A Swedish study of sleep apnea sufferers using OAs shows the disorder can worsen even with therapy adherence and no complaints of sleepiness.

Sensing the need for more research on the long-term efficacy of oral appliances (OAs) designed to treat obstructive sleep apnea (OSA), Marie Marklund, DDS, PhD, decided to study a small group of early treated patients who had been using OAs for at least 15 years. The results, as published in the May 2016 edition of Sleep and Breathing, were alarming.

The study included nine patients (eight males and one female) with a median treatment time of 16.5 years. Each participant had been the subject of polysomnographic recordings before and shortly after initial treatment. The group registered a median apnea-hypopnea index (AHI) score of 17.3 before being fitted with an OA and 7.2 shortly thereafter.

But to the shock of Marklund and her co-authors, the 15-year test results yielded a median AHI score of 35.1 with each patient’s device in place and 32.4 without it.

“I was surprised about the large worsening in disease severity,” says Marklund, who serves as a senior lecturer in the department of orthodontics at Umeå University in Umeå, Sweden. “The patients had not complained about this worsening and were satisfied with the treatment effect from the oral appliances. They did not complain about sleepiness.”

Marklund points to recent studies led by Paul E. Peppard and Nathaniel A. Eiseman as further proof that the severity of OSA tends to increase over time and that sleepiness is likely an “uncertain predictor” when attempting to gauge the success of treatment.

To avoid suboptimal long-term efficacy, Marklund believes patients should be subjected to repeated polysomnographic recordings, be fitted with new devices whenever appropriate, and consider treatments other than OAs, including CPAP devices. Although the group did not demonstrate any change in the degree of mandibular advancement, she notes that bite changes also should be closely monitored.

In addition to continuous testing and the introduction of more devices designed to minimize bite changes, Marklund suggests that further research could include long-term monitoring of factors known or suspected to affect the long-term efficacy of OAs, including changes in the patient’s weight. Ideally, new treatment standards could be designed to address the findings.

“Although it differs between countries regarding organization and economics for sleep apnea treatment, many would benefit from more detailed guidelines for oral appliance therapy,” Marklund says. “These documents should coordinate the need for scheduled follow-ups that consider several aspects of the treatment.”