Simplified Diagnostic and Management Strategies for the Diagnosis and Delivery of Health Care to those with Obstructive Sleep Apnea

Author: Nicholas Antic

Antic, Nicholas, 2008 Simplified Diagnostic and Management Strategies for the Diagnosis and Delivery of Health Care to those with Obstructive Sleep Apnea, Flinders University, School of Medicine

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Obstructive sleep apnea (OSA) is a prevalent disease. Often resources to provide care for OSA are inadequate, leading to long patient waiting times. Simpler validated methods of care are needed. In the first study in Chapter 2, the utility of a new high-sampling rate oximeter to diagnose OSA was explored. The home oximetry data collection was robust, with few failures and the data allowed the “rule in” or “rule out” of moderate-severe OSA with high degree of certainty. It is concluded that home oximetry could replace polysomnography (PSG) as a diagnostic test in a significant proportion of patients, thus allowing limited resources available for the care of those with OSA to be re-directed e.g. towards providing therapy. In Chapter 3, the diagnostic information from the oximeter was used to underpin a study designed to demonstrate that a nurse-led model of care could produce health outcomes in moderate-severe OSA not inferior to physician-led care. A randomised controlled multi-centre non-inferiority clinical trial was performed. 1,427 patients referred to 3 sleep medical centres with possible OSA were assessed. 195 patients were randomised to 2 models of care. Model A, a simplified model, involved home oximetry to diagnose moderate-severe OSA, auto-titrating constant positive airway pressure (APAP) to set a therapeutic constant positive airway pressure (CPAP), with all care supervised by an experienced nurse. Model B involved 2 laboratory PSG’s, to diagnose OSA then titrate CPAP, supervised by a sleep physician. The primary endpoint was change in Epworth Sleepiness Score (ESS) measured before and after 3 months of CPAP. A range of other outcome measures were collected. The change in ESS for nurse-led management (Model A) was not inferior to the physician-led service (Model B) since the lower limit of the two-sided 95% CI did not include -2, the margin of equivalence (difference 0.13, 95% CI -1.52 to -1.25). 11 patients in Model A and 10 in Model B were lost to follow up during the trial. There were no significant differences between Model A and Model B after 3 months of CPAP in any of the other outcome measures, including CPAP adherence at 3 months. It is concluded that a simplified nurse-led model of care can produce non-inferior results to physician-directed care in the management of moderate-severe OSA. In Chapter 4 the efficacy of CPAP in normalising or improving subjective and objective sleepiness, quality of life and selected neurocognitive measures was explored. It was shown that only a proportion of patients (60% on ESS, 35% on FOSQ) normalised their scores after 3 months of CPAP therapy. This is important information. As new health care delivery strategies evolve as a result of the data presented in Chapter 3 and elsewhere, it will be crucially important to train new health care professionals in the complexities of OSA management, such that they are aware that the symptoms of patients presenting for OSA investigations can have multiple aetiologies, and may not always resolve by simply applying CPAP. The data presented in this thesis add to the evidence base in treatment of moderate-severe OSA and will help further evolve health care delivery for this important disease.

Keywords: OSA,diagnosis,simplified management
Subject: Medicine thesis

Thesis type: Doctor of Philosophy
Completed: 2008
School: School of Medicine
Supervisor: R. D McEvoy