By: Atul Malhotra, MD Associate Professor of Medicine, Harvard Medical School
Obstructive sleep apnea has major neurocognitive and cardiovascular sequelae1-4. However, therapy for OSA remains inadequate due to variable efficacy of and variable adherence to the existing therapies5, 6. Thus, efforts are ongoing to identify new therapeutic targets for disease7, 8. For the diagnosis of OSA, in-laboratory polysomnography remains the gold standard. Thus, we are currently using considerable health care expense to determine the apnea hypopnea index, which is an imperfect metric of disease severity9, 10. On the other hand, OSA treatment is typically done with standard nasal CPAP therapy since more expensive forms of positive pressure therapy have no proven benefit over standard CPAP11. Thus, the expense of treating OSA is generally minimized. As a result, for patients who undergo standard in-laboratory diagnosis following by nasal CPAP therapy, we are currently using more health care resources to establish a diagnosis (which is sometimes obvious clinically) than to provide a life-long therapy. Several thoughts are provided here for consideration:
Diagnosis
1. On the diagnostic side, ambulatory monitoring can provide a satisfactory result for the majority of uncomplicated patients12. Thus, in the future, in-laboratory polysomnography may be reserved for more complicated or special cases.
2. In order for in-laboratory polysomnography to remain viable, more information will be required than simply obtaining an apnea hypopnea index13. Although sleep studies currently assess a considerable number of channels and thus generate a lot of data, most of this information does not currently inform patient management or prognosis. Ideally, polysomnography will provide insights into underlying mechanism such as estimates of upper airway muscle responsiveness, arousal threshold, ventilatory control instability etc14. Thus, the treating clinician could be provided with useful information which may influence optimal patient management. In addition, thorough analyses of physiological signals (EKG, EEG, oximetry) may be useful to predict various important outcome measures15, 16. Expensive testing may well be justified if the acquired data were to provide insights into risk (and perhaps prevention) of diabetes complications, cardiac events, motor vehicle accidents etc17.
Treatment
1. The future of sleep apnea therapy likely involves treatment of underlying cause18, 19. That is, if the mechanism(s) underlying obstructive apnea could be defined, emerging data suggest that interventions could be individualized to improve apnea frequency.
2. Nasal CPAP therapy will remain the treatment of choice for OSA until another therapy is shown to be superior20. However, many patients avoid the OSA diagnosis due to their reluctance to be given
