Obstructive sleep apnoea, positive airway pressure treatment and postoperative delirium: protocol for a retrospective observational study

Abstract

Introduction: Obstructive sleep apnoea (OSA) is common among older surgical patients, and delirium is a frequent and serious postoperative complication. Emerging evidence suggests that OSA increases the risk for postoperative delirium. We hypothesise that OSA is an independent risk factor for postoperative delirium, and that in patients with OSA, perioperative adherence to positive airway pressure (PAP) therapy decreases the incidence of postoperative delirium and its sequelae. The proposed retrospective cohort analysis study will use existing datasets to: (i) describe and compare the incidence of postoperative delirium in surgical patients based on OSA diagnosis and treatment with PAP; (ii) assess whether preoperatively untreated OSA is independently associated with postoperative delirium; and (iii) explore whether preoperatively untreated OSA is independently associated with worse postoperative quality of life (QoL). The findings of this study will inform on the potential utility and approach of an interventional trial aimed at preventing postoperative delirium in patients with diagnosed and undiagnosed OSA.

Methods and analysis: Observational data from existing electronic databases will be used, including over 100 000 surgical patients and ~10 000 intensive care unit (ICU) admissions. We will obtain the incidence of postoperative delirium in adults admitted postoperatively to the ICU who underwent structured preoperative assessment, including OSA diagnosis and screening. We will use doubly robust propensity score methods to assess whether untreated OSA independently predicts postoperative delirium. Using similar methodology, we will assess if untreated OSA independently predicts worse postoperative QoL.

Ethics and dissemination: This study has been approved by the Human Research Protection Office at Washington University School of Medicine. We will publish the results in a peer-reviewed venue. Because the data are secondary and high risk for reidentification, we will not publicly share the data. Data will be destroyed after 1 year of completion of active Institutional Review Board (IRB) approved projects.

Keywords: ehr data; obstructive sleep apnea; postoperative delirium.

Figure 1

This figure shows data from 14 962 patients at our preoperative assessment clinic who did not carry a prior obstructive sleep apnoea (OSA) diagnosis.

Figure 2

This figure shows a predicted breakdown of patients based on previous data from our preoperative assessment clinic. Approximately 1300 (13%) of the approximately 10 000 patients in the study cohort will carry a diagnosis of obstructive sleep apnoea (OSA), of whom about half (~650) will have reported non-adherence to home Pap therapy (group B). Of the remaining 8700 patients, based on the current Stop-Bang criteria, about 870 (≥5 out of 8 positive criteria) are very likely to have moderate or severe undiagnosed OSA (group C). Approximately 3480 patients (3 or 4 positive criteria) might have undiagnosed OSA (group D), and ~4350 patients (<3 positive criteria) are unlikely to have undiagnosed OSA (group E). OSA, obstructive sleep apnoea; STOP-BANG, Snoring, Tiredness, Observed Apnea, High Blood Pressure, Body Mass Index>35 kg/m2, Age>50, Neck Circumference>40 cm, Male Gender.