They are not, however, without their problems, including the fact that the questionnaire measurements are highly subjective and can have a placebo effect. “If a patient undergoes surgery and wants to feel better, they sometimes will,” said Dr. Kezirian. “A better assessment would include a combination of metrics. An otolaryngologist could look at the sleep study result, but also at how that patient is doing overall.”
Explore this issue:December 2014
“The goals of surgical OSA treatment are the reduction of cardiovascular risk, increased survival, reduced sleepiness, improved quality of life, and, of course, reduced snoring,” said Dr. Jacobowitz. “These can only be captured by using the AHI in conjunction with other quality of life, physiological, and clinical measurements.
So why haven’t alternate metrics been used more often in the clinical assessment of OSA treatment? Dr. Jacobowitz believes it’s a matter of familiarity and ease with using a single quantifiable parameter—the AHI. “The traditional gold-standard treatment of OSA is CPAP [continuous positive airway pressure], and CPAP was designed to improve AHI,” he added.
There is some evidence validating the use of a variety of metrics in outcome measurements. In the 2012 Laryngoscope study, outcomes not only showed a reduction in AHI (in all indices) but also a reduction in patient-reported symptoms. “OSA is not defined solely by a metric; the diagnosis and management of this condition takes into account patient symptomatology as well as disease severity…. Polysomnographic parameters as outcome measures are important surrogates of some clinical outcomes, such as cardiovascular risk, but they should not be mistaken for clinical outcomes themselves,” said the authors. “Similarly, the definition of surgical success should be by more than just the AHI reduction alone, and other outcomes should be included in assessment of postoperative consideration.”
“For CPAP, although you can normalize the AHI in the sleep lab, often there is residual elevated AHI at home and many patients do not use CPAP for the entire night at home,” added Dr. Jacobowitz. “When you look at this AHI variable with regard to sleep surgery outcome, typically the AHI is reduced significantly but doesn’t normalize completely. At the same time, with respect to meaningful primary clinical outcomes, CPAP and surgery can reduce cardiovascular morbidity and decrease the rate of car accidents despite that imperfect AHI reduction.”
For the future, Dr. Kezirian sees more otolaryngologists adopting broader assessments of patients. “These questionnaires have been around for a while, but they are now being used more often in routine clinical practice. They go beyond just asking, ‘How are you doing?’” he said. “Using the questionnaires helps us determine the benefits of treatment if outcomes are not perfect, so we can tell if someone is making progress. The AHI alone is too simplistic. Patients may have no or little change in their AHI but still feel better, but they can also show major improvement in the AHI but still feel awful, which isn’t good enough either.”