Is the average duration of apneas, hypopneas and desaturations useful in the diagnosis of SAHS?

Sleep Apnea-Hypopnea Syndrome (SAHS) is usually diagnosed by polysomnography, a test that consists of the registration of a wide range of physiological parameters while the patient is asleep. The commercial monitoring devices used in the polysomnography generate a report summarizing the test. Some of the information presented to the clinicians in these reports, such as the Apnea-Hypopnea Index, has been the target of comprehensive clinical studies, and there are detailed clinical guidelines to interpret it. However, these reports also contain other data such as mean and maximum values of the descriptors of various pathological events recorded in the polysomnogram; e.g., the mean and maximum duration of the apneas, hypopneas and desaturations that the patient has experienced. These features have not been studied in the literature. Therefore, guidelines for their interpretation do not exist. This paper attempts to evaluate the usefulness of this information in the diagnosis of SAHS. It also tries to provide guidelines for clinicians on how to interpret it. To this end, we have calculated these features for 210 patients who underwent polysomnographic testing, and we have analyzed their capability to discriminate between healthy and SAHS patients, as well as to stratify the patients according to their severity. Our results suggest that most of them have little or no utility for diagnosing SAHS patients. Therefore, they could be omitted from the reports without significant loss of information.