities that should be considered when using the predictive values of CPAP pressure to determine whether individuals will benefit from oral appliances.

The study, titled “CPAP Pressure for Prediction of Oral Appliance Treatment Response in Obstructive Sleep Apnea,” found that in Australian patients, the majority of whom are Caucasian, a higher therapeutic CPAP pressure requirement in conjunction with age and obstructive sleep apnea (OSA) severity characteristics may be useful to indicate likelihood of success with oral appliances as an alternative therapy.

In an earlier Japanese study, a CPAP pressure cutoff value of 10.5 cm H₂O most reliably classified patients in terms of oral appliance response, with pressures higher than this generally indicating a negative response to oral appliances.

The Australian study results indicate that application of this method of prediction to an Australian population requires a higher cutoff value of 13 cm H₂O for best discrimination, with 100% of patients above this level correctly classified as non-responders and 75% of the patients below this level as responders.

Sutherland

The study states, “This substantial difference in CPAP cutoff values to best classify MAS [mandibular advancement splints] responders and nonresponders between these two populations suggests that there may be an influence of ethnicity factors on the relationship between CPAP pressure and MAS treatment response.”

Asked if the difference in the predictability of CPAP pressures and MAS response between Japanese and Caucasian populations likely mean there are also differences between other ethnicities, researcher Kate Sutherland, PhD, tells Dental Sleep Corner: “One of the reasons for the difference in CPAP level that indicates poor response to MASs between Japanese and Caucasian studies could be differences in risk factors for sleep apnea between these populations.

“There is evidence that obesity is a stronger contributor to OSA in Caucasians compared to Asian populations, which conversely show more restriction of the facial skeleton related to OSA. Such differences in skeletal versus soft tissue proportions may help explain differences in the relationship between CPAP and MAS response.

“Understanding of racial differences in OSA risk factors is still limited but there is some evidence that there are differences in OSA risk factors between other races, for example cranial and facial skeletal structure has been shown to relate to OSA in Caucasians but not African-Americans. Therefore it could be that there are differences between other populations which translate to differences in the CPAP and MAS response association and this would have to be assessed in future studies.”

Simple patient indicators, such as high BMI or severe OSA, which are traditionally thought to indicate poor oral appliance response are often not robust enough to reliably select patients for oral appliance therapy, Sutherland says, adding that there is a need for reliable methods for clinical prediction of oral appliance response. However clinical applicability prediction methods should be simple and cost-effective. Two studies to date have indicated that higher CPAP pressures may be a predictor of poor oral appliance response and this measure may be a cost-effective objective measure in some clinical situations.

However as with any new method, validation of predictive utility is needed before supporting widespread use. “We are not advocating undertaking CPAP pressure determination studies to predict MAS treatment response, but if patients happen to have had such a study it should be factored into decision making about MAS treatment,” Sutherland says.

As for the significance of the Australian study for dentists who treat sleep apnea patients, Sutherland says, “If patients have a known lower CPAP level this could suggest that a patient is a suitable candidate for MAS therapy and provide an indication of likely success with this form of treatment.

“CPAP pressure may be a simple indicator to exclude patients from undertaking MAD therapy who are unlikely to achieve a therapeutic response. However it appears that there may be differences in the actual threshold in different populations, which is interesting.”

Sutherland was part of the research team that included Craig L. Phillips, PhD, Amanda Davies, BSc(Hons), Vasanth K. Srinivasan, MDSc, Oyku Dalci, PhD, Brendon J. Yee, MD, PhD, M. Ali Darendeliler, PhD, Ronald R. Grunstein, MD, PhD, and Peter A. Cistulli, MD, PhD.